JP2003297419A - Manufacturing method for non-aqueous electrolyte battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-aqueous electrolyte battery having an excellent discharge capacity. <P>SOLUTION: The method is to manufacture the non-aqueous electrolyte battery equipped with a positive electrode capable of doping and dedoping lithium electrochemically, a negative electrode capable of doping and dedoping lithium electrochemically, and a non-aqueous electrolyte, wherein unsaturated or non-saturated carbonate derivative is added in an amount of 0.05-5 wt.% to the non-aqueous electrolyte, and after the battery is assembled, the first charging run is conducted in the temperature environment ranging between 30°C and 60°C. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-aqueous electrolyte battery having a negative electrode capable of doping and dedoping lithium, a positive electrode and a non-aqueous electrolyte, and more particularly to a non-aqueous electrolyte battery having an excellent discharge capacity.

[0002]

2. Description of the Related Art Recently, a VTR with a built-in camera, a mobile phone,
Many portable electronic devices such as laptop computers have appeared, and their size and weight have been reduced. As a portable power source for these electronic devices, research and development for improving the energy density of batteries, especially secondary batteries, have been actively promoted. Among them, the lithium ion secondary battery is a lead battery, which is a conventional aqueous electrolyte secondary battery,
Expectations are high because it can provide higher energy density than nickel-cadmium batteries.

However, recent portable electronic devices have a large number of built-in applications and therefore have increased power consumption. Therefore, the portable power source used in the electronic devices has a larger discharge capacity, especially a high capacity. There is a strong demand for secondary batteries.

As an effective solution to this problem, for example, in a lithium ion secondary battery, research and development of a high discharge capacity LiNiO 2 type positive electrode active material, and development and practical use of a new high capacity negative electrode material other than carbon materials Is being actively researched.

However, in order to put these new materials into practical use, there are problems that must be solved, such as reliability and storage characteristics, and further research and development must be carried out in order to put them into practical use.

Therefore, as a means for improving the discharge capacity while using the positive electrode and negative electrode materials currently used,
For example, in a non-aqueous electrolyte secondary battery including a positive electrode capable of doping / de-doping lithium, a negative electrode capable of doping / de-doping lithium, and a non-aqueous electrolytic solution, a vinylene carbonate or a vinylene carbonate derivative is added to the non-aqueous electrolyte. A technique for containing the electrolyte in an electrolytic solution has been reported (Japanese Patent Laid-Open No. 2001-1).
No. 67797).

[0007]

However, in recent years, portable applications have been increasing in applications to be used, power consumption is also increasing, and in order to prolong the usage time of the portable equipment, It is strongly desired to develop an even higher capacity portable power supply.

The present invention has been proposed in view of such a conventional situation, and an object thereof is to provide a non-aqueous electrolyte battery having an excellent discharge capacity.

[0009]

A method for producing a non-aqueous electrolyte battery according to the present invention comprises a positive electrode capable of electrochemically doping and dedoping lithium and a negative electrode capable of electrochemically doping and dedoping lithium. A method for producing a non-aqueous electrolyte battery including a non-aqueous electrolyte, wherein an unsaturated carbonate or an unsaturated carbonate derivative is added to the non-aqueous electrolyte in a range of 0.05% by weight or more and 5% by weight or less. At the same time, after assembling the battery, the battery is characterized by being initially charged under a temperature environment of 30 ° C. or higher and 60 ° C. or lower.

In the method for manufacturing a non-aqueous electrolyte battery according to the present invention as described above, after assembling the battery, 30 ° C. or higher,
By performing the initial charge under a temperature environment of 60 ° C. or less, a non-aqueous electrolyte battery having an excellent discharge capacity can be obtained.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of a non-aqueous electrolyte secondary battery to which the present invention is applied will be described in detail with reference to the drawings.

