JP2002190318A - Solid state electrolyte and nonaqueous electrolytic solution battery using the electrolyte - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid electrolyte which has higher performance of, such as charge/discharge capacity, and by which a battery of high performance can be easily manufactured, and to provide the battery of high performance and productivity using the solid electrolyte. SOLUTION: The solid state electrolyte contains an electrolytic solution and a polymer crosslinked structure, and the crosslinking density of the polymer crosslinked structure specified by a formula (1) (wherein n is the number of kinds of monomers used as precursor of the polymer crosslinked structure; Fi is the molecular weight of the monomer of i-th kind; si is the number of polymerizable double bonds contained in one molecule of the monomer of the i-th kind; and pi is a percentage of mass of monomer of the i-th kind to the total mass of all the kinds of the monomers; and the sum of pi when i is 1 to n is 1) is 0.08 to 0.34.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a solid electrolyte having a non-aqueous electrolyte containing a lithium salt or the like impregnated in a polymer crosslinked structure, and a non-aqueous electrolyte battery using the same.

[0002]

2. Description of the Related Art In recent years, storage batteries with higher energy density have been demanded for miniaturization and portability of portable telephones, video cameras, notebook personal computers, and the like, or practical use of electric vehicles. A non-aqueous electrolyte battery capable of outputting 3 V or more by using an electrolyte in which a salt is dissolved in a solvent is expected. A typical example is a lithium-ion secondary battery that is already on the market. The positive electrode of these non-aqueous electrolyte based batteries, and spinel structure compound such as LiMn ₂ O _4, typically a lithium-containing transition metal composite oxide having an alpha-NaFeO ₂ structure represented by LiMO ₂ and the like utilized it can. Here, M is a single metal element or two or more metal elements selected from Co, Ni, Al, Mn, Ti, Fe and the like. Further, metal oxides such as MnO ₂ and V ₂ O ₅ into which lithium can be inserted, metal sulfides such as TiS ₂ and ZnS ₂ , π-conjugated polymers such as polyaniline and polypyrrole having electrochemical redox activity, It is also possible to use a disulfide compound utilizing the formation and cleavage of a sulfur-sulfur bond in the molecule.

On the other hand, as the negative electrode, metallic lithium or various lithium alloys, various metal oxides such as SnO ₂ , or a carbon material capable of inserting and extracting lithium can be used. As a carbon material, naturally produced graphite or an organic material is fired at a high temperature of 2000 ° C. or higher, and a graphite-based carbon material having a flat potential characteristic with a developed graphite structure or an organic material at a relatively low temperature of 1000 ° C. or lower. A coke-based carbon material or the like that can be expected to have a larger charge / discharge capacity than the graphite-based material family is used. As the combination of the positive electrode and the negative electrode in the lithium ion secondary batteries currently on the market, LiCoO ₂ or LiMn ₂ O
_In many cases, lithium-containing transition metal composite oxides such as ₄ and various kinds of carbon materials are used for the negative electrode. Powder or fibrous metal or carbon may be added to the electrode for the purpose of improving the electron conductivity of the electrode. As the metal, copper, silver, aluminum or the like can be used, and as the carbon, graphite, carbon black, acetylene black, Ketjen black or the like can be used.

[0004] In addition, as a method of manufacturing an electrode, a small amount of a polymer material serving as a binder, for example, a material obtained by dissolving polyvinylidene fluoride (PVDF) in a solvent such as 1-methyl-2-pyrrolidone is used. After applying the electrode mixture made into a paste by dispersing the active material and a conductive auxiliary agent composed of fine powder of carbon or metal as appropriate, on both sides or one side of a metal foil having a thickness of several tens μm serving as an electrode core material, A method for removing an organic solvent is widely used. Examples of other binders include various fluorine rubbers such as ethylene-propylene-diene terpolymer (EP rubber), vinylidene fluoride-propylene copolymer and vinylidene fluoride-hexafluoropropylene copolymer as a solvent. Uniformly dissolved or polytetrafluoroethylene (PTFE), SBR, NBR
Sodium polyacrylate and carboxymethylcellulose (C
There is also a method of using a binder obtained by adding a water-soluble polymer such as MC) as a thickener.

