JP3109460B2 - Ion conductive polymer composition, method for producing the same, and polymer battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ion-conductive polymer composition and a method for producing the same, and more particularly to an electrolyte for a polymer battery, a method for producing the same, and a polymer battery using the same.

[0002]

2. Description of the Related Art With the rapid market expansion of portable information devices such as notebook personal computers and mobile phones in recent years, the demand for small or thin secondary batteries as batteries used in these devices has rapidly increased. I have. Against this background, the development of ion-conductive polymer electrolytes for realizing thin-film batteries has been actively pursued in recent years. The ion conductive polymer electrolyte is mainly divided into a polymer solid electrolyte containing no organic solvent and a polymer gel electrolyte containing an organic solvent.

The following two types of ion-conductive polymer electrolytes are used.
The point is especially important. (1) The metal ions generated by the ion dissociation of the metal salt are easy to move, that is, have high ionic conductivity; and (2) A self-supporting thin film can be formed, and the thin film is resistant to compression and pulling force. It has sufficient resistance, that is, has good mechanical strength.

As a conventional solid polymer electrolyte, a metal oxide is dissolved in a polyethylene oxide (hereinafter referred to as PEO) polymer (US Pat. No. 4,303,748).
Or a polymer obtained by crosslinking a PEO-based polymer with an acryloyl group and dissolving a metal salt therein (JP-A-8-792).
No. 4) is known. However, a completely solid PEO-based polymer containing no solvent has a problem of low ionic conductivity.

To solve this problem, various polymer gel electrolytes having improved ionic conductivity by including an organic solvent in a polymer have been developed. For example, Japanese Patent Publication No. 61-23947
The publication discloses a polymer such as polyvinylidene fluoride,
A polymer gel electrolyte comprising a Group I or Group II metal salt and an organic solvent having excellent solubility in both is disclosed. Also, for example, US Pat. No. 5,296,318 discloses a polymer gel in which an organic solvent solution of a lithium salt is uniformly dispersed in a film of a vinylidene fluoride copolymer with 8 to 25% by weight of hexafluoropropylene. An electrolyte is disclosed. Further, a polymer gel electrolyte using a crosslinked body of a PEO-based polymer has been studied.
JP-109310 discloses that a mixture of a crosslinkable polyethylene oxide, a solution in which an alkali metal salt can be dissolved, and an alkali metal salt is formed, and the mixture is irradiated with light or radiation to crosslink the polyethylene oxide. A method for forming a complex in which a metal salt solution is infiltrated into an ethylene oxide crosslinked product is disclosed.

[0006] In addition, there has been devised a material constitution to improve both the mechanical strength and the ionic conductivity of the ion-conductive polymer electrolyte. For example, JP-A-63
Japanese Patent Application Laid-Open No. -102104 discloses a configuration in which an ion-conductive polymer electrolyte is filled in pores of a polymer porous membrane. JP-A-5-299119 discloses a polymer gel electrolyte comprising an electrolyte solution in a polymer blend having a phase separation structure. Also,
Japanese Patent Application Laid-Open No. 5-325990 discloses a polymer solid electrolyte composed of a polymer serving as a matrix and a polymer containing a solution forming an ion conduction path formed in a network inside the matrix. JP-A-5-299119 and JP-A-5-325990 both disclose a method of producing a fused body of fine polymer particles and impregnating the fused body with a metal salt solution.

Further, in order to improve the performance of an ion-conductive polymer electrolyte, a combination of two or more polymers is disclosed. For example, JP-A-58-757
No. 79 discloses a positive electrode comprising at least one polymer selected from polyvinylidene fluoride, polymethyl methacrylate, and other specific polymers, a lithium salt, a specific organic solvent, a metal lithium anode, and a specific inorganic compound. Is disclosed. Japanese Patent Application Laid-Open No. 9-97618 discloses a polymer alloy film in which a polymer which is hardly soluble and a polymer which is soluble in an organic electrolyte are mixed or compatible with each other, and the polymer is impregnated with the organic electrolyte and gelled. A gel electrolyte is disclosed. In this publication, polyvinylidene fluoride is exemplified as the polymer which is hardly soluble in the organic electrolyte, and polyethylene oxide is exemplified as the polymer which is soluble in the organic electrolyte.

Japanese Patent Application Laid-Open No. H8-165395 discloses a resin composition, not a polymer electrolyte for a battery, but a combination of two or more polymers, such as a thermoplastic resin such as polyvinylidene fluoride. A semiconductive solid composition comprising a polyalkylene oxide and an ion dissociable salt is disclosed. Also, JP-A-8-17
No. 6389 discloses a semiconductive solid composition comprising a thermoplastic resin such as polyvinylidene fluoride, a copolymer of an acrylate substituted polyalkylene oxide and a copolymer of an alkyl acrylate, and further containing an ionic electrolyte. . However, their conductivity is on the order of 10 ^-9 S / cm, and their ionic conductivity is too low as an ion-conductive polymer electrolyte for batteries.

JP-A-8-165395, JP-A-8-165395
The structures described in JP-176389-A and JP-A-9-97618 are common to the present invention in that polyvinylidene fluoride and another polymer are used. Some other polymer materials to be combined with polyvinylidene fluoride (hereinafter referred to as partner polymers) are discussed in the above three publications. The configuration of JP-A-8-165395 uses a polyalkylene oxide as a partner polymer. In Japanese Patent Application Laid-Open No. Hei 8-176389, the compatibility is improved by introducing a polyacrylate structure into the partner polymer. Also, Japanese Patent Application Laid-Open No. 9-976
JP-A No. 18 also describes a configuration using polyethylene oxide or polymethyl methacrylate as a partner polymer.

[0010]

However, the conventional technique has the following various problems.