An example of the structure of the gel electrolyte battery 1 according to this embodiment is shown in FIGS. 1 to 5. This gel electrolyte battery 1 includes a belt-shaped positive electrode 2, a belt-shaped negative electrode 3 arranged to face the positive electrode 2, a gel-shaped electrolyte layer 4 formed on the positive electrode 2 and the negative electrode 3, and a gel-shaped electrolyte layer. The separator 5 is provided between the positive electrode 2 having the electrode 4 formed thereon and the negative electrode 3 having the gel electrolyte layer 4 formed thereon.

The gel electrolyte battery 1 shown in FIG.
5, the positive electrode 2 having the gel electrolyte layer 4 formed thereon and the negative electrode 3 having the gel electrolyte layer 4 shown in FIG. 5 are laminated via the separator 5 and wound in the longitudinal direction, The electrode winding body 6 shown in FIG. 2 and FIG.
As shown in (4), it is covered and hermetically sealed by an exterior film 7 made of an insulating material. Further, the positive electrode 2 has a positive electrode terminal 8
However, the negative electrode terminal 9 is connected to the negative electrode 3,
The positive electrode terminal 8 and the negative electrode terminal 9 are the exterior film 7
It is sandwiched by the sealing part which is the peripheral part of the. Further, a resin film 10 is arranged at a portion where the positive electrode terminal 8 and the negative electrode terminal 9 are in contact with the exterior film 7.

As shown in FIG. 4, the positive electrode 2 has a positive electrode active material layer 2a containing a positive electrode active material formed on both surfaces of a positive electrode current collector 2b. As the positive electrode current collector 2b, for example, a metal foil such as an aluminum foil is used.

The positive electrode active material is not particularly limited, but preferably contains a sufficient amount of Li, for example, the general formula L
iMxOy (where M is Co, Ni, Mn, Fe, A
represents at least one of l, V, and Ti. ), A composite metal oxide composed of lithium and a transition metal, an intercalation compound containing Li, and the like are preferable.

As shown in FIG. 5, the negative electrode 3 has a negative electrode active material layer 3a containing a negative electrode active material and a negative electrode current collector 3b.
Are formed on both sides of. As the negative electrode current collector 3b, a metal foil such as a copper foil is used.

As the negative electrode active material, a metal for lithium 2.
Any material can be used as long as it is a material capable of electrochemically doping / dedoping lithium at a potential of 0 V or less.
For example, non-graphitizable carbon, artificial graphite, natural graphite,
Pyrolytic carbons, cokes (pitch cokes, needle cokes, petroleum cokes, etc.), graphites, glassy carbons, organic polymer compound fired products (phenolic resin,
Carbonized by burning furan resin at an appropriate temperature),
Carbonaceous materials such as carbon fiber, activated carbon and carbon blacks can be used. Further, a metal capable of forming an alloy with lithium and an alloy thereof can also be used. It is also possible to use oxides such as iron oxide, ruthenium oxide, molybdenum oxide, tungsten oxide, titanium oxide, and tin oxide that dope / de-dope lithium at a relatively base potential and other nitrides.

The gel electrolyte layer 4 is formed by gelling a non-aqueous electrolytic solution obtained by dissolving an electrolyte salt in a non-aqueous solvent with a matrix polymer.

Any electrolyte salt can be used as long as it is used in this type of battery. Specifically, for example, LiClO4, LiAsF6, LiPF6, LiBF
4, LiB (C6H5) 4, CH3SO3Li, CF3
SO3Li, LiCl, LiBr, LiN (CF3SO
2) 2 and the like.

Examples of the non-aqueous solvent include propylene carbonate, ethylene carbonate, γ-butyrolactone, γ-valerolactone, diethyl carbonate, dimethyl carbonate, 1,2-dimethoxyethane, 1,2.
-Diethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, 4methyl-1,3dioxolane, diethyl ether, sulfolane,
Non-aqueous solvents such as methylsulfolane, acetonitrile, propionitrile, acetic acid ester, butyric acid ester, and propionic acid ester can be used alone or in combination.