The electrode core material is also called a current collector. Generally, an aluminum foil is often used on the positive electrode side and a copper foil is often used on the negative electrode side. In the electrode immediately after coating and drying, the solvent may be removed during the drying process, so that voids are formed in the electrode and the filling rate may be too low. Thereby, the contact between the particles in the electrode mixture becomes weak, and the electron conductivity becomes insufficient. Therefore, in many cases, the filling rate of the electrode is increased by pressure molding to a desired thickness by a roll press or the like, and the electron conductivity of the electrode is improved.

[0006] Usually, the positive electrode and the negative electrode produced by the above-described method are layered so as not to be deformed through a polymer microporous film serving as a diaphragm so that both sides face each other. After firmly winding it up, inserting it into a metal battery can and finally injecting the electrolyte, caulking it by a mechanical method or completely sealing it by laser welding etc. Manufactured.

Here, a microporous membrane made of polypropylene or polyethylene is used as the diaphragm, and a non-aqueous electrolyte in which a lithium salt is dissolved in an organic solvent is usually used as the electrolyte. As the organic solvent, ethylene carbonate, propylene carbonate, γ-butyrolactone, sulfolane, diethyl carbonate, dimethyl carbonate, dimethoxyethane, diethoxyethane, 2-methyl-tetrahydrofuran, a mixture of two or more types of glymes or the like are used. Can be As a lithium salt, the ionic conductivity when the electrolyte is high, or electrochemically stable in the range of the use potential of the battery,
For the reasons, etc., mainly lithium hexafluorophosphate (LiPF
₆ ), lithium perchlorate (LiClO ₄ ), lithium tetrafluoroborate (LiBF ₄ ) and the like are used. In non-aqueous electrolyte batteries as described above, such as lithium ion secondary batteries, high capacity and long life are desired, but on the other hand, improvement of safety and freedom of battery shape are required. From the viewpoint of improvement and the like, utilization of a solid or solid electrolyte has been studied. In other words, instead of a liquid electrolyte having fluidity, an electrolyte prepared by dissolving a lithium salt in a polymer compound to have ionic conductivity, or a gel in which fluidity is suppressed by holding the electrolyte solution in a polymer crosslinked structure The use of electrolytes in the form of an electrolyte, inorganic ceramics having ionic conductivity, glass, and the like has been studied. By sandwiching a film made of such a solid electrolyte between a positive electrode and a negative electrode to form a battery, it is possible to prevent electrolyte leakage and to make the battery shape itself into a film shape. .

[0008] Among such solid or solid electrolytes, gel electrolytes containing an electrolytic solution have been widely studied from the viewpoints of ionic conductivity and film-forming properties at room temperature. That is, in order to operate as a battery at room temperature, it is necessary that the ionic conductivity at room temperature be on the order of 1 mS / cm or a value equivalent thereto, and that a thin film can be formed. Therefore, at present, it is most practical to use a gel electrolyte in which an electrolyte is fixed with a polymer crosslinked structure. The first conceivable gel electrolyte is a system in which a linear high molecular weight polymer is plasticized with an electrolytic solution. That is, after dissolving the polymer in the electrolytic solution at a high temperature, returning to room temperature after forming the film and gelling, or after diluting the combination of the polymer and the electrolytic solution with a low boiling point solvent to have fluidity,
It is produced by evaporating a low-boiling solvent to form a film.In such a system, although the polymer does not have a chemical cross-linking structure, it is extremely viscous, or the electrolyte and the polymer component The fluidity is lost due to physical cross-linking due to partial phase separation, and the solid can be treated substantially as a solid. Specifically, a gel electrolyte in which a polymer having a relatively large molecular weight such as polyacrylonitrile, polyethylene oxide, ethylene glycol-propylene glycol copolymer, polymethyl methacrylate, or polyvinylidene fluoride is plasticized with an electrolyte is known. I have. These systems have drawbacks such as the necessity of handling a highly viscous solution in the production of the electrolyte and the lack of a chemical cross-linking structure, which causes fluidization at high temperatures.