[0011] JP-A-8-7924 and JP-A-5-924.
In the ion conductive polymer electrolyte disclosed in JP-A-109310, the ionic conductivity and the mechanical strength are improved as compared with the case where the PEO-based polymer is used alone.
Introducing a crosslinkable group such as an acryloyl group into the EO-based polymer increases the material cost, and requires a cross-linking step, thereby increasing the processing cost.

In the ionic conductive polymer electrolyte disclosed in Japanese Patent Publication No. 23947/1986, the mechanical strength is weak when the organic solvent content is large, and conversely when the organic solvent content is small. It has been difficult to simultaneously improve the mechanical strength and the ionic conductivity such that the mechanical strength increases but the ionic conductivity decreases.

The hexafluoropropylene-vinylidene fluoride copolymer disclosed in US Pat. No. 5,296,318 has a higher mechanical strength than the polyvinylidene fluoride homopolymer disclosed in JP-B-61-23947. Although it is improved from the viewpoint of compatibility between strength and ionic conductivity, there still remain problems to be solved, such as the oozing of organic soot from the inside of the membrane at high temperatures.

In the method disclosed in Japanese Patent Application Laid-Open No. 63-102104, an ionic conductive polymer electrolyte having improved ionic conductivity and mechanical strength as compared with the case of a single component can be obtained. In addition, at least a step of forming a polymer porous membrane and a step of filling the pores with an ion-conductive polymer electrolyte are required, which has been troublesome twice. Further, in the method described in JP-A-5-299119 and the method described in JP-A-5-325990, a step of preparing a fused body of polymer fine particles, The step of impregnation is different, and it has been troublesome twice.

Further, in the constitution described in JP-A-58-75779 or the constitution described in JP-A-9-97618, which is a constitution in which two or more kinds of polymers are combined, the ionic conductivity has so far been considered. It is difficult to say that sufficient performance has been obtained in terms of the balance between mechanical strength and mechanical strength.

As described above, it has been difficult for conventional ion conductive polymer electrolytes to simultaneously improve mechanical strength and ionic conductivity. In addition, in order to improve these simultaneously, it is considered to devise the polymer cross-linking and material configuration, but the manufacturing process is complicated,
There were problems in material cost and manufacturing cost.

The present invention has been made to solve these problems, and provides an ion-conductive polymer composition having both good ionic conductivity and good mechanical strength at a low cost by a simple method. Another object of the present invention is to provide a polymer battery which is easy to manufacture and has excellent charge / discharge characteristics.

[0018]

Means for Solving the Problems The present inventors have conducted intensive studies in order to solve the above problems. As a result, a polymer having a carbonyl group in the main chain portion of the repeating unit,
The present inventors have found that the above problems can be solved by simultaneously using a polyvinylidene fluoride-based polymer, and have reached the present invention. That is, the present invention is as follows. 1. 1 to 40% by weight of polymer A having a carbonyl group in the main chain of the repeating unit, 20 to 70% by weight of polyvinylidene fluoride polymer B, 1 to 50% by weight of ion dissociated group I or II metal salt C And 20 to 85% by weight of an organic solvent D capable of ion dissociating the metal salt C.
An ion conductive polymer composition, wherein the polymer A is at least one selected from the group consisting of polycarbonate and polyester carbonate. 2. The above-mentioned 1 wherein the polymer A has a repeating unit molecular weight of 120 or less per carbonyl group.
3. The ion conductive polymer composition according to item 1. 3 . 3. The ion-conductive polymer composition according to the above 1 or 2 , wherein the polymer B is polyvinylidene fluoride. 4 . Metal salt C has the general formula M ⁺ X ^- is represented by, M ⁺ is L
i ⁺ , Na ⁺ , K ⁺ , wherein X ^- is Cl
O ₄ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , CF ₃ SO ₃ ⁻ , (CF ₃ SO ₂ ) _{2
^{N -, (C 2 F 5}} SO 2) 2 N -, (CF 3 SO 2) 3 C -, (C
_{2 F 5 SO 2) 3 C} - is one selected from the group consisting of the 1 to ion-conducting polymer composition according to any one of the three. 5 . 5. The ion-conductive polymer according to any one of 1 to 4 , wherein the organic solvent D is at least one selected from the group consisting of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, and γ-butyrolactone. Composition. 6 . A melt mixture of polymer A and polymer B,
6. The method according to any one of the above items 1 to 5 , further comprising a step of cooling and forming a film to form a thin film, and a step of including, in the thin film, a solution obtained by dissolving a metal salt C in an organic solvent D. A method for producing an ion-conductive polymer composition. 7 . Mixing a polymer A, a polymer B, a metal salt C, an organic solvent D, and a volatile solvent E to form a mixed solution; applying the mixed solution to a solid surface to form a coating film; The method for producing an ion-conductive polymer composition according to any one of the above 1 to 5 , further comprising a step of volatilizing the volatile solvent E from the membrane. <8 . In a polymer battery comprising a positive electrode, a negative electrode, and a polymer electrolyte positioned therebetween, the polymer electrolyte comprises 1 to 40% by weight of a polymer A having a carbonyl group in a main chain portion of a repeating unit, and a polyvinylidene fluoride-based polymer. 20 to 70% by weight of B, 1 to 50% by weight of ion-dissociated Group I or Group II metal salt C, and said metal salt C
Contains 20 to 85% by weight of an organic solvent D capable of ion dissociation.
And the polymer A is a polycarbonate or a polyester.
At least one selected from the group consisting of tercarbonates
A polymer battery comprising the ion conductive polymer composition.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A feature of the present invention is that a polymer having a carbonyl group in the main chain of a repeating unit and a polyvinylidene fluoride polymer are used at the same time. In the field of ion-conductive polymer compositions, there have been considered various partner polymers to be combined with polyvinylidene fluoride-based polymers, and polymers having a carbonyl group in a side chain have been studied. It has been found that using a polymer having a carbonyl group in the main chain of the unit results in an ion-conductive polymer composition having better performance than using a polymer having a carbonyl group in the side chain. This has led to the present invention.