As the matrix polymer, various polymers can be used as long as they absorb the above non-aqueous electrolyte and gelate. For example, fluorine-based polymers such as poly (vinylidene fluoride) and poly (vinylidene fluoride-co-hexafluoropropylene), ether-based polymers such as poly (ethylene oxide) and the same crosslinked products, and poly (acrylonitrile), etc. Can be used. In particular, it is desirable to use a fluoropolymer because of its redox stability.

Further, unsaturated carbonate is added to the non-aqueous electrolyte of the gel electrolyte. By adding unsaturated carbonate to the non-aqueous electrolytic solution, the discharge capacity of the gel electrolyte battery 1 can be improved.

As such an unsaturated carbonate,
Examples include vinylene carbonate, ethylene carbonate, diethyl carbonate, dipropyl carbonate and derivatives thereof, with vinylene carbonate being preferred.

The amount of unsaturated carbonate contained in the non-aqueous electrolyte is preferably in the range of 0.05% by weight or more and 5% by weight or less. When the amount of unsaturated carbonate is less than 0.05% by weight, the effect of improving the discharge capacity cannot be sufficiently obtained. Further, when the amount of unsaturated carbonate is more than 5% by weight, cycle characteristics are deteriorated. Therefore, by setting the amount of unsaturated carbonate in the range of 0.05% by weight or more and 5% by weight or less of the non-aqueous electrolyte, the gel electrolyte battery 1 has a discharge capacity of
It has excellent cycle characteristics.

The gel electrolyte battery 1 according to this embodiment as described above is manufactured as follows.

First, as the positive electrode 2, a positive electrode mixture containing a positive electrode active material and a binder is uniformly applied and dried on a metal foil such as an aluminum foil serving as the positive electrode current collector 2b. The positive electrode active material layer 2a is formed and a positive electrode sheet is produced. As the binder of the positive electrode mixture, a known binder can be used, and a known additive or the like can be added to the positive electrode mixture. Next, the positive electrode sheet is cut into strips. Then, a lead wire made of, for example, aluminum is welded to the non-formed portion of the positive electrode active material layer 2a to form the positive electrode terminal 8. In this way, the strip-shaped positive electrode 2 is obtained.

The negative electrode 3 is formed by uniformly applying a negative electrode mixture containing a negative electrode active material and a binder onto a metal foil such as a copper foil, which will be the negative electrode current collector 3b, and drying it. The active material layer 3a is formed and the negative electrode sheet is manufactured. As the binder for the negative electrode mixture, a known binder can be used, and a known additive or the like can be added to the negative electrode mixture. Next, the negative electrode sheet is cut into strips.
Then, a lead wire made of, for example, nickel is welded to a portion of the negative electrode current collector 3b where the negative electrode active material layer 3a is not formed to form the negative electrode terminal 9. In this way, the strip-shaped negative electrode 3 is obtained.

Next, the gel electrolyte layer 4 is formed on the positive electrode active material layer 2a and the negative electrode active material layer 3a. To form the gel electrolyte layer 4, first, an electrolyte salt is dissolved in a non-aqueous solvent to prepare a non-aqueous electrolytic solution. Then, the matrix polymer is added to this non-aqueous electrolytic solution and well stirred to dissolve the matrix polymer to obtain a sol-like electrolyte solution. At this time, the unsaturated carbonate is added to the non-aqueous electrolyte in the range of 0.05% by weight or more and 5% by weight or less. Next, a predetermined amount of this electrolyte solution is applied on the positive electrode active material layer 2a and the negative electrode active material layer 3a. Then, the matrix polymer is gelated by cooling at room temperature, and the gel electrolyte layer 4 is formed on the positive electrode active material 2a and the negative electrode active material layer 3a.

Then, the strip-shaped positive electrode 2 and negative electrode 3 produced as described above are bonded together via the gel electrolyte layer 4 and pressed to form an electrode laminate. Furthermore, this electrode laminated body is wound in the longitudinal direction to form an electrode wound body 6.

