JP2011086468A - Nonaqueous electrolyte battery - Google Patents

Abstract

The present invention can ensure good conductivity and improve battery characteristics such as charge / discharge cycle characteristics.
A positive electrode 33 is provided with a positive electrode active material layer 33B on both surfaces of a positive electrode current collector 33A. The positive electrode active material layer 33B includes a lithium phosphate compound having an olivine type crystal structure, carbon black having a fibrous carbon and a hollow shell structure as a conductive agent, and polyvinylidene fluoride as a binder.
[Selection] Figure 2

Description

  The present invention relates to a non-aqueous electrolyte battery. More specifically, the present invention relates to a non-aqueous electrolyte battery using a lithium phosphate compound having an olivine crystal structure as a positive electrode.

  In recent years, many portable electronic devices such as a camera-type VTR (Video Tape Recorder), a mobile phone, and a laptop 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.

  Batteries using non-aqueous electrolytes, especially lithium ion secondary batteries, are expected to have higher energy density than lead batteries and nickel cadmium batteries, which are conventional aqueous electrolyte secondary batteries. The market is growing and the market is growing significantly.

  In particular, since the characteristics of lithium ion secondary batteries such as light weight and high energy density are suitable for use in electric vehicles and hybrid electric vehicles, studies aiming to increase the size and output of the batteries have become active.

In a nonaqueous secondary battery represented by a lithium ion secondary battery, an oxide positive electrode such as LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ is generally used as a positive electrode active material. This is because a high capacity, a high voltage can be obtained, and a high filling property can be obtained, which is advantageous for reducing the size and weight of portable devices.

  However, these positive electrodes start releasing oxygen at 200 ° C. to 300 ° C. when heated in a charged state. When oxygen release starts, the flammable organic electrolyte solution is used as the electrolyte solution, so there is a risk that the battery will run out of heat. Therefore, when an oxide positive electrode is used, it is not easy to ensure safety particularly in a large battery.

Accordingly, a positive electrode active material having an olivine type crystal structure such as LiFePO ₄ has been proposed. This positive electrode active material having an olivine-type crystal structure is a positive electrode material that is extremely safe and does not release oxygen even when the temperature exceeds 350 ° C.

In a positive electrode material having an olivine type crystal structure such as LiFePO ₄ , charge / discharge proceeds in a two-layer coexistence state of LiFePO ₄ and FePO ₄ , and thus the potential flatness is very high. For this reason, when performing constant current / constant voltage charging, which is a charging method of a normal lithium ion battery, there is a feature that charging is performed almost in a constant current charging state. Therefore, in a battery using a positive electrode material having an olivine type crystal structure, the charge time can be shortened when charged at the same charge rate as compared with conventional positive electrode materials such as LiCoO ₂ , LiNiO ₂ and LiMn ₂ O _4. is there.

On the other hand, in the positive electrode active material having this olivine type crystal structure, insertion / desorption reaction during battery charging / discharging is slow and electric resistance is large as compared with conventional lithium cobalt oxide (LiCoO ₂ ). As the overvoltage increases, a sufficient charge / discharge capacity cannot be obtained.

  Therefore, in general, a positive electrode active material having an olivine type crystal structure is used for a positive electrode together with a carbon material as a conductive agent in order to reduce electric resistance. In addition, in the positive electrode active material with an olivine type crystal structure, in order to improve the low electron conductivity, the particle diameter of the active material itself is reduced, the specific surface area is increased, or carbon black having a large specific surface area is added. It has been proposed to do. (For example, see Patent Document 1)

JP 2007-35358 A

  However, in a positive electrode using an active material having a small particle diameter or carbon black having a large specific surface area, the required amount of a binder is increased because of poor filling properties. That is, in the production of the coated positive electrode, a positive electrode active material layer is formed on the current collector. However, the stability of the positive electrode mixture slurry required for forming this positive electrode active material layer, the current collector and the positive electrode active material layer, In order to obtain sufficient adhesion strength, the required amount of binder increases.

  When the required amount of the binder is increased, the carbon material used as the conductive agent is only carbon black, and if the content is small, there is a problem that the conductivity is not sufficient and the output characteristics are deteriorated. On the other hand, if the content of carbon black is increased in order to ensure conductivity, the adhesion strength between the current collector foil and the positive electrode active material particles is weakened, and the capacity when repeated charging and discharging is reduced. Problem arises.

  Accordingly, an object of the present invention is to provide a non-aqueous electrolyte battery that can ensure good conductivity and improve battery characteristics such as charge / discharge cycle characteristics when a positive electrode active material having an olivine crystal structure is used for the positive electrode. It is to provide.

  In order to solve the above-described problems, the present invention includes a positive electrode including a positive electrode active material, a conductive agent, and a binder, a negative electrode, and a nonaqueous electrolyte. The positive electrode active material is lithium having an olivine crystal structure. The phosphoric acid compound is included, the conductive agent includes carbon black having a hollow shell structure and fibrous carbon, and the content of the binder is based on the total mass of the positive electrode active material, the conductive auxiliary agent, and the binder. 2 wt% or more and 5 wt% or less, the content of the conductive agent is 40 wt% or more and 60 wt% or less with respect to the content of the binder, and the content of fibrous carbon is equal to the content of the conductive agent. On the other hand, the nonaqueous electrolyte battery is 10 wt% or more and 20 wt% or less.

  In the present invention, a small amount of fibrous carbon is added to carbon black having a hollow shell-like structure to ensure adhesion between the positive electrode active material particles and to ensure conductivity. Furthermore, the adhesiveness between the positive electrode active material particles and the current collector can be improved by covering the surface of the fibrous carbon with the binder. That is, the contact strength between the positive electrode active material particles can be improved by contacting the positive electrode active material particles with the fibrous carbon covered with the binder. In addition, the contact strength between the positive electrode active material particles and the current collector can be improved by contacting the positive electrode active material particles and the current collector through the fibrous carbon covered with the binder. . Thereby, in the non-aqueous electrolyte battery using the positive electrode active material having an olivine type crystal structure, good conductivity can be secured and battery characteristics such as charge / discharge cycle characteristics can be improved.

  According to this invention, while having favorable electroconductivity, there exists an effect that battery characteristics, such as charging / discharging cycling characteristics, can be improved.

It is a disassembled perspective view which shows the structural example of the battery by 1st Embodiment of this invention. It is sectional drawing along the II line of the winding electrode body in FIG. It is sectional drawing which shows the structural example of the battery by the 2nd Embodiment of this invention. It is sectional drawing to which a part of winding electrode body in FIG. 3 was expanded.

Embodiments of the present invention will be described below with reference to the drawings. The description will be given in the following order.
1. First embodiment (first example of battery)
2. Second embodiment (second example of battery)
3. Third embodiment (third example of battery)
4). Other embodiment (modification)

1. First Embodiment A battery according to a first embodiment of the present invention will be described. This battery is, for example, a lithium ion secondary battery in which the capacity of the negative electrode is represented by a capacity component based on insertion and extraction of lithium as an electrode reactant. This battery is a battery using a gel electrolyte in which an electrolytic solution containing an organic solvent is held in a polymer compound.