Polymer A in [0020] The present invention, the main chain moiety having a carbonyl group Lupo Rikabone <br/> bets repeating units, and at least one selected from polyester carbonate preferred. Still more preferably, the repeating unit has a molecular weight of 120 per carbonyl group.
The following things are not good. As such an example, aliphatic number of 4 or less carbon atoms in the alkylene group in Repetitive return unit polycarbonates; for example, polyglycolide, polylactide, Po
Li (β-propiolactone), polyethylene succine
, Polybutylene succinate, polyethylene adipate
Polybutylene adipate, poly (3-hydroxybutyrate)
Acid), polycaprolactone, polyethylene terephthalate
, Polybutylene terephthalate, poly (parahydroxy)
Polyester carbonate and the like produced by subjecting a polyester such as benzoic acid) to melt transesterification with a polycarbonate. The molecular weight of the repeating units to one per carbonyl group may be those exceeding 120, For example 2, 2- bis (4-hydroxyphenyl)
Polycarbonate synthesized from propane (bisphenol A polycarbonate), polycarbonate synthesized from 1,1-bis (4-hydroxyphenyl) cyclohexane (bisphenol Z polycarbonate), 2,
Polycarbonates synthesized from 2-bis (4-hydroxyphenyl) -hexafluoropropane, aromatic polycarbonates such as tetramethylbisphenol A polycarbonate, copolymer-type polycarbonates made from bisphenol and aliphatic glycol, the aromatic polyesters listed above, A polyester carbonate produced by performing a melt transesterification with an aromatic polycarbonate is exemplified . Or the polymer may be used in admixture of two or more.

The port polycarbonate as the polymer A or why polyester carbonates are preferably used, because with no active hydrogen in the polymer main chain moiety, is no lowering the battery performance when used as a battery electrolyte is there. The reason that the polymer A preferably has a molecular weight of a repeating unit of 120 or less per one carbonyl group is that a polymer having a higher carbonyl group content has a higher compatibility with a polyvinylidene fluoride-based polymer. In particular, the molecular weight of the repeating unit per one carbonyl group is 120
The following ports polycarbonate, and polyester carbonates mixes well upon melt mixing, mix may when a mixed solution of an organic solvent.

The polymer A in the present invention needs to have a carbonyl group in the main chain of the repeating unit. For example, a material having a carbonyl group only at a connecting portion between two polymers, such as a fatty acid alkyl ester, is not included.

The terminal of the polymer A in the present invention is not particularly limited, and any element may be bonded, but the terminal is preferably not active hydrogen. That is, the terminal is preferably not a hydroxyl group or a carboxyl group. An example is an alkoxy group such as a methoxy group. This is because, when the ion-conductive polymer composition comprising a terminal polymer having active hydrogen is incorporated into a thin-film battery, active hydrogen may reduce battery performance.

The polymer B in the present invention may be a polyvinylidene fluoride-based polymer. Examples of polymer B include:
Polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-ethylene copolymer, vinylidene fluoride-monofluoroethylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride- Tetrafluoroethylene copolymer, vinylidene fluoride-hexafluoropropylene-
Examples thereof include a tetrafluoroethylene terpolymer, and polyvinylidene fluoride is particularly preferred.

The metal salt C in the present invention is preferably
Formula M ⁺ X ^- is represented by, M ⁺ is Li ^+, Na ^+, a one selected from K ^+, X ^- is _{^{ClO 4 -, BF 4 -,}} P
F ₆ ⁻ , CF ₃ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , (C ₂ F ₅ S
^{_{O 2) 2 N -, (}} CF 3 SO 2) 3 C -, (C 2 F 5 SO 2) 3 C -
It is preferably one selected from the group consisting of
The salt is not particularly limited as long as it is a salt composed of a Group I or Group II metal. In addition to the above, for example, lithium salts such as acetic acid, oxalic acid, trifluoroacetic acid, trichloroacetic acid, methanesulfonic acid, and trichloromethanesulfonic acid, sodium salts, and potassium And the above-mentioned calcium salts and the like.
The anion may be a low molecular weight or a high molecular weight, and may be those obtained by introducing a sulfonic acid group, a carboxyl group, a sulfonylimide group or a sulfonylmethide group into the polymer A or the polymer B in the present invention (in this case, the metal salt C in the present invention). Is determined by the weight of a Group I or Group II metal ion,
This applies to the sum of the weight of the sulfonic acid group portion and the carboxyl group portion that is paired with this ion). The distribution of the metal salt C in the system of the present invention is not particularly limited except that it is ion-dissociated. Although the metal salt C in a state that it cannot be completely dissolved and is not ion-dissociated may exist, it is preferable that almost all of the metal salt C is ion-dissociated and uniformly distributed.

The organic solvent D in the present invention is not particularly limited as long as it can ion dissociate the metal salt C, but it is preferable that the organic solvent D does not easily volatilize.
It is preferably at least one selected from propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, and γ-butyrolactone. Acetone, methyl ethyl ketone, ethyl acetate, cyclohexanone and the like are also included in the range of the organic solvent D in the present invention, although they have a disadvantage that they have a low boiling point and are easily volatilized.