Finally, the electrode winding body 6 is sandwiched by the exterior film 7 made of an insulating material, and the resin film 10 is provided at the portion where the positive electrode terminal 8 and the negative electrode terminal 9 and the exterior film 7 overlap each other.
Distribute. Then, the outer peripheral edge portion of the exterior film 7 is sealed, the positive electrode terminal 8 and the negative electrode terminal 9 are sandwiched in the sealing portion of the exterior film 7, and the electrode winding body 6 is sealed in the exterior film 7. Further, the electrode winding body 6 is heat-treated while being packed by the exterior film 7. The gel electrolyte battery 1 is completed as described above.

When the electrode winding body 6 is packed in the exterior film 7, by placing the resin film 10 in the contact portion between the exterior film 7 and the positive electrode terminal 8 and the negative electrode terminal 9, the exterior film 7 is shorted due to burrs or the like. And the contact property between the exterior film 7 and the positive electrode terminal 8 and the negative electrode terminal 9 is improved.

The material of the resin film 10 is not particularly limited as long as it has adhesiveness to the positive electrode terminal 8 and the negative electrode terminal 9, but polyethylene, polypropylene, modified polyethylene, modified polypropylene, and a mixture thereof may be used. It is preferable to use a polymer or the like made of a polyolefin resin. In addition, the resin film 10
The thickness before heat fusion is preferably in the range of 20 μm to 300 μm. The thickness of the resin film 10 is 2
When the thickness is less than 0 μm, the handleability becomes poor,
If it is thicker than 00 μm, it becomes easier for water to permeate and it becomes difficult to maintain the airtightness inside the battery.

Then, the battery thus manufactured is charged for the first time. As the charging condition, for example, the upper limit voltage is preferably 3.8V to 4.4V. When the voltage is lower than 3.8 V, the effect of improving the discharge capacity is not sufficiently obtained, and when the voltage is higher than 4.4 V, lithium is deposited on the negative electrode and the capacity is reduced. The charging current is preferably in the range of 2C or less. At a current higher than 2C, the effect of improving the discharge capacity cannot be sufficiently obtained. Further, if the time from the end of battery assembly to the start of the first charge decreases, the productivity decreases, so it is preferable to perform the first charge within 5 days.

In the present invention, the initial charging is performed under a temperature environment of room temperature or higher, specifically, a temperature environment of 30 ° C. or higher and 60 ° C. or lower. As described above, 3 for gel electrolyte batteries containing unsaturated carbonate in the electrolyte
The discharge capacity can be further improved by performing the initial charge in a temperature environment of 0 ° C. or higher and 60 ° C. or lower.
If the temperature is lower than 30 ° C, the effect of improving the discharge capacity cannot be sufficiently obtained, and if the temperature is higher than 60 ° C, the cycle characteristics are deteriorated. Therefore, 30 ℃ or more, 60 ℃
By performing the initial charge under the temperature environment of the following range, the gel electrolyte battery 1 becomes excellent in discharge capacity and cycle characteristics.

In the above-described embodiment, the case where the strip-shaped positive electrode 2 and the strip-shaped negative electrode 3 are laminated and further wound in the longitudinal direction to form the electrode winding body 6 has been described as an example.
The present invention is not limited to this, and is applicable to the case where the rectangular positive electrode 2 and the rectangular negative electrode 3 are laminated to form an electrode laminated body, or when the electrode laminated body is alternately folded. is there.

The method of manufacturing the electrode is not limited to the above example, and for example, the electrode active material may be used alone or in combination with a conductive material or a binder and subjected to a process such as molding to obtain a molded product. How to make electrodes. Alternatively, regardless of the presence or absence of a binder, it is possible to manufacture an electrode having strength by pressure-molding while heating the electrode active material.

Further, in the above-mentioned embodiment, the gel electrolyte battery using the gel electrolyte was described as an example, but the present invention is not limited to this, and a non-aqueous electrolyte solution is used. It is also applicable to non-aqueous electrolyte batteries.

