JP2018166088A - Ion conductive solid electrolyte and all solid alkali metal ion secondary battery - Google Patents

Abstract

（式中、Ｘは、炭素数１〜２０のアルキレン基を表す。Ｙは、炭素数２〜３のアルキレン基を表す。式中、ｎは２〜２０の整数を表す。Ｍはリチウムもしくはナトリウムを表す。）
【選択図】なしAn object of the present invention is to provide an ion conductive solid electrolyte having high thermal stability.
The ion conductive solid electrolyte of the present invention contains a PO alkali metal salt represented by the chemical formula (1) and a non-PO alkali metal salt having an anion containing an imide structure. An ion conductive solid electrolyte.
[Chemical 1]

(In the formula, X represents an alkylene group having 1 to 20 carbon atoms. Y represents an alkylene group having 2 to 3 carbon atoms. In the formula, n represents an integer of 2 to 20. M is lithium or sodium. Represents.)
[Selection figure] None

Description

  The present invention relates to an ion conductive solid electrolyte and an all solid alkali metal ion secondary battery.

Conventionally known ion conductive materials include solid electrolytes such as inorganic solid electrolytes using inorganic materials or polymer solid electrolytes using organic polymers, and liquid electrolytes using water or non-aqueous solvents. . Since the solid electrolyte is not fluid like the liquid electrolyte, there is no leakage to the outside, and it is more advantageous than the liquid electrolyte in terms of reliability and device miniaturization.
For example, an electrolyte obtained by mixing a PO-based alkali metal salt, an alkali metal salt having an anion containing an imide structure, and glyme has been proposed, and a solid electrolyte can be obtained depending on the composition to be mixed (Patent Literature). 1). Moreover, when glyme and an alkali metal salt are mixed, the oxygen part of the ether structure of glyme is coordinated to an alkali metal ion to form a complex, and a proposal has been made that thermal stability is improved (Patent Document 2). reference).

Japanese Patent Laying-Open No. 2015-2153 JP 2010-73489 A

  However, although the solid electrolyte described in Patent Document 1 is expected to be applied to an electricity storage device such as a battery, glyme is a highly volatile organic solvent and is still insufficient in thermal stability at present. is there. Further, the solid electrolyte described in Patent Document 2 is still insufficient in terms of thermal stability because a weight reduction is recognized at 100 ° C. in thermogravimetry. Therefore, a solid electrolyte with higher thermal stability is desired.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an ion conductive solid electrolyte having high thermal stability.

The present inventors achieve high thermal stability when the ion conductive solid electrolyte contains a specific PO alkali metal salt and a non-PO alkali metal salt having an anion containing an imide structure. I found that I can do it.
That is, in order to solve the above problems, the following means are provided.

（式中、Ｘは、炭素数１〜２０のアルキレン基を表す。Ｙは、炭素数２〜３のアルキレン基を表す。式中、ｎは２〜２０の整数を表す。Ｍはリチウムもしくはナトリウムを表す。）
［２］ さらに、グライムを前記非Ｐ−Ｏ系アルカリ金属塩に対して０．２モル当量未満含有することを特徴とする［１］に記載のイオン導電性固体電解質。
［３］ 前記イミド構造を含むアニオンは、窒素に２つのスルホニル基が結合したスルホニルイミドアニオンまたは窒素に１つのスルホニル基と１つのカルボニル基が結合したスルホニルカルボニルイミドアニオンであることを特徴とする［１］または［２］に記載のイオン導電性固体電解質。
［４］ ［１］〜［３］のいずれかに記載のイオン導電性固体電解質を用いた全固体アルカリ金属イオン二次電池。 [1] An ion conductive solid electrolyte characterized by containing a PO alkali metal salt represented by the chemical formula (1) and a non-PO alkali metal salt having an anion containing an imide structure.

(In the formula, X represents an alkylene group having 1 to 20 carbon atoms. Y represents an alkylene group having 2 to 3 carbon atoms. In the formula, n represents an integer of 2 to 20. M is lithium or sodium. Represents.)
[2] The ion conductive solid electrolyte according to [1], further comprising less than 0.2 molar equivalent of glyme with respect to the non-PO alkali metal salt.
[3] The anion containing the imide structure is a sulfonylimide anion in which two sulfonyl groups are bonded to nitrogen or a sulfonylcarbonylimide anion in which one sulfonyl group and one carbonyl group are bonded to nitrogen. The ion conductive solid electrolyte according to [1] or [2].
[4] An all-solid alkali metal ion secondary battery using the ion conductive solid electrolyte according to any one of [1] to [3].

According to the ion conductive solid electrolyte according to the present invention, by containing a specific PO-based alkali metal salt and a non-PO-based alkali metal salt having an anion containing an imide structure, high thermal stability is achieved. Can be realized.
In particular, according to the ionic conductive solid electrolyte of one embodiment of the present invention, the specific PO-based alkali metal salt has high ionic conductivity in the solid state, so that it is thermally stable by adding a small amount of glyme. The ion conductivity can be improved while securing the properties.

It is the cross-sectional schematic diagram which expanded the principal part of the all-solid-state alkali metal ion secondary battery which concerns on one Embodiment of this invention.

  Hereinafter, the present embodiment will be described in detail with appropriate reference to the drawings. In the drawings used in the following description, in order to make the characteristics of the present invention easier to understand, there are cases where the characteristic parts are enlarged for the sake of convenience, and the dimensional ratios of the respective components are different from actual ones. is there. The materials, dimensions, and the like exemplified in the following description are examples, and the present invention is not limited to them, and can be appropriately modified and implemented without departing from the scope of the invention.

[Ion conductive solid electrolyte]
An ion conductive solid electrolyte according to an embodiment of the present invention contains a PO alkali metal salt represented by the chemical formula (1) and a non-PO alkali metal salt having an anion containing an imide structure. .