In the present invention, the content of each component is specified (1 to 40% by weight of polymer A, 20 to 70% by weight of polymer B, 1 to 50% by weight of metal salt C, organic solvent D). 20 to 85% by weight), but various disadvantages occur when each component is out of these ranges. When the amount of the polymer A is less than 1% by weight, there is no difference from the ion conductive polymer composition using only the polymer B, and the effects of the present invention cannot be obtained. When the content of the polymer A exceeds 40% by weight and the content of the polymer B is relatively small, it depends on the gel forming ability of the polymer A (whether or not there is a property of being in a gel state including an organic solvent). In most cases, the gel-forming ability is inferior to that of polymer B, which is a polyvinylidene fluoride-based polymer, so that it is difficult to obtain an ion-conductive polymer composition having mechanically good quality. When the amount of the polymer B exceeds 70% by weight and the content of the organic solvent D or the metal salt C is relatively small, ions hardly move or the ion content itself decreases, so that the ion conductivity is high. The ionic conductivity of the molecular composition is significantly reduced. When the amount of the metal salt C exceeds 50% by weight, a large amount of the metal salt C which remains in a crystalline state without ion dissociation precipitates, resulting in an ionically conductive polymer composition having a mechanically unfavorable film quality. When the amount of the organic solvent D exceeds 85% by weight, the mechanical strength of the ion-conductive polymer composition is significantly reduced.

There are two methods for producing the ion-conductive polymer composition of the present invention. One of them (the method according to the invention 6 ) is to cool a molten mixture composed of the polymer A and the polymer B by cooling. A method for producing an ion-conductive polymer composition according to the present invention, comprising a step of forming a thin film by forming a film, and a step of including a solution in which a metal salt C is dissolved in an organic solvent D in the thin film. It is. Another one of the production methods of the present invention (the method according to Invention 7 ) is:
Mixing a polymer A, a polymer B, a metal salt C, an organic solvent D, and a volatile solvent E to form a mixed solution, and applying the mixed solution to a solid surface to form a coating film;
A method for producing an ion-conductive polymer composition according to the present invention, comprising a step of volatilizing a volatile solvent E from the coating film.

In the method according to the invention 6 , the polymer A
As a method for obtaining a molten mixture consisting of
A method in which the powder of the polymer A and the powder of the polymer B are mixed well and heated in an appropriate heating vessel to melt the two may be used, or a method in which the polymer A and the polymer B are melted and then mixed may be used. The combination of the polymer A and the polymer B is preferably such that a uniform molten mixture is obtained, and the temperature at which these are melted is preferably such that a uniform molten mixture is obtained. In this method, as a method of cooling and forming a molten mixture of polymer A and polymer B (hereinafter simply referred to as a molten mixture), the molten mixture is thinly cast on an appropriate solid surface and then left at room temperature. Alternatively, the molten mixture may be thinly cast on a previously cooled solid surface. The temperature of the solid surface on which the molten mixture is cast may be controlled by a suitable temperature controller with a suitable temperature program. It is preferable that the film thickness condition, initial temperature condition, cooling rate, and the like in the method of cooling and film-forming the molten mixture are appropriately set depending on the combination of the types of the materials of the system. As the solid surface on which the molten mixture is cast, any material may be used. Examples of the solid surface that can be used in the present invention include a glass plate surface, a metal plate surface, a surface of a battery electrode surface, a surface of active material particles of a battery, and a thin porous material used for a battery separator. Examples of the surface include a surface inside the hole, a surface of fine particles used as a spacer, a film surface of an organic solid electrolyte and an inorganic solid electrolyte, and a particle surface. Further, in the method of cooling and forming a film of the molten mixture to form a thin film, it is not always necessary to use a solid surface, and the thin film can be formed by, for example, a melt extrusion method. Further, in the method according to the sixth aspect , a solution obtained by dissolving a metal salt C in an organic solvent D (hereinafter referred to as a metal salt C) is added to a thin film (hereinafter referred to as a polymer AB thin film) obtained by cooling and forming the molten mixture. Solution is called)
The polymer AB film may be immersed in a metal salt solution C, over the polymer AB film may be added dropwise to the metal salt solution C.

In the method according to the seventh aspect , the volatile solvent E is not particularly limited as long as a mixed solution of the polymer A, the polymer B, the metal salt C, and the organic solvent D is obtained, and is volatile. However, those having a low boiling point and easy to volatilize at room temperature or slightly heated are preferable. Examples include acetone, methyl ethyl ketone, cyclohexanone, methyl formate, methyl acetate, tetrahydrofuran,
Acetonitrile, dimethyl sulfoxide, dimethoxymethane, dimethoxyethane, diethoxyethane, dimethylformamide, dimethylacetamide, N-methyl-2
-Pyrrolidone and the like. Further, a mixed solvent composed of two or more kinds of organic solvents, for example, a mixed solvent of a solvent for dissolving the polymer A and a solvent for dissolving the polymer B, the metal salt C and the organic solvent D may be used. In this method, any solid surface may be used as the solid surface to which the mixed solution is applied, similarly to the solid surface described in the description of the sixth aspect . In the step of volatilizing the volatile solvent E from the coating film, the volatile solvent may be volatilized by being left at normal temperature and normal pressure, or may be forcibly volatilized by heating or reducing the pressure. It is preferable to appropriately set the temperature condition and the atmospheric pressure condition for volatilization according to the combination of the types of the materials of the system.