The battery according to the present embodiment as described above is not particularly limited in its shape such as a cylindrical type, a prismatic type, a coin type and the like, and can be various sizes such as thin type and large type. can do. Further, the present invention can be applied to both the primary battery and the secondary battery.

[0039]

EXAMPLES Next, Examples and Comparative Examples conducted to confirm the effects of the present invention will be described. In the following examples, specific compound names, numerical values, etc. are described, but it goes without saying that the present invention is not limited to these examples.

<Sample 1> A negative electrode was prepared as follows. First, 100 parts by weight of coal-based coke serving as a filler and 30 parts of coal tar-based pitch serving as a binder.
After mixing with 1 part by weight at about 100 ° C., compression molding was performed with a press to obtain a precursor of a carbon molded body. 100 parts of this precursor
The carbon material molded body obtained by heat treatment at 0 ° C. or lower is further added with 2
Impregnate the binder pitch melted below 00 ° C and
The pitch impregnation / firing process of heat treatment at 000 ° C. or lower was repeated several times. Then, this carbon molded body was heat-treated at 2800 ° C. in an inert atmosphere to obtain a graphitized molded body, which was then pulverized and classified to prepare a sample powder.

The graphite material obtained at this time was subjected to X-ray diffraction measurement, and as a result, the (002) plane spacing was 0.337 nm, and the (002) plane C-axis crystallite thickness was 5.
0.0nm, true density by pycnometer method is 2.23,
Specific surface area according to BET method is 1.6 m 2 / g, particle size distribution according to laser diffraction method is 33.0 μm, and cumulative 10
% Particle size 13.3μm, cumulative 50% particle size 30.6μ
m, the cumulative 90% particle size was 55.7 μm, the average breaking strength of the graphite particles was 7.1 kgf / mm 2, and the bulk density was 0.98 g / cm 3.

90 parts by weight of the mixed sample powder and 10 parts by weight of polyvinylidene fluoride (PVDF) as a binder were mixed to prepare a negative electrode mixture, which was dispersed in N-methylpyrrolidone as a solvent. It was made into a slurry (paste form). A strip-shaped copper foil having a thickness of 10 μm was used as the negative electrode current collector, and the negative electrode mixture slurry was applied to both surfaces of the current collector, dried, and then compression molded at a constant pressure to form 800 mm × 120 mm.
A strip negative electrode was produced by cutting out into a size of mm. The negative electrode lead wire is a copper wire or nickel wire with a diameter of 50 μm of 75 μm.
It was produced by cutting a metal mesh knitted at m intervals. This negative electrode lead wire was spot-welded to the negative electrode current collector-uncoated portion to form a terminal for external connection.

The positive electrode was prepared as follows.
First, a positive electrode active material was synthesized. 0.5 mol of lithium carbonate and 1 mol of cobalt carbonate are mixed, and the mixture is
Firing was performed in air at a temperature of 880 ° C. for 5 hours. As a result of X-ray diffraction measurement of the obtained material, it was in good agreement with the peak of Li2CoO2 registered in the JCPDS file.

This Li2CoO2 was crushed to obtain a powder having an average particle size of 8 μm. Then, 95 parts by weight of this Li2CoO2 powder and 5 parts by weight of lithium carbonate powder are mixed,
91 parts by weight of this mixture, 6 parts by weight of scaly graphite as a conductive agent, and 3 parts by weight of polyvinylidene fluoride as a binder were mixed to prepare a positive electrode mixture, which was dispersed in N-methylpyrrolidone. Into a slurry (paste).

A band-shaped aluminum foil having a thickness of 20 μm was used as a positive electrode current collector, and the positive electrode mixture slurry was uniformly applied to both surfaces of the current collector, dried, and then compression molded at a constant pressure to obtain 640 mm ×. A strip-shaped positive electrode was produced by cutting out to a size of 118 mm. The positive electrode lead wire was produced by cutting a metal net in which aluminum wires having a diameter of 50 μm were woven at intervals of 75 μm. The positive electrode lead wire was spot-welded to the negative electrode current collector-uncoated portion to form a terminal for external connection.

