JP2001167797A - Gel phase electrolyte and gel phase electrolyte cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide gel phase electrolyte having good chemical stability to negative electrode, strength, and liquid maintaining property, and to provide a gel phase electrolyte cell having a large capacity, cycle property, load property, low temperature property by using the gel phase electrolyte. SOLUTION: The nonaqueous electrolyte in which lithium containing solvent electrolyte salt is dissolved in the nonaqueous solvent and is formed is gel phase with matrix polymer to contain derivative of vinylene carbonate or vinylere carbonate in a range of 0.05 wt.%-5 wt.% with respect to the nonaqueous electrolyte.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gel electrolyte in which a non-aqueous electrolyte obtained by dissolving a lithium-containing electrolyte salt in a non-aqueous solvent is gelled by a matrix polymer, and a gel electrolyte using the same. Battery.

[0002]

2. Description of the Related Art As a power source of a portable electronic device, an industrial battery is occupying an important position. In order to reduce the size and weight of the device, it is required that the battery be light and the storage space in the device be used efficiently. A lithium battery having a high energy density and a high power density is most suitable for this.

[0003] Among them, a flexible battery having a high degree of freedom in shape,
Alternatively, a thin, large-area sheet-type battery or a thin, small-area card-type battery is desired, but it is difficult to produce a thin, large-area battery by using a conventional metal can for the exterior.

In order to solve this problem, batteries using an organic / inorganic solid electrolyte or a gel electrolyte using a polymer gel have been studied. In these batteries, since the electrolyte is fixed, the thickness of the electrolyte is fixed, and there is an adhesive force between the electrode and the electrolyte, so that contact can be maintained. For this reason, it is not necessary to confine the electrolytic solution by the metal exterior or to apply pressure to the battery element. Therefore, a film-like exterior can be used,
The battery can be made thin.

[0005] All-solid electrolytes have low ionic conductivity,
Since practical application to batteries is still difficult, gel electrolytes are considered promising. It is conceivable to use a multilayer film composed of a polymer film, a metal thin film, or the like as the exterior. In particular, a moisture-proof multilayer film composed of a heat-sealing resin layer and a metal foil layer can easily achieve a hermetic structure by hot sealing, and has excellent strength and airtightness of the multilayer film itself, and is lighter than a metal exterior. It is promising as a candidate for exterior materials because it is thin and inexpensive.

[0006]

However, the non-aqueous solvent in the gel electrolyte does not constitute the gel electrolyte unless the solvent is compatible with the matrix polymer. In addition, when the film is used for the exterior of a battery and a low-boiling solvent is used, when the battery is placed in a high-temperature environment, the internal pressure of the battery may increase due to an increase in the vapor pressure of the solvent, causing swelling. Therefore, there is a limitation in selecting a solvent.

[0007] Low boiling solvents such as dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate and the like used in lithium ion batteries have a high freezing point and a low viscosity, so that they are extremely effective in increasing the ionic conductivity of the electrolyte at low temperatures. However, as described above, gel electrolyte batteries using a multilayer film for the outer package cannot be used in large quantities due to restrictions on solvent selection due to compatibility and boiling point.

As a solvent for the gel electrolyte for a battery, ethylene carbonate, propylene carbonate, and the like can be used as a substance having a high boiling point and not causing a decomposition reaction that impairs battery performance. Furthermore, we have copolymerized hexafluoropropylene in a weight ratio of 7.5% or less as a matrix polymer having excellent compatibility with these solvents, chemical stability, gel strength, and liquid retention. A copolymer with polyvinylidene fluoride was developed.

Further, when ethylene carbonate and propylene carbonate are used as a mixture as a non-aqueous solvent,
When the amount of propylene carbonate is large, the low temperature characteristics and the load characteristics are improved, but the initial charge / discharge efficiency is poor, so that the battery capacity is small and the cycle characteristics are also deteriorated. Therefore, it was difficult to produce a gel electrolyte battery having excellent battery capacity, cycle characteristics, load characteristics, and low-temperature characteristics.

[0010] The present invention has been proposed in view of the above-mentioned conventional circumstances, and a gel electrolyte having excellent chemical stability, strength, and liquid retaining property, and a battery using the gel electrolyte. An object of the present invention is to provide a gel electrolyte battery satisfying capacity, cycle characteristics, load characteristics, and low-temperature characteristics.

[0011]

The gel electrolyte of the present invention comprises a non-aqueous electrolyte obtained by dissolving a lithium-containing electrolyte salt in a non-aqueous solvent, which is made into a gel form by a matrix polymer, and is formed of vinylene carbonate or vinylene carbonate. The derivative of vinylene carbonate was added to the above non-aqueous electrolyte at 0.0
It is characterized in that it is contained in a range of 5% by weight or more and 5% by weight or less.

