JPH10112215A - Solid electrolyte and non-aqueous battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily manufacture a solid electrolyte in safety, and to provide the high ion conductivity by making a porous body composed of acrylonitrile polymer having bridge structure, impregnated with the solution obtained by dissolving an electrolyte cpd into an organic solvent. SOLUTION: A porous body is composed of acrylonitrile polymer having the bridged structure. For example, the solution composed of acrylonitrile, methyl acrylate, sodium metharyl sulfonate ternary copolymer, polyethylene glycol and butyrolactone is prepared, and a porous sheet is manufactured by performing the predermined treatment. Then an electron beam is applied to the sheet to obtain the bridged sheet, and the sheet is impregnated with the solution of ethylene carbonates propylene carbonate mixed solvent, to obtain a transparent sheet. Thereby a solid electrolyte having high conductivity, superior in the high temperature stability, and having the proper strength even in an area of high quantity of electrolyte solution, can be easily manufactured in safety.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a solid polymer electrolyte and a nonaqueous battery using the solid electrolyte. More specifically, the present invention relates to a so-called hybrid type solid electrolyte having a structure in which an electrolyte solution coexists in a polymer, and a non-aqueous battery using the solid electrolyte.

[0002]

2. Description of the Related Art Recently, miniaturization of mobile phones, personal computers, and the like,
A battery having a high energy density is required for weight reduction, and a lithium ion battery has been developed and industrialized to meet the demand. As the ion transfer medium between the positive electrode and the negative electrode of this battery, a form in which a porous polymer separator having through holes is impregnated with a non-aqueous solvent-based electrolyte solution is used, and leakage of the electrolyte solution impregnated into the separator is performed. In order to prevent this, a battery structure in which the entire battery structure is packaged in a heavy metal container has been commercialized.

On the other hand, a solid-state battery in which a solid electrolyte is used as an ion transfer medium has no liquid leakage, and thus has high reliability and reliability.
Along with improving safety, it is expected to reduce the thickness, form a laminate, and simplify and lighten the package. In particular, a solid polymer electrolyte using an ion-conductive polymer has favorable properties such as forming a laminated structure with a battery because of its processing flexibility, and being able to maintain an interface following a volume change due to ion occlusion and release of an electrode. Expected.

[0004] As an attempt of such a solid polymer electrolyte, an alkali metal salt complex of polyethylene oxide is disclosed by Wright as British Polymer.
Journal, Vol. 7, p. 319 (1975), polymer solid electrolyte materials based on polyphosphazenes, polysiloxanes, and the like, as well as polyalkylene ether-based materials such as polyethylene glycol and polypropylene oxide, have been actively studied. ing. Such a solid polymer electrolyte usually takes a form in which an electrolyte compound is uniformly dissolved in a polymer, and is known as a dry polymer solid electrolyte, but its ionic conductivity is higher than that of an electrolyte solution. The battery was remarkably low and had problems such as limited charge / discharge current density and high battery resistance.

For this reason, various attempts have been made to improve the ionic conductivity by forming a state closer to an electrolyte solution. For example, it is known that a relatively high conductivity can be obtained by adding a plasticizer to a solid electrolyte using polyacrylonitrile or polyvinylidene fluoride as a polymer matrix (Watanabe et al., Macrom)
ol. Chem. , Rapid Commun. , 2
Vol., P741 (1981)). In this case, the conductivity tends to be higher when the amount of the plasticizer is increased, and such an electrolyte is known as a hybrid electrolyte or a gel electrolyte. When the strength is remarkably reduced and the concentration of the plasticizer is increased, the shape can no longer be maintained.

In particular, when polyvinylidene fluoride is used, in order to prepare a gel electrolyte, it is necessary to use a flammable low-boiling solvent or to dissolve the solvent at a high temperature of 120 to 130 ° C. in the solvent of the electrolyte. Also, JP-A-8-1952
No. 20 discloses a method in which a gel electrolyte using polyacrylonitrile is perforated with a stainless steel fine needle in an electrolyte solution to make the gel electrolyte porous. However, since this gel electrolyte is uncrosslinked, it is exposed to high temperatures. If melted, it would dissolve, resulting in the possibility that holes would be crushed or even short-circuited.