<Battery configuration>
FIG. 1 shows an exploded perspective configuration of a battery according to a first embodiment of the present invention. In this battery, a wound electrode body 30 to which a positive electrode lead 31 and a negative electrode lead 32 are attached is accommodated in a film-shaped exterior member 40. This battery has a battery structure called a laminate film type.

  For example, the positive electrode lead 31 and the negative electrode lead 32 are each led out in the same direction from the inside of the exterior member 40 toward the outside. These are made of, for example, a metal material such as aluminum (Al), copper (Cu), nickel (Ni), or stainless steel (SUS), and have a thin plate shape or a mesh shape.

  The exterior member 40 is made of, for example, a rectangular aluminum laminated film in which a nylon film, an aluminum foil, and a polyethylene film are bonded together in this order. In the exterior member 40, for example, a polyethylene film is opposed to the wound electrode body 30, and each outer edge portion is in close contact with each other by fusion or an adhesive. An adhesive film 41 is inserted between the exterior member 40 and the positive electrode lead 31 and the negative electrode lead 32 to prevent intrusion of outside air. The adhesion film 41 is made of a material having adhesion to the positive electrode lead 31 and the negative electrode lead 32, for example, a polyolefin resin such as polyethylene, polypropylene, modified polyethylene, or modified polypropylene.

  The exterior member 40 may be constituted by a laminate film having another structure instead of the above-described three-layer aluminum laminate film, or may be constituted by a polymer film such as polypropylene or a metal film. May be.

  FIG. 2 shows a cross-sectional configuration along line II of the spirally wound electrode body 30 shown in FIG. The wound electrode body 30 is obtained by winding a positive electrode 33 and a negative electrode 34 after being laminated via a separator 35 and an electrolyte 36, and an outermost peripheral portion thereof is protected by a protective tape 37.

<Positive electrode>
In the positive electrode 33, for example, a positive electrode active material layer 33B is provided on both surfaces of a positive electrode current collector 33A having a pair of opposed surfaces. The positive electrode current collector 33A is made of, for example, a metal material such as aluminum (Al), nickel (Ni), or stainless steel (SUS). The positive electrode active material layer 33B includes a positive electrode active material, a conductive agent, and a binder.

(Positive electrode active material)
As the positive electrode active material, a lithium phosphate compound having an olivine type crystal structure is used. The lithium phosphate compound having an olivine type crystal structure is preferably secondary particles.

  Note that a carbon material or the like may be supported on the surface of the lithium phosphate compound, for example, in order to improve conductivity.

  The secondary particles can be granulated by a commonly used method such as spray drying. In the spray drying method, the primary particles described above are dispersed in a solvent together with, for example, a carbon source material, and sprayed in a high-temperature atmosphere. Can be formed.

  Examples of the lithium phosphate compound having an olivine type crystal structure include a compound represented by Formula I.

(Chemical I)
LiM _x PO ₄
(In the formula, M is cobalt (Co), manganese (Mn), iron (Fe), nickel (Ni), magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), vanadium (V ), Niobium (Nb), copper (Cu), zinc (Zn), molybdenum (Mo), calcium (Ca), strontium (Sr), tungsten (W) and zirconium (Zr). X is 0 <x ≦ 1.)

Examples of the compound represented by Chemical I, LiFePO _{4 and, LiFe 1-y Me y PO} 4, LiFe 1-yz Me1 y Me2 z PO 4, LiCoPO 4, LiCo 1-y Me y PO 4, LiMn 1-y Me _y PO ₄ (wherein, Me, Me1, Me2 is cobalt (Co), manganese (Mn), iron (Fe), nickel (Ni), magnesium (Mg), aluminum (Al), boron (B), From titanium (Ti), vanadium (V), niobium (Nb), copper (Cu), zinc (Zn), molybdenum (Mo), calcium (Ca), strontium (Sr), tungsten (W) and zirconium (Zr) 1 is selected, and 0 <y <1 and 0 <z <1).

(Binder)
Examples of the binder include fluorine polymer compounds such as polyvinylidene fluoride (PVdF).

(Conductive agent)
As the conductive agent, fibrous carbon and carbon black having a hollow shell structure are used in combination.

[Carbon black with hollow shell structure]
Carbon black is a submicron fine particle of which almost 95% or more is made of amorphous carbonaceous material. Examples of the carbon black having a hollow shell structure include ketjen black. Ketjen black is a kind of conductive carbon black, has a hollow shell-like structure, has a large number of primary particles per unit mass, and is characterized by a large specific surface area. As the ketjen black, commercially available products such as “manufactured by Lion Corporation, trade name: ketjen black EC” can be used.

[Fibrous carbon]
As the fibrous carbon, for example, vapor grown carbon fiber synthesized by a vapor phase method can be used. Vapor-grown carbon fibers can be produced, for example, by a method in which an organic compound vaporized with iron serving as a catalyst is blown into a high-temperature atmosphere. Vapor-grown carbon fiber can be used as it is produced, heat treated at about 800 ° C. to 1500 ° C., or graphitized at about 2000 ° C. to 3000 ° C. The carbonized one is preferable because the crystallinity of carbon is advanced and it has high conductivity and high pressure resistance.

[Action of carbon black having fibrous carbon and hollow shell structure]
Carbon black having a hollow shell-like structure is considered to form a short distance conductive network according to the size of the basic particles of the aggregate. Fibrous carbon forms a long-distance conductive network corresponding to the length of the major axis. Since the short-range conductive network of carbon black having a hollow shell structure is considered to be reinforcingly bridged by the long-range conductive network of fibrous carbon, it is considered that the conductivity can be improved.

  In addition, since the surface of the fibrous carbon is covered with the binder, the adhesion is improved as compared with the case where only carbon black is used as the conductive agent. That is, the contact strength between the positive electrode active material particles can be improved by contacting the positive electrode active material particles with the fibrous carbon covered with the binder. In addition, the contact strength between the positive electrode active material particles and the current collector can be improved by contacting the positive electrode active material particles and the current collector through the fibrous carbon covered with the binder. .

  The conductivity can be improved by improving the adhesion strength between the positive electrode active material particles. Since the peel strength of the positive electrode active material layer can be improved by improving the adhesion strength between the positive electrode active material particles and the current collector, battery characteristics such as charge / discharge cycle characteristics can be improved.

(Contents of positive electrode active material, conductive agent and binder)
The contents of the positive electrode active material, the conductive agent, and the binder will be described. For example, when polyvinylidene fluoride (PVdF) is used as the binder and carbon black and vapor-grown carbon fiber (fibrous carbon) having a hollow shell structure are used as the conductive agent, the amount of the binder, the conductivity The amount of the agent, the amount of fibrous carbon, and the amount of carbon black having a hollow shell structure are set as follows.

