JP2011096551A - Positive electrode for nonaqueous electrolyte battery, nonaqueous electrolyte battery, and manufacturing method of nonaqueous electrolyte battery - Google Patents

Abstract

（式中、Ａ₁〜Ａ₃はＬｉ，Ｎａ，Ｋ，Ｍｇ，Ｃａ，Ｓｒ，Ｂａであり、Ａ₂およびＡ₃の少なくとも一つは水素原子であっても良い。ＢはＣＦ₃、ＣＨＦ₂、ＣＨ₂Ｆ、およびＣＨ₃で表される官能基）なお、Ｄ１およびＤ２は、式（３）、式（４）で示される構造とする。

（式中、０≦（ａ、ｃ、ｄ、ｆ）≦２、及び１≦ｂ≦１５、及び１≦ｅ≦１６とする。Ｘはフッ素原子であるが、その一部は水素原子や他のハロゲン原子等である）
【選択図】なしProvided is a battery manufacturing method that achieves both capacity retention and high-temperature storage characteristics.
A carboxylate having at least one of a fluorine atom and a chlorine atom exists on the surface of a positive electrode active material layer. The carboxylate is at least one of the structures represented by formula (1) and formula (2).

(In the formula, A _{1 to} A ₃ are Li, Na, K, Mg, Ca, Sr, Ba, and at least one of A ₂ and A ₃ may be a hydrogen atom. B is CF ₃ , CHF. ₂ , functional groups represented by CH ₂ F and CH ₃ ) D1 and D2 have structures represented by the formulas (3) and (4).

(Where 0 ≦ (a, c, d, f) ≦ 2, 1 ≦ b ≦ 15, and 1 ≦ e ≦ 16, X is a fluorine atom, part of which is a hydrogen atom or other Of halogen atoms, etc.)
[Selection figure] None

Description

  The present invention relates to a positive electrode for a non-aqueous electrolyte battery, a non-aqueous electrolyte battery, and a method for producing a non-aqueous electrolyte battery. In particular, the positive electrode for a non-aqueous electrolyte battery can suppress the oxidation activity of the positive electrode surface and improve battery characteristics. The present invention relates to a nonaqueous electrolyte battery and a method for producing a nonaqueous electrolyte battery.

  In recent years, many portable electronic devices such as a camera-integrated VTR, a digital still camera, a mobile phone, a personal digital assistant, and a notebook computer have appeared, and their size and weight have been reduced. As portable power sources for these electronic devices, research and development for improving the energy density of batteries, particularly secondary batteries, are being actively promoted. Among them, a lithium ion secondary battery using carbon as a negative electrode active material, a lithium transition metal composite oxide as a positive electrode active material, and a carbonate ester mixture as an electrolytic solution has been proposed. Such a battery is widely put into practical use because a large energy density can be obtained as compared with a lead battery and a nickel cadmium battery which are conventional non-aqueous electrolyte secondary batteries. In particular, recently, with the aim of further increasing the capacity, reforming of the positive electrode active material and improvement of the charging voltage have been attempted.

  When these batteries with higher capacities are placed in a high-temperature atmosphere in a charged state, the positive electrode deteriorates due to the reaction between the electrolyte solution on the positive electrode surface and the positive electrode active material, resulting in a decrease in capacity after long-term storage. Will be invited. Therefore, there is a technique for suppressing capacity deterioration during high-temperature storage by replacing ethylene carbonate, which is an electrolyte solvent, with propylene carbonate having higher oxidation resistance. However, when a graphite-based material is used as the negative electrode active material, this method cannot be used because propylene carbonate reacts with the negative electrode.

  On the other hand, by adding various additives to the electrolytic solution, it has been studied to form a decomposition film on the electrode surface at the time of the initial charge and suppress decomposition of the electrolytic solution. As an example, Patent Document 1 includes the combined use of a sultone derivative and isocyanuric acid, and Patent Document 2 includes the combined use of a sulfone, a cyclic sulfonate ester, and a high-carbon chain carbonate. ing. Patent Document 3 discloses a method of electrochemically coating a negative electrode by containing a fluoroalkyl compound having excellent chemical stability in an electrolyte.

  In Patent Document 4, there is a method of treating the surface of the positive electrode to coat a stable protective film on the surface of the positive electrode, and there is a report that suppresses the decomposition reaction of the electrolytic solution on the positive electrode. There is a report that these additives are decomposed at the time of the first charge and SEI (Electrolyte Interface: solid electrolyte membrane) is formed on the surface of the electrode, thereby suppressing decomposition with the electrolytic solution at high temperature.

JP 2002-358999 A JP 2007-207483 A JP 2002-117897 A JP 2008-27778 A

  However, in the methods of Patent Documents 1 to 3, since most of the coating is deposited on the negative electrode, it is difficult to suppress the problems caused by the positive electrode and improve long-term storage characteristics. Further, even in the method of Patent Document 4 in which a film is formed on the surface of the positive electrode, the film is dissolved by long-term high-temperature storage, so that it is difficult to suppress deterioration of the positive electrode.

  The present invention is intended to solve the above-described problems, and provides a positive electrode for a non-aqueous electrolyte battery, a non-aqueous electrolyte battery, and a method for manufacturing a non-aqueous electrolyte battery that achieve both high battery capacity and high storage characteristics. With the goal.

In order to solve the above-described problem, the first invention includes a current collector and a positive electrode active material layer containing a positive electrode active material,
A positive electrode for a non-aqueous electrolyte battery in which a carboxylate having at least one of a fluorine atom and a chlorine atom is present on the surface of the positive electrode active material layer.

According to a second aspect of the present invention, there is provided a positive electrode in which a positive electrode active material layer containing a positive electrode active material is formed on at least one surface of a positive electrode current collector;
A negative electrode in which a negative electrode active material layer containing a negative electrode active material is formed on at least one surface of the negative electrode current collector;
A separator provided between the positive electrode and the negative electrode;
With electrolyte,
This is a nonaqueous electrolyte battery in which a carboxylate having at least one of a fluorine atom and a chlorine atom is present on the surface of the positive electrode active material layer.

According to a third aspect of the present invention, a positive electrode active material, a conductive additive, a binder, a solvent, and at least one of a carboxylic acid having at least one of a fluorine atom and a chlorine atom and a carboxylate are mixed. Adjusting the agent, forming a positive electrode active material layer made of a positive electrode mixture on at least one surface of the positive electrode current collector, and producing a positive electrode;
A negative electrode active material, a binder, and a solvent are mixed to prepare a negative electrode mixture, and a negative electrode active material layer made of the negative electrode mixture is formed on at least one surface of the negative electrode current collector to produce a negative electrode And a process of
Adjusting the electrolyte by mixing a non-aqueous solvent and an electrolyte salt;
Producing a battery element in which a positive electrode and a negative electrode are laminated via a separator;
A step of sheathing the battery element and the electrolyte with an exterior member;
A step of providing a carboxylate having at least one of a fluorine atom and a chlorine atom derived from at least one of the carboxylic acid and carboxylate described above on the surface of the positive electrode by charging. is there.

（式中、Ａ₁〜Ａ₃はＬｉ，Ｎａ，Ｋ，Ｍｇ，Ｃａ，Ｓｒ，Ｂａであり、Ａ₂およびＡ₃の少なくとも一つは水素原子であっても良い。ＢはＣＦ₃、ＣＨＦ₂、ＣＨ₂Ｆ、およびＣＨ₃で表される官能基とする。）
なお、Ｄ１およびＤ２は、式（３）、式（４）で示される構造とする。

（式中、０≦（ａ、ｃ、ｄ、ｆ）≦２、及び１≦ｂ≦１６、及び１≦ｅ≦１６とする。Ｘはフッ素原子であるが、その一部は水素原子や他のハロゲン原子、およびハロゲン原子を含んでも良いアルキル基に置換されていても良い。） In the present invention, the carboxylate present on the surface of the positive electrode is preferably at least one of the structures represented by the formulas (1) and (2).

(In the formula, A _{1 to} A ₃ are Li, Na, K, Mg, Ca, Sr, Ba, and at least one of A ₂ and A ₃ may be a hydrogen atom. B is CF ₃ , CHF. ₂ and a functional group represented by CH ₂ F and CH _3. )
Note that D1 and D2 have a structure represented by the formulas (3) and (4).

(Where 0 ≦ (a, c, d, f) ≦ 2, and 1 ≦ b ≦ 16, and 1 ≦ e ≦ 16, X is a fluorine atom, part of which is a hydrogen atom or other And may be substituted with an alkyl group which may contain a halogen atom.)

  In this invention, a stable coating can be reliably formed on the positive electrode surface, and the oxidation activity on the positive electrode surface can be suppressed. That is, the decomposition of the electrolytic solution on the positive electrode surface is suppressed, and an unsuitable film is prevented from being formed on the negative electrode surface.

  According to this invention, it is possible to achieve both suppression of battery capacity reduction and high-temperature storage characteristics as the cycle progresses.

It is a perspective view which shows one structural example of the nonaqueous electrolyte battery by embodiment of this invention. It is sectional drawing along the II-II line of the winding electrode body 10 shown in FIG. It is sectional drawing which shows one structural example of the nonaqueous electrolyte battery by embodiment of this invention. FIG. 4 is an enlarged cross-sectional view illustrating a part of a wound electrode body 30 illustrated in FIG. 3. It is a graph which shows the measurement result of the identification of the positive electrode film by TOF-SIMS.