On the other hand, US Pat. No. 5,240,790 reports a gel electrolyte comprising a polyacrylonitrile, a plasticizer containing γ-butyrolactone, and a lithium salt. Among them, the use of a photoinitiator together with a crosslinking agent is also reported. However, in this case, since it is not porous, the content of the electrolyte solution could not be increased while maintaining high strength, and it was difficult to obtain a sufficiently high conductivity. Further, in this case, the crosslinking agent and the photoinitiator used for crosslinking may adversely affect electrochemically.

On the other hand, it is difficult to use a crosslinked acrylonitrile-based polymer film as a separator for an alkaline battery (JP-A-53-830) and a porous film made of an acrylonitrile-based polymer as a separator for a lead-acid battery. Known (U.S. Pat. No. 42516)
No. 05). These have a similar structure to the hybrid type solid electrolyte in that they are used together with the electrolyte solution in the battery.However, the application is a separator, and since the aqueous electrolyte is used, the polymer matrix is used in the polymer matrix. It was not at all assumed that the electrolyte solution was swollen and used as a gel electrolyte.

Accordingly, a polymer suitable for non-aqueous batteries such as lithium ion batteries, which has appropriate strength even in a region having a large amount of electrolyte solution having high ionic conductivity and which can be manufactured safely and easily. Solid electrolytes were not yet known.

[0010]

DISCLOSURE OF THE INVENTION The present invention provides a polymer solid electrolyte having high ionic conductivity, which can be produced safely and easily even using a flammable non-aqueous solvent, and the polymer solid electrolyte. An object of the present invention is to provide a non-aqueous battery using the same.

[0011]

Means for Solving the Problems The present inventors have conducted research on a solid electrolyte using an acrylonitrile-based polymer, and have reached the present invention. The present invention is as follows. (1) A solution in which an electrolyte compound is dissolved in a non-aqueous solvent is a solution in which an acrylonitrile-based polymer can swell, and a non-aqueous battery in which a porous body made of a cross-linked acrylonitrile-based polymer contains the solution. For solid electrolyte. (2) The solid electrolyte according to the above (1), which is crosslinked by electron beam irradiation. (3) A non-aqueous battery, wherein the electrodes are joined via the solid electrolyte of (1) or (2).

The solid electrolyte of the present invention is formed by impregnating a porous body made of an acrylonitrile polymer having a crosslinked structure with a solution in which an electrolyte compound is dissolved in an organic solvent. It is necessary that a solution capable of swelling the acrylonitrile-based polymer be used as the solution. As described in the prior art, an electrolyte compound and a solid electrolyte formed by adding a solvent to a normal uncrosslinked acrylonitrile-based polymer, the electrolyte compound and the solvent are considered in consideration of the processability when used in a battery. Is limited to about 70%. The solid electrolyte of the present invention is characterized in that a wide range of contents can be selected without being limited by the contents of such an electrolyte compound and a solvent. That is, since the acrylonitrile-based polymer having a crosslinked structure of the present invention can be used in a composition in which the contents of the electrolyte compound and the solvent are increased, a solid electrolyte having high ionic conductivity can be produced. Also, because of this crosslinked structure,
The solid electrolyte of the present invention does not dissolve even at a high temperature, and there is no possibility of short circuit. That is, it has sufficient mechanical strength that it can be used even at high temperatures, and has excellent high-temperature stability.

In addition, the solid electrolyte of the present invention is formed by impregnating a porous body with the above-mentioned electrolyte solution.
Having a liquid phase with high conductivity, higher conductivity is obtained than the conductivity of only the swollen acrylonitrile polymer. The mechanical strength when the solvent content is high is maintained by the crosslinked structure, but when the polymer does not have voids, it is difficult to swell when the degree of crosslinking is increased to increase the strength, and the content of the solvent is reduced. On the other hand, if the material is porous, the liquid amount can be held in the voids, so that a high solvent content can be obtained even at a high strength, and thus a high conductivity can be obtained.

Further, since the solid electrolyte of the present invention is a porous body, the solid electrolyte can be easily impregnated even under a low temperature condition where the electrolyte solution is not originally impregnated. Under these conditions, the polymer phase does not swell in the liquid,
The impregnation can be performed by controlling the amount of the liquid according to the porosity. In this case, by heating the impregnated porous body to an appropriate temperature, the liquid swells with almost no dimensional change, and high conductivity can be exhibited.