Binder amount: 2 wt% or more and 5 wt% or less with respect to the total amount of the positive electrode active material, the conductive agent and the binder.
Conductive agent amount: 40 wt% or more and 60 wt% or less with respect to the binder amount.
Fibrous carbon content: 10 wt% or more and 20 wt% or less with respect to the conductive agent amount.
Carbon black amount having a hollow shell structure: 80 wt% or more and 90 wt% or less with respect to the amount of the conductive agent.

[Binder amount]
The amount of the binder is 2 wt% or more and 5 wt% or less with respect to the total amount of the positive electrode active material, the conductive agent, and the binder. When the content of the binder is less than the above numerical range, the adhesion to the current collector foil is deteriorated. When the content of the binder is larger than the above numerical range, the load characteristics are deteriorated. Moreover, it is preferable that content of a binder is 3 wt% or more and 4 wt% or less with respect to the total amount of a positive electrode active material, a electrically conductive agent, and a binder.

Note that when the positive electrode active material having an olivine type crystal structure is used, the amount of the binder is larger than when a cobalt-based positive electrode active material such as LiCoO ₂ is used. That is, when a cobalt-based positive electrode active material is used, even when the amount of the binder is large, it does not exceed 2 wt%. However, when a positive electrode active material having an olivine type crystal structure is used, a refined active material is used. Therefore, it is necessary to increase the amount of the binder to 2 wt% or more and 5% wt or less.

[Amount of conductive agent]
The amount of the conductive agent is 40 wt% or more and 60 wt% or less with respect to the binder amount. If the amount of the conductive agent is less than the above numerical range, the conductivity is lowered. Even if the amount of the conductive agent is increased from the above numerical range, the conductivity is not dramatically improved. The amount of the conductive agent is preferably 45 wt% or more and 55 wt% or less with respect to the binder amount.

[Fibrous carbon content]
The amount of fibrous carbon is 10 wt% or more and 20 wt% or less with respect to the amount of conductive agent. Within the above numerical range, more excellent characteristics can be obtained. Moreover, it is preferable that the amount of fibrous carbon is 12 wt% or more and 16 wt% or less with respect to the amount of conductive agent.

(Amount of carbon black with hollow shell structure)
The amount of carbon black having a hollow shell structure is 80 wt% or more and 90 wt% or less with respect to the amount of the conductive agent. Within the above numerical range, more excellent characteristics can be obtained. The amount of carbon black having a hollow shell structure is preferably 84 wt% or more and 88 wt% or less.

(Porosity of positive electrode active material layer 33B)
The porosity of the positive electrode active material layer 33B is set to 30% or more and 45% or less, for example. For example, when a cobalt-based positive electrode active material is used, it is set to 25% or less. However, since the olivine type crystal structure of the positive electrode active material uses a refined material, the filling property is poor, so the above range is not exceeded. Is set.

(Peeling strength of positive electrode active material layer 33B)
The peel strength of the positive electrode active material layer 33B is set to, for example, 10 mN / mm or more and 80 mN / mm or less.

<Negative electrode>
In the negative electrode 34, for example, a negative electrode active material layer 22B is provided on both surfaces of a negative electrode current collector 22A having a pair of opposed surfaces. The negative electrode current collector 22A is made of, for example, a metal material such as copper (Cu), nickel (Ni), or stainless steel (SUS). The negative electrode active material layer 22B includes, for example, any one or more of negative electrode materials capable of inserting and extracting lithium as a negative electrode active material. The negative electrode active material layer 22B may contain a conductive agent, a binder, or the like as necessary.

(Negative electrode active material)
Examples of the negative electrode material capable of inserting and extracting lithium include a carbon material, a metal oxide, or a polymer compound.

  Examples of the carbonaceous material include non-graphitizable carbon, graphitizable carbon, artificial graphite such as MCMB (mesocarbon microbeads), natural graphite, pyrolytic carbons, cokes, graphites, and glassy carbons. Organic polymer compound fired bodies, carbon blacks, carbon fibers or activated carbon. Among these, examples of coke include pitch coke, needle coke, and petroleum coke. An organic polymer compound fired body refers to a carbonized material obtained by firing a polymer material such as phenol resin or furan resin at an appropriate temperature, and part of it is non-graphitizable carbon or graphitizable carbon. Some are classified as: Examples of the metal oxide include iron oxide, ruthenium oxide, and molybdenum oxide. Examples of the polymer material include polyacetylene and polypyrrole.

  Examples of the negative electrode material capable of inserting and extracting lithium include materials capable of inserting and extracting lithium and containing at least one of a metal element and a metalloid element as a constituent element. . Use of such a negative electrode material is preferable because a high energy density can be obtained. This negative electrode material may be a single element or an alloy or a compound of a metal element or a metalloid element, or may have at least a part of one or more of these phases. In the present invention, alloys include those containing one or more metal elements and one or more metalloid elements in addition to those composed of two or more metal elements. The alloy in the present invention may contain a nonmetallic element. This structure includes a solid solution, a eutectic (eutectic mixture), an intermetallic compound, or one in which two or more of them coexist.

  Examples of the metal element or metalloid element constituting the negative electrode material include a metal element or metalloid element capable of forming an alloy with lithium. Specifically, magnesium (Mg), boron (B), aluminum (Al), gallium (Ga), indium (In), silicon (Si), germanium (Ge), tin, lead (Pb), bismuth (Bi) ), Cadmium (Cd), silver (Ag), zinc (Zn), hafnium (Hf), zirconium (Zr), yttrium (Y), palladium (Pd) or platinum (Pt). Among these, at least one of silicon (Si) and tin (Sn) is particularly preferable. This is because the ability to occlude and release lithium is large, and a high energy density can be obtained.

  Examples of the negative electrode material containing at least one of silicon (Si) and tin (Sn) include, for example, a simple substance of silicon, an alloy or a compound, a simple substance of tin, an alloy or a compound, or one or more of these. Examples thereof include materials having a phase at least partially. These may be used alone or in combination of two or more.

  As an alloy of silicon, 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). Including. Examples of tin alloys include silicon (Si), nickel (Ni), copper (Cu), iron (Fe), cobalt (Co), and manganese (Mn) as second constituent elements other than tin (Sn). , Zinc (Zn), indium (In), silver (Ag), titanium (Ti), germanium (Ge), bismuth (Bi), antimony (Sb) and chromium (Cr). Including.

  Examples of the tin compound or the silicon compound include those containing oxygen (O) or carbon (C), and include the second constituent element described above in addition to tin (Sn) or silicon (Si). You may go out.