The gel electrolyte according to the present invention as described above contains vinylene carbonate or a derivative of vinylene carbonate in an amount of 0.05% by weight or more and 5% by weight or less based on the nonaqueous electrolyte. Therefore, the chemical stability of the negative electrode and the gel electrolyte becomes excellent. And the gel electrolyte battery using this gel electrolyte has improved initial charge / discharge efficiency and capacity.

Further, the gel electrolyte battery of the present invention comprises a negative electrode having any one of lithium metal, a lithium alloy and a carbon material capable of doping and undoping lithium, and a positive electrode having a composite oxide of lithium and a transition metal. And a gel electrolyte with the negative electrode and the positive electrode interposed therebetween. The gel electrolyte battery according to the present invention is characterized in that the gel electrolyte is a non-aqueous electrolyte obtained by dissolving a lithium-containing electrolyte salt in a non-aqueous solvent, which is formed into a gel by a matrix polymer, and that vinylene carbonate or vinylene is used. The derivative of carbonate was added to the above non-aqueous electrolyte at 0.05%.
It is characterized in that it is contained in a range of not less than 5% by weight and not more than 5% by weight.

In the gel electrolyte battery according to the present invention as described above, the gel electrolyte comprises vinylene carbonate or a derivative of vinylene carbonate in an amount of 0.05% by weight or more and 5% by weight or less with respect to the nonaqueous electrolyte. Since the gel electrolyte is contained in the following range, the gel electrolyte has excellent chemical stability with the negative electrode. Then, the gel electrolyte battery of the present invention using such a gel electrolyte satisfies excellent initial charge / discharge efficiency and battery capacity. In addition, there is an effect of suppressing swelling due to gas generation, and it is possible to prevent a change in the size and shape of the battery.

[0015]

Embodiments of the present invention will be described below.

FIGS. 1 to 3 show one structural example of the gel electrolyte battery according to the present embodiment. This gel electrolyte battery 1
As shown in FIG. 3, includes a strip-shaped positive electrode 2, a strip-shaped negative electrode 3 disposed opposite to the positive electrode 2, and a gel electrolyte layer 4 disposed between the positive electrode 2 and the negative electrode 3. . The gel electrolyte battery 1 has an electrode winding body 5 shown in FIGS. 2 and 3 in which the positive electrode 2 and the negative electrode 3 are stacked via the gel electrolyte layer 4 and wound in the longitudinal direction. , And is covered and sealed by an exterior film 6 made of an insulating material. The positive electrode 2 has a positive electrode terminal 7, and the negative electrode 3 has a negative electrode terminal 8.
Are connected to each other, and the positive electrode terminal 7 and the negative electrode terminal 8 are sandwiched by a sealing portion which is a peripheral portion of the exterior film 6.

The positive electrode 2 has a positive electrode active material layer containing a positive electrode active material formed on both surfaces of a positive electrode current collector. As the positive electrode current collector, for example, a metal foil such as an aluminum foil is used.

The positive electrode active material layer is prepared by, for example, uniformly mixing a positive electrode active material, a conductive material, and a binder to form a positive electrode mixture, and dispersing the positive electrode mixture in a solvent to form a slurry. I do. Next, the slurry is uniformly applied onto the positive electrode current collector by a doctor blade method or the like, dried at a high temperature to remove the solvent, and formed. Here, the positive electrode active material, the conductive material, the binder, and the solvent only need to be uniformly dispersed, and the mixing ratio thereof does not matter.

Here, a composite oxide of lithium and a transition metal is used as the positive electrode active material. Specifically, as the positive electrode active material, LiCoO ₂ , LiNiO ₂ , LiMn ₂
O ₄ and LiAlO ₂ are exemplified. The transition metal element can be used not only in one kind but also in two or more kinds. Examples thereof include LiNi _0.5 Co _0.5 O ₂ and LiNi _0.8 Co _0.2 O ₂ .

As the conductive material, for example, a carbon material or the like is used. As the binder, for example, polyvinylidene fluoride or the like is used. As the solvent, for example, N-methylpyrrolidone or the like is used.

The positive electrode 2 has a positive terminal 7 connected to the other end in the longitudinal direction by spot welding or ultrasonic welding. The positive electrode terminal 7 is desirably a metal foil or mesh-like one, but there is no problem even if it is not a metal as long as it is electrochemically and chemically stable and can conduct. The material of the positive electrode terminal 7 includes, for example, aluminum.

It is preferable that the positive electrode terminal 7 extends in the same direction as the negative electrode terminal 8. However, as long as no short circuit or the like occurs and there is no problem in battery performance, there is no problem in which direction the positive electrode terminal 7 extends. In addition, as long as the connection location of the positive electrode terminal 7 is in electrical contact, the location and method of attachment are not limited to the above examples.