Hereinafter, constituent elements of the solid electrolyte material of the present invention will be sequentially described. The acrylonitrile polymer having a crosslinked structure of the present invention will be described. Examples of the acrylonitrile-based polymer used in the present invention include acrylonitrile homopolymers and copolymers. Examples of copolymerizable monomers include methacrylonitrile; methyl acrylate, ethyl acrylate, and propyl acrylate. And butyl acrylates; methacrylates such as methyl methacrylate, ethyl methacrylate, propyl methacrylate and butyl methacrylate; haloolefins such as vinyl chloride, vinyl fluoride, vinylidene chloride and vinylidene fluoride And acrylamide,
Vinyl amides such as methacrylamide and N-vinylpyrrolidone; vinyl esters such as vinyl acetate and vinyl propionate; vinyl aromatic compounds such as styrene and vinyl pyridine; vinyl carboxylic acids such as acrylic acid and methacrylic acid; styrene sulfonic acid , Allyl sulfonic acid, methallyl sulfonic acid and salts thereof; and a polymer in which two or more of these monomers are copolymerized with acrylonitrile may be used.

Further, these can be used alone or as a mixture of these polymers, and can also be used as a mixture with a polymer containing no acrylonitrile. Here, when the acrylonitrile component is contained as a copolymer or a mixture, if the acrylonitrile component is too small, the ion conductivity becomes too low. Therefore, the component is preferably at least 50% by weight, more preferably at least 75% by weight. It is.

Such an acrylonitrile-based polymer is
It has appropriate solubility in an electrolyte solution generally used in a lithium ion battery which is a typical non-aqueous battery. Therefore, for example, it does not dissolve too much and sticky like polyethylene oxide, and the strength is not too low.On the other hand, compared to polyvinylidene fluoride, it can be prepared at a lower temperature because of its higher solubility. It is not necessary to use another good solvent. In particular, for example, in the case of a copolymer with (meth) acrylic acid ester or the like, swelling tends to occur even at room temperature.

The solid electrolyte of the present invention comprises a porous material comprising the above-mentioned acrylonitrile-based polymer, and is characterized by having a structure in which the acrylonitrile-based polymer is crosslinked. In producing the solid electrolyte of the present invention, the crosslinked structure may be introduced at the time of polymerization, during the formation of the porous structure, or at any stage after the formation, but it is difficult to form the porous structure after the crosslinkage. It is preferred to crosslink after forming the porous structure. Examples of the crosslinking method include a method using hydrazine or a salt thereof, di- or tri (meth)
A method in which a crosslinkable monomer such as an acrylate, di, or triallyl compound is allowed to coexist during the polymerization of acrylonitrile, a method in which a double bond, a reactive group, or the like previously introduced into a polymer is reacted using a radical initiator or radiation irradiation. A method of crosslinking an amide group or a carboxyl group obtained by converting a nitrile group or contained in a copolymer using formalin or a polyhydric alcohol, an electron beam, a γ-ray,
Examples of the method include irradiation with radiation energy such as X-rays and ultraviolet rays, and a method in which a radical initiator is contained and reacted by irradiation with heat or radiation energy. In these cross-linking methods, if there is an additional component such as a cross-linkable monomer or a radical initiator, a trace amount of a residue may cause an electrochemical side reaction, which may cause a decrease in battery performance. Crosslinking by electron beam irradiation without such possibility is preferred.

Regarding the crosslinking conditions when using electron beam irradiation, if the irradiation amount is too small, the crosslinking effect is not sufficient,
Insufficient strength when liquid volume is large. On the other hand, when the irradiation amount is too large, it is not preferable because the liquid becomes brittle or the liquid cannot enter the polymer matrix. The irradiation amount is preferably 0.1 Mrad or more and 100 Mrad or less. 1M especially when no crosslinking agent component is contained
rad to 100 Mrad or less, preferably 5 Mrad
It is more preferably at least 80 Mrad.

The formation of the crosslinked structure can be confirmed by the solubility in the linear polymer-soluble organic solvent. That is, the acrylonitrile-based polymer having the crosslinked structure has a component that does not dissolve in the soluble organic solvent and is not uniformly dissolved, so that the formation of the crosslinked structure can be determined. The soluble solvent slightly differs depending on the copolymer composition of the polymer, but can be determined by a solvent such as dimethylformamide, dimethylacetamide, γ-butyrolactone, dimethylsulfoxide, acetonitrile, and a mixed solution of ethylene carbonate / propylene carbonate.