The polymer battery according to the present invention comprises a positive electrode,
In a polymer battery comprising a negative electrode and a polymer electrolyte located therebetween, there is no particular limitation as long as the polymer electrolyte comprises the ion-conductive polymer composition of the present invention. A primary battery or a secondary battery may be used.
As the configuration of the polymer battery in the present invention, for example,
The positive electrode and the negative electrode may be adhered to both surfaces of the thin film of the ion-conductive polymer composition of the present invention, or another member may be provided between the thin film of the ion-conductive polymer composition of the present invention and the positive electrode and the negative electrode. May be sandwiched. The form of the polymer battery of the present invention is not limited at all. It may be a coin type, a cylindrical type, a card type, or a square type. Regarding the arrangement of the electrodes,
A configuration in which flat plates are bonded to each other or a wound type may be used.
Further, a configuration in which a positive electrode, a negative electrode, and a plurality of layers of the ion-conductive polymer composition of the present invention are laminated and connected in series or in parallel may be used. The method for producing the polymer battery of the present invention is not limited at all. For example, a method of applying a molten mixture of the polymer A and the polymer B according to the present invention to the surface of the positive electrode, including a solution obtained by dissolving the metal salt C in the organic solvent D according to the present invention, and bonding the negative electrode, A method in which a mixed solution of the polymer A, the polymer B, the metal salt C, the organic solvent D, and the volatile solvent E in the present invention is applied to the surface of the positive electrode, and the volatile solvent E is volatilized from the coating film. .

The positive electrode active material contained in the positive electrode of the polymer battery is not limited at all. Examples thereof include vanadium oxide, lithium cobaltate, lithium manganate, polyaniline, disulfide compound, polypyrrole, poly (ethylenedioxythiophene), Conventionally known materials such as poly (alkylthiophene), carbon, or a mixture of any of these materials may be used. The shape of the positive electrode active material is also particularly limited, and examples thereof include a plate shape, a thin film shape, a particle shape, and a porous shape. In the present invention, the positive electrode may include a current collector, a binder, an auxiliary conductive agent, an ionic conductor, and the like in addition to the positive electrode active material. Examples of the current collector include metal foils such as copper, iron, nickel, aluminum, and tin. Examples of the binder include polyethylene,
Examples thereof include polypropylene, polytetrafluoroethylene, polyvinylidene fluoride, polyhexafluoropropylene, and copolymers and crosslinked products thereof.
The binder and the ion-conductive polymer composition of the present invention may be integrally formed by using the same material composition. Examples of the auxiliary conductive agent include carbon particles, polyaniline, polypyrrole, metal particles, and the like.

Examples of the negative electrode in the polymer battery include those obtained by dispersing natural graphite, mesophase carbon microbeads, and the like in a binder, an ion conductor, or the like, and coating the resultant on a current collector. In addition, a group I or group II elemental metal or an alloy thereof with another metal may be included as an active material. Aluminum, lead, tin, cadmium, silver,
Indium, zinc, antimony, mercury, magnesium,
Calcium etc. are mentioned as an example.

As a structure similar to the present invention, a polymer solid electrolyte in which an electrolyte solution is contained in a polymer matrix having a phase separation structure is disclosed (Japanese Patent Laid-Open No. 5-2 / 1993).
No. 99119). Also disclosed is a polymer solid electrolyte comprising a polymer matrix and an ion conduction path formed in a continuous network by phase separation from the polymer matrix in the polymer matrix (Japanese Patent Application Laid-Open No. H5-205). 325
990). However, any of those disclosed in these publications uses a fused body of polymer fine particles as a mechanical support phase or an ion conduction path, and has a different configuration from those produced from the production method of the present invention. . Further, as another configuration similar to the present invention, a configuration in which a polymer alloy film in which a poorly soluble polymer and a soluble polymer are mixed or compatible with each other in an organic electrolyte solution is produced, and the organic electrolyte solution is impregnated and gelled. It has been disclosed (Japanese Unexamined Patent Application Publication No.
97618). However, there is no description of a configuration in which a polymer having a carbonyl group in the main chain portion of the repeating unit and polyvinylidene fluoride are mixed, which is different from the configuration of the present invention.

According to the present invention, the following advantages are recognized.

(A) In the ion-conductive polymer composition, the polymer A has a carbonyl group in the main chain portion of the repeating unit, and the polymer B is a polyvinylidene fluoride-based polymer. A uniform ion conductive polymer composition film can be obtained by a method for producing the conductive polymer composition or the like. This has good compatibility between the polymer having a carbonyl group in the main chain portion of the repeating unit and the polyvinylidene fluoride polymer, and is uniform when both are melted and mixed or when a mixed solution is prepared using a common solvent. It is considered that a molten mixture or a mixed solution can be easily obtained. Further, by using the polymer B as polyvinylidene fluoride, an ion-conductive polymer composition having excellent mechanical strength can be obtained as compared with the case where another polyvinylidene fluoride-based polymer is used. This is probably because polyvinylidene fluoride homopolymer is the polymer having the highest crystallinity among polyvinylidene fluoride polymers. In addition, by using a metal salt C and an organic solvent D selected from those described in Inventions 4 and 5 , both the ionic conductivity and the mechanical strength are lower than when other materials are used. A good ion conductive polymer composition is obtained.

(B) Invention 6 of ion conductive polymer composition
According to the production method described in (1), it is possible to obtain an ion-conductive polymer composition of the present invention that is homogeneous and has favorable film quality in terms of compatibility between the ionic conductivity and the mechanical strength of the ion-conductive polymer composition. . Further, after the film is formed, the film can be stored in a dry state, and a solution obtained by dissolving the metal salt C in the organic solvent D can be included in another step, so that the ion conductive polymer composition or the polymer using the same can be contained. It is convenient for mass production of batteries.

(C) Invention 7 of ion conductive polymer composition
According to the production method described in (1), it is possible to obtain an ion-conductive polymer composition of the present invention that is homogeneous and has favorable film quality in terms of compatibility between the ionic conductivity and the mechanical strength of the ion-conductive polymer composition. . Further, all the steps can be performed at room temperature, and the manufacturing cost can be reduced.