An embodiment of the present invention will be described below with reference to the drawings.
1. First Embodiment (Example of Laminated Film Type Nonaqueous Electrolyte Battery)
2. Second Embodiment (Example of nonaqueous electrolyte battery having a cylindrical shape)

First Embodiment (1-1) Configuration of Nonaqueous Electrolyte Battery The positive electrode in the present invention has a positive electrode film made of a carboxylate having fluorine atoms formed on the positive electrode surface. The coating derived from at least one of the carboxylic acid and carboxylate having a fluorine atom on the surface of the positive electrode is stable even under strongly acidic conditions, and is stable even when the nonaqueous electrolyte battery is stored for a long period of time. Oxidation activity suppression effect is expressed. With the film forming method of the present invention, it is possible to preferentially form a film on the positive electrode.

  This nonaqueous electrolyte battery is, for example, a lithium ion nonaqueous electrolyte battery, and FIG. 1 is a perspective view showing a configuration example of the nonaqueous electrolyte battery according to the first embodiment of the present invention. This nonaqueous electrolyte battery is, for example, a nonaqueous electrolyte secondary battery. This nonaqueous electrolyte battery has a configuration in which a wound electrode body 10 to which a positive electrode lead 11 and a negative electrode lead 12 are attached is housed inside a film-like exterior member 1 and has a flat shape. .

  Each of the positive electrode lead 11 and the negative electrode lead 12 has a strip shape, for example, and is led out from the inside of the exterior member 1 to the outside, for example, in the same direction. The positive electrode lead 11 is made of a metal material such as aluminum (Al), and the negative electrode lead 12 is made of a metal material such as nickel (Ni).

[Exterior material]
The exterior member 1 is a laminated film having a structure in which, for example, an insulating layer, a metal layer, and an outermost layer are laminated in this order and bonded together by a lamination process or the like. For example, the exterior member 1 has the insulating layer side as the inner side, and the outer edge portions are in close contact with each other by fusion bonding or an adhesive.

  The insulating layer is made of, for example, a polyolefin resin such as polyethylene, polypropylene, modified polyethylene, modified polypropylene, or a copolymer thereof. This is because moisture permeability can be lowered and airtightness is excellent. The metal layer is made of foil-like or plate-like aluminum, stainless steel, nickel, iron, or the like. The outermost layer may be made of, for example, the same resin as the insulating layer, or may be made of nylon or the like. This is because the strength against tearing and piercing can be increased. The exterior member 1 may include a layer other than the insulating layer, the metal layer, and the outermost layer.

  Between the exterior member 1 and the positive electrode lead 11 and the negative electrode lead 12, an adhesion film 2 for improving the adhesion between the positive electrode lead 11 and the negative electrode lead 12 and the inside of the exterior member 1 and preventing intrusion of outside air. Has been inserted. The adhesion film 2 is made of a material having adhesion to the positive electrode lead 11 and the negative electrode lead 12. When the positive electrode lead 11 and the negative electrode lead 12 are made of the above-described metal material, it is preferably made of a polyolefin resin such as polyethylene, polypropylene, modified polyethylene, or modified polypropylene.

  FIG. 2 is a sectional view taken along line II-II of the spirally wound electrode body 10 shown in FIG. The wound electrode body 10 is obtained by stacking and winding a positive electrode 13 and a negative electrode 14 with a separator 15 and an electrolyte 16, and the outermost peripheral portion is protected by a protective tape 17.

[Positive electrode]
The positive electrode 13 includes, for example, a positive electrode current collector 13A and a positive electrode active material layer 13B provided on both surfaces of the positive electrode current collector 13A. A film made of a carboxylate having a fluorine atom is formed on the surface of the positive electrode active material. The positive electrode current collector 13A is made of, for example, a metal material such as aluminum, nickel, or stainless steel.

  The positive electrode active material layer 13B includes one or more positive electrode materials capable of inserting and extracting lithium as a positive electrode active material, and includes a conductive additive such as a carbon material, and polyvinylidene fluoride. Or a binder such as polytetrafluoroethylene. The positive electrode active material layer 13B may contain at least one of fluorine-containing carboxylic acid and carboxylate.

[Positive electrode coating]
Examples of the carboxylate having a fluorine atom that forms a film formed on the surface of the positive electrode include the following formulas (1) and (2).

（式中、Ａ₁〜Ａ₃はＬｉ，Ｎａ，Ｋ，Ｍｇ，Ｃａ，Ｓｒ，Ｂａであり、Ａ₂およびＡ₃の少なくとも一つは水素原子であっても良い。ＢはＣＦ₃、ＣＨＦ₂、ＣＨ₂Ｆ、およびＣＨ₃で表される官能基とする。）

(In the formula, A _{1 to} A ₃ are Li, Na, K, Mg, Ca, Sr, Ba, and at least one of A ₂ and A ₃ may be a hydrogen atom. B is CF ₃ , CHF. ₂ and a functional group represented by CH ₂ F and CH _3. )

  Here, the dicarboxylate salt represented by the formula (2) is preferable because it has high crystallinity and can provide a higher effect as a film.

In addition, D ₁ and D ₂ in the formulas (1) and (2) have a structure represented by the following formulas (3) and (4).

（式中、０≦（ａ、ｃ、ｄ、ｆ）≦２、及び１≦ｂ≦１６、及び１≦ｅ≦１６とする。Ｘはフッ素原子であるが、その一部は水素原子や他のハロゲン原子、およびハロゲン原子を含んでも良いアルキル基に置換されていても良い。）

(Where 0 ≦ (a, c, d, f) ≦ 2, and 1 ≦ b ≦ 16, and 1 ≦ e ≦ 16, X is a fluorine atom, part of which is a hydrogen atom or other And may be substituted with an alkyl group which may contain a halogen atom.)

  The higher the carbon number of the main chain, the higher the effect of the carboxylate having fluorine that constitutes the positive electrode film. However, when the number of carbon atoms increases, that is, when b> 16 in formula (3) and e> 17 in formula (4), the solubility in the solvent used for the positive electrode mixture is lost, which is not preferable.

  The reason why the carboxylate forming the coating on the positive electrode surface has fluorine is because the oxidation resistance of the coating is important. Fluorine bonds strongly with hydrogen. For example, when a certain amount of fluorine atoms are contained in the main chain of the carboxylate, the main chain becomes difficult to be decomposed due to steric hindrance. In addition, when there is a double bond, the bonded portion becomes an active site and is easily decomposed. Therefore, a carboxylate salt in which the main chain is saturated and X in the formulas (3) and (4) is all halogen atoms is most preferable. Thereby, even if it has some substituents, the oxidation resistance of carboxylate does not change. When a film is formed with a carboxylate having no fluorine, the film is not preferable because the film is decomposed at the positive electrode.

  The structure of the positive electrode surface coating can be analyzed by the TOF-SIMS method (time-of-flight secondary ion mass spectrometry).

  Such a coating includes a carboxylate having a fluorine atom in which at least one of a carboxylic acid having a fluorine atom and a carboxylate added to the positive electrode mixture at the time of forming a positive electrode active material layer reacts with a lithium salt at the first charge of the battery. Formed as a result of precipitation. The carboxylate having a fluorine atom forms a film so as to be deposited on the surface of the positive electrode. Moreover, at least one of the carboxylic acid and carboxylate having unreacted fluorine atoms may be contained in the positive electrode active material 13B. At least one of the carboxylic acid and carboxylate having unreacted fluorine atoms decreases as charge / discharge proceeds.

  Examples of the carboxylic acid having a fluorine atom to be added to the positive electrode mixture include the following.

Examples of monocarboxylic acids include CF ₃ —COOH, CF ₃ —CF ₂ —COOH, CF ₃ — (CF ₂ ) ₂ —COOH, CF ₃ — (CF ₂ ) ₃ —COOH, CF ₃ — (CF _{2). ) 4 -COOH, CF 3 - (} CF 2) 5 -COOH, CF 3 - (CF 2) 6 -COOH, CF 3 - (CF 2) 7 -COOH, CF 3 - (CF 2) 8 -COOH, CF _3- (CF ₂ ) ₉ -COOH, CF _3- (CF ₂ ) ₁₀ -COOH, CF _3- (CF ₂ ) ₁₁ -COOH, CF _3- (CF ₂ ) ₁₂ -COOH, CF _3- (CF ₂ ) _{13 -COOH, CF 3 - (CF} 2) 14 -COOH, CF 3 - (CF 2) 15 -COOH, CF 3 - (CF 2) 16 -COOH, CF 3 -CH 2 -COOH, CF 3 -CF 2 _{-CH 2 -COOH, CF 3 - (} CF 2) 2 -CH 2 -COOH, CF 3 - (CF 2) 3 -CH 2 -COOH, CF 3 _{(CF 2) 4 -CH 2 -COOH} , CF 3 - (CF 2) 5 -CH 2 -COOH, CF 3 - (CF 2) 6 -CH 2 -COOH, CF 3 - (CF 2) 7 -CH 2 —COOH, CF ₃ — (CF ₂ ) ₈ —CH ₂ —COOH, CF ₃ — (CF ₂ ) ₉ —CH ₂ COOH, CF ₃ — (CF ₂ ) ₁₀ —CH ₂ —COOH, CF ₃ — (CF _{2 ) 11 -CH 2 -COOH, CF 3} - (CF 2) 12 -CH 2 -COOH, CF 3 - (CF 2) 13 -CH 2 -COOH, CF 3 - (CF 2) 14 -CH 2 -COOH, CF _3- (CF ₂ ) ₁₅ --CH ₂ --COOH, CF _3- (CH ₂ ) ₂ --COOH, CF ₃ --CF _2- (CH ₂ ) ₂ --COOH, CF _3- (CF ₂ ) _2- (CH _{2) 2 -COOH, CF 3 -} (CF 2) 3 - (CH 2) 2 -COOH, CF 3 - (CF 2) 4 - (CH 2) 2 -COOH, CF 3 - (CF 2) 5 - ( CH _{2) 2} -CO _{H, CF 3 - (CF 2} ) 6 - (CH 2) 2 -COOH, CF 3 - (CF 2) 7 - (CH 2) 2 -COOH, CF 3 - (CF 2) 8 - (CH 2) 2 _{-COOH, CF 3 - (CF 2} ) 9 - (CH 2) 2 -COOH, CF 3 - (CF 2) 10 - (CH 2) 2 -COOH, CF 3 - (CF 2) 11 - (CH 2) _{2 -COOH, CF 3 - (CF} 2) 12 - (CH 2) 2 -COOH, CF 3 - (CF 2) 13 - (CH 2) 2 -COOH, CF 3 - (CF 2) 14 - (CH 2 ) ₂ -COOH.