（式中、Ｘは、炭素数１〜２０のアルキレン基を示す。Ｙは、炭素数２〜３のアルキレン基を示す。式中、ｎは２〜２０の整数を示す。Ｍはリチウムもしくはナトリウムを示す。）

(In the formula, X represents an alkylene group having 1 to 20 carbon atoms. Y represents an alkylene group having 2 to 3 carbon atoms. In the formula, n represents an integer of 2 to 20. M represents lithium or sodium. Is shown.)

Further, the lithium ion conductive solid electrolyte may not contain glyme or may contain a small amount of glyme so as not to lower the thermal stability. For example, it is preferable to contain less than 0.2 molar equivalents with respect to the non-PO-based alkali metal salt. By containing less than 0.2 molar equivalent of glyme with respect to the non-PO-based alkali metal salt, ion conductivity can be improved while ensuring thermal stability.
The PO-based alkali metal salt represented by the chemical formula (1) has high ionic conductivity in a solid state, and therefore does not require addition of glyme. Therefore, a decrease in thermal stability due to the addition of a large amount of glyme can be prevented.

(PO alkali metal salt)
The PO alkali metal salt is at least one of a phosphonic acid alkali metal salt, a phosphoric acid alkali metal salt, and a phosphinic acid alkali metal salt. The PO alkali metal salt represented by the chemical formula (1) according to one embodiment of the present invention (hereinafter sometimes referred to as “the PO alkali metal salt of the present invention”) is a phosphonic acid alkali. It is a metal salt.
In the chemical formula (1), X represents an alkylene group having 1 to 20 carbon atoms. Examples of the alkylene group having 1 to 20 carbon atoms include linear alkylene having 1 to 20 carbon atoms such as methylene group, ethylene group, propylene group, butylene group, pentylene group, hexylene group, heptylene group, and octalene group. Groups. In addition, methylmethylene group; methylethylene group; 1-methylpropylene group, 2-methylpropylene group, 3-methylpropylene group; 1-methylbutylene group, 2-methylbutylene group, 3-methylbutylene group, 4-methylbutylene Group: 1-methylpentylene group, 2-methylpentylene group, 3-methylpentylene group, 4-methylpentylene group, 5-methylpentylene group; 1-methylhexylene group, 2-methylhexylene group And an alkylene group having 2 to 20 carbon atoms having a branched structure of a methyl group, such as 3-methylhexylene group, 4-methylhexylene group, 5-methylhexylene group, 6-methylhexylene group and the like. It is done.
X is preferably a linear alkylene group having 1 to 20 carbon atoms such as a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group and an octalene group, More preferably, it is a linear alkylene group of ˜9.
Y represents an alkylene group having 2 to 3 carbon atoms. Examples of the alkylene group having 2 to 3 carbon atoms include an ethylene group, a propylene group, and a methylethylene group. An ethylene group is preferred.
n shows the integer of 2-20. It is preferably an integer of 2 to 15, more preferably an integer of 2 to 10, and still more preferably 5 to 8.
M represents lithium or sodium. Lithium is preferred.

(Non-PO alkali metal salt)
The non-PO alkali metal salt having an anion containing an imide structure according to the present invention (hereinafter sometimes referred to as “non-PO alkali metal salt of the present invention”) is an anion containing an imide structure. It may be different from the P—O-based alkali metal salt. That is, the non-PO-based alkali metal salt of the present invention is different from phosphonic acid-based alkali metal salts, phosphoric acid-based alkali metal salts, and phosphinic acid-based alkali metal salts.
The anion containing an imide structure according to the present invention is preferably a sulfonylimide anion in which two sulfonyl groups are bonded to nitrogen or a sulfonylcarbonylimide anion in which one sulfonyl group and one carbonyl group are bonded to nitrogen. A sulfonylimide anion is more preferred.
Examples of the sulfonylimide anion include bis (trifluoromethanesulfonyl) imide anion (TFSI), bis (pentafluoroethanesulfonyl) imide anion (BETI), bis (fluorosulfonyl) imide anion (FSI), and fluorosulfonyltrifluoromethanesulfonylimide. Anion (FTA), 4,4,5,5, -tetrafluoro-1,3,2-dithiazoline-1,1,3,3-tetraoxide anion (CTFSI) and the like can be mentioned.
Examples of the sulfonylcarbonylimide anion include 2,2,2-trifluoro-N- (trifluoromethylsulfonyl) acetamide anion (TSAC). The anion containing an imide structure is preferably an organic anion.
The non-PO-based alkali metal salt of the present invention has an alkali metal ion as a cation paired with the above-described anion. As the alkali metal, for example, lithium, sodium, potassium and the like are preferable, and lithium is more preferable. This alkali metal is preferably the same type as that contained in the PO alkali metal salt of the present invention.
As a combination of an anion and a cation, for example, LiTFSI, NaTFSI, LiFSI, and NaFSI are preferable, and LiTFSI is more preferable.

(Glime)
Glyme is a general term for linear symmetric glycol diethers and may be represented by, for example, R—O (CH ₂ CH ₂ O) _n —R.

  Here, R is any one of an alkyl group having 1 to 9 carbon atoms which may be substituted with fluorine, a phenyl group which may be substituted with a halogen atom, and a cyclohexyl group which may be substituted with a halogen atom. is there. n is 1-5.

  Examples of the alkyl group in the above formula include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, pentyl group, isopentyl group, hexyl group, heptyl group, octyl group, and nonyl group. These alkyl groups may be substituted at any position with fluorine. When the number of alkyl groups exceeds 9, the polarity of glyme becomes weak, so that the solubility of the alkali metal salt tends to decrease. For this reason, the alkyl group preferably has a smaller number of carbon atoms, preferably a methyl group or an ethyl group, and most preferably a methyl group.