  In particular, as a negative electrode material containing at least one of silicon (Si) and tin (Sn), for example, tin (Sn) is used as the first constituent element, and in addition to the tin (Sn), the second configuration What contains an element and a 3rd structural element is preferable. Of course, this negative electrode material may be used together with the negative electrode material described above. The second constituent element is cobalt (Co), iron (Fe), magnesium (Mg), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), nickel (Ni), copper (Cu ), Zinc (Zn), gallium (Ga), zirconium (Zr), niobium (Nb), molybdenum (Mo), silver (Ag), indium (In), cerium (Ce), hafnium (Hf), tantalum (Ta) ), Tungsten (W), bismuth (Bi), and silicon (Si). The third constituent element is at least one selected from the group consisting of boron (B), carbon (C), aluminum (Al), and phosphorus (P). This is because the cycle characteristics are improved by including the second element and the third element.

  Among them, tin (Sn), cobalt (Co) and carbon (C) are included as constituent elements, and the content of carbon (C) is in the range of 9.9 mass% to 29.7 mass%, tin (Sn) In addition, a CoSnC-containing material in which the ratio of cobalt (Co) to the total of cobalt (Co) (Co / (Sn + Co)) is in the range of 30% by mass to 70% by mass is preferable. This is because in such a composition range, a high energy density is obtained and an excellent cycle characteristic is obtained.

  This CoSnC-containing material may further contain other constituent elements as necessary. Examples of other constituent elements include silicon (Si), iron (Fe), nickel (Ni), chromium (Cr), indium (In), niobium (Nb), germanium (Ge), titanium (Ti), and molybdenum. (Mo), aluminum (Al), phosphorus (P), gallium (Ga), bismuth (Bi), and the like are preferable, and two or more of them may be included. This is because the capacity characteristic or cycle characteristic is further improved.

  The CoSnC-containing material has a phase containing tin (Sn), cobalt (Co), and carbon (C), and this phase has a low crystallinity or an amorphous structure. preferable. In the CoSnC-containing material, it is preferable that at least a part of carbon that is a constituent element is bonded to a metal element or a metalloid element that is another constituent element. The decrease in cycle characteristics is thought to be due to aggregation or crystallization of tin (Sn) or the like, but such aggregation or crystallization is suppressed when carbon is combined with other elements. It is.

  Examples of the measurement method for examining the bonding state of elements include X-ray photoelectron spectroscopy (XPS). In this XPS, in the apparatus calibrated so that the 4f orbit (Au4f) peak of gold atom is obtained at 84.0 eV, the peak of 1s orbit (C1s) of carbon appears at 284.5 eV in the case of graphite. . Moreover, if it is surface contamination carbon, it will appear at 284.8 eV. In contrast, when the charge density of the carbon element is high, for example, when carbon is bonded to a metal element or a metalloid element, the C1s peak appears in a region lower than 284.5 eV. That is, when the peak of the synthetic wave of C1s obtained for the CoSnC-containing material appears in a region lower than 284.5 eV, a metal in which at least a part of carbon (C) contained in the CoSnC-containing material is another constituent element Bonded with element or metalloid element.

  In XPS, for example, the peak of C1s is used to correct the energy axis of the spectrum. Usually, since surface-contaminated carbon exists on the surface, the C1s peak of the surface-contaminated carbon is set to 284.8 eV, which is used as an energy standard. In XPS, the waveform of the C1s peak is obtained as a form including the surface contamination carbon peak and the carbon peak in the CoSnC-containing material. For example, by analyzing using commercially available software, the surface contamination The carbon peak and the carbon peak in the CoSnC-containing material are separated. In the waveform analysis, the position of the main peak existing on the lowest bound energy side is used as the energy reference (284.8 eV).

(Conductive agent)
Examples of the conductive agent include carbon materials such as graphite and carbon black. These may be used alone or in combination of two or more. Note that the conductive agent may be a metal material or a conductive polymer as long as it is a conductive material.

(Binder)
Examples of the 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 used alone or in combination of two or more. However, as shown in FIG. 1, when the positive electrode 33 and the negative electrode 34 are wound, it is preferable to use a styrene butadiene rubber or a fluorine rubber having high flexibility.

(Electrolytes)
The electrolyte 36 includes an electrolytic solution and a polymer compound that holds the electrolytic solution, and is in a so-called gel form. The gel electrolyte is preferable because high ion conductivity (for example, 1 mS / cm or more at room temperature) is obtained and liquid leakage is prevented.

[Electrolyte]
The electrolytic solution includes a solvent and an electrolyte salt. Examples of the solvent include carbonate solvents such as ethylene carbonate, propylene carbonate, vinylene carbonate, dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate, 1,2-dimethoxyethane, 1-ethoxy-2-methoxyethane, 1,2 -Ether solvents such as diethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, lactone solvents such as γ-butyrolactone, γ-valerolactone, δ-valerolactone, ε-caprolactone, nitrile solvents such as acetonitrile, sulfolane solvents Nonaqueous solvents such as phosphoric acids, phosphoric acid ester solvents, and pyrrolidones. Any one kind of solvents may be used alone, or two or more kinds thereof may be mixed and used. When propylene carbonate is contained in the solvent, it is preferable to contain 40 wt% or more of propylene carbonate with respect to the electrolytic solution.

As the electrolyte salt, lithium salts such as LiPF ₆ , LiClO ₄ , LiBF ₄ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiAsF ₆ can be used. Any one of these lithium salts may be used, or two or more thereof may be mixed and used.

[Polymer compound]
Examples of the polymer compound include polyacrylonitrile, polyvinylidene fluoride, a copolymer of polyvinylidene fluoride and polyhexafluoropyrene, polytetrafluoroethylene, polyhexafluoropropylene, polyethylene oxide, polypropylene oxide, polyphosphazene, poly Examples thereof include siloxane, polyvinyl acetate, polyvinyl alcohol, polymethyl methacrylate, polyacrylic acid, polymethacrylic acid, styrene-butadiene rubber, nitrile-butadiene rubber, polystyrene, and polycarbonate. These may be used alone or in combination of two or more. In particular, from the viewpoint of electrochemical stability, polyacrylonitrile, polyvinylidene fluoride, polyhexafluoropropylene, polyethylene oxide, or the like is preferable.

  The content of the electrolyte salt is preferably in the range of 0.3 mol / kg or more and 3.0 mol / kg or less with respect to the solvent. Outside this range, the ionic conductivity is extremely lowered, so that there is a possibility that sufficient capacity characteristics and the like may not be obtained. However, the solvent in this case is not only a liquid solvent but also a broad concept including those having ion conductivity capable of dissociating the electrolyte salt. Accordingly, when a polymer compound having ion conductivity is used, the polymer compound is also included in the solvent.