As the electrolyte, a PVdF type gel electrolyte was used. First, a polymer (A) having a weight average molecular weight of 700,000 and a polymer (B) having a molecular weight of 700,000 in which hexafluoropropylene is copolymerized with vinylidene fluoride in a proportion of 7% by weight. , A: B = 9: 1 in a weight ratio, a non-aqueous electrolyte and dimethyl carbonate (DMC), which is a solvent for the polymer, are mixed in a weight ratio of 1: 4: 8, respectively. Was stirred and dissolved at 70 ° C. to obtain a sol-like electrolyte. The non-aqueous electrolyte is ethylene carbonate (EC) as a non-aqueous solvent.
Propylene carbonate (PC) and vinylene carbonate (VC) were mixed at a ratio shown in Table 1 below (in the case of sample 1, 50: 50: 0), and lithium hexafluorophosphate (LiPF6) was used as an electrolyte salt. ), 0.8
It was prepared by dissolving at a concentration of mol / kg.

Then, the sol electrolyte was applied onto the surfaces of the positive electrode and the negative electrode using a bar coater, and the solvent was volatilized in a constant temperature bath at 70 ° C. to form a gel electrolyte. Then, the positive electrode and the negative electrode were laminated and wound flat to prepare a battery element, which was vacuum-encapsulated in a laminate film to prepare a gel electrolyte battery.

The initial charge / discharge efficiency of the sample battery manufactured as described above was evaluated. First, with respect to the battery, at a predetermined temperature shown in Table 1 (in the case of Sample 1, 20
C.), the upper limit voltage of 4.2 V, the current of 0.2 C, and the constant current and constant voltage charging under the conditions of 10 hours. Next, 0.2 C constant current discharge was performed to a final voltage of 3.0 V in a 23 ° C. constant temperature bath. The initial charge / discharge efficiency (%) was evaluated by obtaining the ratio of the obtained initial discharge capacity and initial charge capacity by the following formula.

Initial charge / discharge efficiency (%) = (initial discharge capacity)
/ (Initial charge capacity) × 100 When this value is too low, the waste of the charged active material is large. In addition, 1 C is a current value for discharging the rated capacity of the battery in 1 hour.

<Sample 2 to Sample 35> Sample 1 except that the non-aqueous solvent of the sol electrolyte and the ambient temperature during charging after battery assembly were changed as shown in Table 1 below. Similarly, a gel electrolyte battery was produced.

Further, the cycle characteristics of the sample battery were evaluated as follows. Each battery was subjected to constant-current constant-voltage charging under the conditions of an upper limit voltage of 4.2 V, a current of 1 C, and 3 hours in an atmosphere of 23 ° C., and then a constant-current discharge of 1 C was performed until a final voltage of 3.0 V. Repeated many times. Measure the change with time of the discharge capacity obtained for each cycle,
The discharge capacity retention ratio (%) at the 200th cycle was calculated by calculating the ratio of the discharge capacity at the 3rd cycle and the discharge capacity at the 200th cycle by the following equation.

Discharge capacity retention rate (%) = (200th cycle discharge capacity) / (3rd cycle discharge capacity) × 100 For each sample battery, the evaluation results of the initial charge / discharge efficiency and the discharge capacity retention rate were calculated as sol. Table 1 shows the non-aqueous solvent of the solid electrolyte and the ambient temperature at the time of charging after the battery is assembled.

