JP2001332303A - Gel electrolyte precursor and nonaqueous secondary cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous secondary cell improved in reliability, rate characteristics and cycle life. SOLUTION: For the nonaqueous secondary cell comprising a positive electrode 1, a negative electrode 2 and a gel electrolyte layer 3 arranged between the electrodes 1 and 2 and containing a nonaqueous electrolyte, a first polymer insoluble in the nonaqueous electrolyte and a second polymer having the property of gelling the nonaqueous electrolyte, the volume ratio of the first polymer to the second polymer in the gel electrolyte layer 3 is within a range of 0.1 to 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a gel electrolyte precursor and a non-aqueous secondary battery.

[0002]

2. Description of the Related Art In recent years, with the development of electronic equipment, there has been a demand for the development of a secondary battery that is small, lightweight, has a high energy density, and can be repeatedly charged and discharged. Such a secondary battery includes a negative electrode using lithium or a lithium alloy as an active material, a positive electrode containing an oxide, sulfide, or selenide such as molybdenum, vanadium, titanium, or niobium as an active material, and a nonaqueous electrolyte. A non-aqueous electrolyte secondary battery having the following is known.

In addition, instead of a negative electrode using lithium or a lithium alloy as an active material, a carbonaceous material (for example, coke, graphite, carbon fiber, resin fired body, and pyrolytic carbon) that absorbs and releases lithium ions is included. A non-aqueous electrolyte secondary battery using a negative electrode has been proposed. According to the secondary battery, deterioration of negative electrode characteristics due to dendritic deposition is improved, and cycle life and safety are increased as compared with a secondary battery including a negative electrode using lithium or a lithium alloy as an active material.

In such a non-aqueous electrolyte secondary battery, the non-aqueous electrolyte is merely impregnated in the electrode group. However, in order to further improve safety, it is easy to reduce the thickness and weight. For this reason, attempts have been made to hold a non-aqueous electrolyte solution in a polymer (for example, see Japanese Patent Application Laid-Open No.
Publication No.).

[0005] However, a non-aqueous electrolyte secondary battery in which a non-aqueous electrolyte is held by a polymer is not sufficient in reliability, rate characteristics and cycle life.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a gel electrolyte precursor capable of improving the reliability, rate characteristics and cycle life of a non-aqueous secondary battery.

An object of the present invention is to provide a non-aqueous secondary battery having improved reliability, rate characteristics, and cycle life.

[0008]

The gel electrolyte precursor according to the present invention comprises a first polymer which is hardly soluble in a non-aqueous electrolyte and a second polymer which has a property of gelling the non-aqueous electrolyte. A gel electrolyte precursor for obtaining a gel electrolyte by impregnating a non-aqueous electrolyte solution with a non-aqueous electrolyte solution containing a gel electrolyte precursor, and then cooling the gel electrolyte precursor, wherein the volume ratio of the first polymer to the second polymer is Is in the range of 0.1 to 5.

A non-aqueous secondary battery according to the present invention is provided with a positive electrode, a negative electrode, and a non-aqueous electrolyte, a first polymer that is hardly soluble in a non-aqueous electrolyte, and a non-aqueous electrolyte. In a non-aqueous secondary battery comprising a gel electrolyte layer containing a second polymer having a property of gelling an aqueous electrolyte, a volume ratio of the first polymer to the second polymer in the gel electrolyte layer is , 0.1 to 5 within the range.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a non-aqueous secondary battery according to the present invention will be described.

[0011] The non-aqueous secondary battery includes an exterior material and an electrode group housed in the exterior material. The electrode group includes:
A positive electrode, a negative electrode, a first polymer disposed between the positive electrode and the negative electrode, and a non-aqueous electrolyte, a first polymer having low solubility in the non-aqueous electrolyte, and a second polymer having a property of gelling the non-aqueous electrolyte. And a gel electrolyte layer containing: The volume ratio of the first polymer to the second polymer in the gel electrolyte layer is in the range of 0.1 to 5.

Next, the positive electrode, the negative electrode, the gel electrolyte layer and the packaging material will be described.

1) Positive Electrode This positive electrode is formed from a current collector in which a positive electrode layer containing an active material and a conductive material is supported.