(Separator)
The separator 35 separates the positive electrode 33 and the negative electrode 34 and allows lithium ions to pass through while preventing a short circuit of current due to contact between the two electrodes. The separator 35 is made of, for example, a porous film made of a synthetic resin such as polytetrafluoroethylene, polypropylene, or polyethylene, or a porous film made of ceramic, and these two or more kinds of porous films are laminated. It may be a structure. Among them, a porous film made of polyolefin is preferable because it is excellent in short-circuit preventing effect and can improve battery safety by a shutdown effect. In particular, polyethylene is preferable because a shutdown effect can be obtained within a range of 100 ° C. or more and 160 ° C. or less and the electrochemical stability is excellent. Polypropylene is also preferable, and other resins having chemical stability may be copolymerized with polyethylene or polypropylene, or may be blended.

<Battery manufacturing method>
The battery described above is manufactured as follows, for example.

  First, a precursor solution containing an electrolytic solution, a polymer compound, and a mixed solvent is prepared, applied to each of the positive electrode 33 and the negative electrode 34, and then the mixed solvent is volatilized to form the electrolyte 36. Subsequently, the positive electrode lead 31 is attached to the positive electrode current collector 33A, and the negative electrode lead 32 is attached to the negative electrode current collector 34A.

  Subsequently, after laminating the positive electrode 33 and the negative electrode 34 on which the electrolyte 36 is formed via the separator 35, the positive electrode 33 and the negative electrode 34 are wound in the longitudinal direction, and the protective tape 37 is adhered to the outermost peripheral portion. Form. Subsequently, for example, the wound electrode body 30 is sandwiched between the exterior members 40 and the outer edge portions of the exterior member 40 are brought into close contact with each other by thermal fusion or the like, thereby enclosing the wound electrode body 30. At that time, the adhesion film 41 is inserted between the positive electrode lead 31 and the negative electrode lead 32 and the exterior member 40. Thereby, the battery shown in FIG. 1 and FIG. 2 can be obtained.

  Moreover, you may manufacture this battery as follows.

  First, after attaching the positive electrode lead 31 and the negative electrode lead 32 to the positive electrode 33 and the negative electrode 34, respectively, the positive electrode 33 and the negative electrode 34 are stacked and wound through the separator 35, and the protective tape 37 is adhered to the outermost periphery. . Thereby, the wound body which is the precursor of the wound electrode body 30 is formed.

  Next, the wound body is sandwiched between the exterior members 40, and the remaining outer peripheral edge portions except for the outer peripheral edge portion on one side are brought into close contact with each other by heat fusion or the like, thereby being housed inside the bag-shaped exterior member 40. Next, an electrolyte composition containing an electrolytic solution, a monomer that is a raw material of the polymer compound, a polymerization initiator, and other materials such as a polymerization inhibitor as necessary is prepared, and a bag-shaped exterior member After injecting into the inside of 40, the opening part of the exterior member 40 is sealed by heat sealing or the like. Finally, the gel electrolyte 36 is formed by thermally polymerizing the monomer to obtain a polymer compound. Thereby, the battery shown in FIG. 1 and FIG. 2 can be obtained.

  Moreover, you may manufacture this battery as follows.

  First, the positive electrode lead 31 and the negative electrode lead 32 are attached to the positive electrode 33 and the negative electrode 34, respectively. Next, the positive electrode 33 and the negative electrode 34 are laminated and wound via a separator 35 coated with a polymer compound on both sides, and a protective tape 37 is adhered to the outermost peripheral portion, whereby a wound electrode body. 30 is formed.

  Examples of the polymer compound include a polymer containing vinylidene fluoride as a component, that is, a homopolymer, a copolymer, or a multi-component copolymer. Specifically, a binary copolymer having polyvinylidene fluoride, vinylidene fluoride and hexafluoropropylene as components, and a ternary copolymer having vinylidene fluoride, hexafluoropropylene and chlorotrifluoroethylene as components. Etc. In addition, the high molecular compound may contain the other 1 type, or 2 or more types of high molecular compound with the polymer which uses the above-mentioned vinylidene fluoride as a component.

  Next, after injecting the above-described electrolyte into the exterior member 40, the opening of the exterior member 40 is sealed by thermal fusion or the like. Finally, the exterior member 40 is heated while applying a load, and the separator 35 is brought into close contact with the positive electrode 33 and the negative electrode 34 through the polymer compound. Thereby, the electrolytic solution is impregnated in the polymer compound, and the polymer compound is gelled to form the electrolyte 36. Thus, the battery shown in FIGS. 1 and 2 can be obtained.

<Effect>
In the nonaqueous electrolyte battery according to the first embodiment of the present invention, good conductivity can be ensured and battery characteristics such as charge / discharge cycle characteristics can be improved.

2. Second Embodiment A battery according to a second embodiment of the present invention will be described. The battery according to the second embodiment of the present invention is the battery according to the first embodiment except that the electrolytic solution is used as it is instead of the electrolytic solution held in the polymer compound (electrolyte 36). It is the same. Therefore, in the following, the configuration will be described in detail with a focus on differences from the first embodiment.

<Battery configuration>
In the battery according to the second embodiment of the present invention, an electrolytic solution is used instead of the gel electrolyte 36. Therefore, the wound electrode body 30 has a configuration in which the electrolyte 36 is omitted, and the separator 35 is impregnated with the electrolytic solution.

<Battery manufacturing method>
This battery is manufactured as follows, for example.

  First, for example, a positive electrode active material, a binder, and a conductive agent are mixed to prepare a positive electrode mixture, and dispersed in a solvent such as N-methyl-2-pyrrolidone to prepare a positive electrode mixture slurry. Next, this positive electrode mixture slurry is applied to both sides, dried and compression molded to form the positive electrode active material layer 33B, and the positive electrode 33 is produced. Next, for example, the positive electrode lead 31 is joined to the positive electrode current collector 33A by, for example, ultrasonic welding or spot welding.

  Further, for example, a negative electrode material and a binder are mixed to prepare a negative electrode mixture, and dispersed in a solvent such as N-methyl-2-pyrrolidone to prepare a negative electrode mixture slurry. Next, the negative electrode mixture slurry is applied to both surfaces of the negative electrode current collector 34A, dried, and compression molded to form the negative electrode active material layer 34B, whereby the negative electrode 34 is produced. Next, for example, the negative electrode lead 32 is joined to the negative electrode current collector 34A by, for example, ultrasonic welding or spot welding.

  Subsequently, after the positive electrode 33 and the negative electrode 34 are wound through the separator 35 and sandwiched between the exterior members 40, an electrolytic solution is injected into the exterior member 40 to seal the exterior member 40. Thereby, the battery shown in FIGS. 1 and 2 is obtained.

<Effect>
The second embodiment of the present invention has the same effect as that of the first embodiment.

3. Third Embodiment FIG. 3 shows a sectional configuration of a battery according to a third embodiment of the present invention. This battery is a non-aqueous electrolyte battery using an electrolytic solution containing an organic solvent. This battery has a battery structure called a cylindrical type.