Next, there is a method of polymerizing various (meth) acrylate monomers and vinyl monomers. That is, this is a method in which a monomer having a polymerizable double bond is dissolved in an electrolytic solution, and the monomer is polymerized using heat, light, radiation, or a radical initiator. At this time, by adding a partially polyfunctional monomer, a crosslinked structure is formed during the polymerization reaction, the fluidity is lost, and the entire system can be solidified while holding the electrolytic solution. Such examples include various (meth) acrylate monomers such as methyl methacrylate and ethyl methacrylate, vinyl acetate,
Some monomers are polymerized by dissolving monomers such as styrene and its derivatives in the electrolyte.At this time, polyfunctional ethylene glycol dimethacrylate and ethylene dimethacrylate coexist and they are copolymerized. Thereby, a crosslinked structure is formed, and the entire system loses fluidity. In addition, those obtained by polymerizing a macromonomer such as polyethylene glycol ethyl ether methacrylate or polyethylene glycol dimethacrylate in an electrolytic solution are known. Examples of the polymerization method include photopolymerization by irradiation with ultraviolet rays or electron beams, or thermal polymerization in the presence of a radical initiator such as dibenzoyl peroxide or azobisisobutyronitrile. Similarly, there is a method of solidifying the entire system by forming a crosslinked structure using a polyaddition type chemical reaction such as urethanation or epoxy reaction. When producing a solid electrolyte by a polymerization method or a chemical cross-linking method, it is not always necessary to handle a highly viscous solution, and is excellent in stability and liquid retention because it is solidified in a final shape in the production of a battery, and Since it has a chemical cross-linking structure, it has high heat resistance. In addition, it is possible to obtain a thin and high-strength electrolyte membrane by impregnating the undiluted solution in advance into a porous body, a nonwoven fabric, or the like and solidifying it. In addition, there is a method in which a film is prepared in advance from a polymer having a high affinity for an electrolytic solution, and the electrolytic solution is swelled to impart ionic conductivity. Specifically, studies are being made on systems such as polyvinylidene fluoride copolymers and acrylonitrile-butadiene rubber. In these systems, the polymer film may be made porous or crosslinked in advance in consideration of an increase in strength or a change in volume after swelling. These systems are inferior in liquid retention because they are impregnated with an electrolytic solution later, and have a problem that the electrolytic solution oozes out over time.

[0010]

Although the properties and performance of the solid electrolytes produced as described above are important, the productivity and performance of batteries using these electrolytes are more important. Needless to say. When a solid electrolyte containing a gel electrolyte is used for a battery, the battery performance is lower than that of a battery using only an electrolytic solution because the ion conductivity is low in principle. Further, it is difficult to control the interface between the electrolyte and the battery, and the battery performance greatly depends on the manufacturing method of the battery. Further, the gel electrolyte as described above alone has low mechanical strength and is often difficult to handle. Furthermore, the gel electrolyte itself and its raw material are extremely sensitive to moisture and must be handled in an ultra-dry atmosphere. The large number of steps in an ultra-dry atmosphere and the presence of complicated steps in the manufacture of batteries lead to a significant increase in cost. Therefore, there has been a strong demand for the development of a solid electrolyte that has high performance such as charge / discharge capacity and that can be used to produce a high-performance battery with high productivity.