  The phenyl group which may be substituted with a halogen atom is not particularly limited, but 2-chlorophenyl group, 3-chlorophenyl group, 4-chlorophenyl group, 2,4-dichlorophenyl group, 2-bromophenyl group, 3- Examples include bromophenyl group, 4-bromophenyl group, 2,4-dibromophenyl group, 2-iodophenyl group, 3-iodophenyl group, 4-iodophenyl group, 2,4-iodophenyl group and the like.

  The cyclohexyl group which may be substituted with a halogen atom is not particularly limited, but 2-chlorocyclohexyl group, 3-chlorocyclohexyl group, 4-chlorocyclohexyl group, 2,4-dichlorocyclohexyl group, 2-bromocyclohexyl group. Group, 3-bromocyclohexyl group, 4-bromocyclohexyl group, 2,4-dibromocyclohexyl group, 2-iodocyclohexyl group, 3-iodocyclohexyl group, 4-iodocyclohexyl group, 2,4-diiodocyclohexyl group and the like. Can be mentioned.

  About n showing the repeating number of an ethylene oxide unit, 1-7 are preferable, More preferably, it is 2-8, Most preferably, it is 4-6.

  A glyme may be used individually by 1 type, and may mix and use 2 or more types.

(Composition of ion conductive solid electrolyte)
In the ion conductive solid electrolyte of one embodiment of the present invention, the ratio of the PO alkali metal salt of the present invention and the non-PO alkali metal salt of the present invention is not particularly limited. What contains 0.5-4.0 molar equivalent of the PO alkali metal salt of this invention with respect to the non-PO alkaline metal salt of this invention is preferable, and contains 1.0-3.0 molar equivalent Are more preferable, and those containing 1.5 to 2.5 molar equivalents are more preferable.
If it is less than 0.5 molar equivalent, the desired ionic conductivity cannot be ensured because there are few alkali metals required for ionic conductivity. On the other hand, if it exceeds 4.0 molar equivalents, a P—O-based alkali metal salt that is too high in concentration and cannot be ionically dissociated is produced, so that it becomes a resistance and the desired ionic conductivity cannot be ensured.

  The PO-based alkali metal salt according to an embodiment of the present invention has high ionic conductivity in a solid state. Therefore, even if glyme is not included in the ionic conductive solid electrolyte (glyme-free), high ionic conductivity is obtained. Can have. The glyme-free ionic conductive solid electrolyte of this embodiment can prevent a decrease in thermal stability due to the addition of glyme, and can simultaneously realize high ionic conductivity and high thermal stability.

In the ion conductive solid electrolyte of the other embodiment of the present invention, the ratio of the PO alkali metal salt of the present invention and the non-PO alkali metal salt of the present invention is not particularly limited. What contains 0.5-4.0 molar equivalent of the PO alkali metal salt of this invention with respect to the non-PO alkaline metal salt of this invention is preferable, and contains 1.0-3.0 molar equivalent Are more preferable, and those containing 1.5 to 2.5 molar equivalents are more preferable. May contain glyme. It is preferable to contain less than 0.2 molar equivalent of glyme with respect to the non-PO alkali metal salt. More preferably, it is contained in an amount of 0.15 molar equivalent or less, more preferably 0.10 molar equivalent or less, and particularly preferably 0.05 molar equivalent or less. For example, 0.001 to 0.18 molar equivalent, preferably 0.01 to 0.15 molar equivalent, more preferably 0.01 to 0.10 molar equivalent of glyme with respect to the non-PO-based alkali metal salt, It preferably contains 0.01 to 0.50 molar equivalent.
When the content is 0.2 molar equivalent or more, the decrease in thermal stability due to the addition of glyme becomes large, and it becomes difficult to obtain desired thermal stability. Moreover, since glyme is liquid, when it contains 0.2 molar equivalent or more, fluidity | liquidity will express and it will become difficult to maintain a solid state.
Since the PO-based alkali metal salt of the present invention has high ionic conductivity in the solid state, it can have high ionic conductivity even if the ionic conductive solid electrolyte does not contain a large amount of glyme. As described above, the ionic conductive solid electrolyte of this embodiment containing a small amount of glyme that does not affect the thermal stability of the solid electrolyte can improve the ionic conductivity while ensuring the thermal stability. .

(Method for producing ion conductive solid electrolyte)
As a method for producing an ion conductive solid electrolyte according to an embodiment of the present invention, for example, a raw material containing the PO alkali metal salt of the present invention and the non-PO alkali metal salt of the present invention is mixed. It may be obtained. There is no restriction | limiting in particular in a mixing method. When mixing, it is preferable to mix in an atmosphere with a dew point of −80 ° C. or lower or an inert gas atmosphere, for example, an atmosphere of nitrogen gas, helium gas, argon gas, or the like, in order to prevent mixing of water. More preferably, it is in an argon gas atmosphere. The temperature during mixing is preferably 20 to 80 ° C. Moreover, you may stir using a stirrer etc. in order to dissolve an alkali metal salt as needed.
For example, instead of the PO alkali metal salt of the present invention, a corresponding PO alkali metal compound into which no alkali metal is introduced may be used. In this case, it is preferable to add the alkali metal compound to the raw material in order to introduce the alkali metal into the corresponding PO-based alkali metal compound to obtain the PO-based alkali metal salt of the present invention. As an alkali metal compound, n-butyllithium etc. can be used conveniently, for example. Such a thing may be obtained by mixing a corresponding PO-based alkali metal compound, a non-PO-based alkali metal salt of the present invention, and an alkali metal compound. Moreover, it was obtained by introducing an alkali metal by adding an alkali metal compound to a product obtained by mixing the corresponding PO alkali metal compound and the non-PO alkali metal salt of the present invention. It may be a thing.

  When mixing the raw materials, for example, a solvent such as acetonitrile, tetrahydrofuran, dimethyl carbonate, diethyl carbonate, ethanol, methanol, acetone, or N-methylpyrrolidone may be used.