(D) In the ion-conductive polymer composition of the present invention, the mechanical strength of the ion-conductive polymer composition can be made uniform, and the ion-conductive polymer composition may be divided into a portion having a high mechanical strength and a portion having a low mechanical strength. In addition, an ionic conductive polymer composition having excellent mechanical strength as a whole can be obtained, and also the ionic conductivity of the ionic conductive polymer composition can be uniform, and a portion having a high ionic conductivity and a portion having a low ionic conductivity depending on a place. It does not split into parts. (E) In a polymer battery comprising a positive electrode, a negative electrode, and a polymer electrolyte located therebetween, the polymer electrolyte is made of the ion conductive polymer composition of the present invention, thereby improving the ion conductivity. Irregularities in the inflow and outflow of ions on the surfaces of the positive electrode and the negative electrode are reduced without being divided into a portion having a high ionic conductivity and a portion having a low ionic conductivity depending on the location of the molecular composition, whereby a polymer battery having excellent charge / discharge characteristics can be obtained.

[0040]

Reference Example 1 In an argon atmosphere, polyethylene succinate and polyvinylidene fluoride were mixed at a weight ratio of 3: 7, melted at 200 ° C., and a self-supporting thin film was obtained by a usual hot pressing method. A 1M LiPF ₆ / propylene carbonate solution (hereinafter referred to as “metal salt solution”) was kept at 60 ° C., and the above-mentioned polymer blend thin film was immersed together with the stainless steel plate for 3 hours, pulled up, and allowed to stand at room temperature for 1 hour. Excess liquid adhering to the thin film and stainless steel plate was wiped off.
There was thus obtained a thin film of ion-conducting polymer composition. The composition thin film was peeled and cut into a desired shape to obtain a sample for measuring ionic conductivity and a sample for measuring mechanical strength.

REFERENCE EXAMPLE 2 In an argon atmosphere, polyethylene succinate, polyvinylidene fluoride, LiPF ₆ , propylene carbonate, and dimethylformamide (hereinafter, DMF) were mixed in the following manner:
The mixture was mixed at a weight ratio of 9: 1: 9: 100, and stirred at 60 ° C. to obtain a mixed solution. This mixed solution was thinly applied on a mirror-polished stainless steel plate in an argon atmosphere. Furthermore, in 60 ° C., by evaporating the DMF moderately reduced pressure to obtain a thin film of ion-conducting polymer composition. The composition thin film was peeled and cut into a desired shape to obtain a sample for measuring ionic conductivity and a sample for measuring mechanical strength.

REFERENCE EXAMPLE 3 Polybutylene terephthalate and polyvinylidene fluoride were mixed at a weight ratio of 3: 7 in an argon atmosphere and mixed at 250 ° C.
And a self-supporting thin film was obtained by a usual hot pressing method. Thereafter, in the same manner as in Reference Example 1, a sample for measuring ionic conductivity and a sample for measuring mechanical strength were obtained.

REFERENCE EXAMPLE 4 Polybutylene terephthalate and vinylidene fluoride-tetrafluoroethylene copolymer (tetrafluoroethylene content: 30%, hereinafter referred to as PVDFTFE) were mixed at a weight ratio of 3: 7 in an argon atmosphere and mixed at 250 ° C. Melt in
A self-supporting thin film was obtained by a usual hot pressing method.
Thereafter, in the same manner as in Reference Example 1, a sample for measuring ionic conductivity and a sample for measuring mechanical strength were obtained.

Example 1 Bisphenol Z polycarbonate (manufactured by Mitsubishi Gas Chemical Company, trade name: Iupilon Z-200, hereinafter referred to as BPZPC) in an argon atmosphere PVDFTFE, Li
PF ₆ , propylene carbonate, and tetrahydrofuran (hereinafter, THF) were mixed at a weight ratio of 1: 9: 1: 9: 100, and stirred at room temperature to obtain a mixed solution. The above mixed solution is thinly applied on a mirror-polished stainless steel plate in an argon atmosphere, and at room temperature, the pressure is appropriately reduced to volatilize THF to obtain a thin film of the ion-conductive polymer composition of the present invention. Was. Thereafter, in the same manner as in Reference Example 2, a sample for measuring ionic conductivity and a sample for measuring mechanical strength were obtained.

Comparative Example 1 Polyvinylidene fluoride, LiPF ₆ , polypropylene carbonate, and DMF were mixed at a weight ratio of 10: 1: 9: 100, and stirred at room temperature to obtain a mixed solution. Hereinafter, Reference Example 2
In the same manner as in the above, a sample for measuring ionic conductivity and a sample for measuring mechanical strength were obtained.

[0046] Battery Reference Example 1 This example uses the positive electrode active material a metal oxide, lithium-ion occluding carbon material in the negative electrode, ion-conductive polymer composition to a polymer electrolyte positioned between these in the positive electrode 1 shows an example of a polymer battery. FIG. 1 is a schematic sectional view of this polymer battery.

As shown in FIG. 1, the battery of this embodiment has a positive electrode layer 2 formed on one surface of a positive electrode current collector 1 and a negative electrode layer 4 formed on a surface of a negative electrode current collector 5. There are laminated so as to sandwich in close contact with the ion-conductive polymer electrolyte layer 3, and a fixed structure Ri by the hotmelt 6. This polymer battery was manufactured in an argon atmosphere as follows.

Lithium cobaltate having an average particle size of 5 μm, acetylene black, polyvinylidene fluoride, and N-methyl-2-pyrrolidone were mixed and dispersed at a weight ratio of 10: 1: 1: 30, and the mixture was stirred well. This was uniformly applied on one side of an aluminum foil by a wire bar method, and dried under vacuum at 100 ° C. for 2 hours to remove the solvent. Excess portions of the positive electrode layer thus manufactured were removed from the positive electrode current collector so as to have an appropriate size, thereby producing a positive electrode layer 2 and a positive electrode current collector 1 having a capacity of about 25 mAh.