[0011]

Means for Solving the Problems The present inventors have made intensive studies in view of the above problems, and as a result, have solved the above problems by controlling the crosslink density of a polymer crosslinked structure holding an electrolyte solution within a predetermined range. The present inventors have found that the present invention can be performed, and have accomplished the present invention based on this finding. That is, the present invention
(1) A solid comprising an electrolyte solution and a polymer crosslinked structure, wherein the polymer crosslinked structure defined by the following formula (1) has a crosslink density of 0.08 to 0.34. Electrolyte,

[0012]

(Equation 2)

[0013] (wherein, n is the number of types of monomer used as precursors of the polymeric crosslinked structure, F _i is the molecular weight of i-th type of monomer, s _i is the i-th type of monomer molecule The number of polymerizable double bonds contained therein.
p _i is the ratio of the mass of the i-th monomer type to the sum of the masses of all types of monomers, and the sum of p _i from 1 to n is 1. (2) The solid electrolyte according to (1), wherein the polymer crosslinked structure is formed by a polymerization reaction of a (meth) acrylate monomer previously dissolved in an electrolytic solution.
(3) The solid electrolyte according to (2), wherein the (meth) acrylate monomer contains ethylene dimethacrylate, (4) a monomer having a single reaction point and two or more monomers. At least one kind of monomer having a reaction point of the following is copolymerized in an electrolytic solution to form a polymer crosslinked structure having a crosslinking density defined by the above formula (1) of 0.08 to 0.34. (1) The method for producing a solid electrolyte according to (1), (2) or (3), and (5) comprising the solid electrolyte according to (1), (2) or (3). A non-aqueous electrolyte battery, and (6) a battery cell obtained by processing a positive electrode, a negative electrode and a diaphragm into a final battery form, comprising a (meth) acrylate monomer and an electrolyte (1). Inject the undiluted solution of the solid electrolyte described in (2) or (3) Impregnated Te, then there is provided a method of manufacturing a nonaqueous electrolyte based batteries, characterized in that to solidify. Here, the polymer crosslinked structure refers to a structure having a retaining property of stably retaining the polymer by impregnating the electrolyte.

[0014]

DETAILED DESCRIPTION OF THE INVENTION In the present invention, the performance of a solid electrolyte and a battery using the same can be improved by controlling the crosslink density of a polymer crosslinked structure contained in the solid electrolyte. That is, even though the polymer compound itself forming the polymer crosslinked structure is almost the same, the solid electrolyte and the solid electrolyte were dramatically used by introducing a predetermined ratio of the crosslinked structure defined in the present invention. The performance of the battery can be improved. In the production of a conventional gel electrolyte, when a polymerizable monomer is polymerized in an electrolytic solution, a polyfunctional monomer for introducing a crosslinking point is used in an order of several% based on the total mass of all the monomers.
In the present invention, the cross-linking density of the polymer cross-linked structure of the solid electrolyte is 0.08 to 0.1 in a value defined by the following formula (1).
Polyfunctional monomers are usually used in the order of tens of percent of the total monomer mass in order to achieve a value of 34, preferably 0.11 to 0.25.

[0015]

(Equation 3)

[0016] (wherein, n is the number of types of monomer used as precursors of the polymeric crosslinked structure, F _i is the molecular weight of i-th type of monomer, s _i is the i-th type of monomer molecule The number of polymerizable double bonds contained therein.
p _i is the ratio of the mass of the i-th monomer to the sum of the masses of all the monomers, and the sum of p _i from 1 to n is 1. ) (S _i -1) in the above formula (1) represents the number of crosslinking points generated from the monomer. For example, a monomer having s = 1, such as methyl methacrylate or ethyl methacrylate, can only produce a linear polymer, and does not cause a crosslinking point, and a monomer having s = 2, such as ethylene dimethacrylate, has a crosslinking point of one. Come out. Further, two crosslink points are generated from a monomer having s = 3 such as a triacrylate compound. Therefore, the formula (1) represents the number of crosslinking points per 1 mol of the monomer used as a precursor of the polymer crosslinked structure contained in the solid electrolyte of the present invention. In the present invention, by defining the crosslink density of the polymer crosslinked structure using the above formula (1), the crosslink density can be determined regardless of the chemical structure of the polymerized polymer crosslinked structure.