  Examples of the method for producing an ion conductive solid electrolyte according to another embodiment of the present invention include, for example, the PO alkali metal salt of the present invention, the non-PO alkali metal salt of the present invention, and a small amount of glyme. It is good also as what was obtained by mixing the raw material containing these. Further, for example, a phosphonic acid compound into which no alkali metal is introduced may be used instead of the phosphonic acid alkali metal salt which is the PO alkali metal salt of the present invention. In this case, since an alkali metal is introduced into the phosphonic acid compound to obtain a phosphonic acid alkali metal salt, it is preferable to add the alkali metal compound to the raw material. As an alkali metal compound, n-butyllithium etc. can be used conveniently, for example. Such a thing may be obtained by mixing the PO compound of the present invention, the non-PO alkali metal salt of the present invention, a certain small amount of glyme, and an alkali metal compound. In addition, an alkali metal compound is introduced by adding an alkali metal compound to a product obtained by mixing a PO compound of the present invention, a non-PO alkali metal salt of the present invention, and a small amount of glyme. It is good also as what was obtained.

(Formation of ion conductive solid electrolyte layer)
The method for forming the ion conductive solid electrolyte layer from the ion conductive solid electrolyte of each embodiment of the present invention is not particularly limited.

  For example, there is a method of preparing an electrolyte layer laminated between electrodes or a part thereof (an electrolyte membrane having about half the thickness of the electrolyte layer). In this case, a solution containing an ionic conductive solid electrolyte (for example, a solution of acetonitrile) is applied on a suitable film such as a polyethylene terephthalate (PET) film or a polypropylene film, and is heated and dried in an inert atmosphere or vacuum. Manufactured by drying (vacuum oven).

  Alternatively, the separator is manufactured by, for example, impregnating a solution containing an ion conductive solid electrolyte, and drying by heating or vacuum drying (vacuum oven).

  The drying conditions are determined according to the solution and cannot be uniquely defined. For example, the drying conditions are usually 30 to 110 ° C. and 0.5 to 15 hours. When a volatile solvent such as acetonitrile is used, it is preferable that the solvent is volatilized by natural drying before heat drying.

(Ion conductivity)
In the ionic conductive solid electrolyte of the present invention, high thermal stability and high ionic conductivity can be exhibited simultaneously. The reason why such an effect is obtained is still unclear, but is presumed as follows.
In the ion conductive solid electrolyte composed of the PO alkali metal salt of the present invention and the non-PO alkali metal salt of the present invention, it is considered that the alkali metal ions are conducted as follows.
Step (1): A non-PO alkali metal salt having an anion containing an imide structure dissociates into an alkali metal ion and an anion containing an imide structure.
Step (2): The generated alkali metal ions move to ethylene oxide (present in the PO-based alkali metal salt of the present invention).
Step (3): Alkali metal ions are conducted by the segmental motion of ethylene oxide.
The ionic conductivity of such an ionic conductive solid electrolyte depends on the terminal group of the PO alkali metal salt. Here, the non-PO alkali metal salt of the present invention is LiTFSI, the PO alkali metal salt is a phosphonic acid lithium salt (in the chemical formula (1), Y is ethylene, n is an integer of 4, M Represents lithium as an example.
One sulfonyl group of the TFSI anion interacts with the Li ⁺ cation of the phosphonic acid lithium salt (coordination bond), thereby stabilizing the composite salt structure. Due to this interaction, the negative charge density of the TFSI anion is dispersed and lowered, so that the mobility (dissociation) of Li ⁺ from the TFSI anion to ethylene oxide is improved.
(A) When the terminal is a methyl group and X has 1 to 3 carbon atoms For example, as shown in chemical formula (2), although steps (1) and (2) occur, the distance between the TFSI anion and ethylene oxide is short. The lithium ions (Li ⁺ ) once dissociated too much recombine with the TFSI anion. As a result, the ionic conductivity of Li ⁺ decreases.

(B) When terminal is OH group (PO alkali metal salt of the present invention)
For example, as shown in chemical formula (3), even when the distance between the TFSI anion and ethylene oxide is too close, such as when the carbon number of X is 1 to 3, the terminal OH group protons form hydrogen bonds with the TFSI anion. Li ⁺ ions are extruded, and recombination between Li ⁺ and TFSI anions is blocked. Compared with the terminal methyl group, the degree of dissociation of LiTFSI as the non-PO alkali metal salt of the present invention is improved. As a result, the amount of Li ⁺ ions contributing to ionic conduction is increased compared to the case of the terminal methyl group.

[All-solid alkali metal ion secondary battery]
FIG. 1 is an enlarged schematic cross-sectional view of a main part of an all solid alkali metal ion secondary battery according to an embodiment of the present invention. As shown in FIG. 1, the all-solid alkali metal ion secondary battery 10 includes a laminate 4 having a first electrode layer 1, a second electrode layer 2, and a solid electrolyte layer 3. The first electrode layer 1 and the second electrode layer 2 form a pair of electrodes.

  Each first electrode layer 1 is connected to a first external terminal 5, and each second electrode layer 2 is connected to a second external terminal 6. The first external terminal 5 and the second external terminal 6 are electrical contacts with the outside.

(Laminate)
The stacked body 4 includes a first electrode layer 1, a second electrode layer 2, and a solid electrolyte layer 3. One of the first electrode layer 1 and the second electrode layer 2 functions as a positive electrode layer, and the other functions as a negative electrode layer. The polarity of the electrode layer varies depending on which polarity is connected to the external terminal. Hereinafter, in order to facilitate understanding, the first electrode layer 1 is referred to as a positive electrode layer 1, and the second electrode layer 2 is referred to as a negative electrode layer 2.