Examples of the active material include various oxides (eg, lithium-manganese composite oxides such as LiMn ₂ O ₄ , manganese dioxide, lithium-containing nickel oxides such as LiNiO _2, and lithium-containing nickel oxides such as LiCoO _2). Examples thereof include cobalt oxide, lithium-containing cobalt nickel oxide, amorphous vanadium pentoxide containing lithium, and chalcogen compounds (for example, titanium disulfide, molybdenum disulfide, and the like). Among them, it is preferable to use a lithium manganese composite oxide, a lithium-containing cobalt oxide, and a lithium-containing nickel oxide.

As the current collector, for example, expanded metal made of aluminum, aluminum foil, mesh made of aluminum, punched metal made of aluminum, or the like can be used.

Examples of the conductive material include artificial graphite, carbon black (eg, acetylene black), nickel powder, and the like.

The positive electrode is prepared by, for example, preparing a slurry by kneading a positive electrode active material, a conductive material and a binder in the presence of a solvent, applying the slurry to a current collector, drying the slurry, and pressing the slurry. It is produced by performing molding.

Examples of the binder include polyvinylidene fluoride, styrene / butadiene copolymer, carboxymethyl cellulose and derivatives thereof.

Further, a polymer having a binding function and a function of retaining a non-aqueous electrolyte may be added to the positive electrode layer instead of the binder. Examples of such a polymer include a polyethylene oxide derivative, a polypropylene oxide derivative, a polymer containing the derivative, a copolymer of vinylidene fluoride (VdF) and hexafluoropropylene (HFP), and a polyacrylonitrile derivative.

2) Negative Electrode This negative electrode is formed of a negative electrode layer containing an active material supported on a current collector.

[0021] Examples of the active material include a carbonaceous material that stores and releases lithium ions. Such carbonaceous materials include, for example, those obtained by firing organic polymer compounds (eg, phenolic resin, polyacrylonitrile, cellulose, etc.), those obtained by firing coke and mesophase pitch, and those made by artificial graphite. And carbonaceous materials represented by natural graphite and the like. Above all, it is preferable to use a carbonaceous material obtained by firing the mesophase pitch at a temperature of 500 to 3000 ° C. under normal pressure or reduced pressure.

As the current collector, for example, copper expanded metal, copper foil, copper mesh, copper punched metal, or the like can be used.

The negative electrode includes artificial graphite, natural graphite, carbon black, acetylene black,
Ketjen black, nickel powder, conductive materials of polyphenylene derivatives, and fillers such as olefin polymers and carbon fibers are allowed.

For the negative electrode, for example, a slurry is prepared by kneading a negative electrode active material and a binder in the presence of a solvent, the slurry is applied to a current collector, dried, and then press-molded. It is produced by

Examples of the binder include those similar to those described above for the positive electrode.

Further, in place of the binder, a polymer having a binding function and a function of retaining a non-aqueous electrolyte may be added to the negative electrode layer. Examples of such a polymer include those similar to those described above for the positive electrode.

3) Gel Electrolyte Layer The gel electrolyte layer contains a non-aqueous electrolyte, a first polymer which is hardly soluble in the non-aqueous electrolyte, and a second polymer which has a property of gelling the non-aqueous electrolyte. The volume ratio of the first polymer to the second polymer is in the range of 0.1-5.

The first polymer serves as a skeleton in the gel electrolyte layer, and contributes to improving the mechanical strength of the gel electrolyte layer. Further, it is preferable that the first polymer can minimize the inhibition of ionic conductivity. Therefore, it is desirable that the first polymer has a property of swelling in the non-aqueous electrolyte, though it hardly dissolves in the non-aqueous electrolyte. Examples of the first polymer having such properties include a polyolefin copolymer, polyvinylidene fluoride (PVdF), and the like.
Examples of the polyolefin copolymer include a polyethylene-vinyl acetate copolymer (EVA), a polyethylene-methacrylic acid copolymer, and an ethylene-ethyl acrylate copolymer. As the first polymer, one type or two or more types selected from the types described above can be used. Among them, PVdF is preferable because it has high resistance to an electrolytic solution and has a small barrier for ion transfer.

The first polymer preferably has a degree of swelling described below of 30% by mass or less. If the degree of swelling exceeds 30%, the property of being hardly soluble in the non-aqueous electrolyte may be impaired, and the gel electrolyte may not be able to contribute to the improvement of the mechanical strength. In particular, the degree of swelling is preferably in the range of 8 to 20% by mass. By setting the swelling degree in such a range, both the ionic conductivity and the mechanical strength of the gel electrolyte layer can be further improved.