[0053]

[Table 1]

In Table 1, first, samples 1 to 7 and samples 8 to 14 having the same charging temperature but different VC concentrations were used.
Samples 15-21, Samples 22-28, Sample 2
9 to 35, it can be seen that the sample in which VC is added to the electrolytic solution has improved charge / discharge efficiency and discharge capacity as compared with the sample in which VC is not added.
However, the effect of improving the charge / discharge efficiency and discharge capacity was not sufficiently obtained in the sample in which the amount of VC added was 0.03% by weight, and the sample in which the amount of VC added was 6% by weight, In addition to charge / discharge efficiency and discharge capacity, cycle characteristics have deteriorated. On the other hand, in the sample in which the amount of VC added is in the range of 0.05% by weight or more and 5% by weight or less, good charge / discharge efficiency, discharge capacity and cycle characteristics are obtained.

Next, Samples 1, 8, 15, 22, 29, Samples 2, 9, 16, 23, 30, Samples 3, 10, 17, with the same VC addition amount and different charging temperatures were used.
24, 31, Samples 4, 11, 18, 25, 32, Samples 5, 12, 19, 26, 33, Samples 6, 1
3,20,27,34, Samples 7,14,21,2
Comparing 8 and 35, respectively, in the sample in which VC is not added and the sample in which the amount of VC added is 0.03% by weight, the discharge capacity is not improved even if the ambient temperature at the time of initial charging is changed. On the other hand, in the samples in which the amount of VC added is in the range of 0.05% by weight or more and 5% by weight or less, the discharge capacity is improved by increasing the ambient temperature during charging above room temperature. .

It is considered that by adding VC, VC forms a film on the negative electrode at the time of initial charge and the initial charge and discharge efficiency and discharge capacity are improved, but by charging at a temperature higher than room temperature. It seems that the film on the negative electrode formed during the first charge was more effectively formed.

However, in the sample in which the amount of VC added is 6% by weight, the effect of improving the discharge capacity can be seen,
The cycle characteristics have deteriorated.

Further, looking at the temperature dependence, it is confirmed that the discharge capacity is improved when the ambient temperature at the time of the first charge is 30 ° C. or higher, but when it exceeds 60 ° C., the improvement rate of the discharge capacity is decreased. Furthermore, the cycle characteristics also deteriorated compared to the battery charged at 20 ° C.

From the above results, there is an optimum value for the amount of VC added and the ambient temperature at the time of initial charging, and the amount of VC added is preferably in the range of 0.05% by weight or more and 5% by weight or less. The ambient temperature during charging is 30 ° C or higher, 60
It was confirmed that the range of ℃ or less is preferable. In the present invention, by defining the added amount of VC and the ambient temperature at the time of initial charging, the synergistic effect of these can dramatically improve the charge / discharge efficiency, discharge capacity and cycle characteristics.

In the next experiment, the same experiment was conducted by changing the ratio of EC and PC.

<Sample 36 to Sample 45> In the same manner as in Sample 1, except that the nonaqueous solvent of the sol electrolyte and the ambient temperature at the time of charging after battery assembly were changed as shown in Table 2 below. A gel electrolyte battery was produced.

The initial charge / discharge efficiency and discharge capacity retention rate of each of the sample batteries manufactured as described above were evaluated in the same manner as in the above-mentioned method. The results are shown in Table 2 together with the non-aqueous solvent of the sol electrolyte and the ambient temperature at the time of charging after battery assembly.

[0063]

[Table 2]

As is clear from Table 2, even when the ratio of EC and PC was changed, the improvement of the discharge capacity was confirmed when the atmospheric temperature at the time of the first charge was 30 ° C. or higher.
When the temperature exceeds 60 ° C, the rate of improvement in discharge capacity decreases, and the cycle characteristics also deteriorate as compared with the battery charged at 20 ° C. In other words, there is an optimum value for the ambient temperature at the time of the first charge regardless of the ratio of EC and VC, and is 30 ° C or higher, 6
It was confirmed that the range of 0 ° C. or lower is preferable.

In the next experiment, the same experiment was conducted by changing the charging condition.

<Sample 46 to Sample 57> A sample battery prepared in the same manner as in Sample 1 was initially charged under the charging conditions shown in Table 3 below, and the initial charge / discharge efficiency and discharge capacity retention ratio were the same as those described above. It evaluated similarly. The results are shown in Table 3 together with the non-aqueous solvent of the sol-like electrolyte, the ambient temperature at the time of charging after battery assembly, and the charging conditions.