  In the laminate 4, the positive electrode layers 1 and the negative electrode layers 2 are alternately laminated via the solid electrolyte layers 3. The charging / discharging of the all-solid alkali metal ion secondary battery 10 is performed by the exchange of alkali metal ions between the positive electrode layer 1 and the negative electrode layer 2 through the solid electrolyte layer 3.

(Positive electrode layer and negative electrode layer)
The positive electrode layer 1 includes a positive electrode current collector layer 1A and a positive electrode active material layer 1B containing a positive electrode active material. The negative electrode layer 2 includes a negative electrode current collector layer 2A and a negative electrode active material layer 2B containing a negative electrode active material.

(Current collector layer)
The positive electrode current collector layer 1A and the negative electrode current collector layer 2A preferably have high electrical conductivity. Therefore, the positive electrode current collector layer 1A and the negative electrode current collector layer 2A preferably contain a low-resistance metal such as silver, palladium, gold, platinum, aluminum, copper, or nickel. Among these low resistance metals, aluminum and copper hardly react with the positive electrode active material, the negative electrode active material, and the solid electrolyte. Therefore, when the positive electrode current collector layer 1A and the negative electrode current collector layer 2A containing aluminum or copper are used, the internal resistance of the all-solid alkali metal ion secondary battery 10 can be reduced over a long period of time. The composition of the positive electrode current collector layer 1A and the negative electrode current collector layer 2A may be the same or different.
The positive electrode current collector layer 1A and the negative electrode current collector layer 2A may each include a positive electrode active material and a negative electrode active material described later. The content ratio of the active material contained in each current collector layer is not particularly limited as long as it functions as a current collector. For example, the volume ratio of the low resistance metal / positive electrode active material or the low resistance metal / negative electrode active material is preferably 90/10 to 70/30.
The positive electrode current collector layer 1A and the negative electrode current collector layer 2A contain a positive electrode active material and a negative electrode active material, respectively, so that the positive electrode current collector layer 1A, the positive electrode active material layer 1B, the negative electrode current collector layer 2A, and the negative electrode active material Adhesion with the layer 2B is improved.

(Positive electrode active material layer)
The positive electrode active material layer 1B is formed on one side or both sides of the positive electrode current collector layer 1A. The positive electrode active material layer 1 </ b> B is mainly composed of a positive electrode active material, a positive electrode binder, and a necessary amount of positive electrode conductive additive.
The positive electrode active material used for the positive electrode active material layer 1B includes lithium ion insertion and extraction, lithium ion desorption and insertion (intercalation), or counter ions (for example, PF ₆ ⁻ ) of lithium ions and lithium ions. An electrode active material capable of reversibly proceeding doping and dedoping can be used.
For example, lithium cobaltate (LiCoO ₂ ), lithium nickelate (LiNiO ₂ ), lithium manganese spinel (LiMn ₂ O ₄ ), and the general formula: LiNi _x Co _y Mn _z M _a2 (x + y + z + a = 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1, 0 ≦ a ≦ 1, and M is one or more elements selected from Al, Mg, Nb, Ti, Cu, Zn, and Cr) Oxide, lithium vanadium compound (LiV ₂ O ₅ ), olivine type LiMPO ₄ (where M is one or more elements selected from Co, Ni, Mn, Fe, Mg, Nb, Ti, Al, Zr, or VO) shown), lithium titanate _{(Li 4 Ti 5 O 12)} , LiNi x Co y Al z O 2 ( composite metal oxide such as 0.9 <x + y + z < 1.1) can be mentioned.
The constituent ratio of the positive electrode active material in the positive electrode active material layer 1B is preferably 80% or more and 90% or less by mass ratio. The constituent ratio of the positive electrode conductive additive in the positive electrode active material layer 1B is preferably 0.5% to 10% by mass ratio, and the constituent ratio of the binder in the positive electrode active material layer 1B is 0 by mass ratio. It is preferably 5% or more and 10% or less.

The positive electrode binder bonds the active materials to each other and bonds the active material to the positive electrode current collector 1A. The binder is not particularly limited as long as the above-described bonding is possible. For example, polyvinylidene fluoride (PVDF), polyethersulfone (PESU), polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer ( FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), ethylene-tetrafluoroethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE) ), A fluororesin such as polyvinyl fluoride (PVF).
In addition to the above, as the binder, for example, vinylidene fluoride-hexafluoropropylene-based fluororubber (VDF-HFP-based fluororubber), vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene-based fluororubber (VDF-HFPPTFE-based) Fluororubber), vinylidene fluoride-pentafluoropropylene-based fluororubber (VDF-PFP-based fluororubber), vinylidene fluoride-pentafluoropropylene-tetrafluoroethylene-based fluororubber (VDF-PFP-TFE-based fluororubber), vinylidene fluoride Ride-perfluoromethyl vinyl ether-tetrafluoroethylene fluoro rubber (VDF-PFMVE-TFE fluoro rubber), vinylidene fluoride-chlorotrifluoroethylene fluoro rubber It may be used vinylidene fluoride-based fluorine rubbers such as rubber (VDF-CTFE-based fluorine rubber).
Further, as the binder, an electron conductive conductive polymer or an ion conductive conductive polymer may be used. Examples of the electron conductive conductive polymer include polyacetylene. In this case, since the binder also functions as a conductive material, it is not necessary to add a conductive material. Examples of the ion conductive conductive polymer include a compound obtained by combining a polymer compound such as polyethylene oxide and polypropylene oxide with a lithium salt or an alkali metal salt mainly composed of lithium.

  The conductive auxiliary agent for positive electrode is not particularly limited as long as it improves the conductivity of the positive electrode active material layer 1B, and a known conductive auxiliary agent can be used. Examples thereof include carbon-based materials such as graphite and carbon black, metal fine powders such as copper, nickel, stainless steel, and iron, and conductive oxides such as ITO.