That is, the polymer to be measured is dissolved in a solvent and cast, and the volume is 2 × 2 × 0.1
A test sheet (cm ³ ) is prepared. LiBF ₄ was added to a solvent in which ethylene carbonate and γ-butyrolactone were mixed at a volume ratio of 1: 3, and the concentration of LiBF ₄ was 1.0 m.
ol / l to prepare a test electrolyte solution. The test sheet is immersed in a test electrolyte at 25 ° C. for 24 hours. After immersion, excess electrolyte (free electrolyte) irrelevant to the swelling of the test sheet is wiped off. Then, the weight W ₁ of the test sheets was measured to calculate the following (1) swelling ratio of the polymer from the equation (%).

Swelling ratio (%) of polymer = {(W ₁ −W ₀ ) / W ₁ } × 100 (1) where W ₁ is the weight (g) of the test sheet after the immersion test. , W ₀ represents the weight (g) of the test sheet before the immersion test.

The first polymer is more preferably a thermoplastic resin in addition to the property of swelling in the non-aqueous electrolyte. An application step for forming a gel electrolyte layer by forming the first polymer from a thermoplastic resin;
The rolling process and the stretching process can be easily performed. At the same time, the gel electrolyte layer can be made from a polymer blend. Has the property of swelling in non-aqueous electrolyte,
Examples of the first polymer which is a thermoplastic resin include, for example, polyolefin copolymers (eg, ethylene-vinyl acetate copolymer, ethylene-methacrylic acid copolymer, ethylene-ethyl acrylate copolymer), polyvinylidene fluoride Ride (PVdF) and the like.
As the first polymer, one type or two or more types selected from the types described above can be used.

The second polymer is, for example, polyethylene oxide (PEO) and its derivatives, polypropylene oxide (PPO) and its derivatives, a copolymer of vinylidene fluoride and hexafluoropropylene (PVdF-HFP), and polyacrylonitrile ( P
AN) and at least one polymer selected from the group consisting of derivatives thereof. In particular,
Polyacrylonitrile (PAN) and its derivatives, which can fix many electrolytes with a small amount of polymer, are desirable. Examples of the PAN derivative include a copolymer containing acrylonitrile as a monomer component. Examples of the copolymer containing acrylonitrile as a monomer component include an acrylonitrile-vinyl acetate copolymer, an acrylonitrile-methyl acrylate copolymer, and an acrylonitrile-ethyl acrylate copolymer. Further, SAN, ABS and the like, which are rubbers containing acrylonitrile, may be mentioned.

Preferably, the first polymer and the second polymer are incompatible and form a sea-island structure in the gel electrolyte layer.

The volume ratio of the first polymer to the second polymer is in the range of 0.1 to 5 (the volume of the second polymer is V ₂ and the volume of the first polymer is V ₁ . when the is calculated by V ₁ / V _2). This is due to the following reasons. The skeleton of the gel electrolyte layer is mainly formed from the first polymer. Further, the second polymer mainly contributes to the ion conduction of the gel electrolyte layer. Further, the second polymer has a role of suppressing volatilization of the non-aqueous electrolyte. The non-aqueous electrolyte is held by the first polymer and the second polymer. When the volume ratio is less than 0.1, the morphological stability (electrolytic solution holding power and mechanical strength) of the gel electrolyte layer is reduced. As a result, handling during battery manufacture is poor. In addition, since an internal short circuit easily occurs, the reliability of the secondary battery is impaired.
On the other hand, when the volume ratio exceeds 5, the ionic conductivity of the gel electrolyte layer decreases, and the internal impedance of the secondary battery increases, so that the charge / discharge efficiency decreases and the cycle life decreases. A more preferable range of the volume ratio is 0.4 to 2.5.

The volume ratio of the first polymer to the second polymer in the gel electrolyte layer in the non-aqueous secondary battery is measured, for example, by the method described below.

First, the secondary battery is disassembled, and the gel electrolyte layer is taken out. Solvent extraction from this gel electrolyte layer
For example, acetone, ethanol, and water are used) to extract the electrolyte solution and take out the polymer component. The obtained polymer components are separated by utilizing the difference in solubility in a solvent, and the abundance ratio of each component is identified. Thereafter, infrared absorption (IR), nuclear magnetic resonance (NMR), paramagnetic resonance (E
Each polymer component is identified by an analytical instrument such as SR) and differential scanning calorimetry (DSC). From these results, the volume ratio of the first polymer to the second polymer can be determined.