In the negative electrode 3, a negative electrode active material layer containing a negative electrode active material is formed on both surfaces of a negative electrode current collector.
As the negative electrode current collector, for example, a metal foil such as a copper foil is used.

In the negative electrode active material layer, first, for example, a negative electrode active material, and if necessary, a conductive material and a binder are uniformly mixed to form a negative electrode mixture, and this negative electrode mixture is dispersed in a solvent. To make a slurry. Next, the slurry is uniformly applied on the negative electrode current collector by a doctor blade method or the like, dried at a high temperature to remove the solvent, and formed. Here, the negative electrode active material, the conductive material, the binder, and the solvent only need to be uniformly dispersed, and the mixing ratio does not matter.

As the negative electrode active material, a lithium metal, a lithium alloy or a carbon material capable of doping and undoping lithium is used. Specifically, examples of the carbon material that can be doped with and dedoped with lithium include graphite, non-graphitizable carbon, and graphitizable carbon.

As the conductive material, for example, a carbon material or the like is used. As the binder, for example, polyvinylidene fluoride or the like is used. As the solvent, for example, N-methylpyrrolidone or the like is used.

The negative electrode 3 has a negative terminal 8 connected to the other end in the longitudinal direction by spot welding or ultrasonic welding. The negative electrode terminal 8 is preferably made of a metal foil or mesh. However, there is no problem even if it is not a metal as long as it is electrochemically and chemically stable and can conduct electricity. Examples of the material of the negative electrode terminal 8 include copper and nickel.

It is preferable that the negative electrode terminal 8 protrudes in the same direction as the positive electrode terminal 7. However, as long as no short circuit or the like occurs and there is no problem in battery performance, there is no problem in any direction. In addition, as long as the connection location of the negative electrode terminal 8 is in electrical contact, the location and method of attachment are not limited to the above examples.

The gel electrolyte contains a non-aqueous solvent, an electrolyte salt, and a matrix polymer. Further, as described later, in the gel electrolyte battery 1 of the present invention, vinylene carbonate or a derivative thereof is added to the gel electrolyte.

As the non-aqueous solvent, a known solvent used as a non-aqueous solvent for a non-aqueous electrolyte can be used. Specifically, solvents such as ethylene carbonate, propylene carbonate, γ-butyrolactone, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, dipropyl carbonate, ethyl propyl carbonate, or a solvent obtained by substituting the hydrogen of a carbonic acid ester with a halogen, etc. Can be

One of these solvents may be used alone, or a plurality thereof may be mixed with a predetermined composition. Among them, it is particularly preferable to use a mixed solvent in which ethylene carbonate and propylene carbonate are mixed in a weight ratio of 15:85 to 75:25. If the amount of ethylene carbonate is too large, the low-temperature characteristics of the gel electrolyte battery 1 will be impaired. If the amount of propylene carbonate is too large, the initial charge / discharge efficiency, battery capacity, and cycle characteristics will not be good.

As the electrolyte salt, those soluble in the above-mentioned non-aqueous solvent can be used. Examples of the cation include an alkali metal ion such as lithium and an alkaline earth metal ion. Further, as anions, BF ₄ ⁻ , PF ₆ ⁻ , C
F ₃ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ⁻
And the like. Then, an electrolyte salt obtained by combining these cations and anions is used. As the electrolyte salt used, for example, LiPF ₆ , LiB
F ₄ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ S
O ₂ ) ₂ and LiClO ₄ .

There is no problem with the concentration of the electrolyte salt as long as it can be dissolved in the above-mentioned solvent, but the lithium ion concentration is 0.4 mol / kg or more and 1.0 mol / kg or less with respect to the non-aqueous solvent. Is preferably within the range. If the lithium ion salt concentration exceeds 1.0 mol / kg, the low temperature characteristics and the cycle characteristics of the gel electrolyte battery 1 will be deteriorated. Further, when the lithium ion concentration is 0.1.
If it is less than 4 mol / kg, a sufficient capacity cannot be secured.

The matrix polymer gels a non-aqueous electrolyte obtained by dissolving the electrolyte salt in the non-aqueous solvent. Such matrix polymers include polyvinylidene fluoride, polyethylene oxide,
Examples include polymers containing polypropylene oxide, polyacrylonitrile, and polymethacrylonitrile in the repeating unit. One of these polymers may be used alone, or two or more may be used in combination.

Among them, it is particularly preferable to use, as the matrix polymer, polyvinylidene fluoride or a copolymer in which hexafluoropropylene is introduced into polyvinylidene fluoride at a ratio of 7.5% or less. Such a polymer has a number average molecular weight in the range of 500,000 to 700,000 or a weight average molecular weight in the range of 210,000 to 310,000 and an intrinsic viscosity of 1.7 to 2.1. ing.