The porous material referred to in the present invention is not limited as long as it has pores inside the polymer, and the shape of the pores is not limited. The porosity of the porous body is preferably in the range of 10 to 95%, more preferably 20 to 95%, and still more preferably 40 to 95%. If it is less than 10%, the above-mentioned properties as a porous material cannot be exhibited, and if it exceeds 95%, it is difficult to obtain sufficient strength after swelling.

The shape of the solid electrolyte of the present invention is not particularly limited. However, when used as an electrolyte between the electrodes of a battery, it is preferably in the form of a sheet. In this case, a film having a thickness of about 1 to 500 μm is generally used. If the thickness is less than 1 μm, the strength is insufficient, and short-circuit easily occurs between the electrodes. If the thickness exceeds 500 μm, the effective electric resistance of the entire film becomes too high.

The method for producing the porous material used in the present invention is not particularly limited. For example, the method described in JP-B-58-56378 or JP-B-52-3343 can be used. That is, specifically, the polymer is dissolved in an appropriate solvent, an additive such as a surfactant is added if necessary, and the resultant is immersed in a non-solvent in the form of a liquid film to be coagulated to form a solvent. And additives are washed and removed. At this time, if necessary, a hot water treatment or a wet heat treatment is performed. Depending on the type and amount of the solvent and additives used at this time, the temperature condition, the presence or absence of the substrate with respect to the liquid film, the porosity, the pore diameter, the shape of the pore, etc., those having a dense layer on the surface and those without the dense layer Even in the case of having a dense layer, it can be manufactured by selecting one having only one side or having both sides.

The solid electrolyte of the present invention is formed by impregnating a porous body made of an acrylonitrile polymer having the above-mentioned crosslinked structure with a solution in which an electrolyte compound is dissolved in a non-aqueous solvent. In particular, the swelling of the electrolyte solution in the crosslinked polymer results in high ionic conductivity. In particular, since the material to be impregnated is a porous material composed of a polymer portion and a pore portion, the pore portion is filled with the electrolyte solution and the polymer portion is swollen with the electrolyte solution, so that high ionic conductivity is obtained. Bring. Materials used for ordinary battery separators, for example, polyolefin porous membranes, are used without being swollen by an electrolyte solution, and are used on the assumption that the separator does not swell even in the battery structure. However, the skeletal portion of this separator does not contribute to ionic conduction, so that it gives only low ionic conductivity as a whole. It is preferable that the polymer matrix is impregnated and swelled with the electrolyte solution in the solid electrolyte because the entire polymer matrix can contribute to ionic conduction and provides high ionic conductivity.

Impregnating the acrylonitrile polymer,
The solution in which the electrolyte compound is dissolved in the non-aqueous solvent is selected from those in which the polymer can swell. Generally, when a polymer is swollen with a solvent or a solution, the size changes with a large increase in volume. In many cases, it expands in all directions, but when stress is applied by stretching etc., the stress is relieved, and depending on the direction, it may shrink, but in any case, when it swells, deformation occurs . In fact, in the present invention, if the deformation exceeds 20% in the length direction, it can be considered that the electrolyte is substantially swollen by the electrolyte solution. At this time, the swelling temperature is preferably equal to or lower than the boiling point of the solvent in which the electrolyte compound is dissolved. Therefore, the fact that the polymer is swollen with the electrolyte solution can be visually confirmed from the deformation of the size when the polymer is immersed in the electrolyte solution at a predetermined temperature.