The non-aqueous electrolyte comprises an electrolyte such as a lithium salt dissolved in a non-aqueous solvent.

Examples of the non-aqueous solvent include ethylene carbonate (EC) and propylene carbonate (P
C), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC),
Ethyl methyl carbonate (EMC), γ-butyrolactone (γ-BL), sulfolane, acetonitrile, 1,
2-dimethoxyethane, 1,3-dimethoxypropane,
Dimethyl ether, tetrahydrofuran (THF), 2
-Methyltetrahydrofuran and the like.
The non-aqueous solvents may be used alone or in combination of two or more.

Examples of the electrolyte include lithium perchlorate (LiClO ₄ ) and lithium hexafluorophosphate (L
iPF _6), lithium borofluoride (LiBF _4), lithium hexafluoroarsenate (LiAsF _6), lithium salts such as lithium trifluoromethane sulfonate (LiCF ₃ SO ₃₎ may be mentioned.

The amount of the electrolyte dissolved in the non-aqueous solvent is desirably 0.2 mol / L to 2 mol / L.

The gel electrolyte layer is produced, for example, by the method described below.

First, a gel electrolyte layer precursor is prepared by the method (1) or (2).

(1) The first polymer and the second polymer are mixed in a powder state, plasticized by heating and formed into a sheet to obtain a polymer blend film.

(2) The first polymer and the second polymer are dissolved in a solvent, and a gel electrolyte layer precursor is obtained from the obtained slurry by casting.

Next, an electrode group is prepared by interposing a gel electrolyte layer precursor between the positive electrode and the negative electrode, and the obtained electrode group is impregnated with a non-aqueous electrolytic solution, and then heated to heat the non-aqueous electrolytic solution. Is gelled and cooled to obtain a gel electrolyte layer from the gel electrolyte layer precursor. In addition,
The impregnation, heating and cooling of the non-aqueous electrolyte are desirably performed in a dry environment.

In order to further improve the strength of the gel electrolyte layer, an inorganic filler such as crystalline silica or fused silica, and a core material such as a nonwoven fabric or a microporous film are added when preparing the gel electrolyte layer precursor. You may.

4) Exterior material As the exterior material, for example, a sheet in which a metal layer is interposed between a thermoplastic resin layer and a resin layer can be mentioned.

The thermoplastic resin layer functions as a heat sealing surface of the exterior material. Examples of the heat-fusible resin include modified polyethylene phthalate, acid-modified polyethylene, acid-modified polypropylene, ionomer, ethylene vinyl acetate (EVA) and the like. The thermoplastic resin layer may have a single layer or a multilayer structure composed of a plurality of thermoplastic resins.

The metal layer has a role of preventing intrusion of moisture. The metal layer can be formed from, for example, aluminum, nickel, and stainless steel.

The resin layer has a role of protecting the metal layer. The resin layer can be formed from, for example, polyolefin such as polyethylene terephthalate (PET) and polypropylene. The resin layer,
It can be a single layer or a multilayer structure composed of a plurality of resins.

FIGS. 1 and 2 show an example of the non-aqueous secondary battery according to the present invention.

That is, the non-aqueous secondary battery has an electrode group mainly composed of a positive electrode 1, a negative electrode 2, and a gel electrolyte layer 3 disposed between the positive electrode 1 and the negative electrode 2. Is provided. The positive electrode 1 includes a porous current collector 4 and a positive electrode layer 5 supported on both surfaces of the current collector 4. On the other hand, the negative electrode 2 includes a porous current collector 6 and a negative electrode layer 7 supported on both surfaces of the current collector 6. The band-shaped positive terminal 8 is
The current collector 4 of each positive electrode 1 is extended in a belt shape.
On the other hand, the strip-shaped negative electrode terminal 9 is obtained by extending the current collector 6 of the negative electrode 2 in a strip shape. For example, a positive electrode lead 10 made of a strip-shaped aluminum plate is connected to the two positive electrode terminals 8. For example, the negative electrode lead 11 made of a strip-shaped copper plate
Is connected to the negative electrode terminal 9. The electrode group having such a configuration is hermetically sealed in a state in which the positive electrode lead 10 and the negative electrode lead 11 extend from the exterior material 12 within the exterior material 12.