(Negative electrode active material layer)
The negative electrode active material layer 2B includes a negative electrode active material, and further includes a negative electrode binder and a negative electrode conductive additive as necessary.
The negative electrode active material should just be a compound which can occlude / release lithium ion, and can use the well-known negative electrode active material for lithium secondary batteries. Examples of the negative electrode active material include carbon materials such as metallic lithium, graphite capable of occluding and releasing lithium ions (natural graphite, artificial graphite), carbon nanotubes, non-graphitizable carbon, graphitizable carbon, and low-temperature calcined carbon. Metals that can be combined with lithium such as aluminum, silicon and tin, amorphous compounds mainly composed of oxides such as SiO _x (0 <x <2) and tin dioxide, lithium titanate (Li ₄ Ti ₅ And particles containing O ₁₂ ) and the like.

  Examples of the conductive assistant for the negative electrode include carbon powders such as carbon blacks, carbon nanotubes, carbon materials, fine metal powders such as copper, nickel, stainless steel and iron, a mixture of carbon materials and fine metal powders, and conductive oxides such as ITO. Things.

  The binder used for a negative electrode can use the same thing as a positive electrode. In addition, for example, cellulose, styrene / butadiene rubber, ethylene / propylene rubber, polyimide resin, polyamideimide resin, acrylic resin, or the like may be used as the binder.

The contents of the negative electrode active material, the conductive material, and the binder in the negative electrode active material layer 2B are not particularly limited. The constituent ratio of the negative electrode active material in the negative electrode active material layer 2B is preferably 70% or more and 98% or less by mass ratio. The constituent ratio of the conductive material in the negative electrode active material layer 2B is preferably 1% or more and 20% or less by mass ratio, and the constituent ratio of the binder in the negative electrode active material layer 2B is 1% or more and 10% or less by mass ratio. It is preferable that
By making content of a negative electrode active material and a binder into the said range, in the obtained negative electrode active material layer 2B, the tendency for the amount of binders to be too small to form a strong negative electrode active material layer can be suppressed. In addition, the amount of the binder that does not contribute to the electric capacity increases, and the tendency that it is difficult to obtain a sufficient volume energy density can be suppressed.

(Solid electrolyte layer)
The solid electrolyte layer 3 is provided between the positive electrode layer 1 and the negative electrode layer 2. The solid electrolyte layer 3 includes the above-described ion conductive solid electrolyte. By including the above-described ion conductive solid electrolyte, the alkali metal ion conductivity and thermal stability of the solid electrolyte layer 3 are increased, so that the all solid alkali metal ion secondary battery of the present embodiment has high thermal stability. .

(External terminal)
The first external terminal 5 and the second external terminal 6 of the all-solid alkali metal ion secondary battery 10 are preferably made of a material having a high conductivity. For example, silver, gold, platinum, aluminum, copper, tin, or nickel can be used. The first external terminal 5 and the second external terminal 6) may be made of the same material, or may be made of different materials. The external terminal may be a single layer or a plurality of layers.

(Protective layer)
In addition, the all-solid-state alkali metal ion secondary battery 10 may have a protective layer on the outer periphery of the laminate 4 for protecting the laminate 4 and the terminals electrically, physically, and chemically. The material constituting the protective layer is preferably excellent in insulation, durability and moisture resistance and environmentally safe. For example, it is preferable to use glass, ceramics, thermosetting resin, or photocurable resin. Only one type of material for the protective layer may be used or a plurality of materials may be used in combination. The protective layer may be a single layer, but it is preferable to provide a plurality of layers. Among these, an organic-inorganic hybrid in which a thermosetting resin and ceramic powder are mixed is particularly preferable.

(Method for producing all-solid alkali metal ion secondary battery)
First, each material of the positive electrode current collector layer 1A, the positive electrode active material layer 1B, the solid electrolyte layer 3, the negative electrode active material layer 2B, and the negative electrode current collector layer 2A constituting the laminate 4 is pasted.

  The method of pasting is not particularly limited. For example, a paste can be obtained by mixing powder of each material in a vehicle. Here, the vehicle is a general term for the medium in the liquid phase. The vehicle generally includes a solvent, a dispersant, and a binder. By this method, the paste for the positive electrode current collector layer 1A, the paste for the positive electrode active material layer 1B, the paste for the solid electrolyte layer 3, the paste for the negative electrode active material layer 2B, and the paste for the negative electrode current collector layer 2A Is made.

  Next, a green sheet is produced. The green sheet is obtained by applying the prepared paste on a base material such as PET (polyethylene terephthalate) in a desired order, drying it as necessary, and then peeling the base material. The method for applying the paste is not particularly limited. For example, known methods such as screen printing, coating, transfer, doctor blade, etc. can be employed.

  The produced green sheets are stacked in the desired order and the number of layers. Alignment, cutting, etc. are performed as necessary to produce a green sheet laminate. When manufacturing a parallel type or series-parallel type battery, it is preferable to align and stack so that the end face of the positive electrode layer does not coincide with the end face of the negative electrode layer.

  You may produce a green sheet laminated body using the positive electrode unit and negative electrode unit which are demonstrated below.

  The positive electrode unit is a unit in which solid electrolyte layer 3 / positive electrode active material layer 1B / positive electrode current collector layer 1A / positive electrode active material layer 1B are laminated in this order. This positive electrode unit can be manufactured as follows. First, a solid electrolyte layer forming paste is formed into a sheet shape on a PET film by a doctor blade method, and dried to form the solid electrolyte layer 3. Next, the positive electrode active material layer 1B paste is printed on the formed solid electrolyte layer 3 and dried to form the positive electrode active material layer 1B.

  Next, a positive electrode current collector forming paste is printed on the formed positive electrode active material layer 1B by screen printing and dried to form the positive electrode current collector layer 1A. Next, the positive electrode active material layer 1B paste is printed again on the formed positive electrode current collector layer 1A by screen printing and dried to form the positive electrode active material layer 1B. And a positive electrode active material layer unit is produced by peeling a PET film.