As the dicarboxylic acid, as an _{example, HOOC-CF 3 -COOH, HOOC-} (CF 2) 2 -COOH, HOOC- (CF 2) 3 -COOH, HOOC- (CF 2) 4 -COOH, HOOC- ( CF ₂ ) ₅ —COOH, HOOC— (CF ₂ ) ₆ —COOH, HOOC— (CF ₂ ) ₇ —COOH, HOOC— (CF ₂ ) ₈ —COOH, HOOC— (CF ₂ ) ₉ —COOH, HOOC— ( _{CF 2) 10 -COOH, HOOC- (} CF 2) 11 -COOH, HOOC- (CF 2) 12 -COOH, HOOC- (CF 2) 13 -COOH, HOOC- (CF 2) 14 -COOH, HOOC- ( _{CF 2) 15 -COOH, HOOC- (} CF 2) 16 -COOH, HOOC-CH 2 -CF 3 -CH 2 -COOH, HOOC-CH 2 - (CF 2) 2 -CH 2 -COOH, HOOC-CH 2 - (CF _{2) 3} -C _{2 -COOH, HOOC-CH 2 -} (CF 2) 4 -CH 2 -COOH, HOOC-CH 2 - (CF 2) 5 -CH 2 -COOH, HOOC-CH 2 - (CF 2) 6 -CH 2 - _{COOH, HOOC-CH 2 - (} CF 2) 7 -CH 2 -COOH, HOOC-CH 2 - (CF 2) 8 -CH 2 -COOH, HOOC-CH 2 - (CF 2) 9 -CH 2 -COOH, _{HOOC-CH 2 - (CF 2} ) 10 -CH 2 -COOH, HOOC-CH 2 - (CF 2) 11 -CH 2 -COOH, HOOC-CH 2 - (CF 2) 12 -CH 2 -COOH, HOOC- _{CH 2 - (CF 2) 13} -CH 2 -COOH, HOOC-CH 2 - include _{(CF 2) 14 -CH 2 -COOH} .

  The halogen atom contained in the main chain may be chlorine in addition to fluorine. This is because there is a strong bond between chlorine and hydrogen. Further, instead of the above-mentioned carboxylic acid containing fluorine, a salt of carboxylic acid containing fluorine may be used. Carboxylic acid and carboxylate can be used in combination.

[Positive electrode active material]
As a positive electrode material capable of inserting and extracting lithium, for example, a lithium-containing compound is preferable. This is because a high energy density can be obtained. Examples of the lithium-containing compound include a composite oxide containing lithium and a transition metal element, and a phosphate compound containing lithium and a transition metal element. Especially, what contains at least 1 sort (s) of the group which consists of cobalt, nickel, manganese, and iron as a transition metal element is preferable. This is because a higher voltage can be obtained. The chemical formula thereof is represented by, for example, Li _x M1O ₂ or Li _y M2PO ₄ . In the formula, M1 and M2 represent one or more transition metal elements. The values of x and y vary depending on the charge / discharge state, and are generally 0.05 ≦ x ≦ 1.10 and 0.05 ≦ y ≦ 1.10.

Examples of the composite oxide containing lithium and a transition metal element include lithium / cobalt composite oxide (Li _x CoO ₂ ), lithium / nickel composite oxide (Li _x NiO ₂ ), and lithium nickel cobalt composite oxide (Li _x Ni _1-y Co _y O ₂ (y <1)), lithium nickel cobalt manganese composite oxide (Li _x Ni _(1-vw) Co _v Mn _w O ₂ (v + w <1)), or spinel structure And lithium-manganese composite oxide (LiMn ₂ O ₄ ). In particular, a composite oxide containing cobalt is preferable because a high capacity can be obtained and excellent cycle characteristics can be obtained. Examples of the phosphoric acid compound containing lithium and a transition metal element include a lithium iron phosphate compound (LiFePO ₄ ) or a lithium iron manganese phosphate compound (LiFe _1-u Mn _u PO ₄ (u <1)). Is mentioned.

In particular, the battery system using a lithium / nickel composite oxide as the positive electrode active material is most effective in the coating of the present invention. Since a large amount of lithium hydroxide remains in the lithium / nickel composite oxide, the added fluorine-containing carboxylic acid is neutralized in the positive electrode mixture, and it becomes easier to form a fluorine-containing carboxylate film. Because. Specifically, a composite oxide having a large amount of solid solution of nickel as a transition metal, that is, a composite oxide containing nickel as a main transition metal (Li _x Ni _1-z A _z O ₂ (z <0.5, A Is a solid-soluble transition metal other than Ni.))) Is highly effective when used as a positive electrode active material. Further, for example, when a lithium-nickel composite oxide (Li _x NiO ₂ ) and a composite oxide of a transition metal other than nickel are mixed to form a positive electrode active material, the lithium-nickel composite oxide (Li _x A high effect is obtained when, for example, 50% or more of NiO ₂ ) is mixed.

  In addition, examples of positive electrode materials capable of occluding and releasing lithium include oxides such as titanium oxide, vanadium oxide and manganese dioxide, disulfides such as titanium disulfide and molybdenum sulfide, and niobium selenide. And a conductive polymer such as sulfur, polyaniline or polythiophene.

  The positive electrode material capable of inserting and extracting lithium may be other than the above. Moreover, the positive electrode material illustrated above may be mixed 2 or more types by arbitrary combinations.

[Binder and conductive agent]
Examples of the positive electrode binder include synthetic rubbers such as styrene butadiene rubber, fluorine rubber or ethylene propylene diene, and polymer materials such as polyvinylidene fluoride. These may be single and multiple types may be mixed.

  Examples of the positive electrode conductive agent include carbon materials such as graphite, carbon black, acetylene black, and ketjen black. These may be single and multiple types may be mixed. The positive electrode conductive agent may be a metal material or a conductive polymer as long as it is a conductive material.

[Negative electrode]
The negative electrode 14 includes, for example, a negative electrode current collector 14A and a negative electrode active material layer 14B provided on both surfaces of the negative electrode current collector 14A. A negative negative electrode film is preferably formed on the surface of the negative electrode active material. The negative electrode current collector 14A is made of, for example, a metal foil such as a copper foil.

  The film formed on the negative electrode surface is decomposed at a voltage lower than at least one of the carboxylic acid and carboxylate containing fluorine that is the source of the positive electrode film (a voltage higher than 0.5 V at the negative electrode potential), It is formed using a material that does not cause an increase in resistance due to the film. By using a material that decomposes at a lower voltage than at least one of fluorine-containing carboxylic acid and carboxylate, it decomposes faster than at least one of fluorine-containing carboxylic acid and carboxylate during the initial charge, and the negative electrode surface is coated. Form. Therefore, a coating derived from at least one of carboxylic acid and carboxylate containing fluorine that increases the resistance of the negative electrode surface is not formed on the negative electrode surface, and a sufficient amount of coating can be formed on the positive electrode surface. .

  As such a material, a halogenated cyclic carbonate, a cyclic ester having an unsaturated bond, a cyclic anhydride, or the like is used. This is because the cyclic ester is weak against reduction and easily forms a film. Examples of such materials include succinic anhydride, phthalic anhydride, vinylene carbonate (VC), propene sultone (PRS), and the like.

  Moreover, as a halogenated cyclic carbonate, the following formula | equation (5) is mentioned, for example.

  Moreover, in Formula (5), when R1-R4 is an alkyl group or a halogenated alkyl group, it is preferable that the carbon number is about 1 or 2. Specific examples include compounds represented by the following formulas (5-1) to (5-21).

  That is, 4-fluoro-1,3-dioxolan-2-one represented by formula (5-1), 4-chloro-1,3-dioxolan-2-one represented by formula (5-2), formula (5- 3) 4,5-difluoro-1,3-dioxolan-2-one, tetrafluoro-1,3-dioxolan-2-one of formula (5-4), 4-fluoro- of formula (5-5) 5-chloro-1,3-dioxolan-2-one, 4,5-dichloro-1,3-dioxolan-2-one of formula (5-6), tetrachloro-1,3 of formula (5-7) -Dioxolan-2-one, 4,5-bistrifluoromethyl-1,3-dioxolan-2-one of formula (5-8), 4-trifluoromethyl-1,3-dioxolane of formula (5-9) -2-one, 4,5-difluoro-4,5-dimethyl-1,3 of formula (5-10) Dioxolan-2-one, 4-methyl-5,5-difluoro-1,3-dioxolan-2-one of formula (5-11), 4-ethyl-5,5-difluoro- of formula (5-12) 1,3-dioxolan-2-one and the like.