The non-aqueous secondary battery according to the present invention described above is provided with a positive electrode, a negative electrode, a first non-aqueous electrolyte which is disposed between the positive electrode and the negative electrode, and which is hardly soluble in the non-aqueous electrolyte. A gel electrolyte layer containing a polymer and a second polymer having a property of gelling the non-aqueous electrolyte. The volume ratio of the first polymer to the second polymer in the gel electrolyte layer is in the range of 0.1 to 5.

According to such a secondary battery, both the morphological stability and the ionic conductivity of the gel electrolyte layer can be satisfied. As a result, the internal resistance of the secondary battery can be reduced, so that a decrease in capacity at the time of discharging at a high rate can be suppressed, and the charge and discharge efficiency can be increased to improve the cycle life. Further, handling during the battery manufacturing process can be improved. Furthermore, since the internal short circuit occurrence rate can be reduced, the reliability of the secondary battery can be improved.

Accordingly, it is possible to realize a non-aqueous secondary battery that simultaneously satisfies the rate characteristics, cycle life, and reliability.

[0057]

Embodiments of the present invention will be described below with reference to the drawings.

Example 1 First, a test gel electrolyte layer was prepared in order to evaluate the ionic conductivity and form stability of the gel electrolyte layer.

(Preparation of Gel Electrolyte Layer Precursor) Polyvinylidene fluoride powder (PVd
F) and polyacrylonitrile powder (PAN) as the second polymer were mixed at a volume ratio (volume ratio of the first polymer to the second polymer) of 2, and then 200
The mixture was plasticized by heating to ° C. and formed into a sheet to prepare a gel electrolyte layer precursor.

The swelling ratio of the first polymer was measured by the method described below. 20 parts by mass of PVdF powder was N-
It is dissolved in 80 parts by mass of a solvent composed of methyl-2-pyrrolidone and cast, and the volume is 2 × 2 × 0.1 (c
m ³ ) was prepared. The obtained test sheet was immersed in the above-mentioned test electrolyte at 25 ° C. for 24 hours. After immersion, excess electrolyte (free electrolyte) irrelevant to the swelling of the test sheet was wiped off. Next, the weight W _{1 of the} test sheet was measured, and the swelling ratio (%) of the polymer was obtained from the above-described formula (1).
As a result, the swelling ratio was 16%.

(Preparation of Non-Aqueous Electrolyte) LiBF ₄ has a concentration of 1 M / L in a non-aqueous solvent obtained by mixing ethylene carbonate (EC) and γ-butyrolactone (BL) at a volume ratio of 1: 3. To prepare a non-aqueous electrolyte solution.

After the gel electrolyte layer precursor was immersed in the non-aqueous electrolyte, they were heated at 100 ° C. for 3 minutes to gel the non-aqueous electrolyte, and then cooled at −20 ° C. for 2 hours. By returning the temperature to room temperature, a test gel electrolyte layer having a sea-island structure was obtained.

Next, a non-aqueous secondary battery was assembled by the method described below in order to evaluate the rate characteristics and cycle life.

(Preparation of Positive Electrode) 88% by mass of LiCoO ₂
And 7% by mass of acetylene black, and 5% by mass of polyvinylidene fluoride as a binder.
A paste was prepared by dispersing in 2-pyrrolidone. The obtained paste was applied to a current collector made of aluminum foil having a thickness of 20 μm to a thickness of 100 μm by a doctor blade method.
It is applied so as to have a width of 150 mm, formed into a sheet, and 150
A positive electrode was prepared by cutting the length into mm.

(Preparation of Negative Electrode) A paste was prepared by dispersing 95% by mass of mesophase pitch carbon fiber and 5% by mass of polyvinylidene fluoride as a binder in N-methyl-2-pyrrolidone. The obtained paste was applied to a current collector made of a copper foil having a thickness of 12 μm by a doctor blade method so as to have a thickness of 100 μm and a width of 150 mm, formed into a sheet, and cut into a length of 160 mm to produce a negative electrode. .