The exterior film 6 is for hermetically packing an electrode wound body 5 in which the positive electrode 2 and the negative electrode 3 are laminated via the gel electrolyte layer 4 and wound in the longitudinal direction. This exterior film is made of, for example, a moisture-proof and insulating multilayer film in which an aluminum foil is sandwiched between a pair of resin films.

In the gel electrolyte battery according to the present invention, vinylene carbonate or a derivative thereof is added to the gel electrolyte. By adding vinylene carbonate or a derivative thereof to the gel electrolyte, the chemical stability of the gel electrolyte with respect to the negative electrode can be increased. Then, by using a gel electrolyte having excellent chemical stability with respect to the negative electrode, the initial charge / discharge efficiency of the gel electrolyte battery 1 can be improved, and a high battery capacity can be obtained.

As described above, one of the great advantages of the gel electrolyte battery is that a lightweight multilayer film can be used for the exterior. However, when a gas is generated due to decomposition of a non-aqueous solvent at the time of the first charge as in the case of a lithium ion secondary battery, the gel electrolyte battery using a multilayer film for the exterior has a major problem that the battery swells. there were.

The present inventor has found that by adding vinylene carbonate or a derivative thereof to the gel electrolyte, in addition to the above-described effects, it is possible to suppress gas generation due to charging and to prevent battery expansion. Was.

The amount of vinylene carbonate or a derivative thereof added is 0.05 to 0.05% of the solvent in the gel electrolyte.
It is preferable to be in the range of not less than 5% by weight and not more than 5% by weight.
If the amount of vinylene carbonate is less than 0.05% by weight, the effect of improving the charge / discharge efficiency cannot be sufficiently obtained, and a high battery capacity and initial charge / discharge efficiency cannot be obtained. On the other hand, if the amount of vinylene carbonate exceeds 5% by weight, the discharge characteristics at low temperatures are rather deteriorated.

Therefore, the amount of vinylene carbonate or a derivative thereof added to the solvent in the gel electrolyte is set to 0.1.
When the content is in the range of 05% by weight or more and 5% by weight or less, the charge / discharge efficiency can be improved without lowering the discharge characteristics at a low temperature, and a high battery capacity and cycle characteristics can be obtained. Further, the more preferable addition amount of vinylene carbonate or its derivative is in the range of 0.5% by weight or more and 3% by weight or less based on the solvent in the gel electrolyte. By setting the amount of vinylene carbonate to be in the range of 0.5% by weight or more and 3% by weight or less based on the solvent in the gel electrolyte, the above-described characteristics can be further improved.

Further, it is preferable that difluoroanisole (DFA) is added to the non-aqueous electrolyte constituting the gel electrolyte. By adding difluoroanisole to the non-aqueous electrolyte, the charge and discharge efficiency of the gel electrolyte battery 1 can be improved, and a high discharge capacity can be obtained. The addition amount of difluoroanisole is preferably in the range of 0.2% by weight or more and 2% by weight or less based on the nonaqueous electrolyte.

In the gel electrolyte battery 1 of the present invention having the above-described structure, since the gel electrolyte is added with vinylene carbonate or a derivative thereof, the initial charge / discharge efficiency of the battery is improved, and a high battery capacity is obtained. Will have
Further, the battery has excellent cycle characteristics. In addition, the gel electrolyte battery 1 of the present invention in which vinylene carbonate or a derivative thereof is added to the gel electrolyte suppresses gas generation due to charge and discharge. And has high reliability.

In the gel electrolyte battery 1, FIG.
As shown in FIG. 3 to FIG. 3, it is preferable that a resin piece 9 is disposed at a contact portion between the exterior film 6 and the positive electrode terminal 7 and the negative electrode terminal 8. By arranging the resin pieces 9 at the contact portions between the exterior film 6 and the positive terminal 7 and the negative terminal 8, short-circuiting of the exterior film 6 due to burrs and the like is prevented, and the exterior film 6, the positive terminal 7 and the negative terminal 8 are prevented. And the adhesiveness with the resin is improved.

In the gel electrolyte battery 1, a separator may be provided in the gel electrolyte layer 4.
By disposing the separator in the gel electrolyte layer 4, an internal short circuit due to the contact between the positive electrode 2 and the negative electrode 3 can be prevented.

In the above-described embodiment, the gel electrolyte battery 1 is formed by laminating a strip-shaped positive electrode 2 and a strip-shaped negative electrode 3 with a gel electrolyte layer 4 interposed therebetween, and further wound in the longitudinal direction. Although the case where the electrode winding body 5 is used has been described as an example, the present invention is not limited to this, and a laminated electrode body obtained by laminating a positive electrode and a negative electrode via a gel electrolyte layer. The present invention is also applicable to a case in which the electrode is used, or a case in which a so-called serpentine-shaped electrode body is formed without being wound.