In the present invention, a (meth) acrylate monomer is preferable as a monomer used as a precursor of the polymer crosslinked structure. Examples of the monomer having s = 1 that can be used in the present invention include methyl methacrylate, ethyl methacrylate, butyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, and the like. As the monomer of s = 2, for example,
Examples include ethylene dimethacrylate and butylene dimethacrylate. Examples of the monomer having s = 3 include glycerin trimethacrylate.

The electrolytic solution that can be used in the present invention is not particularly limited as long as it is a non-aqueous electrolytic solution that is commonly used in batteries. Similarly, a single organic solvent or a mixture of two or more kinds of the organic solvents described in the section of the prior art is dissolved in a single or a mixture of two or more kinds of the lithium salts described in the section of the prior art. Used as electrolyte. At this time, the concentration of the lithium salt is
The water content is desirably 0.2 to 2.0 (mol / L), and the water content is desirably 20 ppm or less.

In the present invention, the proportion of the polymer crosslinked structure contained in the solid electrolyte is 3 to 5 times that of the solid electrolyte.
0% by mass is preferred. If the proportion of the polymer crosslinked structure is too low, the mechanical strength as an electrolyte is poor, while if it is too high, sufficient ion conductivity may not be obtained.

In the solid electrolyte of the present invention, a low molecular compound (monomer), which is a precursor of a polymer crosslinked structure, preferably has a crosslink density defined by the above formula (1) in the electrolytic solution. It is manufactured by preparing an undiluted solution of a solid electrolyte containing the mixture at a mixing ratio within a specified range, and gelling (solidifying) this by a usual method such as heating. For example, when a polymer crosslinked product is formed by polymerization of a low molecular weight compound, a monomer having a single reaction site (a compound having _si of 1 in the above formula (1), that is, a compound giving a linear polymer by homopolymerization) ) And a monomer having two or more reactive sites (s _i
Are two or more compounds).
The crosslink density of the polymer crosslinked structure to be produced can be easily controlled by adjusting the ratio of their use so that the crosslink density defined by the above formula (1) falls within the range defined by the present invention. Can be. For example, when a polymer crosslinked structure is formed using methyl methacrylate and ethylene dimethacrylate, the crosslink density of the polymer crosslinked structure increases as the ratio of ethylene dimethacrylate increases. It is possible to control the crosslinking density by changing the molecular weight of the monomer having two or more reaction points, but it is possible to control the monomer having a single reaction point with two or more reaction points. When the ratio is adjusted by using a combination of the monomers, the range in which the crosslink density and the chemical structure of the polymer chain can be controlled is much wider.

The stock solution of the solid electrolyte according to the present invention may appropriately contain a polymerization initiator and the like in addition to the electrolyte solution and the monomer. The polymerization initiator can be appropriately selected depending on the type of the monomer used. For example, an azo compound such as azobisisobutyronitrile and an organic peroxide such as dibenzoyl peroxide can be used.

In the production of the non-aqueous electrolyte battery of the present invention using the solid electrolyte, the undiluted solution of the solid electrolyte is added to a cell in which the positive electrode / diaphragm / negative electrode is assembled into a final battery form. By injecting in the same manner as injecting a normal electrolytic solution, and then performing heating etc. to gel the stock solution,
A battery with no liquid leakage can be provided by a simple manufacturing process. In this manufacturing method, there is no need for a step of forming an electrolyte membrane or a step of independently handling the formed electrolyte membrane, and the method is substantially the same as a method of manufacturing a battery in which a normal electrolytic solution is directly injected. A battery having a solid electrolyte can be manufactured. In addition, since the solid electrolyte is first formed into a gel within the pores of the diaphragm and the electrode, the solid electrolyte is very excellent in integration as a battery. The non-aqueous electrolyte battery of the present invention is not particularly limited except that it has the solid electrolyte of the present invention, and its shape, the positive electrode, the material of the negative electrode and the like are used for ordinary non-aqueous electrolyte batteries. Can be used. FIG. 1 shows an example of a film-shaped lithium ion secondary battery using the solid electrolyte of the present invention. As shown in the cross-sectional view of FIG. 1B, the undiluted electrolyte solution is sealed under reduced pressure in an integrated battery cell composed of an exterior material 4 made of an aluminum laminate sheet, a LiCoO ₂ positive electrode 1, a carbon negative electrode 2, and a battery partition 3, and then heated. By solidifying, a film-shaped lithium ion secondary battery shown in a perspective view in FIG. 1A can be manufactured. In FIG. 1, 5 is a positive electrode tab, 6 is a negative electrode tab,
Reference numeral 7 denotes a heat-sealing sealing portion. FIG. 1B is a view showing A in FIG.
FIG. 4 is a cross-sectional explanatory view (only a central portion).