<Battery configuration>
In this battery, a wound electrode body 20 in which a positive electrode 21 and a negative electrode 22 are wound through a separator 23 and a pair of insulating plates 12 and 13 are housed in a battery can 11 having a substantially hollow cylindrical shape. Is. The battery can 11 is made of, for example, iron (Fe) plated with nickel (Ni), and one end and the other end thereof are closed and opened, respectively. The pair of insulating plates 12 and 13 are disposed so as to sandwich the wound electrode body 20 and extend perpendicular to the wound peripheral surface.

  A battery lid 14 and a safety valve mechanism 15 and a heat sensitive resistance element (Positive Temperature Coefficient; PTC element) 16 provided inside thereof are caulked through a gasket 17 at the open end of the battery can 11. The battery can 11 is hermetically sealed. The battery lid 14 is made of, for example, the same material as the battery can 11. The safety valve mechanism 15 is electrically connected to the battery lid 14 via the heat sensitive resistance element 16.

  In the safety valve mechanism 15, when the internal pressure becomes a certain level or more due to an internal short circuit or external heating, the electric power between the battery lid 14 and the wound electrode body 20 is reversed by reversing the disk plate 15 </ b> A. Connection is broken. The heat sensitive resistance element 16 limits the current by increasing the resistance in accordance with the temperature rise, and prevents abnormal heat generation due to a large current. The gasket 17 is made of, for example, an insulating material, and asphalt is applied to the surface thereof.

  For example, a center pin 24 is inserted in the center of the wound electrode body 20. In the wound electrode body 20, a positive electrode lead 25 made of aluminum (Al) or the like is connected to the positive electrode 21, and a negative electrode lead 26 made of nickel or the like is connected to the negative electrode 22. The positive electrode lead 25 is electrically connected to the battery lid 14 by welding to the safety valve mechanism 15, and the negative electrode lead 26 is electrically connected to the battery can 11 by welding.

  FIG. 2 shows an enlarged part of the spirally wound electrode body 20 shown in FIG. The positive electrode 21 is obtained by providing a positive electrode active material layer 21B on both surfaces of a positive electrode current collector 21A. The negative electrode 22 is provided with a negative electrode active material layer 22B on both surfaces of a negative electrode current collector 22A, and the negative electrode active material layer 22B is disposed so as to face the positive electrode active material layer 21B. The configurations of the positive electrode current collector 22A, the positive electrode active material layer 22B, the negative electrode current collector 22A, the negative electrode active material layer 22B, and the separator 23 are, for example, the same as those described in the first embodiment.

(Electrolyte)
The configuration is the same as that described in the first embodiment.

<Battery manufacturing method>
The battery described above is manufactured as follows, for example.

  First, for example, the positive electrode 21 is manufactured by forming the positive electrode active material layers 21B on both surfaces of the positive electrode current collector 21A. When forming the positive electrode active material layer 21B, a positive electrode mixture obtained by mixing a powder of a positive electrode active material, a conductive agent, and a binder is dispersed in a solvent such as N-methyl-2-pyrrolidone. A paste-like positive electrode mixture slurry is obtained. Then, the positive electrode mixture slurry is applied to the positive electrode current collector 21A and dried, followed by compression molding.

  For example, the negative electrode 22 is produced by forming the negative electrode active material layer 22B on both surfaces of the negative electrode current collector 22A according to the same procedure as that of the positive electrode 21.

  Next, the cathode lead 25 is attached by welding to the cathode current collector 21A, and the anode lead 26 is attached by welding to the anode current collector 22A.

  Next, the wound electrode body 20 is formed by winding the positive electrode 21 and the negative electrode 22 through the separator 23. And after welding the front-end | tip part of the positive electrode lead 25 to the safety valve mechanism 15 and welding the front-end | tip part of the negative electrode lead 26 to the battery can 11, the battery can 11 is sandwiched between the pair of insulating plates 12 and 13. Store inside.

  Next, an electrolytic solution is injected into the battery can 11 and impregnated in the separator 23. Finally, the battery lid 14, the safety valve mechanism 15, and the heat sensitive resistance element 16 are fixed to the opening end of the battery can 11 by caulking through the gasket 17. Thus, the battery shown in FIGS. 1 and 2 can be obtained.

<Effect>
In the third embodiment of the present invention, the same effect as in the first embodiment can be obtained.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these examples.

<Example 1>
A positive electrode mixture was prepared by mixing LiFePO ₄ powder, vapor-grown carbon fiber and ketjen black as a conductive agent, and polyvinylidene fluoride as a binder in the following mass ratio.
“LiFePO ₄ : Vapor growth carbon fiber: Ketjen black: Polyvinylidene fluoride = 97: 0.1: 0.9: 2”

  Next, this positive electrode mixture was dispersed in N-methyl-2-pyrrolidone as a solvent to form a positive electrode mixture slurry, which was uniformly applied to both surfaces of a positive electrode current collector made of a strip-shaped aluminum foil having a thickness of 20 μm.

  Next, a positive electrode active material layer was formed by compression molding with a roll press after a drying process, and then cut out to 50 mm × 350 mm to produce a positive electrode. An aluminum positive electrode lead was connected to one end of the positive electrode current collector.

  A negative electrode mixture was prepared by mixing mesocarbon microbeads (MCMB) as a negative electrode active material and polyvinylidene fluoride (PVdF) as a binder. Next, this negative electrode mixture was dispersed in N-methyl-2-pyrrolidone as a solvent to form a negative electrode mixture slurry, which was uniformly applied to both surfaces of a negative electrode current collector made of a strip-shaped copper foil having a thickness of 15 μm.

  Next, after forming a negative electrode active material layer by compression molding with a roll press after a drying process, the negative electrode was produced by cutting out to 52 mm × 370 mm. Thereafter, a negative electrode lead made of nickel was connected to one end of the negative electrode current collector.

Next, an electrolytic solution in which LiPF ₆ is dissolved in a mixed solvent in which ethylene carbonate (EC) and propylene carbonate (PC) are mixed at a volume ratio (EC: PC) = 60: 40 so as to be 0.7 mol / kg. Was made.

  Next, the electrolytic solution was held in a copolymer of vinylidene fluoride and hexafluoropropylene to obtain a gel electrolyte. The ratio of hexafluoropropylene in the copolymer was 6.9 wt%.

  Gel electrolytes were formed on both surfaces of the produced positive electrode and negative electrode, laminated and wound through a separator to obtain a wound electrode body. As the separator, a microporous membrane made of polyethylene was used. Next, this wound electrode body was covered with a laminate film, and the periphery of the wound electrode body was sealed. The nonaqueous electrolyte battery of Example 1 was produced as described above.