The shape of the gel electrolyte battery 1 according to the present embodiment as described above is not particularly limited, such as a cylindrical shape and a square shape, and various sizes such as a thin shape and a large size. Can be Further, the present invention is applicable to both primary batteries and secondary batteries.

[0048]

EXAMPLES In the following examples, in order to confirm the effects of the present invention, a gel electrolyte battery having the above-described structure was manufactured and its characteristics were evaluated.

<Sample 1> First, a positive electrode was prepared as follows.

To manufacture the positive electrode, first, 92% by weight of lithium cobalt oxide (LiCoO ₂ ), 3% by weight of powdered polyvinylidene fluoride, and 5% by weight of powdered graphite were prepared.
The slurry was dispersed in N-methylpyrrolidone to prepare a slurry positive electrode mixture. Next, this positive electrode mixture was uniformly applied to both surfaces of an aluminum foil serving as a positive electrode current collector.
By drying under reduced pressure for 4 hours, a positive electrode active material layer was formed. Then, this was pressed into a positive electrode sheet by a roll press, and the positive electrode sheet was 50 mm × 3.
The positive electrode was cut out into a 00 mm band. An aluminum lead was welded to a portion of the positive electrode current collector where the active material layer was not formed to form a positive electrode terminal.

Next, a negative electrode was prepared as follows.

To manufacture the negative electrode, first, artificial graphite was
1% by weight and 9% by weight of powdered polyvinylidene fluoride were dispersed in N-methylpyrrolidone to prepare a slurry negative electrode mixture. Next, the negative electrode mixture was uniformly applied to both surfaces of a copper foil serving as a negative electrode current collector, and dried under reduced pressure at 120 ° C. for 24 hours to form a negative electrode active material layer. This was pressed into a negative electrode sheet by a roll press, and the negative electrode sheet was 52 mm × 320 mm.
Was cut out to form a negative electrode. A nickel lead was welded to a portion of the negative electrode current collector where the active material layer was not formed to form a negative electrode terminal.

Then, a gel electrolyte layer was formed on the positive electrode and the negative electrode produced as described above. To form a gel electrolyte layer, first, polyvinylidene fluoride copolymerized with hexafluoropropylene at a ratio of 6.9%, a non-aqueous electrolyte, and dimethyl carbonate are mixed.
The mixture was stirred and dissolved to obtain a sol-like polymer electrolyte solution.

Here, the non-aqueous electrolyte solution was prepared by mixing LiPF ₆ with ethylene carbonate (EC) and propylene carbonate (PC) in a mixed solvent of 6: 4.
Was dissolved at a rate of 0.85 mol / kg. Further, 2,4-difluoroanisole (DFA) was added at a ratio of 1% by weight, and vinylene carbonate (VC) was added at a ratio of 0.5% by weight.
In the ratio of

Next, the obtained sol-like polymer electrolyte solution was uniformly applied to both surfaces of the positive electrode and the negative electrode. After that, it was dried to remove the solvent. Thus, gel electrolyte layers were formed on both surfaces of the positive electrode and the negative electrode.

Next, a strip-shaped positive electrode having a gel electrolyte layer formed on both sides and a strip-shaped negative electrode having gel electrolyte layers formed on both sides, which were produced as described above, were laminated. The laminate was wound in the longitudinal direction to obtain a wound electrode.

Finally, the wound body is sandwiched by an exterior film in which an aluminum foil is sandwiched between a pair of resin films, and the outer peripheral edge of the exterior film is heat-sealed under reduced pressure to seal the winding. The body was sealed in an exterior film.
At this time, a resin piece was applied to the positive electrode terminal and the negative electrode terminal, and the relevant portion was sandwiched between the sealing portions of the exterior film. Thus, a gel electrolyte battery was completed.

<Sample 2> to <Sample 69> Except that the composition of the non-aqueous electrolyte constituting the sol-state electrolyte solution was as shown in Tables 1 to 4, a gel-like solution was prepared in the same manner as in Sample 1. The electrolyte battery was completed.

In the sample 40, a mixture of polyacrylonitrile and polymethacrylonitrile was used as a matrix polymer. Polyacrylonitrile having a molecular weight of 200,000, polymethacrylonitrile having a molecular weight of 180,000, ethylene carbonate, propylene carbonate, and LiPF ₆ are mixed in a weight ratio of 1: 1: 9: 9: 1.7.
At 90 ° C. to dissolve the polymer at 90 ° C. This was applied on the electrode in the same manner as in the case of Sample 1, and was gradually cooled to gel. Then, a belt-like positive electrode and a negative electrode on which a gel electrolyte layer is formed are laminated via a separator made of porous polyolefin to form a laminate, and the laminate is further wound in the longitudinal direction to form an electrode. I got a body. This wound electrode body was sealed in an exterior film in the same manner as in Sample 1.