Next, the same polyethylene succinate, polyvinylidene fluoride and LiPF as used in Reference Example 2 were used.
₆ , a mixture of propylene carbonate and DMF 6
The mixed solution kept at 0 ° C. was thinly applied on the positive electrode layer. During this 60 ° C., by evaporating the DMF moderately reduced pressure, to form a ion-conducting polymer composition film 3. Further, an extra portion of the thin film was scraped off to adjust the size and the film thickness.

On the other hand, polyvinylidene fluoride, N-methyl-2-pyrrolidone, powdered petroleum coke, and acetylene black were mixed at a weight ratio of 1: 30: 20: 1 and stirred well. This was uniformly applied on one side of a stainless steel foil by a wire bar method, and dried in vacuum at 100 ° C. for 2 hours.
The solvent was removed. Next, an unnecessary portion was removed from the negative electrode current collector so that it became the same size as the positive electrode layer, thereby removing
A negative electrode layer 4 and a negative electrode current collector 5 having a capacity of mAh were produced.

Next, a hot-press type hot melt is placed on the outer periphery of the positive electrode current collector, and the ion-conductive polymer electrolyte layer on the positive electrode layer is tightly sandwiched between the positive electrode layer and the negative electrode layer. Thus, the negative electrode layer and the negative electrode current collector were combined in the positional relationship as shown in FIG. Then, the hot melt 6 was completely adhered to the outer peripheral end of the current collector by heating to complete the polymer battery.

Battery Manufacturing Reference Example 2 A weight ratio of polyethylene succinate, polyvinylidene fluoride, lithium bis (trifluoromethylsulfonyl) imide (hereinafter LiTFSI), propylene carbonate and DMF was 1: 9: 2: 9: 100. And mix with
The mixture was stirred at 60 ° C. to obtain a mixed solution. The above mixed solution,
A thin coating was applied on the positive electrode layer on the same positive electrode current collector as used in Battery Manufacturing Reference Example 1 . Thereafter, a polymer battery was completed in the same manner as in Battery Manufacturing Reference Example 1 .

Battery Manufacturing Reference Example 3 Polyethylene succinate, polyvinylidene fluoride, L
iPF ₆ , ethylene carbonate, propylene carbonate, and DMF were mixed at a weight ratio of 2: 18: 2: 9: 9: 200 and stirred at 60 ° C. to obtain a mixed solution. This mixed solution was thinly applied on the positive electrode layer on the same positive electrode current collector as that used in Battery Manufacturing Reference Example 1 . Later, it made the battery
A polymer battery was completed in the same manner as in Reference Example 1 .

[0054] thin film battery Reference Example 4 cell manufacturing similarly form a positive electrode layer on the positive electrode current collector as in Reference Example 1, further Similarly ion conductive polymer compositions and batteries Reference Example 1 thereon Was formed. Further, an extra portion of the thin film was scraped off to adjust the size and the film thickness.

Next, a hot-press type hot melt is placed on the outer periphery of the positive electrode current collector, and then a lithium foil (negative electrode layer) having the same size as the above-mentioned ion conductive polymer composition layer is formed.
Was placed on the ion-conductive polymer composition layer, and a stainless steel foil (negative electrode current collector) having the same size as the positive electrode current collector was further mounted thereon. Then, by heating, the hot melt was completely adhered to the outer peripheral end of the current collector to complete the polymer battery.

Battery Manufacturing Comparative Example 1 On the same positive electrode layer used in Battery Manufacturing Reference Example 1 , the same polyvinylidene fluoride and Li used in Comparative Example 1 were used.
A uniform solution of PF ₆ , propylene carbonate, and DMF was thinly applied. At room temperature, moderately reduced pressure
By volatilizing F, a thin film of the ion-conductive polymer composition was formed. Further, an extra portion of the thin film was scraped off to adjust the size and the film thickness. Hereafter, reference examples of battery manufacturing
In the same manner as in Example 1 , a polymer battery was completed.

[0057] In the battery production Comparative Example 2 Battery Reference Example 4, except for using the same ion conductive polymer composition as that used in battery manufacturing Comparative Example 1 as the ion conductive polymer composition layer cell production A polymer battery was completed in the same manner as in Reference Example 4 . (Evaluation Method and Result of Sample) The conductivity of the ion-conductive polymer composition in Example 1 , Reference Examples 1 to 4 and Comparative Example 1 was measured by pressing each of the two stainless steel electrodes appropriately. It was measured by the AC impedance method. Moreover, Example 1 , Reference Examples 1-4
As for the mechanical strength of the ion-conductive polymer composition in Comparative Example 1, the tensile strength was measured by an ordinary method. Table 1 shows the ionic conductivity and the tensile strength of the ion-conductive polymer composition in Example 1 , Reference Examples 1 to 4 and Comparative Example 1.

[0058] In addition, the battery Reference Example 1-4 and made the battery
A charge / discharge test was performed on the polymer batteries manufactured in Comparative Examples 1 and 2 . In the charge / discharge test, first, 5m from the charging direction
With the current of A, the battery is charged until the battery voltage reaches 4.5 V, and
After a 0-minute rest period, the battery was discharged at the same current until the battery voltage reached 2.0 V. Hereinafter, this charge / discharge operation was repeated 100 times, and the change in capacity was calculated from the amount of current flowing. Table 2 two installment <br/> made the capacity of the reduction degree for repeated charging and discharging of the polymer battery, in comparison with the ratio of the charge-discharge capacity C ₁₀₀ to the initial capacity C _0.