  Further, 4-trifluoromethyl-5-fluoro-1,3-dioxolan-2-one of the following formula (5-13), 4-trifluoromethyl-5-methyl-1,3 of the formula (5-14) -Dioxolan-2-one, 4-fluoro-4,5-dimethyl-1,3-dioxolan-2-one of formula (5-15), 4,4-difluoro-5- (of formula (5-16) 1,1-difluoroethyl) -1,3-dioxolan-2-one, 4,5-dichloro-4,5-dimethyl-1,3-dioxolan-2-one of formula (5-17), formula (5 -18) 4-ethyl-5-fluoro-1,3-dioxolan-2-one, formula (5-19) 4-ethyl-4,5-difluoro-1,3-dioxolan-2-one, formula (5-20) 4-ethyl-4,5,5-trifluoro-1,3-dioxy Run 2-one, the formula (5-21) 4-methyl-1,3-dioxolane-2-one.

  These may be used alone or in combination of two or more. Among them, the cyclic carbonate having halogen as a constituent element is preferably 4-fluoro-1,3-dioxolan-2-one of the formula (5-1), and 4,5-difluoro-1 of the formula (5-3). , 3-dioxolan-2-one is more preferred. This is because they are easily available and higher effects can be obtained. In particular, as 4,5-difluoro-1,3-dioxolan-2-one, a trans isomer is preferable to a cis isomer in order to obtain a higher effect.

  The halogenated cyclic carbonate is added to, for example, an electrolyte, and a negative electrode film is formed by charging.

  The negative electrode active material layer 14B includes, for example, one or more negative electrode materials capable of occluding and releasing lithium as a negative electrode active material, and a conductive additive as necessary. And may contain a binder.

[Negative electrode active material]
Examples of the negative electrode active material capable of inserting and extracting lithium include carbon materials such as non-graphitizable carbon such as graphite and carbon black, and graphitizable carbon such as petroleum coke and pitch coke. It is done. Any one of these carbon materials may be used alone, or two or more of them may be mixed and used, or two or more of them having different average particle diameters may be mixed and used.

  Further, examples of the negative electrode material capable of inserting and extracting lithium include a material containing a metal element or a metalloid element capable of forming an alloy with lithium as a constituent element. Specifically, a simple substance, alloy, or compound of a metal element capable of forming an alloy with lithium, or a simple substance, alloy, or compound of a metalloid element capable of forming an alloy with lithium, or one or more of these. The material which has these phases in at least one part is mentioned.

  Examples of such metal elements or metalloid elements include tin (Sn), lead (Pb), aluminum, indium (In), silicon (Si), zinc (Zn), antimony (Sb), and bismuth (Bi). , Cadmium (Cd), magnesium (Mg), boron (B), gallium (Ga), germanium (Ge), arsenic (As), silver (Ag), zirconium (Zr), yttrium (Y) or hafnium (Hf) Is mentioned. Among them, the group 14 metal element or metalloid element in the long-period periodic table is preferable, and silicon (Si) or tin (Sn) is particularly preferable. This is because silicon (Si) and tin (Sn) have a large ability to occlude and release lithium, and a high energy density can be obtained.

  As an alloy of silicon (Si), for example, as a second constituent element other than silicon (Si), tin (Sn), nickel (Ni), copper (Cu), iron (Fe), cobalt (Co), manganese (Mn), zinc (Zn), indium (In), silver (Ag), titanium (Ti), germanium (Ge), bismuth (Bi), antimony (Sb), and chromium (Cr). The thing containing 1 type is mentioned. As an alloy of tin (Sn), for example, as a second constituent element other than tin (Sn), silicon (Si), nickel (Ni), copper (Cu), iron (Fe), cobalt (Co), manganese (Mn), zinc (Zn), indium (In), silver (Ag), titanium (Ti), germanium (Ge), bismuth (Bi), antimony (Sb), and chromium (Cr). The thing containing 1 type is mentioned.

  Examples of the compound of silicon (Si) or tin (Sn) include those containing oxygen (O) or carbon (C), and in addition to silicon (Si) or tin (Sn), Two constituent elements may be included.

[Electrolytes]
The electrolyte includes an electrolyte salt and a solvent that dissolves the electrolyte salt. Examples of the electrolyte salt include lithium hexafluorophosphate (LiPF ₆ ), lithium perhydrochloride (LiClO ₄ ), lithium tetrafluoroborate (LiBF ₄ ), and lithium bistrifluoromethanesulfonylimide (LiN (SO ₂ CF _{3). 2} ), lithium salts such as lithium bispentafluoromethanesulfonylimide (LiN (SO ₂ C ₂ F ₅ ) ₂ ), or lithium hexafluoroarsenate (LiAsF ₆ ). Any one of the electrolyte salts may be used, or two or more of them may be mixed and used.

  Examples of the solvent include lactone solvents such as γ-butyrolactone, γ-valerolactone, δ-valerolactone, and ε-caprolactone, and carbonate ester solvents such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate. , 1,2-dimethoxyethane, 1-ethoxy-2-methoxyethane, 1,2-diethoxyethane, ether solvents such as tetrahydrofuran or 2-methyltetrahydrofuran, nitrile solvents such as acetonitrile, sulfolane solvents, phosphoric acids , Phosphate solvents, or non-aqueous solvents such as pyrrolidones. Any one type of solvent may be used alone, or two or more types may be mixed and used.

  Among these, as the non-aqueous solvent, it is preferable to use a solvent containing at least one member selected from the group consisting of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate. This is because a sufficient effect can be obtained. In this case, in particular, ethylene carbonate or propylene carbonate having a high viscosity (high dielectric constant) solvent (for example, relative dielectric constant ε ≧ 30) and dimethyl carbonate having a low viscosity solvent (for example, viscosity ≦ 1 mPa · s). It is preferable to use a mixture containing diethyl carbonate or ethyl methyl carbonate. This is because the dissociation property of the electrolyte salt and the ion mobility are improved, so that a higher effect can be obtained.

  The electrolyte contains a holding body containing a polymer compound that holds the electrolytic solution, and may be in a so-called gel form. The electrolytic solution may be swollen into a polymer.

  The polymer compound only needs to absorb the solvent and gel, and examples of the polymer include polyvinyl formal represented by the following formula (6), polyacrylate represented by the following formula (7), Examples thereof include polyvinylidene fluoride represented by the following formula (8).

（式中、Ｒ＝Ｃ_nＨ２_n-1Ｏ_m、１＜ｎ＜８、０＜ｍ＜４）

_{(Wherein, R = C n H2 n-} 1 O m, 1 <n <8,0 <m <4)

  In addition, fluorine polymer compounds such as polyvinylidene fluoride (PVdF) or a copolymer of vinylidene fluoride (VdF) and hexafluoropropylene (HFP), a crosslinked product containing polyethylene oxide (PEO) or polyethylene oxide, etc. And those containing an ether polymer compound, polyacrylonitrile (PAN), polypropylene oxide (PEO) or polymethyl methacrylate (PMMA) as a repeating unit. Any one of these polymer compounds may be used alone, or two or more thereof may be mixed and used.

In particular, from the viewpoint of redox stability, a fluorine-based polymer compound is desirable, and among them, a copolymer containing vinylidene fluoride and hexafluoropropylene as components is preferable. Furthermore, this copolymer contains monoesters of unsaturated dibasic acids such as monomethylmaleic acid ester, halogenated ethylenes such as ethylene trifluorochloride, cyclic carbonates of unsaturated compounds such as vinylene carbonate, or epoxy group-containing compounds. An acrylic vinyl monomer may be included as a component. This is because higher characteristics can be obtained.

[Separator]
The separator 15 separates the positive electrode 13 and the negative electrode 14 and allows lithium ions to pass through while preventing a short circuit of current due to contact between the two electrodes. Any separator may be used as long as it is electrically stable and chemically stable with respect to the positive electrode active material, the negative electrode active material or the solvent, and has no electrical conductivity. Good. For example, a polymer nonwoven fabric, a porous film, glass or ceramic fibers in a paper shape can be used, and a plurality of these may be laminated. In particular, a porous polyolefin film is preferably used, and a composite of this with a heat-resistant material made of polyimide, glass, ceramic fibers, or the like may be used. The separator 15 is impregnated with the electrolyte described above.

  In this nonaqueous electrolyte battery, when charged, for example, lithium ions are released from the positive electrode 13 and inserted in the negative electrode 14 through the electrolytic solution impregnated in the separator 15. On the other hand, when discharging is performed, for example, lithium ions are released from the negative electrode 14 and inserted in the positive electrode 13 through the electrolytic solution impregnated in the separator 15.

  According to this non-aqueous electrolyte battery, when the capacity of the negative electrode 14 is expressed based on insertion and extraction of lithium, the electrolytic solution according to the first embodiment described above is provided, so that the electrolysis is performed at the time of charge and discharge. The decomposition reaction of the liquid is suppressed. Therefore, it is possible to improve the cycle characteristics and the storage characteristics particularly during high temperature use.

(1-2) Manufacturing method of nonaqueous electrolyte battery Next, the manufacturing method of a nonaqueous electrolyte battery is demonstrated.