The solvent composition of the non-aqueous electrolyte and the concentration of vinylene carbonate added are shown below for Samples 1 to 69. In the case of conditions different from those of Sample 1, such as electrode materials and electrolyte salts, such conditions are also shown in the table. Unless otherwise specified, the same as Sample 1.

Table 1 shown below shows samples 1 to
9 shows a nonaqueous electrolyte composition of a battery in Sample 15. Table 2 shows the compositions of the nonaqueous electrolytes of the batteries in Samples 16 to 40. Table 3 shows the compositions of the nonaqueous electrolytes of the batteries in Samples 41 to 54. Table 4 shows the sample 55
7 shows the composition of the non-aqueous electrolyte of the battery in Sample 69.

[0062]

[Table 1]

[0063]

[Table 2]

[0064]

[Table 3]

[0065]

[Table 4]

Samples 1 to 5 produced as described above
For the gel electrolyte battery of Sample 69, cycle characteristics, initial charge / discharge efficiency, low-temperature discharge characteristics, load characteristics, and characteristics of initial discharge capacity were evaluated.

In the following evaluation method, 1C
Is the current value at which the rated capacity of the battery is discharged in one hour, and 0.2 C, 0.5 C, and 3 C are the current values at which the rated capacity of the battery is discharged in 5 hours, 2 hours, and 20 minutes, respectively. It is a value.

As the cycle characteristics, a constant current constant voltage charge of 4.2 V and 1 C and a 3 V cut-off constant current discharge of 1 C were performed, and a change in discharge capacity for each cycle was measured. Here, the capacity retention rate after 300 cycles was examined, and 80% or more was regarded as good. The 80% capacity retention after 300 cycles is a value generally required in the specifications of portable electronic devices at present.

(Discharge capacity at 300th cycle) / (Discharge capacity at 5th cycle) The initial charge / discharge efficiency was 4.2 V, 0.1 C constant current / constant voltage charge, 0.1 C constant current discharge, cutoff. An initial charge / discharge test was performed at 3 V, and the charge / discharge battery capacity at that time was evaluated. If this value is too small, the waste of the input active material increases. 80% or more was regarded as good.

(Initial discharge capacity) / (initial charge capacity) The low-temperature discharge characteristics are as follows.
The evaluation was made based on the ratio between the 5C discharge capacity and the 0.5C discharge capacity in an environment of 23 ° C. The case where this value was 35% or more was regarded as good. This is in a cold region around -20 ° C,
This corresponds to the battery capacity required to make at least one emergency call with a mobile phone or the like.

(0.5 C discharge capacity at −20 ° C.) /
(0.5 C discharge capacity at 23 ° C.) As load characteristics, 3C discharge capacity at room temperature and 0.5 C
The evaluation was made based on the ratio to the C discharge capacity. A case where this value was 90% or more was regarded as good. Since mobile phones consume power by pulse discharge, high current performance is required. A value of 90% or more is a value necessary to satisfy the demand for telephone.

(3C discharge capacity) / (0.5C discharge capacity) The discharge capacity was evaluated based on the initial discharge capacity, and was determined to be good if it was 600 mAh or more from the battery design.

Tables 5 to 8 show the results of evaluating the cycle characteristics, initial charge / discharge efficiency, low-temperature discharge characteristics, load characteristics, and initial discharge capacity of the gel electrolyte batteries of Samples 1 to 69.

Table 5 below shows that samples 1 to
14 shows the result of evaluating the characteristics of the battery of Sample 15. Table 6 shows the battery characteristic evaluation results of Samples 16 to 40. Table 7 shows the results of evaluating the characteristics of the batteries of Samples 41 to 54. Table 8 shows samples 55-55.
19 shows the result of evaluating the characteristics of the battery in Sample 69.

[0075]

[Table 5]

[0076]

[Table 6]

[0077]

[Table 7]

[0078]

[Table 8]

As is clear from Tables 5 to 8, in a gel electrolyte battery using a mixed solvent of ethylene carbonate and propylene carbonate, the charge and discharge efficiency was improved by adding vinylene carbonate to the gel electrolyte. The battery capacity can be greatly improved. Furthermore, the cycle characteristics are improved even if a large amount of propylene carbonate is contained.