[0059]

[Table 1]

[0060]

[Table 2] From the results in Table 1, it can be seen that the ionic conductivity was improved in both the examples and the reference examples of the ion-conductive polymer composition of the present invention as compared with the conventional comparative example 1. Regarding the tensile strength, it can be seen that both the examples and the reference examples of the ion-conductive polymer composition of the present invention have excellent mechanical strength as compared with the conventional comparative example 1. Compared with examples and reference examples to each other, best ionic conductivity in case of using polyethylene succinate as the polymer A, then the case of using the port polybutylene terephthalate, then that in the case of using a bisphenol Z polycarbonate It turns out that it is in order. This is the content of carbonyl groups in the polymer (polyethylene succinate: one carbonyl group for a molecular weight of 72, polybutylene terephthalate: one carbonyl group for a molecular weight of 110, bisphenol Z polycarbonate: one carbonyl group for a molecular weight of 294) It is presumed that the larger the amount, the better the compatibility with the polyvinylidene fluoride polymer and the better the film quality.

From the results shown in Table 2, the battery production reference examples 1 to 4 are more conventional than those of the same electrode configuration.
It turns out that it has more excellent charge / discharge repetition resistance than battery manufacture comparative examples 1 and 2 .

[0062]

According to the present invention, the following effects are observed in the ion conductive polymer composition. The first effect is that an ionic conductive polymer composition having good ionic conductivity and good mechanical strength can be obtained. Although the reason has not been completely elucidated yet, the compatibility between the polymer having a carbonyl group in the main chain portion of the repeating unit and the polyvinylidene fluoride-based polymer is good. This is considered to be because a homogeneous molten mixture or a mixed solution can be easily obtained when a mixed solution is prepared by using the composition, and an ion-conductive polymer composition having preferable film quality can be obtained. The second effect is that the above-mentioned ion conductive polymer composition can be obtained at a lower cost than ever. The reason is that the conventional complicated steps of forming the network-like polymer portion having mechanical strength and the ion conduction path in separate steps are not required.

According to the present invention, the following effects can be obtained in the polymer battery. The first effect is that manufacturing is easy. The reason for this is that, as described above, the ion-conductive polymer composition of the present invention can be produced without requiring complicated steps as in the related art. The second effect is that a polymer battery having excellent charge / discharge characteristics can be obtained. The reason is that, as the electrolyte layer between the positive electrode and the negative electrode, the ionic conductivity and the mechanical strength are both good, and the mechanical strength is excellent as a whole without being divided into a high mechanical strength part and a low mechanical strength part depending on the location. This is because the ion-conductive polymer composition of the present invention has a uniform ionic conductivity without being divided into a portion having a high ionic conductivity and a portion having a low ionic conductivity depending on a location.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing one example of a polymer battery of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 positive electrode current collector 2 positive electrode layer 3 ion conductive polymer electrolyte layer 4 negative electrode layer 5 negative electrode current collector 6 hot melt

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI H01M 6/18 H01M 6/18 E 6/22 6/22 C 10/40 10/40 B (72) Inventor Etsuo Hasegawa Tokyo 5-7-1 Shiba, Minato-ku NEC Corporation (56) References JP-A-11-54124 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 27/16 , 69/00 C08K 3/24 H01B 1/06-1/12 H01M 6/18-6/22 H01M 10/40 CA (STN)

Claims (8)

(57) [Claims] 1 to 40% by weight of a polymer A having a carbonyl group in the main chain portion of a repeating unit, 20 to 70% by weight of a polyvinylidene fluoride-based polymer B, and an ion-dissociated Group I or Group II metal salt C. 1 to 50% by weight, and 20 to 8 organic solvents D capable of ion dissociating the metal salt C.
An ion conductive polymer composition containing 5% by weight, wherein the polymer A is at least one selected from the group consisting of polycarbonate and polyester carbonate. 2. The ion conductive polymer composition according to claim 1, wherein the polymer A has a repeating unit having a molecular weight of 120 or less per carbonyl group. Wherein the polymer B is, according to claim 1 or 2 ion conductive polymer composition according polyvinylidene fluoride. Wherein the metal salt C has the general formula M ⁺ X ^- in expressed, M
⁺ Is one selected from Li ⁺ , Na ⁺ , and K ⁺ , and X ⁻
Are ClO ₄ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , CF ₃ SO ₃ ⁻ , (CF ₃ S
O ₂ ) ₂ N ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ⁻ , (CF ₃ SO ₂ )
_{^{3 C -, (C 2 F}} 5 SO 2) 3 C - 1 selected from the group consisting of
The ion-conductive polymer composition according to any one of claims 1 to 3 , wherein 5. The organic solvent D is ethylene carbonate,
The ion conductive polymer composition according to any one of claims 1 to 4 , wherein the composition is at least one selected from the group consisting of propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, and γ-butyrolactone. 6. A step of cooling and forming a molten mixture comprising a polymer A and a polymer B into a thin film,
The method for producing an ion-conductive polymer composition according to any one of claims 1 to 5 , further comprising a step of including a solution in which the metal salt C is dissolved in the organic solvent D. 7. A step of mixing a polymer A, a polymer B, a metal salt C, an organic solvent D, and a volatile solvent E to form a mixed solution, and applying the mixed solution to a solid surface to form a coating film. The method for producing an ion-conductive polymer composition according to any one of claims 1 to 5 , comprising a step and a step of volatilizing the volatile solvent E from the coating film. 8. A polymer battery comprising a positive electrode, a negative electrode, and a polymer electrolyte located therebetween, wherein the polymer electrolyte contains 1 to 40% by weight of a polymer A having a carbonyl group in a main chain portion of a repeating unit, 20 to 70% by weight of a polyvinylidene fluoride polymer B, 1 to 50% by weight of an ion-dissociated Group I or Group II metal salt C, and 20 to 85% of an organic solvent D capable of ion-dissociating the metal salt C
Wt% observed containing the polymer A, polycarbonate and
Small number selected from the group consisting of polyester carbonate
A polymer battery comprising at least one ion-conductive polymer composition.