[Production method of positive electrode]
A positive electrode active material, a binder, and a conductive aid such as a carbon material are mixed to prepare a positive electrode mixture, and the positive electrode mixture is dispersed in a solvent such as N-methyl-2-pyrrolidone to obtain a mixed solution To prepare. Next, a carboxylate having fluorine is added to the mixed solution. At this time, it is preferable that the addition amount of the carboxylate having fluorine is 0.01 wt% or more and 10 wt% or less. Thereby, the positive electrode mixture slurry is adjusted.

  Next, this positive electrode mixture slurry is applied to the positive electrode current collector 13A and dried, and then compression-molded by a roll press or the like to form the positive electrode active material layer 13B, whereby the positive electrode 13 is obtained.

[Production method of negative electrode]
A negative electrode active material and a binder are mixed to prepare a negative electrode mixture, and the negative electrode mixture is dispersed in a solvent such as N-methyl-2-pyrrolidone to obtain a negative electrode mixture slurry. Next, after applying this negative electrode mixture slurry to the negative electrode current collector 14A and drying the solvent, the negative electrode active material layer 14B is formed by compression molding using a roll press or the like, and the negative electrode 14 is obtained.

[Method for producing non-aqueous electrolyte]
The non-aqueous electrolyte is obtained by mixing a predetermined amount of electrolyte salt with the above-described non-aqueous solvent, and then expressing the formula (5), specifically, for example, the formula (5-1) to the formula (5-20). It is obtained by mixing and adjusting a compound to be prepared.

  In addition, it is preferable that the addition amount of halogenated carbonate is 0.01 to 10 weight%, and it is more preferable that it is 2.0 to 10 weight%. When the addition amount is too small, the negative electrode film derived from the halogenated carbonate cannot cover the negative electrode surface. Moreover, when there is too much addition amount, there will be too many surface films formed in the negative electrode surface, and the resistance in the negative electrode surface will increase.

[Assembly method of non-aqueous electrolyte battery]
The positive electrode lead 11 is attached to each end of the positive electrode current collector 13A by welding to each of the positive electrode 13 and the negative electrode 14, and the negative electrode lead 12 is attached to the end portion of the negative electrode current collector 14A by welding. Next, the positive electrode 13 and the negative electrode 14 are laminated via a separator 15 to form a laminated body, and then the laminated body is wound in the longitudinal direction, and a protective tape 17 is adhered to the outermost peripheral portion to form a wound electrode body. 10 is formed. Finally, for example, the wound electrode body 10 is sandwiched between the exterior members 1 and the outer edge portions of the exterior member 1 are brought into close contact with each other by thermal fusion or the like and sealed. At that time, the adhesion film 2 is inserted between the positive electrode lead 11 and the negative electrode lead 12 and the exterior member 1. Thereby, the nonaqueous electrolyte battery shown in FIGS. 1 and 2 is completed.

  By charging the completed nonaqueous electrolyte battery, a film made of a carboxylate having fluorine is formed on the positive electrode, and a film derived from a halogenated cyclic carbonate is formed on the negative electrode.

2. Second Embodiment Next, a configuration of a nonaqueous electrolyte battery 20 according to a second embodiment of the present invention will be described with reference to FIGS. FIG. 3 shows a configuration of a nonaqueous electrolyte battery 20 according to the second embodiment of the present invention.

(2-1) Configuration of Nonaqueous Electrolyte Battery This nonaqueous electrolyte battery 20 is a so-called cylindrical type, and a strip-shaped positive electrode 31, a strip-shaped negative electrode 32, and the like inside a substantially hollow cylindrical battery can 21. Has a wound electrode body 30 wound through a separator 33.

  The separator 33 is impregnated with an electrolytic solution that is a liquid electrolyte. The battery can 21 is made of, for example, iron (Fe) plated with nickel (Ni), and has one end closed and the other end open. Inside the battery can 21, a pair of insulating plates 22 and 23 are arranged perpendicular to the winding peripheral surface so as to sandwich the winding electrode body 30.

  At the open end of the battery can 21, a battery lid 24, a safety valve mechanism 25 and a heat sensitive resistance (PTC) element 26 provided inside the battery lid 24 are caulked via a gasket 27. It is attached by being. Thereby, the inside of the battery can 21 is sealed.

  The battery lid 24 is made of the same material as the battery can 21, for example. The safety valve mechanism 25 is electrically connected to the battery lid 24 via the heat sensitive resistance element 26. The safety valve mechanism 25 causes the disk plate 25 </ b> A to reverse and disconnect the electrical connection between the battery lid 24 and the wound electrode body 30 when the internal pressure of the battery exceeds a certain level due to an internal short circuit or external heating. It has become.

  When the temperature rises, the heat-sensitive resistor element 26 limits the current by increasing the resistance value, and prevents abnormal heat generation due to a large current. The gasket 27 is made of, for example, an insulating material, and asphalt is applied to the surface.

  The wound electrode body 30 is wound around a center pin 34, for example. A positive electrode lead 35 made of aluminum (Al) or the like is connected to the positive electrode 31 of the spirally wound electrode body 30, and a negative electrode lead 36 made of nickel (Ni) or the like is connected to the negative electrode 32. The positive electrode lead 35 is welded to the safety valve mechanism 25 to be electrically connected to the battery lid 24, and the negative electrode lead 36 is welded to and electrically connected to the battery can 21.

  4 is an enlarged cross-sectional view illustrating a part of the spirally wound electrode body 30 illustrated in FIG. The wound electrode body 30 is obtained by stacking and winding a positive electrode 31 and a negative electrode 32 with a separator 33 interposed therebetween.

  The positive electrode 31 includes, for example, a positive electrode current collector 31A and a positive electrode active material layer 31B provided on both surfaces of the positive electrode current collector 31A. The negative electrode 32 includes, for example, a negative electrode current collector 32A and a negative electrode active material layer 32B provided on both surfaces of the negative electrode current collector 32A. The configurations of the positive electrode current collector 31A, the positive electrode active material layer 31B, the negative electrode current collector 32A, the negative electrode active material layer 32B, the separator 33, and the electrolytic solution are respectively the positive electrode current collector 13A and the positive electrode in the first embodiment described above. This is the same as the active material layer 13B, the negative electrode current collector 14A, the negative electrode active material layer 14B, the separator 15, and the electrolytic solution.

(2-2) Method for Manufacturing Nonaqueous Electrolyte Battery Next, a method for manufacturing the nonaqueous electrolyte battery 20 according to the second embodiment of the present invention will be described.

  The positive electrode 31, the negative electrode 32, and the electrolyte are produced in the same manner as in the first embodiment.

  Next, the positive electrode lead 35 is attached to the positive electrode current collector 31A by welding or the like, and the negative electrode lead 36 is attached to the negative electrode current collector 32A by welding or the like. Thereafter, the positive electrode 31 and the negative electrode 32 are wound through the separator 33, and the front end portion of the positive electrode lead 35 is welded to the safety valve mechanism 25 and the front end portion of the negative electrode lead 36 is welded to the battery can 21.

  Then, the wound positive electrode 31 and negative electrode 32 are sandwiched between a pair of insulating plates 22 and 23 and housed inside the battery can 21. After the positive electrode 31 and the negative electrode 32 are accommodated in the battery can 21, the electrolyte is injected into the battery can 21 and impregnated in the separator 33.

  Thereafter, the battery lid 24, the safety valve mechanism 25, and the heat sensitive resistance element 26 are fixed to the opening end portion of the battery can 21 by caulking through the gasket 27. Thus, the nonaqueous electrolyte battery 20 shown in FIG. 3 is produced.

  As in the first embodiment, the completed nonaqueous electrolyte battery 20 is charged to form a film made of a carboxylate having fluorine on the positive electrode and a film derived from a halogenated cyclic carbonate on the negative electrode. Is done.

  Specific examples of the present invention will be described in detail below, but the present invention is not limited thereto. The additives used in the following examples and comparative examples are as follows.

[Example 1]
In Example 1, the battery is evaluated by changing the additive added to the positive electrode mixture.

<Example 1-1>
[Production of positive electrode]
94 parts by weight of lithium / nickel composite oxide (LiNiO ₂ ) as a positive electrode active material, 3 parts by weight of graphite as a conductive material, and 3 parts by weight of polyvinylidene fluoride (PVdF) as a binder were mixed homogeneously. Methyl pyrrolidone was added. Then, the carboxylate of the said Formula (9) was added to this mixed solution 0.55.0 weight% with respect to the positive electrode active material, and the positive mix was obtained. The “wt%” is a value when the positive electrode active material is 100 wt%, and the meaning of “wt%” is the same in the following description.

  Next, the obtained positive electrode mixture was uniformly applied on both sides of a 10 μm thick aluminum foil and dried to form a positive electrode mixture layer (volume density of the mixture: 3.40 g / cc) of 30 μm per side. And it was set as the positive electrode sheet. Finally, the positive electrode sheet was cut into a shape having a width of 50 mm and a length of 300 mm to produce a positive electrode.

[Production of negative electrode]
97 parts by weight of MCMB (mesocarbon microbeads) graphite as a negative electrode active material and 3 parts by weight of PVdF as a binder were homogeneously mixed, and N-methylpyrrolidone was added to obtain a negative electrode mixture. Subsequently, this negative electrode mixture was uniformly applied on both sides of a 10 μm-thick copper foil serving as a negative electrode current collector and dried to form a negative electrode mixture layer having a thickness of 30 μm per side (volume density of the mixture: 1.80 g / cc) was formed as a negative electrode sheet. Finally, the negative electrode sheet was cut into a shape having a width of 50 mm and a length of 300 mm to produce a negative electrode.