When a macromonomer having a large molecular weight is used in the electrolyte stock solution, the viscosity of the stock solution increases, and it may be difficult to inject the electrolyte into the pores of the electrode or the battery. From this viewpoint, the electrolyte stock solution preferably does not contain a macromonomer having a polyalkylene oxide structure such as polyethylene oxide, and the molecular weight of the monomer contained in the electrolyte stock solution is preferably 400 or less, more preferably 200 or less. To In addition, since the polyalkylene oxide structure in the polymer compound causes strong interaction with lithium ions and the like, the transport number of lithium ions and the like is low, and the mobility of lithium ions and the like itself required for charging and discharging of the battery may be poor. Many.

The solid electrolyte of the present invention can be used for various electrochemical devices including a positive electrode, a diaphragm, a negative electrode and the like, in addition to the above-mentioned battery, for example, a capacitor, an electrochromic device (electrochemical display element) and the like. Can be used.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on embodiments. In addition, comparative examples for further clarifying the effects of the present invention are also shown. In Examples and Comparative Examples, a battery in which a positive electrode and a negative electrode were mainly bonded to both surfaces of a diaphragm, that is, an integrated battery cell in which the positive electrode / diaphragm / negative electrode was completely integrated was used.

1. 90 g of LiCoO ₂ (manufactured by Nikko Fine Products) as an active material for producing a LiCoO ₂ positive electrode
And graphite powder as a conductive agent (manufactured by Lonza, trade name KS-
6), 3 g of PVDF as a binder and 42 g of 1-methyl-2-pyrrolidone were kneaded to prepare an electrode mixture paste. The mass of the electrode mixture after drying was about 20 mg on one side of an aluminum foil having a thickness of 30 μm.
/ Cm ² and heated at 100 ° C. to dissipate 1-methyl-2-pyrrolidone. Then, compression molding using a roll press machine
A CoO ₂ electrode was made. LiCo produced by this method
The O ₂ electrode, simply referred to as positive electrode in the following examples.
In the production of a battery cell described later, an electrode having a size of 30 × 30 mm was used in which the electrode mixture was partially peeled off and a tab was formed.

2. Preparation of carbon negative electrode Graphite-based carbon active material (trade name B, manufactured by Petka Co., Ltd.)
L924) 94 g, PVDF 6 g and 1 as a binder
An electrode mixture paste was prepared by kneading 70 g of -methyl-2-pyrrolidone. This paste has a thickness of 20
The mass of the electrode mixture after drying on one side of a copper foil of
g / cm ² and heated at 100 ° C. to dissipate 1-methyl-2-pyrrolidone. Thereafter, a carbon electrode was produced by compression molding with a roll press. The carbon electrode produced by this method is simply referred to as a negative electrode in the following examples. In the production of a battery cell to be described later, an electrode having a size of 31 × 31 mm in which the electrode mixture was partially peeled off and a tab was formed was used.