(Assembly and Activation of Battery) The obtained positive electrode and negative electrode were laminated with the above-mentioned gel electrolyte layer precursor interposed therebetween, thereby producing an electrode group. The obtained electrode group was inserted into a bag made of a laminate film composed of a thermoplastic resin layer / aluminum foil / resin layer, dried under vacuum at 80 ° C. for 12 hours, and then injected with the nonaqueous electrolyte under an argon atmosphere. . Subsequently, the positive electrode terminal and the negative electrode terminal were sealed by heating and pressure bonding in a state of protruding outside the bag. The non-aqueous electrolyte is gelled by sandwiching the assembled secondary battery between metal plates at 100 ° C. for 3 minutes, then cooled at −20 ° C. for 2 hours, and returned to room temperature to obtain a non-aqueous solution having a design capacity of 100 mAh. A secondary battery was manufactured.

The obtained secondary battery has a capacity of 0.
Activation was performed by applying a constant current-constant voltage charge at a current of 2 CmA and a final voltage of 4.2 V.

(Examples 2 to 7 and Comparative Examples 1 and 2) Except that the volume ratio of the first polymer, the second polymer, and the first polymer to the second polymer was changed as shown in Table 1 below. In the same manner as in Example 1 described above, a test gel electrolyte layer and a nonaqueous secondary battery were produced.

The swelling ratio of the ethylene-vinyl acetate copolymer (EVA) used as the first polymer in Example 7 was measured by the method described below. EVA powder 10
A part by mass is dissolved in 90 parts by mass of a solvent composed of tetrahydrofuran and cast, and the volume is 2 × 2 × 0.1 (c
m ³ ) was prepared. The obtained test sheet was immersed in the above-mentioned test electrolyte at 25 ° C. for 24 hours. After immersion, excess electrolyte (free electrolyte) irrelevant to the swelling of the test sheet was wiped off. Next, the weight W _{1 of the} test sheet was measured, and the swelling ratio (%) of the polymer was obtained from the above-described formula (1).
As a result, the swelling ratio was 5%.

Comparative Example 3 A microporous separator made of polyolefin was interposed between the positive electrode and the negative electrode as described in Example 1 to form an electrode group. After the obtained electrode group was inserted into a bag made of a laminate film similar to that described in Example 1, a non-aqueous electrolyte similar to that described in Example 1 was injected. Next, the positive electrode terminal and the negative electrode terminal were heated and press-bonded in a state where they protruded to the outside of the bag, thereby closing the container, thereby producing a non-aqueous secondary battery having a designed capacity of 100 mAh.

The obtained test gel electrolyte layers of Examples 1 to 7 and Comparative Examples 1 and 2 and the separator impregnated with the nonaqueous electrolyte of Comparative Example 3 were sandwiched between two nickel electrodes having a fixed area. After sealing in an aluminum laminate film, the impedance was measured at −20 ° C., 0 ° C., and 20 ° C. by the alternating current method, and the ionic conductivity at −20 ° C., 0 ° C., and 20 ° C. was obtained. It is described together.

With respect to the obtained gel electrolyte layers of Examples 1 to 7 and Comparative Examples 1 and 2, 2 × 2 × 0.1 (c
m ³ ) was prepared, left in a closed container for 24 hours, and the presence or absence of seepage of the electrolytic solution was visually checked.
The case where there is bleeding is C, the case where the surface is wet is B, and the case where there is almost no change from before standing is A. The results are also shown in Table 1 below.

The obtained gel electrolyte layers of Examples 1 to 7 and Comparative Examples 1 and 2 were 2 × 2 × 0.1 (c
m ³ ) was prepared and placed on a glass plate.
When a weight having an area of 1 × 1 (cm ² ) and a weight of 50 g is placed thereon, C indicates that the deformation is large, B indicates the degree of the deformation is small, and A indicates that there is little change in appearance. The results are shown in Table 1 below.

The obtained Examples 1 to 7 and Comparative Example 1
0.2 Cm at 20 ° C.
A, the discharge capacity at the time of discharging at a current of 0.5 CmA, 1 CmA, and 2 CmA to a final voltage of 3.0 V was measured. 0.
Assuming that the discharge capacity at 2C is 100%, 0.5C, 1C,
It shows the discharge capacity at 2C, and the results are shown in Table 2 below.

The obtained secondary batteries of Examples 1 to 7 and Comparative Examples 1 to 3 were charged at 20 ° C. with a cut-off voltage of 4.2 V at 1.0 C and charged with a cut-off voltage of 3.0 V at 1.0 C. The discharge was repeated 50 cycles, and the capacity retention rate after 50 cycles (discharge capacity after 50 cycles when the initial capacity was 100%) was determined. The results are shown in Table 2 below.