<Example 2>
Example 1 except that LiFePO ₄ powder, vapor-grown carbon fiber and ketjen black as a conductive agent, and polyvinylidene fluoride as a binder were mixed in the following mass ratio to prepare a positive electrode mixture. Similarly, a nonaqueous electrolyte battery of Example 2 was produced.
“LiFePO ₄ : Vapor growth carbon fiber: Ketjen black: Polyvinylidene fluoride = 96.8: 0.24: 0.96: 2”

<Example 3>
Example 1 except that LiFePO ₄ powder, vapor-grown carbon fiber and ketjen black as a conductive agent, and polyvinylidene fluoride as a binder were mixed in the following mass ratio to prepare a positive electrode mixture. Similarly, a nonaqueous electrolyte battery of Example 3 was produced.
“LiFePO ₄ : Vapor growth carbon fiber: Ketjen black: Polyvinylidene fluoride = 95.8: 0.12: 1.08: 3”

<Example 4>
Example 1 except that LiFePO ₄ powder, vapor-grown carbon fiber and ketjen black as a conductive agent, and polyvinylidene fluoride as a binder were mixed in the following mass ratio to prepare a positive electrode mixture. Similarly, a nonaqueous electrolyte battery of Example 4 was produced.
“LiFePO ₄ : Vapor growth carbon fiber: Ketjen black: Polyvinylidene fluoride = 95.5: 0.225: 1.275: 3”

<Example 5>
Example 1 except that LiFePO ₄ powder, vapor-grown carbon fiber and ketjen black as a conductive agent, and polyvinylidene fluoride as a binder were mixed in the following mass ratio to prepare a positive electrode mixture. Similarly, a nonaqueous electrolyte battery of Example 5 was produced.
“LiFePO ₄ : Vapor growth carbon fiber: Ketjen black: Polyvinylidene fluoride = 93.6: 0.36: 2.04: 4”

<Example 6>
Example 1 except that LiFePO ₄ powder, vapor-grown carbon fiber and ketjen black as a conductive agent, and polyvinylidene fluoride as a binder were mixed in the following mass ratio to prepare a positive electrode mixture. Similarly, a nonaqueous electrolyte battery of Example 6 was produced.
“LiFePO ₄ : Vapor growth carbon fiber: Ketjen black: Polyvinylidene fluoride = 93: 0.4: 1.6: 5”

<Comparative Example 1>
Example 1 except that LiFePO ₄ powder, vapor-grown carbon fiber and ketjen black as a conductive agent, and polyvinylidene fluoride as a binder were mixed in the following mass ratio to prepare a positive electrode mixture. Similarly, a nonaqueous electrolyte battery of Comparative Example 1 was produced.
“LiFePO ₄ : Vapor growth carbon fiber: Ketjen black: Polyvinylidene fluoride = 97.75: 0.1125: 0.6375: 1.5”

<Comparative Example 2>
Example 1 except that LiFePO ₄ powder, vapor-grown carbon fiber and ketjen black as a conductive agent, and polyvinylidene fluoride as a binder were mixed in the following mass ratio to prepare a positive electrode mixture. Similarly, the nonaqueous electrolyte battery of Comparative Example 2 was produced.
“LiFePO ₄ : Vapor growth carbon fiber: Ketjen black: Polyvinylidene fluoride = 97.3: 0.035: 0.665: 2”

<Comparative Example 3>
Comparative Example as in Example 1 except that a positive electrode mixture was prepared by mixing LiFePO ₄ powder, ketjen black as a conductive agent, and polyvinylidene fluoride as a binder in the following mass ratio. 3 non-aqueous electrolyte batteries were produced.
“LiFePO ₄ : Ketjen Black: Polyvinylidene fluoride = 95.5: 1.5: 3”

<Comparative example 4>
Same as Example 1 except that LiFePO ₄ powder, vapor-grown carbon fiber and acetylene black as a conductive agent, and polyvinylidene fluoride as a binder were mixed in the following mass ratio to prepare a positive electrode mixture. Thus, a nonaqueous electrolyte battery of Comparative Example 4 was produced.
“LiFePO ₄ : Vapor growth carbon fiber: Acetylene black: Polyvinylidene fluoride = 95.8: 0.12: 1.08: 3”

<Comparative Example 5>
Example 1 except that LiFePO ₄ powder, vapor-grown carbon fiber and ketjen black as a conductive agent, and polyvinylidene fluoride as a binder were mixed in the following mass ratio to prepare a positive electrode mixture. Similarly, a nonaqueous electrolyte battery of Comparative Example 5 was produced.
“LiFePO ₄ : Vapor growth carbon fiber: Ketjen black: Polyvinylidene fluoride = 95.2: 0.45: 1.35: 3”

<Comparative Example 6>
Except that the LiFePO ₄ powder, vapor-grown carbon fiber as a conductive agent, and polyvinylidene fluoride as a binder were mixed in the following mass ratio to prepare a positive electrode mixture, the same as in Example 1, A nonaqueous electrolyte battery of Comparative Example 6 was produced.
“LiFePO ₄ : Vapor growth carbon fiber: Polyvinylidene fluoride = 95.5: 1.5: 3”

<Comparative Example 7>
Example 1 except that LiFePO ₄ powder, vapor-grown carbon fiber and ketjen black as a conductive agent, and polyvinylidene fluoride as a binder were mixed in the following mass ratio to prepare a positive electrode mixture. Similarly, a nonaqueous electrolyte battery of Comparative Example 7 was produced.
“LiFePO ₄ : Vapor growth carbon fiber: Ketjen black: Polyvinylidene fluoride = 94.6: 0.35: 1.05: 4”

<Comparative Example 8>
Example 1 except that LiFePO ₄ powder, vapor-grown carbon fiber and ketjen black as a conductive agent, and polyvinylidene fluoride as a binder were mixed in the following mass ratio to prepare a positive electrode mixture. Similarly, a nonaqueous electrolyte battery of Comparative Example 8 was produced.
“LiFePO ₄ : Vapor growth carbon fiber: Ketjen black: Polyvinylidene fluoride = 93.4: 0.39: 2.21: 4”

<Comparative Example 9>
Example 1 except that LiFePO ₄ powder, vapor-grown carbon fiber and ketjen black as a conductive agent, and polyvinylidene fluoride as a binder were mixed in the following mass ratio to prepare a positive electrode mixture. Similarly, a nonaqueous electrolyte battery of Comparative Example 9 was produced.
“LiFePO ₄ : Vapor growth carbon fiber: Ketjen black: Polyvinylidene fluoride = 92: 0.75: 2.25: 5”

<Comparative Example 10>
Example 1 except that LiFePO ₄ powder, vapor-grown carbon fiber and ketjen black as a conductive agent, and polyvinylidene fluoride as a binder were mixed in the following mass ratio to prepare a positive electrode mixture. Similarly, a nonaqueous electrolyte battery of Comparative Example 10 was produced.
“LiFePO ₄ : Vapor growth carbon fiber: Ketjen black: Polyvinylidene fluoride = 91.75: 0.4125: 2.3375: 5.5”

<Evaluation>
(Evaluation of cycle characteristics)
The cycle characteristics were evaluated as described below. First, 1 C constant current constant voltage charge was performed up to an upper limit of 3.6 V for a total charge time of 2 hours, and then 1 C constant current discharge was performed up to a final voltage of 2.5 V to perform charge and discharge. Moreover, this charging / discharging operation was repeated 500 times. For the capacity retention rate, the ratio of the discharge capacity at the 500th cycle to the discharge capacity at the first cycle was determined by the following (formula A).
(Formula A)
Capacity maintenance rate (%)
= ("Discharge capacity at 500th cycle" / "Discharge capacity at the first cycle") x 100 (%)

  The measurement results are shown in Table 1.