The amount of vinylene carbonate added is
Good characteristics are obtained when the content is in the range of 0.05% by weight or more and 5% by weight or less, more preferably in the range of 0.5% by weight or more and 3% by weight with respect to the non-aqueous electrolyte in the gel electrolyte. Have been obtained.

The amount of vinylene carbonate added was 0.05
If the content is less than 10% by weight, the strength and stability of the gel are not sufficiently high, the effect of improving the charge / discharge efficiency cannot be sufficiently obtained, and high battery capacity and cycle characteristics cannot be obtained. The initial charge / discharge efficiency and battery capacity are greatly improved as the amount of vinylene carbonate added is increased. In addition, the effect of suppressing battery swelling is enhanced. However, when the added amount of vinylene carbonate exceeds 5% by weight, the load characteristics are slightly reduced, and the low-temperature characteristics are significantly reduced.

On the other hand, it can be seen that the non-aqueous solvent composition of the non-aqueous electrolyte shows good characteristics when the weight ratio of ethylene carbonate to propylene carbonate is in the range of 15:85 to 75:25. If the amount of ethylene carbonate is too large, the low-temperature properties will be impaired. If the amount of propylene carbonate is too large, the initial charge / discharge efficiency and battery capacity will not be good.

As the electrolyte salt concentration, the lithium ion concentration with respect to the non-aqueous solvent is 0.4 mol / kg or more,
Good characteristics are obtained in the range of 1.0 mol / kg. If the electrolyte salt concentration exceeds 1.0 mol / kg, low-temperature characteristics and cycle characteristics will be deteriorated. On the other hand, if the electrolyte salt concentration is lower than 0.4 mol / kg, a sufficient capacity cannot be secured. Further, by using an imide-based salt, low-temperature characteristics and battery capacity can be improved.

Further, it can be seen that by adding difluoroanisole to the non-aqueous electrolyte, the charge / discharge efficiency of the gel electrolyte battery can be further improved and a high discharge capacity can be obtained.

Further, the swelling of the battery due to the generation of gas at the time of the first charge was also examined. The swelling of the battery was evaluated by the ratio of the battery volume immediately after the initial charge to the battery volume immediately before the charge.

As a result, in the batteries of Samples 1 to 3 to which 0.5% by weight of VC was added, the battery volume immediately after the initial charging compared to immediately before the charging was 103.9%. Also,
In the batteries of Samples 4 to 6 to which VC was added in an amount of 1.0% by weight, the battery volume immediately after initial charging and immediately after initial charging was 103.6%. In addition, in the batteries of Samples 7 to 9 to which 2.0% by weight of VC was added, the battery volume immediately after the initial charge compared to immediately before the charge was 101.3%.
In addition, in the batteries of Samples 10 to 12 to which 3.0% by weight of VC was added, the battery volume immediately after the initial charging compared to immediately before the charging was 100.6%. Also, VC is set to 5.0.
In the batteries of Samples 13 to 15 to which the weight% was added, the battery volume immediately after the first charge with respect to immediately before the charge was 10%.
0.1%. On the other hand, in the batteries of Samples 55 to 59 to which VC was not added, the battery volume immediately after the initial charging compared to immediately before the charging was 109.8%.

As described above, in a gel electrolyte battery using a mixed solvent of ethylene carbonate and propylene carbonate, by adding vinylene carbonate to the gel electrolyte, even if a large amount of propylene carbonate is contained, the charging It can be seen that gas generation can be suppressed and swelling of the battery can be prevented. Also, it is understood that the effect is higher as the amount of vinylene carbonate added is larger.

Sample 60 to which 6.0% by weight of VC was added
In the batteries of Sample 64, the battery volume immediately after the initial charge compared to immediately before the charge was 100.0%, and in the batteries of Sample 65 to Sample 69 added with 7.0% by weight of VC,
The battery volume immediately after the initial charge compared to immediately before the charge is 100.0
%, From the viewpoint of suppressing battery swelling, it is preferable that the amount of vinylene carbonate is large. However, as described above, if the amount of vinylene carbonate is too large, the load characteristics and low-temperature characteristics deteriorate.

[0089]

Since the gel electrolyte of the present invention contains vinylene carbonate or a derivative thereof, the chemical stability between the gel electrolyte and the negative electrode can be improved.

And, such chemical stability, strength,
The gel electrolyte battery of the present invention using the gel electrolyte having excellent liquid retention properties is an excellent battery satisfying battery capacity, cycle characteristics, load characteristics, and low-temperature characteristics. The gel electrolyte battery of the present invention that achieves such excellent performance greatly contributes to the development of industries related to portable electronic devices.

[Brief description of the drawings]

FIG. 1 is a perspective view showing one configuration example of a gel electrolyte battery of the present invention.

FIG. 2 is a perspective view showing a state where an electrode winding body is accommodated in an exterior film.