[Preparation of electrolyte]
As a solvent, ethylene (EC) and diethyl carbonate (DEC) were mixed. With respect to this mixed solvent, lithium hexafluorophosphate (LiPF ₆ ) as an electrolyte salt and 4-fluoro-1,3-dioxolane of formula (5-1) which is a halogenated carbonate as an SEI forming agent 2-one was added.

At that time, the composition of the mixed solvent was EC: DEC = 40: 60 by weight ratio, and the concentration of LiPF ₆ in the electrolytic solution was 1.0 mol / kg. Further, the addition amount of 4-fluoro-1,3-dioxolan-2-one of the formula (5-1) was added at 2.0% by weight / EL. Note that “wt% / EL” is a value when the solvent is 100 wt%, and has a different meaning from “wt%” when the positive electrode active material is 100 wt%.

[Separator]
A separator having 2 μm of polyvinylidene fluoride applied to both sides of a 7 μm-thick microporous polyethylene film was used as a separator.

[Battery assembly]
The positive electrode and the negative electrode produced as described above were laminated and wound via a separator to form a battery element, and the electronic element was packaged with an exterior material made of an aluminum laminate film. Subsequently, the outer packaging material around the battery element was heat-sealed, leaving one side. Next, 2 g of the electrolyte solution was poured into the exterior material, and the remaining one side was heat-sealed under reduced pressure to produce a laminate type battery. The capacity of this battery was 800 mAh.

[Battery evaluation]
(A) Discharge capacity maintenance rate The produced battery was charged with a constant current at a current of 800 mA in an environment of 23 ° C., and when the battery voltage reached 4.2 V, the battery was switched to a constant voltage charge, and the total charge time was 3 The battery was charged until it was time. Thereafter, the battery was discharged at a current of 800 mAh, and when the battery voltage reached 3.0 V, the discharge was terminated and the discharge capacity (initial discharge capacity) was measured.

  Subsequently, charging / discharging was repeated 300 cycles under the above-described charging / discharging conditions, and the discharge capacity at the 300th cycle was measured. Thereafter, the discharge capacity retention ratio was calculated from {(discharge capacity at 300th cycle / initial discharge capacity) × 100}.

(B) High-temperature storage test The produced battery was charged with a constant current at a current of 800 mA in an environment of 23 ° C. When the battery voltage reached 4.2 V, the battery was switched to a constant voltage charge, and the total charging time was 3 hours. The battery was charged until Thereafter, the battery was discharged at a current of 800 mAh, and when the battery voltage reached 3.0 V, the discharge was terminated and the discharge capacity (initial discharge capacity) was measured.

  Thereafter, charging was performed under the same charging conditions, and a battery having a battery voltage of 4.2 V was stored in an environment of 65 ° C. for 20 days. Subsequently, after discharging under the same conditions as in (a), the discharge capacity after a storage test when charging and discharging for one cycle was measured. Thereafter, the capacity recovery rate after high-temperature storage was calculated from {(discharge capacity after storage test / initial discharge capacity) × 100}.

<Example 1-2> to <Example 1-14>
A battery was prepared in the same manner as in Example 1-1 except that the carboxylate added to the positive electrode mixture was changed to the material of the above formula (10) to formula (22) as shown in Table 1 below. The battery was evaluated.

<Comparative Example 1-1>
A battery was produced in the same manner as in Example 1-1 except that the carboxylate was not added to the positive electrode mixture, and the battery was evaluated.

<Comparative Example 1-2> to <Comparative Example 1-7>
A battery was prepared in the same manner as in Example 1-1, except that the carboxylate added to the positive electrode mixture was changed to the material of the above formula (23) to formula (28) as shown in Table 1 below. The battery was evaluated.

  Table 1 below shows the configurations and evaluation results of the examples and comparative examples.

  As can be seen from Table 1, for each comparative example using a carboxylate containing no fluorine, Examples 1-1 to 1-14 using a carboxylate containing a fluorine atom in the main chain are: The capacity deterioration suppressing effect after high temperature storage was confirmed. In Comparative Examples 1-2 to 1-7, it is considered that the film formed on the positive electrode has poor oxidation resistance and was decomposed during high-temperature storage.

[Identification of positive electrode coating]
The battery of Example 1-11 was charged at a constant current of 800 mA in an environment of 23 ° C., and when the battery voltage reached 4.2 V, the battery was switched to constant voltage charging until the total charging time reached 3 hours. Charged. Thereafter, the battery was discharged at a current of 800 mAh until the battery voltage reached 3.0V. Next, the discharged battery was disassembled, and positive electrode surface analysis was performed by the TOF-SIMS method (time-of-flight secondary ion mass spectrometry). As a result, as shown in FIG. 5, a signal derived from a carboxylate containing fluorine of formula (19) in the positive ion species was confirmed.

[Example 2]
In Example 2, the battery was evaluated by changing the amount of carboxylate added.

<Example 2-1>
The carboxylate added to the positive electrode mixture was changed to the above formula (12), and the amount of carboxylate was 0.01% by weight with respect to the positive electrode active material, as in Example 1-1. A battery was produced.

[Battery evaluation]
(A) Discharge capacity maintenance ratio About the produced battery, the discharge capacity maintenance ratio was computed by the method similar to Example 1. FIG.

(B) High-temperature storage test About the produced battery, the discharge capacity maintenance factor was computed by the method similar to Example 1. FIG.

<Example 2-2> to <Example 2-8>
A battery was produced in the same manner as in Example 2-1, except that the amount of carboxylate added to the positive electrode mixture was changed as shown in Table 2 below, and the battery was evaluated.

<Example 2-9> to <Example 2-16>
The battery was prepared in the same manner as in Example 2-1, except that the carboxylate added to the positive electrode mixture was changed to the above formula (19) and the addition amount of the carboxylate was changed as shown in Table 2 below. The battery was fabricated and evaluated.

<Comparative Example 1>
A battery was produced in the same manner as in Example 2-1, except that the carboxylate was not added to the positive electrode mixture, and the battery was evaluated.

  Table 2 below shows the configurations and evaluation results of the examples and comparative examples.

  As can be seen from Table 2, in each comparative example in which the carboxylate containing fluorine was not used, the batteries of the examples using the carboxylate of formula (12) and formula (19) had a high temperature storage. The capacity deterioration suppressing effect could be confirmed. Further, when the amount of fluorocarboxylic acid added is 5.0% by weight or more, the capacity deterioration during storage at high temperature can be suppressed, but the discharge capacity retention rate is reduced. This is considered to be caused by the fact that the fluorocarboxylic acid that has not reacted completely at the positive electrode is dissolved in the electrolytic solution and easily deposited as a coating on the negative electrode at the home of charge and discharge. For this reason, it is particularly preferable that the addition amount is 0.05.0% by weight or more and 2% by weight or less because both the discharge capacity and the high-temperature storage characteristics can be achieved.

  In addition, in the formula (12) which is a monocarboxylate and the formula (19) which is a dicarboxylate, it was found that the use of the dicarboxylate is more effective and preferable when the addition amount is the same.

[Example 3]
In Example 3, the battery is evaluated by changing the addition position of the carboxylate.

<Example 3-1>
A battery was fabricated in the same manner as in Example 1-1 except that the above-described formula (19) was used as the carboxylate to be added, and the addition amount was changed to 0.5.0% by weight.

[Battery evaluation]
(A) Discharge capacity maintenance ratio About the produced battery, the discharge capacity maintenance ratio was computed by the method similar to Example 1. FIG.

(B) High-temperature storage test About the produced battery, the discharge capacity maintenance factor was computed by the method similar to Example 1. FIG.

(C) Battery swelling amount First, the thickness of the produced battery before the first charge was measured. Subsequently, constant current charging was performed at a current of 800 mA in an environment of 23 ° C., and when the battery voltage reached 4.2 V, switching to constant voltage charging was performed until the total charging time was 3 hours. Thereafter, the battery thickness after the first charge was measured. Then, the amount of battery swelling after the first charge was calculated from (thickness after the first charge−thickness before the first charge).

<Comparative Example 3-1>
A battery was produced in the same manner as in Example 3-1, except that the carboxylate was not added, and the battery was evaluated.

<Comparative Example 3-2>
A battery was produced in the same manner as in Example 3-1, except that the carboxylate of the above formula (19) was added to the electrolytic solution, and the battery was evaluated.

<Comparative Example 3-3>
A battery was prepared in the same manner as in Example 3-1, except that the above-described formula (19) carboxylate was added to both the positive electrode mixture and the electrolytic solution in an amount of 0.5% by weight, and the battery was evaluated. It was.

  Table 3 below shows the configurations and evaluation results of the examples and comparative examples.

  As can be seen from Table 3, in comparison with Example 3-1 in which a carboxylate containing fluorine was added to the positive electrode mixture, in Comparative Example 3-1 in which no carboxylic acid was added, the battery swells and discharge capacity after the first charge Although the retention rate was the same, the capacity deterioration after storage at high temperature occurred remarkably.