(Evaluation)
As shown in Table 1, in Examples 1 to 6, lithium iron phosphate was used as the positive electrode active material, ketjen black and vapor-grown carbon fiber were used as the conductive agent, and polyvinylidene fluoride was used as the binder. In Examples 1 to 6, the amount of the conductive agent and the amount of the binder were each in the optimum range. That is, the amount of the binder was set in the range of 2 wt% to 5 wt% with respect to the total amount of the positive electrode active material, the conductive agent, and the binder. The amount of the conductive agent was set in the range of 40 wt% to 60 wt% with respect to the binder amount. The amount of vapor-grown carbon fiber was in the range of 10 wt% or more and 20 wt% or less with respect to the amount of the conductive agent. Thereby, in Example 1- Example 6, it has confirmed that a favorable cycle characteristic was acquired.

  On the other hand, in Comparative Example 1, since the amount of the binder is 1.5 wt% with respect to the total amount of the positive electrode active material, the conductive agent and the binder, the adhesion of the current collector is weak and good cycle characteristics are obtained. Was not obtained. In Comparative Example 2, the conductive agent amount relative to the binder amount is less than the above optimal range, and the vapor growth carbon fiber amount relative to the conductive agent amount is less than the above optimal range. I couldn't. In Comparative Example 3, since no vapor-grown carbon fiber was used, good cycle characteristics could not be obtained. In Comparative Example 4, since acetylene black having no hollow shell structure was used instead of ketjen black which is carbon black having a hollow shell structure, good cycle characteristics could not be obtained. In Comparative Example 5, since the amount of vapor grown carbon fiber relative to the amount of the conductive agent was larger than the above optimal range, good cycle characteristics could not be obtained. In Comparative Example 6, since no ketjen black was used, good cycle characteristics could not be obtained. In Comparative Example 7, the conductive material with respect to the binder amount was less than the above optimal range, and the vapor growth carbon fiber amount with respect to the conductive agent amount was greater than the above optimal range, so that good cycle characteristics could not be obtained. . In Comparative Example 8, the amount of the conductive agent with respect to the amount of the binder is larger than the above optimal range, and the amount of the vapor growth carbon fiber with respect to the amount of the conductive agent is less than the above optimal range. It was. In Comparative Example 9, the amount of vapor-grown carbon fiber relative to the amount of the conductive agent was larger than the above optimal range, so that good cycle characteristics could not be obtained. In Comparative Example 10, since the amount of the binder was larger than the above optimal range, good cycle characteristics could not be obtained.

4). Other Embodiments The present invention is not limited to the above-described embodiments of the present invention, and various modifications and applications are possible without departing from the spirit of the present invention.

  In the above-described embodiments and examples, the case where the electrolytic solution or the gel electrolyte in which the electrolytic solution is held in the polymer compound is used as the electrolyte of the battery of the present invention has been described. However, other types of electrolytes are used. It may be. Other electrolytes include ion conductive ceramics, ion conductive glass, or a mixture of an ion conductive inorganic compound such as an ionic crystal and an electrolyte, a mixture of another inorganic compound and an electrolyte, and these Or a mixture of an inorganic compound and a gel electrolyte.

  In the above-described embodiments and examples, a battery having a cylindrical or laminated film type battery structure and a battery having a wound structure in which an electrode is wound have been described, but the present invention is not limited thereto. For example, the present invention can be similarly applied to a battery having another battery structure such as a square type, a coin type, or a button type, and a battery having a laminated structure in which electrodes are laminated, and the same effect can be obtained. Can do.

DESCRIPTION OF SYMBOLS 11 ... Battery can 12, 13 ... Insulation board 14 ... Battery cover 15A ... Disc board 15 ... Safety valve mechanism 16 ... Heat sensitive resistance element 17 ... Gasket 20 ... Winding Rotating electrode body 21: Positive electrode 21A: Positive electrode current collector 21B: Positive electrode active material layer 22 ... Negative electrode 22A ... Negative electrode current collector 22B ... Negative electrode active material layer 23 ... Separator 24 ... Center pin 25 ... Positive electrode lead 26 ... Negative electrode lead 27 ... Gasket 30 ... Winding electrode body 31 ... Positive electrode lead 32 ... Negative electrode lead 33 ... Positive electrode 33A .... Positive electrode current collector 33B ... Positive electrode active material layer 34 ... Negative electrode 34A ... Negative electrode current collector 34B ... Negative electrode active material layer 35 ... Separator 36 ... Electrolyte 37 ... Protection Tape 40 ... exterior member 41 ... Wearing film

Claims (6)

A positive electrode provided with a positive electrode active material layer including a positive electrode active material, a conductive agent and a binder;
A negative electrode,
With non-aqueous electrolyte,
The positive electrode active material includes a lithium phosphate compound having an olivine type crystal structure,
The conductive agent includes carbon black having a hollow shell structure and fibrous carbon,
The content of the binder is 2 wt% or more and 5 wt% or less with respect to the total mass of the positive electrode active material, the conductive agent and the binder,
The content of the conductive agent is 40 wt% or more and 60 wt% or less with respect to the content of the binder,
The non-aqueous electrolyte battery in which the content of the fibrous carbon is 10 wt% or more and 20 wt% or less with respect to the content of the conductive agent. The nonaqueous electrolyte battery according to claim 1, wherein the fibrous carbon is a vapor growth carbon fiber. The nonaqueous electrolyte battery according to claim 1, wherein the carbon black having a hollow shell structure is ketjen black. The non-aqueous electrolyte battery according to claim 1, wherein the binder is a fluorine-based polymer compound. The nonaqueous electrolyte battery according to claim 4, wherein the fluorine-based polymer compound is polyvinylidene fluoride. The nonaqueous electrolyte battery according to claim 1, wherein the lithium phosphate compound having an olivine type crystal structure is a lithium phosphate compound represented by Formula I.
(Chemical I)
LiM _x PO ₄
(In the formula, M is cobalt (Co), manganese (Mn), iron (Fe), nickel (Ni), magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), vanadium (V ), Niobium (Nb), copper (Cu), zinc (Zn), molybdenum (Mo), calcium (Ca), strontium (Sr), tungsten (W) and zirconium (Zr). X is 0 <x ≦ 1.)

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