FIG. 3 is a sectional view taken along line AB in FIG.

[Explanation of symbols]

1 gel electrolyte battery, 2 positive electrode, 3 negative electrode, 4
Gel electrolyte layer, 5 electrode wound body, 6 exterior film, 7 positive terminal, 8 negative terminal, 9 resin piece

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tomitaro Hara 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Inventor Goro Shibamoto 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Within Sony Corporation (72) Inventor Nari Goto 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo F-term within Sony Corporation (reference) 5G301 AA30 CD01 DA01 DA42 DE01 5H024 AA02 BB07 CC04 EE09 FF21 GG01 HH01 HH02 HH08 5H029 AJ03 AJ05 AK03 AL06 AM03 AM05 AM07 AM16 BJ04 CJ08 EJ12 HJ01 HJ10

Claims (12)

[Claims] 1. A non-aqueous electrolyte obtained by dissolving a lithium-containing electrolyte salt in a non-aqueous solvent is a gel electrolyte obtained by gelling with a matrix polymer, wherein vinylene carbonate or a derivative of vinylene carbonate is used. 0.05% by weight or more based on the non-aqueous electrolyte, 5
A gel electrolyte characterized by being contained in a range of not more than% by weight. 2. The non-aqueous solvent comprises ethylene carbonate and propylene carbonate in a weight ratio of 15:85 to 7:
The gel electrolyte according to claim 1, wherein the mixed solvent is a mixed solvent mixed in a ratio of 5:25. 3. The method according to claim 1, wherein the lithium-containing electrolyte salt is Li
PF ₆ , LiBF ₄ , LiN (CF ₃ SO ₂ ) ₂ or LiN
(C ₂ F ₅ SO ₂ ) ₂ is contained, and the lithium-containing electrolyte salt is contained so that the lithium ion concentration with respect to the non-aqueous solvent is in the range of 0.4 mol / kg or more and 1.0 mol / kg or less. 2. The method according to claim 1, wherein
The gel electrolyte as described in the above. 4. A polymer comprising at least one of polyvinylidene fluoride, polyethylene oxide, polypropylene oxide, polyacrylonitrile, and polymethacrylonitrile as a repeating unit is used as the matrix polymer. 2. The gel electrolyte according to 1. 5. The matrix polymer according to claim 4, wherein the matrix polymer comprises polyvinylidene fluoride or a copolymer of polyvinylidene fluoride and hexafluoropropylene at a ratio of 7.5% or less. Gel electrolyte. 6. The gel electrolyte according to claim 1, wherein difluoroanisole is added in an amount of 0.2% by weight or more and 2% by weight or less in said non-aqueous electrolyte. 7. A negative electrode having any one of lithium metal, a lithium alloy and a carbon material capable of doping and undoping lithium, a positive electrode having a composite oxide of lithium and a transition metal, and the negative electrode and the positive electrode An intervening, gel-like electrolyte is provided, and the above-mentioned gel-like electrolyte is formed by gelling a non-aqueous electrolyte obtained by dissolving a lithium-containing electrolyte salt in a non-aqueous solvent with a matrix polymer, and vinylene carbonate or vinylene. A gel electrolyte battery comprising a carbonate derivative in an amount of 0.05% by weight or more and 5% by weight or less based on the nonaqueous electrolyte. 8. The non-aqueous solvent comprises ethylene carbonate and propylene carbonate in a weight ratio of 15: 85-7.
The gel electrolyte battery according to claim 7, wherein the mixed solvent is a mixed solvent mixed in a ratio of 5:25. 9. The method according to claim 9, wherein the lithium-containing electrolyte salt is Li
PF ₆ , LiBF ₄ , LiN (CF ₃ SO ₂ ) ₂ or LiN
(C ₂ F ₅ SO ₂ ) ₂ is contained, and the lithium-containing electrolyte salt is contained so that the lithium ion concentration with respect to the non-aqueous solvent is in the range of 0.4 mol / kg or more and 1.0 mol / kg or less. 8. The method according to claim 7, wherein
The gel electrolyte battery according to the above. 10. A polymer comprising at least one of polyvinylidene fluoride, polyethylene oxide, polypropylene oxide, polyacrylonitrile and polymethacrylonitrile in a repeating unit as the matrix polymer. 8. The gel electrolyte battery according to 7. 11. The matrix polymer according to claim 10, wherein the matrix polymer contains polyvinylidene fluoride or a copolymer of polyvinylidene fluoride and hexafluoropropylene at a ratio of 7.5% or less. Gel electrolyte battery. 12. The gel electrolyte battery according to claim 7, wherein difluoroanisole is added to the non-aqueous electrolyte in a range of 0.2% by weight or more and 2% by weight or less.