3. Preparation of Integrated Battery Cell In a glass bottle, 2.5 g of PVDF powder (VP850, manufactured by Daikin Industries, Ltd.) having an average particle size of 6 μm and ethanol 4
7.5 g were mixed and irradiated with ultrasonic waves in an ultrasonic cleaner to disperse the PVDF powder. This PVDF powder dispersion is transferred to a glass Petri dish, and hydrophilic PTFE is dispersed.
A microporous membrane (manufactured by Nippon Millipore Co., Ltd., trade name: JGWP membrane filter) cut out to 35 × 35 mm was immersed and wetted on both sides to adhere PVDF powder, then taken out and sandwiched between the positive electrode and the negative electrode. It was fixed from both sides with a glass plate. After heating and vacuum drying at 60 ° C. to dissipate the ethanol, the polymer is heated at 200 ° C. for 10 minutes in a nitrogen stream to melt the PVDF powder, thereby obtaining hydrophilic PT.
The FE microporous membrane was bonded to the positive electrode and the negative electrode to produce a battery cell in which the positive electrode / diaphragm / negative electrode was completely integrated.

4. Preparation of electrolyte stock solution Methyl methacrylate (molecular weight F₁= 100.12, polymerization
Number of possible double bonds s ₁= 1) and ethyl methacrylate
(F₂= 198.22, s₂= 2) and the quality shown in Table 1.
Monomer mixture mixed in quantitative ratio (95: 5 to 40:60)
And a mixture of ethylene carbonate and diethylene in a volume ratio of 1: 1.
1M LiBF in a mixture of ethyl carbonate_FourDissolve
The electrolyte solution and the monomer mixture that have been
The solution was mixed so that the mass ratio of the solution was 15:85.
Finally, azobisisobutyronitrile is used as a polymerization initiator.
Tolyl was added in an amount of 1000 ppm to prepare an electrolyte stock solution. What
Note that the preparation of the electrolyte stock solution and subsequent handling are all dew points.
In dry air below -60 ° C or in an argon atmosphere
I went in.

5. Battery Conversion An undiluted electrolyte solution was injected into the integrated battery cell under reduced pressure. That is, the integrated battery cell produced by the above method was put into a pressure-resistant container, and the whole was subjected to about 100 kPa using a dry vacuum pump.
The electrolyte solution was introduced so that the battery was completely immersed therein, and the electrolyte solution was injected into the integrated battery cell by leaving it in the reduced pressure state for 3 minutes and returning to normal pressure for 10 minutes. . Thereafter, the battery cell was taken out of the container, and the battery cell was sealed in a large aluminum laminate sheet bag so that the terminal portion was completely contained. In this state, the mixture was heated at 80 ° C. for 2 hours to solidify the electrolyte stock solution. After solidifying the electrolyte stock solution, take out the battery cell from the bag,
After confirming that the electrolyte has been solidified and removing excess electrolyte on the surface of the battery cell, finally, as shown in FIG. By encapsulating the film-shaped lithium ion battery No. 4 in the exterior material 4 under reduced pressure, Nos. 1 to 12 were produced.

For comparison, in the same manner as above, except that only an electrolyte obtained by dissolving 1M LiBF ₄ in a mixture of ethylene carbonate and diethyl carbonate at a volume ratio of 1: 1 was used instead of the electrolyte solution. Film-shaped lithium ion battery No. 13 was produced.

6. Charge / discharge cycle test In the charge / discharge test of the battery, the battery was charged for 5 hours at a maximum current of 6 mA in a constant temperature bath at 25 ° C. with a charging upper limit voltage of 4.2 V. On the other hand, the discharge was performed until the battery voltage reached 2.7 V at a constant current of 6 mA. In addition, a pause of 15 minutes was provided between charging and discharging. Table 1 shows the results of this test.
Are shown together.