  Further, in Comparative Example 3-2 in which a carboxylate containing fluorine was added to the electrolytic solution, the discharge capacity retention rate and the high-temperature storage characteristics were lowered, and the battery swell after the first charge became very large. In Comparative Example 3-2 in which a carboxylate containing fluorine was added to both the positive electrode mixture and the electrolytic solution, although the high-temperature storage characteristics were the same as in Example 3-1, the discharge capacity retention rate was reduced. In addition, the battery swelling after the first charge became very large.

  As described above, when a carboxylate containing fluorine is added to the electrolytic solution, a film is formed on the negative electrode preferentially in the charge / discharge process, so that the film formation on the positive electrode becomes insufficient. For this reason, it is guessed that the decomposition of the electrolyte solution due to the oxidation activity on the positive electrode surface could not be prevented. When a carboxylate containing fluorine was added to both the positive electrode mixture and the electrolyte, the recovery rate after storage was improved, but a decrease in the discharge capacity retention rate due to the formation of a film on the negative electrode was observed. . That is, it has been found that a remarkable effect can be obtained by adding a carboxylate containing fluorine only to the positive electrode mixture.

[Example 4]
In Example 4, the positive electrode active material was changed to produce a battery and evaluated.

<Example 4-1>
As the positive electrode active material, lithium / nickel composite oxide (LiNiO ₂ ) was used as in Example 1-1. Example 1-1 except that the carboxylate added to the positive electrode mixture is the above-described formula (18), and the addition amount of the carboxylate is 0.5% by weight with respect to the positive electrode active material. A battery was produced in the same manner.

[Battery evaluation]
(A) Discharge capacity maintenance ratio About the produced battery, the discharge capacity maintenance ratio was computed by the method similar to Example 1. FIG.

(B) High-temperature storage test About the produced battery, the discharge capacity maintenance factor was computed by the method similar to Example 1. FIG.

<Example 4-2>
A battery was produced and evaluated in the same manner as in Example 4-1, except that the amount of carboxylate added was 2.0 wt% with respect to the positive electrode active material.

<Example 4-3>
A battery was produced in the same manner as in Example 4-1, except that lithium-cobalt composite oxide (LiCoO ₂ ) was used as the positive electrode active material, and the battery was evaluated.

<Example 4-4>
A battery was produced and evaluated in the same manner as in Example 4-1, except that lithium-cobalt composite oxide (LiCoO ₂ ) was used as the positive electrode active material and the addition amount was 2.0 wt%. .

<Example 4-5>
A battery was fabricated and evaluated in the same manner as in Example 4-1, except that lithium-manganese composite oxide (LiMnO ₂ ) was used as the positive electrode active material. In Example 4-5, the end-of-charge voltage at the time of battery evaluation was 3.7V.

<Example 4-6>
A battery was fabricated and evaluated in the same manner as in Example 4-1, except that lithium-manganese composite oxide (LiMnO ₂ ) was used as the positive electrode active material and the addition amount was 2.0% by weight. . In Example 4-6, the end-of-charge voltage at the time of battery evaluation was 3.7V.

<Comparative Example 4-1>
A battery was produced in the same manner as in Example 4-1, except that the carboxylate was not added to the positive electrode mixture, and the battery was evaluated.

<Comparative Example 4-2>
A battery was produced and evaluated in the same manner as in Example 4-1, except that lithium-cobalt composite oxide (LiCoO ₂ ) was used as the positive electrode active material and no carboxylate was added to the positive electrode mixture. .

<Comparative Example 4-3>
A battery was fabricated and evaluated in the same manner as in Example 4-1, except that lithium-manganese composite oxide (LiMnO ₂ ) was used as the positive electrode active material and no carboxylate was added to the positive electrode mixture. . In Comparative Example 4-3, the end-of-charge voltage at the time of battery evaluation was 3.7V.

  Table 4 below shows the configurations and evaluation results of the examples and comparative examples.

As can be seen from Table 4, high-temperature storage characteristics can be improved even when lithium-cobalt composite oxide (LiCoO ₂ ) or lithium-manganese composite oxide (LiMnO ₂ ) is used as the positive electrode active material. It was. That is, it was found that the positive electrode film derived from the carboxylate having fluorine has an effect of suppressing the oxidation activity on the surface of the positive electrode even in the cobalt-based and manganese-based positive electrode active materials.

[Example 5]
In Example 5, the battery voltage at full charge was changed to produce a battery and evaluated.

<Example 5-1>
Example 1-1 except that the carboxylate added to the positive electrode mixture is the above-described formula (19), and the addition amount of the carboxylate is 0.5% by weight with respect to the positive electrode active material. A battery was produced in the same manner.

[Battery evaluation]
(A) Discharge capacity maintenance ratio About the produced battery, the discharge capacity maintenance ratio was computed by the method similar to Example 1. FIG.

(B) High-temperature storage test About the produced battery, the discharge capacity maintenance factor was computed by the method similar to Example 1. FIG.

<Example 5-2>
A battery was produced and evaluated in the same manner as in Example 5-1, except that the amount of carboxylate added was 2.0% by weight based on the positive electrode active material.

<Example 5-3>
A battery was produced in the same manner as in Example 5-1, and the battery was evaluated with the end-of-charge voltage at the time of battery evaluation being 4.35V.

<Example 5-4>
A battery was prepared and evaluated in the same manner as in Example 5-1, except that the amount of carboxylate added was 2.0% by weight based on the positive electrode active material.

<Comparative Example 5-1>
A battery was produced in the same manner as in Example 5-1, except that the carboxylate was not added, and the battery was evaluated.

<Comparative Example 5-2>
A battery was produced in the same manner as in Example 5-1, except that the carboxylate was not added, and the battery was evaluated with a charge end voltage of 4.35 V at the time of battery evaluation.

  Table 5 below shows the configurations and evaluation results of the examples and comparative examples.

  As can be seen from Table 5, when a carboxylate containing fluorine is added to the positive electrode mixture, the discharge capacity retention rate and the high-temperature storage characteristics are remarkable even when the battery voltage is as high as 4.35 V. The improvement effect was confirmed.

[Example 6]
In Example 6, a battery was produced by changing the halogenated carbonate to be added to the electrolytic solution and evaluated.

<Example 6-1>
As the halogenated carbonate to be added to the electrolytic solution, 4-fluoro-1,3-dioxolan-2-one of the formula (5-1) was used as in Example 1-1. A battery was fabricated in the same manner as in Example 1-1 except that the above formula (19) was used as the carboxylate added to the positive electrode mixture, and the addition amount was 0.01 wt%.

[Battery evaluation]
(A) Discharge capacity maintenance ratio About the produced battery, the discharge capacity maintenance ratio was computed by the method similar to Example 1. FIG.

(B) High-temperature storage test About the produced battery, the discharge capacity maintenance factor was computed by the method similar to Example 1. FIG.

<Example 6-2>
As the halogenated carbonate to be added to the electrolytic solution, 4-fluoro-1,3-dioxolan-2-one of the formula (5-1) was used as in Example 1-1. A battery was produced in the same manner as in Example 6-1 except that the above formula (19) was used as the carboxylate to be added to the positive electrode mixture, and the addition amount was 0.05.0% by weight. Evaluation of the battery Went.

<Example 6-3>
As the halogenated carbonate to be added to the electrolytic solution, 4-fluoro-1,3-dioxolan-2-one of the formula (5-1) was used as in Example 1-1. A battery was prepared in the same manner as in Example 6-1 except that the above formula (19) was used as the carboxylate to be added to the positive electrode mixture, and the addition amount was 2.0% by weight, and the battery was evaluated. It was.

<Example 6-4>
As the halogenated carbonate to be added to the electrolytic solution, 4-fluoro-1,3-dioxolan-2-one of the formula (5-1) was used as in Example 1-1. A battery was produced in the same manner as in Example 6-1 except that the above formula (19) was used as the carboxylate to be added to the positive electrode mixture, and the addition amount was 10% by weight, and the battery was evaluated.

<Example 6-5>
As the halogenated carbonate to be added to the electrolytic solution, 4-fluoro-1,3-dioxolan-2-one of the formula (5-1) was used as in Example 1-1. A battery was produced in the same manner as in Example 6-1 except that the above formula (19) was used as the carboxylate added to the positive electrode mixture, and the addition amount was 20% by weight, and the battery was evaluated.

<Example 6-6>
Example 6 except that 4,5-difluoro-1,3-dioxolan-2-one of formula (5-3) was used as the halogenated carbonate to be added to the electrolytic solution, and the addition amount was 2.0% by weight. A battery was produced in the same manner as in Example 1, and the battery was evaluated.

<Comparative Example 6-1>
A battery was produced in the same manner as in Example 6-1 except that the carboxylic acid of the formula (5-1) was not added to the positive electrode mixture, and the battery was evaluated.

<Comparative Example 6-2>
The same procedure as in Example 6-1 except that the addition amount of the halogenated carbonate added to the electrolytic solution was 0.05.0% by weight, and the carboxylic acid of the formula (5-1) was not added to the positive electrode mixture. A battery was produced and the battery was evaluated.

<Comparative Example 6-3>
A battery was prepared in the same manner as in Example 6-1, except that the amount of halogenated carbonate added to the electrolytic solution was 2.0% by weight and the carboxylic acid of formula (5-1) was not added to the positive electrode mixture. The battery was fabricated and evaluated.

<Comparative Example 6-4>
A battery was fabricated in the same manner as in Example 6-1 except that the addition amount of the halogenated carbonate added to the electrolytic solution was 10% by weight and the carboxylic acid of the formula (5-1) was not added to the positive electrode mixture. The battery was evaluated.