In fact, whether or not the solution can swell depends on the type and concentration of the electrolyte compound, but is mainly governed by the type of solvent used. For the acrylonitrile polymer in the case of the present invention, examples of such a non-aqueous solvent include cyclic carbonates such as ethylene carbonate, propylene carbonate and butylene carbonate; chains such as dimethyl carbonate, methyl ethyl carbonate and methyl ethyl carbonate. Carbonate;
cyclic esters such as γ-butyl lactone and propiolactone; nitrile compounds such as acetonitrile and propionitrile; mixtures of these solvents; and mixtures containing these solvents;

As the electrolyte compound used by dissolving in these non-aqueous solvents, any of organic acids, organic salts, inorganic acids and inorganic salts can be used. Examples of this include inorganic acids such as tetrafluoroboric acid, perchloric acid, sulfuric acid, phosphoric acid, hydrofluoric acid, hydrochloric acid, trifluoromethanesulfonic acid, perfluorobutanesulfonic acid, bis (trifluoromethanesulfonyl) imidic acid, acetic acid, Examples thereof include organic acids such as trifluoroacetic acid and propionic acid, and inorganic acids and metal salts of these organic acids. These can be used singly or as a mixture of a plurality of electrolyte compounds. Further, a perfluorosulfonic acid-based polymer or perfluorocarboxylic acid-based polymer or a metal salt thereof can also be used as the electrolyte compound of the present invention. One type of cation selected from protons, alkali metal cations, alkaline earth metal cations, transition metal cations, rare earth metal cations, and the like can be used as these electrolyte cations, or a mixture of a plurality of cations can be used.

The type of the cation differs depending on the use. For example, when the solid electrolyte of the present invention is used for a lithium battery, it is preferable to use a lithium salt as an electrolyte compound to be added. In particular, when used in a lithium secondary battery, it is preferable to select a lithium salt having high electrochemical stability as an electrolyte compound because charge and discharge need to be repeated. For example, CF ₃ SO ₃ Li, C ₄ F ₉
SO ₃ Li, (CF ₃ SO ₂ ) ₂ NLi, LiBF ₄ ,
LiPF ₆ , LiClO ₄ , LiAsF _{6 and the} like can be mentioned.

As for the concentration of the electrolyte compound contained in the solution, in general, the higher the concentration of the electrolyte compound, the higher the carrier ion concentration capable of ion transfer and the higher the ion conductivity, which is preferable. It is suppressed and the ionic conductivity is rather lowered. Therefore, the range is preferably about 0.1 to 5 mol / liter, more preferably 0.5 to 3 mol / liter.

The amount of the solution contained in the solid electrolyte is determined in consideration of the mechanical strength, ionic conductivity, etc. of the solid electrolyte. However, in the solid electrolyte of the present invention, the amount of the solution is smaller than that of the conventionally known polyacrylonitrile-based solid electrolyte. In comparison, it has the advantage of not impairing the mechanical strength even at high solution contents. The amount of the solution varies depending on the type of the solution, the composition of the acrylonitrile-based polymer, and the structure of the porous body, but is generally from 10 to 98%, preferably from 20 to 98% by weight of the solid electrolyte.
97%, more preferably 40-95%.

The solid electrolyte of the present invention can be obtained by incorporating the above-described solution in which the electrolyte compound is dissolved in a non-aqueous solvent into a porous body made of a crosslinked acrylonitrile polymer. Although the method for including is not particularly limited, for example, the following method may be mentioned. 1) It is immersed in a heated solution of the electrolyte compound as required for swelling. 2) If it does not swell at room temperature, it is impregnated at room temperature and then heated to the required temperature. In particular, the latter case has a feature that the dimensional change upon swelling is small. Further, since the acrylonitrile-based polymer used in the present invention is a porous body, it is easy to impregnate the liquid after sandwiching the porous body with an electrode. in this case,
By using the method 2) in combination, a battery can be manufactured with almost no dimensional change even during swelling.

Next, a battery in which electrodes are joined via the solid electrolyte of the present invention will be described. The battery of the present invention has a structure in which a positive electrode and a negative electrode are joined via the above-mentioned solid electrolyte. For example, when the battery is a lithium battery, a substance capable of inserting and extracting lithium ions is used for the positive electrode and the negative electrode of the electrode. As the positive electrode material, a material having a higher potential than the negative electrode, for example, Li _1-x Co
O ₂ , Ln _1-x NiO ₂ , Li _1-x Mn ₂ O ₄ , Li
_1-x MO ₂ (0 <x <1) (M is Co, Ni, Mn, F
e represents a mixture. ), Li _2-y Mn ₂ O ₄ (0 <y <
2), crystalline Li _1-x V ₂ O ₅ , amorphous Li
_2-y V ₂ O ₅ (0 <y <2), Li _{1.2-x ′} Nb ₂ O
₅ Oxides such as (0 <x ′ <1.2), Li _1-x Ti
S ₂ , Li _1-x MoS ₂ , Li _3-z NbSe ₃ (0 <z
Organic compounds such as metal chalcogenides such as <3), polypyrrole, polythiophene, polyaniline, polyacene derivatives, polyacetylene, polythienylenevinylene, polyarylenevinylene, dithiol derivatives, and disulfide derivatives can be mentioned.