  The negative electrode unit is a unit in which solid electrolyte layer 3 / negative electrode active material layer 2B / negative electrode current collector layer 2A / negative electrode active material layer 2B are laminated in this order. This negative electrode unit can be produced by forming the solid electrolyte layer 3, the negative electrode active material layer 2B, the negative electrode current collector layer 2A, and the negative electrode active material layer 2B in the same procedure as the above positive electrode unit. .

  A positive electrode unit and a negative electrode unit are laminated to produce a green sheet laminate. At this time, lamination is performed so that the solid electrolyte layer 3 of the positive electrode unit and the negative electrode active material layer 2B of the negative electrode unit, or the positive electrode active material layer 1B of the positive electrode unit and the solid electrolyte layer 3 of the negative electrode unit are in contact. Thus, positive electrode active material layer 1B / positive electrode current collector layer 1A / positive electrode active material layer 1B / solid electrolyte layer 3 / negative electrode active material layer 2B / negative electrode current collector layer 2A / negative electrode active material layer 2B / solid electrolyte layer 3 Is obtained in this order. Each unit is shifted and stacked so that the positive electrode current collector layer 1A of the positive electrode unit extends only to one end surface and the negative electrode current collector layer 2A of the negative electrode unit extends only to the other surface. Sheets for the solid electrolyte layer 3 having a predetermined thickness may be further stacked on both surfaces of the produced green sheet laminate.

  The produced green sheet laminate is pressure bonded together. Crimping is performed while heating. The heating temperature is, for example, 40 to 95 ° C.

(Terminal formation)
The first external terminal 5 and the second external terminal 6 are attached to the obtained laminate. The first external terminal 5 and the second external terminal 6 are formed so as to be in electrical contact with the positive electrode current collector layer 1A and the negative electrode current collector layer 2A, respectively. For example, the positive electrode current collector layer 1A and the negative electrode current collector layer 2A exposed from the side surface of the laminate can be formed by using a known method such as a sputtering method, a dipping method, or a spray coating method. When forming only in a predetermined part, it forms by masking etc. with a tape, for example.

  The embodiments of the present invention have been described in detail with reference to the drawings. However, the configurations and combinations of the embodiments in the embodiments are examples, and the addition and the omission of the configurations are within the scope not departing from the gist of the present invention. , Substitutions, and other changes are possible.

  According to the procedure shown below, the ion conductive solid electrolytes of Examples 1 to 17 and Comparative Examples 1 to 7 were produced, and the ion conductivity was evaluated. Moreover, thermal stability evaluation was performed.

  The compounds used in Examples 1 to 17 and Comparative Example 1 are shown in Table 1. Specifically, as the PO-based alkali metal salt compound represented by the chemical formula (1), Compound No. And the structural formula and n corresponding to X, Y and M in chemical formula (1), respectively.

〔化学式（１）において、Ｘは、炭素数１〜２０のアルキレン基を示す。Ｙは、炭素数２〜３のアルキレン基を示す。式中、ｎは２〜２０の整数を示す。Ｍはリチウムもしくはナトリウムを示す。〕

[In chemical formula (1), X shows a C1-C20 alkylene group. Y represents an alkylene group having 2 to 3 carbon atoms. In formula, n shows the integer of 2-20. M represents lithium or sodium. ]

  Compound No. used in Comparative Example 2 15 is shown in Table 1. Specifically, when the terminal group of the PO-based alkali metal salt compound represented by the chemical formula (1) is not a HO group but a methyl group, it corresponds to X, Y, and M in the chemical formula (1), respectively. The structural formula and n are listed.

  The compounds used in Comparative Examples 3 to 7 are shown in Table 1. Specifically, as the PO-based alkali metal salt compound represented by the chemical formula (1), Compound No. And the structural formula and n corresponding to X, Y and M in chemical formula (1), respectively.

〔化学式（１）において、Ｘは、炭素数２、６、もしくは２２のアルキレン基を示す。Ｙは、炭素数１、２、もしくは４のアルキレン基を示す。式中、ｎは１、６、もしくは２２の整数を示す。Ｍはリチウムを示す。〕

[In the chemical formula (1), X represents an alkylene group having 2, 6, or 22 carbon atoms. Y represents an alkylene group having 1, 2, or 4 carbon atoms. In the formula, n represents an integer of 1, 6, or 22. M represents lithium. ]

“Synthesis of PO Alkali Metal Salt Compound of the Present Invention”
(Synthesis Example 1)
Compound No. The synthesis method 1 is shown below.

(Synthesis Examples 2 to 13)
Compound No. In the same manner as in Compound 1, 2 to 13 were synthesized. Each structure is shown in Table 1.

(Synthesis Example 14)
Compound No. 1 was used except that NaOH was used instead of LiOH. In the same manner as in Compound 1, 14 was synthesized. The structure is shown in Table 1.

(Synthesis Example 15)
Compound No. The 15 synthesis methods are shown below.

(Synthesis Examples 16 to 20)
Compound No. In the same manner as in Compound 1, 16-20 were synthesized. Each structure is shown in Table 1.

Example 1
<Preparation of ionic conductive solid electrolyte>
As the PO-based alkali metal salt of the present invention, the compound No. 1 obtained in Synthesis Example 1 was used. 1 was used, and the non-PO-based alkali metal salt of the present invention was a lithium salt represented by the following chemical formula (6) (hereinafter referred to as LiTFSI).

  In the glove box, the compound No. obtained in Synthesis Example 1 was obtained. 1 and LiTFSI were mixed so that the molar ratio was 1: 0.5. An ion conductive solid electrolyte of this example was produced.