[0067]

[Table 3]

As is clear from Table 3, when the upper limit voltage during the first charge is 3.8 V or higher, the discharge capacity is confirmed to be improved, but when it exceeds 4.4 V, the cycle characteristics are deteriorated. That is, it was confirmed that the upper limit voltage at the time of initial charging has an optimum value, and a range of 3.8 V or more and 4.4 V or less is preferable.

Further, as is clear from Table 3, when the current value at the time of initial charging exceeds 2C, the discharge capacity is lowered and the cycle characteristics are also lowered. That is, there is an optimum value for the current value at the time of initial charging, and a range of 2C or less is preferable.

In this example, the gel electrolyte battery was used for the evaluation, but the present invention is not limited to this example, and the same effect can be obtained in the non-aqueous electrolyte battery. You can

[0071]

EFFECTS OF THE INVENTION In the present invention, unsaturated carbonate is added to the non-aqueous electrolyte in the range of 0.05% by weight or more and 5% by weight or less, and the ambient temperature in the initial charge after battery assembly is 30 ° C. As described above, by setting the temperature in the range of 60 ° C. or less, a non-aqueous electrolyte battery having excellent discharge capacity and cycle characteristics can be realized.

[Brief description of drawings]

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

FIG. 2 is a perspective view showing a state in which a battery element is housed in an exterior film.

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

FIG. 4 is a perspective view showing a configuration of a positive electrode.

FIG. 5 is a perspective view showing a configuration of a negative electrode.

[Explanation of symbols]

1 gel electrolyte battery, 2 positive electrode, 3 negative electrode, 4
Gel electrolyte layer, 5 separator, 6 electrode winding body, 7 exterior film, 8 positive electrode lead, 9 negative electrode lead, 10 resin film

Continued front page    (72) Inventor Ken Segawa             6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Soni             -Inside the corporation (72) Inventor Masashi Shibuya             6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Soni             -Inside the corporation F term (reference) 5H029 AJ03 AK03 AL06 AL12 AM03                       AM05 AM07 AM16 BJ02 BJ14                       CJ07 CJ16 HJ02 HJ14 HJ18

Claims (6)

[Claims] 1. A method for producing a non-aqueous electrolyte battery comprising a positive electrode capable of electrochemically doping / dedoping lithium, a negative electrode capable of electrochemically doping / dedoping lithium, and a non-aqueous electrolyte. The unsaturated carbonate or the unsaturated carbonate derivative is added to the above non-aqueous electrolyte in the range of 0.05 wt% or more and 5 wt% or less, and after assembling the battery, A method for manufacturing a non-aqueous electrolyte battery, which comprises performing initial charging under a temperature environment in a range. 2. The upper limit voltage during the first charge is 3.8 V.
The method for producing a non-aqueous electrolyte battery according to claim 1, wherein the voltage is in the range of 4.4 V or less. 3. The method for producing a non-aqueous electrolyte battery according to claim 1, wherein the unsaturated carbonate is vinylene carbonate. 4. The positive electrode active material is a composite oxide of lithium and a transition metal, and the negative electrode active material is a metal capable of forming an alloy with lithium and an alloy thereof, or a carbonaceous material. The method for producing a non-aqueous electrolyte battery according to claim 1. 5. The positive electrode and the negative electrode are formed by forming an electrode active material layer on a strip-shaped electrode current collector, and the positive electrode and the negative electrode are laminated with a separator interposed therebetween and are wound many times in the longitudinal direction. The method for producing a non-aqueous electrolyte battery according to claim 1, wherein the method is used as an electrode element. 6. The non-aqueous electrolyte is a gel electrolyte in which a non-aqueous electrolyte solution obtained by dissolving an electrolyte salt in a non-aqueous solvent is gelled by a matrix polymer. A method for producing the non-aqueous electrolyte battery described.