As the negative electrode, a material having a lower potential than the positive electrode is used. Examples of this include metal lithium such as metal lithium, aluminum / lithium alloy, magnesium / aluminum / lithium alloy, AlSb, Mg ₂ Ge,
Intermetallic compounds such as NiSi ₂ , graphite, coke, carbon-based materials such as low-temperature fired polymers, SnM-based oxides (M represents Si, Ge, Pb), Si _1-y M ′ _y O
_z (M 'represents W, Sn, Pb, B, etc.), a lithium solid solution of a metal oxide such as titanium oxide and iron oxide, Li ₇ MnN ₄ , Li ₃ FeN ₂ , and Li _3-x Co _{x
N, Li 3-x NiN,} Li 3-x Cu x N, Li 3 B
Ceramics such as nitrides of N ₂ , Li ₃ AlN ₂ , and Li ₃ SiN ₃ are exemplified. However, when lithium ions are reduced at the negative electrode and used as metallic lithium, the material is not limited to the above, as long as the material has conductivity.

The positive electrode and the negative electrode used in the battery of the present invention are obtained by molding the above-mentioned materials into a predetermined shape. As this form, either a continuous body or a binder dispersion of a powder material can be used. As the former method of forming a continuous body, electrolytic deposition, electrolytic dissolution, vapor deposition, sputtering, CV
D, melt processing, sintering, compression and the like are used. In the latter case, the powdered electrode material is mixed with a binder and molded. As the binder material, fluorine-based polymers such as polyvinylidene fluoride, poly (hexafluoropropylene-vinylidene fluoride) copolymer, and styrene-
A hydrocarbon polymer such as butadiene copolymer, styrene-acrylonitrile copolymer, styrene-acrylonitrile-butadiene copolymer, or a polymer precursor is used, and an acrylonitrile-based polymer having a crosslinked structure of the present invention is used as a binder. You can also. A current collector may be provided on each of the electrodes composed of the positive electrode and the negative electrode with a material having low electric resistance. The positive electrode / solid electrolyte /
An electrolyte and / or a non-aqueous solvent, which is a component of the present invention, can be introduced into a battery having a negative electrode structure by impregnation, diffusion, or the like.

In the case of a lithium battery, the battery has a structure in which a positive electrode and a negative electrode are joined via a solid electrolyte. For example, a sheet-shaped, roll-shaped, or folded structure can be formed in units of a positive electrode / solid electrolyte / negative electrode in which a sheet-shaped positive electrode, a negative electrode, and a solid electrolyte are sequentially laminated. Also,
It is also possible to form an assembled battery in which electrodes of a battery unit are connected in parallel or / and in series. In particular, in the case of a polymer battery, the series connection structure is simple, so that the voltage can be increased by the number of stacked layers in series connection. In addition, if necessary, take out current to the battery electrode, connect external terminals for injection, current-voltage control element, functional element that prevents electrode connection when heat is generated, prevent moisture permeation of electrode units and laminates, protect structure, etc. A protective layer can be provided or packaged.

The solid electrolyte of the present invention can be suitably used when used in a non-aqueous battery using an organic solvent such as a lithium ion battery, and is preferable. In addition, it can be applied as an ion transfer medium such as a capacitor, an electrochemical sensor, and an electrochromic display element, which is preferable because a product having high industrial value can be provided.

[0037]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail with reference to the following examples. In addition, the measurement of ionic conductivity is performed by using an AC impedance method in which an electrochemical cell is formed by sandwiching an electrolyte thin film between metal electrodes, and an AC is applied between the electrodes to measure a resistance component. Calculated from real impedance intercept.