<Comparative Example 6-5>
A battery was fabricated in the same manner as in Example 6-1 except that the addition amount of the halogenated carbonate added to the electrolytic solution was 20% by weight and the carboxylic acid of the formula (5-1) was not added to the positive electrode mixture. The battery was evaluated.

<Comparative Example 6-6>
4,5-Difluoro-1,3-dioxolan-2-one of the formula (5-3) was used as the halogenated carbonate to be added to the electrolytic solution, and the addition amount was 2.0% by weight. Further, no fluorocarboxylic acid was added to the positive electrode mixture. Except for this, a battery was produced in the same manner as in Example 6-1, and the battery was evaluated.

<Comparative Example 6-7>
A battery was produced in the same manner as in Example 6-1 except that both the halogenated carbonate and the carboxylic acid were not added, and the battery was evaluated.

<Comparative Example 6-8>
A battery was prepared and evaluated in the same manner as in Example 6-1 except that the halogenated carbonate was not added and the amount of the carboxylic acid of formula (19) was 2.0% by weight.

  Table 6 below shows the configurations and evaluation results of the examples and comparative examples.

  As can be seen from Table 6, each example in which a carboxylate containing fluorine was added to the positive electrode mixture and a halogenated carbonate was added to the electrolyte solution was able to achieve both a discharge capacity retention ratio and high-temperature storage characteristics. In particular, in Comparative Examples 6-1 to 6-6 in which the carboxylate containing fluorine is not added to the positive electrode, the high-temperature storage is achieved when compared with Examples in which the amount of carboxylate added is the same. The characteristics have deteriorated. This is presumably because the film derived from the carboxylate containing fluorine was not formed on the positive electrode, and the oxidation activity on the surface of the positive electrode could not be suppressed.

  Further, in Comparative Example 6-6 in which no halogenated carbonate was added to the electrolytic solution and no carboxylate was added to the positive electrode mixture, the high-temperature storage characteristics were similarly lowered. Further, in Comparative Example 6-7 in which no halogenated carbonate was added to the electrolytic solution, both the discharge capacity retention ratio and the high temperature storage characteristics were lowered. This is because the carboxylate containing fluorine added to the positive electrode preferentially forms a film on the negative electrode surface during charge and discharge, and lithium carboxylate is formed on the negative electrode, resulting in an increase in resistance. Moreover, it is thought that the film derived from the carboxylate containing fluorine was not sufficiently formed on the positive electrode surface, and the oxidation activity on the positive electrode surface could not be suppressed.

  In particular, the effect of high-temperature storage characteristics is remarkable when the amount of carboxylate added is in the range of 0.05 wt% to 10 wt%, and the amount of carboxylate added is 2.0 wt% to 10 wt%. By setting it as the following range, the remarkable effect was able to be acquired in both high temperature storage characteristics and a discharge capacity maintenance factor.

  Although one embodiment of the present invention has been specifically described above, the present invention is not limited to the above-described embodiment, and various modifications based on the technical idea of the present invention are possible.

  For example, the numerical values given in the above embodiment are merely examples, and different numerical values may be used as necessary. Moreover, it can be used for batteries having shapes such as a laminate film type, a square type other than a cylindrical type, and a coin type.

DESCRIPTION OF SYMBOLS 1 ... Exterior member 2 ... Adhesion film 10, 30, 53 ... Winding electrode body 11, 35 ... Positive electrode lead 12, 36 ... Negative electrode lead 13, 31 ... Positive electrode 13A, 31A ... Positive current collector 13B, 31B ... Positive electrode active material layer 14, 32 ... Negative electrode 14A, 32A ... Negative electrode current collector 14B, 32B ... Negative electrode active material layer 15, 33 ... Separator 16 ... Electrolyte 17 ... Protective tape 21 ... Battery can 22,23 ... Insulating plate 24 ... Battery cover 25 ... Safety valve mechanism 25A ... Disk plate 26 ... Heat feeling Resistance element 27 ... Gasket 34 ... Center pin

Claims (13)

A current collector and a positive electrode active material layer containing a positive electrode active material;
The positive electrode for nonaqueous electrolyte batteries in which the carboxylate which has at least one of a fluorine atom and a chlorine atom exists in the surface of the said positive electrode active material layer. The positive electrode for a nonaqueous electrolyte battery according to claim 1, wherein the carboxylate is at least one of structures represented by formula (1) and formula (2).

(In the formula, A _{1 to} A ₃ are Li, Na, K, Mg, Ca, Sr, Ba, and at least one of A ₂ and A ₃ may be a hydrogen atom. B is CF ₃ , CHF. ₂ and a functional group represented by CH ₂ F and CH _3. )
Note that D1 and D2 have a structure represented by the formulas (3) and (4).

(Where 0 ≦ (a, c, d, f) ≦ 2, and 1 ≦ b ≦ 16, and 1 ≦ e ≦ 16, X is a fluorine atom, part of which is a hydrogen atom or other And may be substituted with an alkyl group which may contain a halogen atom.) The positive electrode for a non-aqueous electrolyte battery according to claim 2, wherein the positive electrode active material is a composite oxide mainly containing nickel as a transition metal. A positive electrode in which a positive electrode active material layer containing a positive electrode active material is formed on at least one surface of the positive electrode current collector;
A negative electrode in which a negative electrode active material layer containing a negative electrode active material is formed on at least one surface of the negative electrode current collector;
A separator provided between the positive electrode and the negative electrode;
With electrolyte,
A nonaqueous electrolyte battery in which a carboxylate having at least one of a fluorine atom and a chlorine atom is present on the surface of the positive electrode active material layer. The non-aqueous electrolyte battery according to claim 4, wherein the carboxylate is at least one of structures represented by formula (1) and formula (2).

(In the formula, A _{1 to} A ₃ are Li, Na, K, Mg, Ca, Sr, Ba, and at least one of A ₂ and A ₃ may be a hydrogen atom. B is CF ₃ , CHF. ₂ and a functional group represented by CH ₂ F and CH _3. )
Note that D1 and D2 have a structure represented by the formulas (3) and (4).

(Where 0 ≦ (a, c, d, f) ≦ 2, and 1 ≦ b ≦ 16, and 1 ≦ e ≦ 16, X is a fluorine atom, part of which is a hydrogen atom or other And may be substituted with an alkyl group which may contain a halogen atom.) The nonaqueous electrolyte battery according to claim 5, wherein a film derived from at least one of a cyclic anhydride, a cyclic carbonate having an unsaturated bond, and a halogenated cyclic carbonate is formed on the surface of the negative electrode active material layer. The halogenated cyclic ester carbonate is at least one of 4-fluoro-1,3-dioxolan-2-one and 4,5-difluoro-1,3-dioxolan-2-one. The nonaqueous electrolyte battery described. A positive electrode mixture is prepared by mixing a positive electrode active material, a conductive additive, a binder, a solvent, and at least one of carboxylic acid and carboxylate having at least one of a fluorine atom and a chlorine atom. Forming a positive electrode active material layer comprising the positive electrode mixture on at least one surface of the current collector to produce a positive electrode;
A negative electrode active material, a binder, and a solvent are mixed to prepare a negative electrode mixture, and a negative electrode active material layer made of the negative electrode mixture is formed on at least one surface of the negative electrode current collector to form a negative electrode. Manufacturing process;
Adjusting the electrolyte by mixing a non-aqueous solvent and an electrolyte salt;
Producing a battery element in which the positive electrode and the negative electrode are laminated via a separator;
A step of sheathing the battery element and the electrolyte with an exterior member;
And a step of providing a carboxylate having at least one of a fluorine atom and a chlorine atom derived from at least one of the carboxylic acid and the carboxylate on the surface of the positive electrode by charging the non-aqueous electrolyte battery. The non-addition amount according to claim 8, wherein an addition amount of the carboxylic acid and the carboxylate salt having at least one of the fluorine atom and the chlorine atom is 0.01 wt% or more and 5.0 wt% or less with respect to the positive electrode active material. A method for producing a water electrolyte battery. In at least one of the step of adjusting the electrolyte or the step of preparing the negative electrode, at least one of a cyclic anhydride, a cyclic carbonate having an unsaturated bond, and a halogenated cyclic carbonate is added to the electrolyte or the negative electrode mixture. The manufacturing method of the nonaqueous electrolyte battery according to claim 9 to be added. The halogenated cyclic carbonate is at least one of 4-fluoro-1,3-dioxolan-2-one and 4,5-difluoro-1,3-dioxolan-2-one. The nonaqueous electrolyte battery described. The method for producing a nonaqueous electrolyte battery according to claim 11, wherein the addition amount of the halogenated cyclic carbonate is 0.01 wt% or more and 10 wt% or less with respect to the nonaqueous solvent. The method for producing a non-aqueous electrolyte battery according to claim 8, wherein the carboxylate is at least one of structures represented by formula (1) and formula (2).

(In the formula, A _{1 to} A ₃ are Li, Na, K, Mg, Ca, Sr, Ba, and at least one of A ₂ and A ₃ may be a hydrogen atom. B is CF ₃ , CHF. ₂ and a functional group represented by CH ₂ F and CH _3. )
Note that D1 and D2 have a structure represented by the formulas (3) and (4).

(Where 0 ≦ (a, c, d, f) ≦ 2, and 1 ≦ b ≦ 16, and 1 ≦ e ≦ 16, X is a fluorine atom, part of which is a hydrogen atom or other And may be substituted with an alkyl group which may contain a halogen atom.)

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