<Ion conductivity measurement>
First, an ion conductive solid electrolyte solution was prepared in a glove box. Specifically, Compound No. An ion conductive solid electrolyte containing 0.1 g of compound 1 and 0.037 g of LiTFSI was dissolved in 5 ml of acetonitrile.

Next, a sample for measuring ionic conductivity was prepared. A glass filter having a diameter of 10 mm and a thickness of 30 μm was sufficiently impregnated with the solution, and was naturally dried to volatilize acetonitrile, and then the glass filter was filled with a solid electrolyte. Furthermore, it vacuum-dried at 80 degreeC for 12 hours. This was sandwiched between stainless steel electrodes having a diameter of 10 mm and used as measurement samples. After measuring the film thickness of the solid electrolyte at that time, impedance measurement was performed at 25 ° C. The impedance measurement was performed at 0.5 pts / sec between 1 MHz and 0.1 Hz with an amplitude voltage of 100 mV. The resistance value (R) was obtained from the obtained Cole-Cole plot. From this value (R), film thickness t (cm), and electrode area S (cm ² ), ion conductivity σ (Scm ⁻¹ ) was calculated according to the following formula.
σ = 1 / R × t / S
The results are shown in Table 1.

<Thermal stability evaluation>
The thermal stability of the ion conductive solid electrolyte was evaluated by thermogravimetry using a TG / DTA6200 manufactured by Seiko Instrument. Measurement is performed at a rate of temperature increase of 10 ° C./min from room temperature to 400 ° C. to obtain a temperature (° C.) when the weight decreases by 5%, and the temperature is fixed at 100 ° C. and the weight decreases by 10%. It was done by the method of calculating the time to do. The results are shown in Table 1.

(Examples 2 to 13)
Compound Nos. Obtained in Synthesis Examples 2 to 13 Except using 2 to 13 respectively, in the same manner as in Example 1, ion conductive solid electrolytes of Examples 2 to 13 were produced.

(Example 14)
Compound No. obtained in Synthesis Example 14 14 was used, and in place of LiTFSI, NaTFSI shown below was used, and an ion conductive solid electrolyte of this example was produced in the same manner as in Example 1.

  The obtained ion conductive solid electrolyte was evaluated in the same manner as in Example 1. Table 1 shows the results of ionic conductivity and thermal stability evaluation.

(Example 15)
Compound No. obtained in Synthesis Example 4 4 and the addition of 0.05 mole equivalent of triethyl glycol dimethyl ether shown below (hereinafter referred to as glyme (G3)) to LiTFSI as the glyme. A solid electrolyte was prepared.

  The obtained ion conductive solid electrolyte was evaluated in the same manner as in Example 1. The results of ionic conductivity and thermal stability evaluation are shown in Table 1.

(Example 16)
An ion conductive solid electrolyte of this example was produced in the same manner as in Example 15 except that 0.1 molar equivalent of glyme (G3) with respect to LiTFSI was added.
The obtained ion conductive solid electrolyte was evaluated in the same manner as in Example 1. The results of ionic conductivity and thermal stability evaluation are shown in Table 1.

(Example 17)
An ion conductive solid electrolyte of this example was produced in the same manner as in Example 15 except that 0.15 molar equivalent of glyme (G3) with respect to LiTFSI was added.
The obtained ion conductive solid electrolyte was evaluated in the same manner as in Example 1. The results of ionic conductivity and thermal stability evaluation are shown in Table 1.

(Comparative Example 1)
An ionic conductive solid electrolyte of this comparative example was produced in the same manner as in Example 15 except that 0.2 molar equivalent of glyme (G3) with respect to LiTFSI was added.
The obtained ion conductive solid electrolyte was evaluated in the same manner as in Example 1. The results of ionic conductivity and thermal stability evaluation are shown in Table 1.

(Comparative Example 2)
Compound No. obtained in Synthesis Example 15 Except for using 15, an ion conductive solid electrolyte of this comparative example was produced in the same manner as in Example 1.
The obtained ion conductive solid electrolyte was evaluated in the same manner as in Example 1. The results of ionic conductivity and thermal stability evaluation are shown in Table 1.

(Comparative Examples 3 to 7)
Compound Nos. Obtained in Synthesis Examples 16 to 20 Except using 16 to 20 respectively, the ion conductive solid electrolytes of Comparative Examples 3 to 7 were produced in the same manner as in Example 1.
The obtained ion conductive solid electrolyte was evaluated in the same manner as in Example 1. Table 1 shows the results of ionic conductivity and thermal stability evaluation.

DESCRIPTION OF SYMBOLS 1 ... Positive electrode layer, 1A ... Positive electrode collector layer, 1B ... Positive electrode active material layer, 2 ... Negative electrode layer, 2A ... Negative electrode collector layer, 2B ... Negative electrode active material layer, 3 ... Solid electrolyte layer, 4 ... Laminate 5 ... first external terminal, 6 ... second
External terminal, 10 ... All solid alkali metal ion secondary battery

Claims (4)

An ion conductive solid electrolyte comprising a PO alkali metal salt represented by the chemical formula (1) and a non-PO alkali metal salt having an anion containing an imide structure.

(In the formula, X represents an alkylene group having 1 to 20 carbon atoms. Y represents an alkylene group having 2 to 3 carbon atoms. In the formula, n represents an integer of 2 to 20. M is lithium or sodium. Represents.)   2. The ion conductive solid electrolyte according to claim 1, further comprising less than 0.2 molar equivalent of glyme with respect to the non-PO-based alkali metal salt.   The anion containing the imide structure is a sulfonylimide anion in which two sulfonyl groups are bonded to nitrogen or a sulfonylcarbonylimide anion in which one sulfonyl group and one carbonyl group are bonded to nitrogen. The ion conductive solid electrolyte according to claim 2.   An all solid alkali metal ion secondary battery using the ion conductive solid electrolyte according to claim 1.

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