[0038]

Examples 1 and 2 15 parts by weight of an acrylonitrile / methyl acrylate / sodium methallylsulfonate copolymer (95 / 4.5 / 0.5% by weight, respectively), 10 parts by weight of polyethylene glycol having an average molecular weight of 600, γ-
A solution consisting of 75 parts by weight of butyrolactone was prepared, and the solution was cast on a glass plate at room temperature such that the liquid film became 100 μm, and then immediately at room temperature (Example 1) or 70 ° C.
(Example 2) The porous sheet was immersed in water, washed with water and alcohol, and dried to prepare a porous sheet having a film thickness of 91 μm and 151 μm, respectively, and a porosity of 75% and 84%, respectively. Next, the sheet is irradiated with an electron beam at 60 Mrad,
A crosslinked sheet was made. Crosslinking of the sheet was confirmed by insolubility at room temperature in a 1: 1 mixed solution of ethylene carbonate and propylene carbonate. Next, each sheet was immersed in a 1 mol / L solution of a 1: 1 mixed solvent of LiBF ₄ in ethylene carbonate / propylene carbonate at room temperature for 30 minutes to obtain a transparent sheet swollen in the solution. At this time, the area after swelling was 240% and 200%, respectively, before swelling, and the film thickness was 130 μm and 148 μm, respectively. Excess solution on the sheet surface was wiped off. The sheet is sandwiched between stainless steel sheets, and impedance measurement (EG & G 3
As a result, the ionic conductivity at room temperature was 1.4 mS / cm (Example 1) and 1.6 mS / cm (Example 2).

[0039]

Example 3 Acrylonitrile 3 described in Examples 1 and 2
15% by weight of the original copolymer was dissolved in 70% by weight nitric acid at -3 ° C to prepare a defoaming stock solution. This stock solution was extruded from a flat slit die into water at room temperature to obtain a wet coagulated membrane sheet.
After washing thoroughly with water, heat-treat it in hot water of 85 ° C. for 3 minutes in a tensioned state fixed to a wooden frame, and then dry to a film thickness of 105 μm.
m, a dried porous sheet having a porosity of 79% was obtained. This sheet was irradiated with an electron beam of 60 Mrad to obtain a crosslinked porous sheet. Next, this sheet was immersed in a 1 mol / L solution of a 1: 1 mixed solvent of LiBF ₄ in ethylene carbonate / propylene carbonate at room temperature for 30 minutes to obtain a transparent sheet swollen in the solution. At this time, the area after swelling was 180% of that before swelling, and the film thickness was 123 μm. Excess solution on the sheet surface was wiped off. When the sheet was sandwiched between stainless steel sheets and impedance measurement was performed, the ionic conductivity at room temperature was 1.5 mS.
/ Cm.

[0040]

Examples 4 and 5 A solution comprising 17 parts by weight of polyacrylonitrile and 83 parts by weight of dimethyl sulfoxide was prepared.
The solution was cast on a glass plate at room temperature (Example 4) or 60 ° C. (Example 5) so that the liquid film became 100 μm, and immediately at room temperature (Example 4) or 70 ° C. (Example 5). It was immersed in water, washed with water and alcohol, and dried to prepare a porous sheet having a thickness of 95 μm and 76 μm, respectively, and a porosity of 78% and 81%, respectively. Next, the sheet was irradiated with an electron beam at 30 Mrad to produce a crosslinked sheet. Crosslinking of the sheet was confirmed by insolubility at room temperature in a 1: 1 mixed solution of ethylene carbonate and propylene carbonate. Next, each sheet was immersed in a 1 mol / liter solution of a 1: 1 mixed solvent of LiBF ₄ in ethylene carbonate / propylene carbonate at 100 ° C. for 1 hour to obtain a transparent sheet swollen in the solution. At this time, the area after swelling was 350% and 290% before swelling, the film thickness was 89 μm, respectively.
It was 82 μm. Excess solution on the sheet surface was wiped off. The sheet is sandwiched between stainless steel sheets,
When the impedance was measured, the ionic conductivity at room temperature was 2.0 mS / cm (Example 4).
It was 1.8 mS / cm (Example 5).