[0076]

[Table 1]

[0077]

[Table 2]

As is clear from Tables 1 and 2, the secondary of Examples 1 to 7 provided with the gel electrolyte layer in which the volume ratio of the first polymer to the second polymer was in the range of 0.1 to 5 The battery has a high ionic conductivity in the gel electrolyte layer, and is excellent in electrolyte retention ability and mechanical strength, and has a rate characteristic and a capacity retention rate after 50 cycles that are different from those of the solution type secondary battery of Comparative Example 3. It can be seen that they are almost equivalent.

On the other hand, the first polymer with respect to the second polymer
The secondary battery of Comparative Example 1 including the gel electrolyte layer in which the volume ratio of the polymer was less than 0.1 had an electrolyte retention capacity and a mechanical strength of the gel electrolyte as compared with the secondary batteries of Examples 1 to 7. It turns out that it is inferior. On the other hand, the first for the second polymer
The secondary battery of Comparative Example 2 including the gel electrolyte layer having a volume ratio of the polymer of more than 5 has a lower ionic conductivity of the gel electrolyte layer than the secondary batteries of Examples 1 to 7, and has a high rate. It can be seen that the discharge capacity at the time of discharging is greatly reduced, and the capacity retention after 50 cycles is reduced.

[0080]

As described above in detail, according to the present invention, it is possible to provide a gel electrolyte precursor capable of improving the reliability, rate characteristics and cycle life of a non-aqueous secondary battery. Further, according to the present invention, a non-aqueous secondary battery having improved reliability, rate characteristics, and cycle life can be provided.

[Brief description of the drawings]

FIG. 1 is a plan view showing an example of a non-aqueous secondary battery according to the present invention.

FIG. 2 is a sectional view showing the non-aqueous secondary battery of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Positive electrode, 2 ... Negative electrode, 3 ... Gel electrolyte layer, 4 ... Positive electrode collector, 5 ... Positive electrode layer, 6 ... Negative electrode current collector, 7 ... Negative electrode layer, 12 ... Exterior material.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08K 5/42 C08K 5/42 C08L 23/08 C08L 23/08 25/12 25/12 27/16 27 / 16 27/20 27/20 33/20 33/20 55/02 55/02 71/02 71/02 (72) Inventor Masahiro Iwaku 3-4-10 Minamishinagawa, Shinagawa-ku, Tokyo Toshiba Battery Corporation F Term (reference) 4J002 BB06W BB07W BB08W BC06X BD14W BD14X BD16X BG10X BN15X CH02X DD036 DE196 DH006 DK006 EV256 GQ00 HA05 5H029 AJ02 AJ14 AK03 AL07 AL08 AM03 AM04 AM05 AM07 AM16 CJ02 CJ13EJ12

Claims (4)

[Claims] 1. A gel electrolyte precursor containing a first polymer which is hardly soluble in a non-aqueous electrolyte and a second polymer having a property of gelling the non-aqueous electrolyte is impregnated with the non-aqueous electrolyte. A gel electrolyte precursor for obtaining a gel electrolyte by cooling after heating, wherein a volume ratio of the first polymer to the second polymer is in a range of 0.1 to 5. Characterized gel electrolyte precursor. 2. The swelling ratio of the first polymer is 30%.
The gel electrolyte precursor according to claim 1, wherein: 3. The second polymer is polyethylene oxide (PEO) and its derivatives, polypropylene oxide (PPO) and its derivatives, and a copolymer of vinylidene fluoride and hexafluoropropylene (PVd).
2. The gel electrolyte precursor according to claim 1, comprising at least one polymer selected from the group consisting of F-HFP) and polyacrylonitrile (PAN) and derivatives thereof. 4. A non-aqueous electrolyte, a first polymer which is hardly soluble in the non-aqueous electrolyte and a property of gelling the non-aqueous electrolyte, which is disposed between the positive electrode, the negative electrode, and the positive electrode and the negative electrode. A non-aqueous secondary battery comprising: a gel electrolyte layer containing a second polymer having a volume ratio of the first polymer to the second polymer in the gel electrolyte layer in the range of 0.1 to 5. Non-aqueous secondary battery characterized by the following.