[0033]

[Table 1]

As is clear from the results in Table 1, the expression (1)
The battery of the example of the present invention in which the crosslink density determined by the above was 0.08 to 0.34 had a discharge capacity of 80% or more of the battery into which the electrolyte was injected as it was at the third cycle, and 5%.
It can be seen that the discharge capacity at the 0th cycle is large and the cycle characteristics are also excellent. A battery having a too low crosslinking density defined by the formula (1) has insufficient initial discharge capacity, and
The discharge capacity at the cycle is much lower. On the other hand, in a battery having an excessively high cross-linking density defined by the formula (1), although the decrease in discharge capacity due to the number of cycles is small,
The discharge capacity itself is small, and a sufficient capacity is not obtained. In the above Examples, those containing 15 to 50% by mass of dimethacrylate ethylene (No. 3 to 10) are within the range of the crosslinking density defined in the present invention, and all of them are sufficient. Although a battery having performance was obtained, ethylene dimethacrylate contained 20 to 40% by mass (crosslink density defined by the formula (1) was 0.11 to 0.2%).
5) (Nos. 4 to 8) have particularly excellent performance. These batteries have a discharge capacity in the third cycle of 90% or more higher than that of a battery using only the electrolytic solution, and have excellent cyclability, and use the electrolytic solution as it is despite the use of a solid electrolyte. It can be seen that the battery has extremely high battery performance close to that of the battery.

[0035]

The solid electrolyte of the present invention can have a high charge / discharge capacity when used in a battery or the like, and has an excellent property that the capacity does not decrease much after repeated charge / discharge. It can be easily produced using a stock solution containing an electrolytic solution and a monomer compound which is a precursor of a polymer crosslinked structure. The non-aqueous electrolyte battery of the present invention can be manufactured in the same manufacturing process as injecting the electrolyte solution as it is using the undiluted solution, and the use of a solid electrolyte prevents liquid leakage, It has a high degree of freedom in shape and has high battery performance close to a battery using an electrolytic solution as it is. In addition, the battery of the present invention eliminates the step of forming an electrolyte membrane and the step of assembling the battery using the electrolyte membrane in the manufacture of the battery, so the number of steps in an ultra-dry atmosphere is greatly reduced, and the battery manufacturing process is extremely simple. become.

[Brief description of the drawings]

FIG. 1A is a perspective view of a film-shaped lithium ion battery as an embodiment of the battery of the present invention, and FIG. 1B is a cross-sectional explanatory view of AA in FIG. .

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 LiCoO ₂ Positive electrode 2 Carbon negative electrode 3 Battery diaphragm 4 Aluminum laminate film exterior material 5 Positive electrode tab 6 Negative electrode tab 7 Heat sealing sealing part

Claims (6)

[Claims] 1. A cross-linking density of the polymer cross-linked structure defined by the following formula (1), comprising an electrolyte solution and a polymer cross-linked structure: 0.08 to 0.34. Solid electrolyte. (Equation 1) (Wherein, n is the number of types of monomer used as precursors of the polymeric crosslinked structure, F _i is the molecular weight of i-th type of monomer, s _i is contained in the i-th type of monomer molecule P _i is the ratio of the mass of the i-th monomer to the sum of the masses of all the monomers, and the sum of p _i from 1 to n is 1) 2. The solid electrolyte according to claim 1, wherein the polymer crosslinked structure is formed by a polymerization reaction of a (meth) acrylate monomer previously dissolved in an electrolytic solution. 3. The solid electrolyte according to claim 2, wherein the (meth) acrylate monomer contains ethylene dimethacrylate. 4. A copolymer having at least one of a monomer having a single reactive site and a monomer having two or more reactive sites is copolymerized in an electrolytic solution to obtain a crosslink density defined by the above formula (1). 4. The method for producing a solid electrolyte according to claim 1, wherein a polymer crosslinked structure having a value of 0.08 to 0.34 is formed. 5. 5. A non-aqueous electrolyte battery comprising the solid electrolyte according to claim 1, 2, or 3. 6. The undiluted solution of a solid electrolyte according to claim 1, which comprises a (meth) acrylate monomer and an electrolytic solution in a battery cell in which a positive electrode, a negative electrode and a diaphragm are processed into a final battery form. A method for producing a non-aqueous electrolyte battery, which comprises injecting, impregnating, and then solidifying.