[0041]

Examples 6 and 7 The sheets prepared in Examples 4 and 5 were
It was immersed in a 1 mol / liter solution of iBF _{4 in} a 1: 1 mixed solvent of ethylene carbonate / propylene carbonate at room temperature for 30 minutes to obtain a transparent sheet impregnated with the solution. The film thickness was 103 μm and 85 μm, respectively, and the area did not change before and after impregnation. Excess solution on the sheet surface was wiped off. The sheet was sandwiched between stainless steel sheets, and the impedance was measured. As a result, the ionic conductivity at room temperature was 0.3 mS / cm, and the ionic conductivity was 0.3 mS / cm.
It was 4 mS / cm. Next, the electrochemical cell was heated to 100 ° C.
After holding for 1 hour at room temperature, the mixture was allowed to cool to room temperature, and the impedance was measured again. As a result, the ion conductivity at room temperature was 1.2 mS / cm (Example 6) and 1.4 mS / c, respectively.
m (Example 7).

[0042]

Example 8 After mixing predetermined amounts of lithium hydroxide and cobalt oxide, the mixture was heated at 750 ° C. for 5 hours, and the average particle size was 10 μm.
The LiCoO ₂ powder was synthesized. The powder and carbon black were converted to polyvinylidene fluoride (Kureha Chemical Industry, KF1
100) was mixed and dispersed in an N-methylpyrrolidone solution (5% by weight) to prepare a slurry. The composition of the solid content in the slurry was LiCoO ₂ (85%), carbon black (8%), and polymer (7%). The slurry was applied on an aluminum foil by a doctor blade method and dried to prepare a sheet having a thickness of 110 μm.

Next, a slurry was prepared by mixing the above-mentioned N-methylpyrrolidone solution of polyvinylidene fluoride (5% by weight) with needle coke powder having an average particle diameter of 10 μm (dry weight mixing ratio: needle coke (92%)). %),
Polymer (8%)). The slurry was applied to a metal copper sheet by a doctor blade method to form a film (electrode layer) with a dry film thickness of 120 μm.

The LiCoO ₂ electrode sheet and the needle coke electrode sheet were each cut into 2 cm squares, and the LiBF ₄ solution swelling sheet (electrolyte sheet) prepared in Example 5 was cut into 2.3 cm squares to obtain two electrode sheets. Is laminated so that the electrolyte sheet is sandwiched between the needle coke (negative electrode) /
A battery joined with the electrolyte sheet / LiCoO ₂ (positive electrode) was formed. Then, a stainless steel terminal was attached to the positive electrode and the negative electrode of the battery, connected to the terminals of the glass cell, respectively, and sealed in an argon atmosphere.

The battery was charged to a charge / discharge machine (Hokuto Denko 101SM).
Charge / discharge was performed at a current density of 3 mA / cm ² using 6). The potential between the electrodes after charging was 4.2 V (4.2 V constant potential charging after constant current), and charging was confirmed. The discharge was performed at a constant current of 2.7 V with a cutoff voltage of 2.7 V.
The initial charge / discharge efficiency is 80%, and the charge / discharge efficiency after the second time is 99%.
%, Repeated charging and discharging were possible, and it was found that the battery operated as a secondary battery.

[0046]

Example 9 A battery was prepared in the same manner as in Example 8, except that a sheet impregnated with a LiBF ₄ solution at room temperature was used. After the battery was held at 100 ° C. for 2 hours, it was allowed to cool to room temperature, and then charged and discharged in the same manner as in Example 8. After charging, the potential between the electrodes was 4.2 V (4.2 V after constant current). (Potential charging), and charging was confirmed. Discharge is 2.7V cut-off voltage.
As a result of constant current discharge, the initial charge and discharge efficiency is 80% or more,
The charge / discharge efficiency after the second time was 99% or more, and charge / discharge was possible repeatedly, confirming that the battery operated as a secondary battery.

[0047]

The solid electrolyte of the present invention has high conductivity, excellent high-temperature stability, has appropriate strength even in a region where the amount of electrolyte solution is large, and can be manufactured safely and easily. An object of the present invention is to provide an excellent solid-state battery using this as an ion transfer medium.

Claims (3)

[Claims] 1. A solution in which an electrolyte compound is dissolved in a non-aqueous solvent is a solution in which an acrylonitrile-based polymer is swellable, and a non-aqueous solution in which a porous body made of a cross-linked acrylonitrile-based polymer contains the solution. Solid electrolyte for water-based batteries. 2. The solid electrolyte according to claim 1, wherein the solid electrolyte is crosslinked by electron beam irradiation. 3. A non-aqueous battery, wherein electrodes are joined via the solid electrolyte according to claim 1.