JP2002170576A - Nonaqueous electrolyte cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic electrolyte cell which uses fluorocarbon excellent in high-temperature preserving performance and intermittent discharge characteristics as a positive pole. SOLUTION: There are provided a positive pole comprising fluorocarbon in which easily-graphatizable carbon or graphite material with plane interval of (002) plane being 3.50 Å or below is a starting carbon material, a negative pole capable of releasing lithium ion, and an organic electrolyte containing propanesultone, with an open circuit voltage being 3.5 V or lower after preliminary discharge.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a non-aqueous electrolyte battery using carbon fluoride as a positive electrode active material, and more particularly to a non-aqueous electrolyte battery excellent in high-temperature storage characteristics and intermittent discharge performance.

[0002]

2. Description of the Related Art A nonaqueous electrolyte battery using carbon fluoride as a positive electrode active material and lithium metal or an alloy thereof as a negative electrode has a high energy density and can be reduced in size and weight. Including the main power supply for mobile devices
It is used for various purposes such as a backup power supply for stationary equipment. In response to requests from these devices, various proposals for improving battery characteristics have been made and put to practical use. For example, while improving the utilization rate of the positive electrode active material,
In order to improve the storage characteristics in an environment of 5 ° C., the spacing between (002) planes is set to 3.40 to
Configuration using 3.50 mm coke (JP-B-56-46)
No. 670), and a structure using a mixed solvent of propylene carbonate or ethylene carbonate and a low-viscosity solvent of 1,2-dimethoxyethane as an electrolytic solution in order to improve heavy load discharge characteristics (Japanese Patent Publication No. 58-121991). ) Has been proposed.

However, in recent years, as portable devices have become more sophisticated and multifunctional, demands for batteries as power sources have become more severe, and storage characteristics in a high-temperature environment of 60 ° C. or more and high load. Are required to have both intermittent discharge characteristics. However, at present, a battery satisfying these characteristics has not been provided. For example, storage characteristics at high temperatures, and even when combining the above-described respective configurations that individually improve the discharge characteristics, after storing the battery that has undergone intermittent discharge in an environment of 60 ° C or more, to a heavy load discharge When supplied again, a large voltage drop is observed at the beginning of discharge. If this voltage drop becomes remarkable, the discharge voltage will drop to 1.0 V or less, and the operating voltage of the device will be greatly reduced, causing a problem that the device will not be able to operate. This problem is caused by an increase in the internal resistance of the battery due to high-temperature storage, but no specific remedy can be found.

[0004]

In order to solve the above-mentioned problems, a sulfite compound having an S—O bond is used as a solvent for a non-aqueous electrolyte battery, and a solvent for the electrolyte in a positive electrode current collector or a battery can is used. There has been proposed a configuration in which the material of the liquid contact portion is used for a valve metal such as Al, Ti, or Zr or an alloy thereof.
In this configuration, the valve metal forms a passivation film on the surface by anodic oxidation in an electrolytic solution, and oxidative decomposition of a compound having an SO bond is prevented. It has also been shown that this can improve the cycle characteristics of the secondary battery and the long-term storage characteristics of the battery (JP-A-11-1625).
No. 11). However, since the use of valve metal is indispensable for components such as a battery case, general-purpose metal materials such as stainless steel cannot be used, and there are problems in terms of productivity and cost of components.

The present invention provides an inexpensive non-aqueous electrolyte battery excellent in intermittent discharge characteristics while suppressing an increase in the internal impedance of the non-aqueous electrolyte battery which is generated when the battery is stored in a high-temperature environment. The purpose is to provide.

[0006]

As a result of intensive studies to achieve the above object, the present inventors found that the value of the spacing of the (002) plane was 3.5 as a starting material for carbon fluoride of the positive electrode.
Non-aqueous electrolysis that satisfies high-temperature storage characteristics and intermittent discharge characteristics by using a graphitizable carbon or graphitic material at 0 ° or less and containing propane sultone as an electrolytic solution and applying an appropriate preliminary discharge. It has been found that a liquid battery can be obtained. That is, the non-aqueous electrolyte battery of the present invention comprises a negative electrode made of metal lithium or a lithium alloy, a positive electrode made of fluorocarbon, and an organic electrolyte,
The fluorocarbon is a graphitizable carbon or a graphitic material having a (002) plane spacing of 3.50 ° or less as a starting carbon material, and the organic electrolyte contains propane sultone. The open circuit voltage after the preliminary discharge is 3.5 V or less.

A nonaqueous electrolyte battery according to the present invention basically comprises a negative electrode made of lithium or an alloy thereof, a positive electrode made of fluorocarbon and a nonaqueous electrolyte, and (002) as a starting material of fluorocarbon. By using a graphitizable carbon or a graphitic material having a plane spacing of 3.50 ° or less and combining the obtained fluorocarbon and an organic electrolyte containing propane sultone, high-temperature storage characteristics, In addition, a battery having excellent intermittent discharge characteristics can be obtained. For this reason, for example, even when the battery was stored in an environment of 60 ° C. or higher after the discharge and then discharged again, the voltage drop was small and the heavy load discharge characteristics were good. Furthermore, the storage state before storage was significantly improved compared to the conventional configuration, regardless of the depth of discharge. These effects are thought to be because propane sultone forms a dense organic film on the surface of the fluorocarbon when lithium is inserted into the fluorocarbon by the discharge reaction, thereby forming a film having a high electric resistance. Decomposition of the organic solvent which is a factor is suppressed. Further, it is presumed that since the propane sultone film had good conductivity, the discharge characteristics after storage at high temperature, especially the intermittent discharge characteristics, were improved.

In the nonaqueous electrolyte battery according to the present invention, the open circuit voltage after the preliminary discharge is set to 3.5 V or less. Generally, the open-circuit voltage after assembling the non-aqueous electrolyte is about 3.6 V. However, as described above, the battery using the non-aqueous electrolyte containing propane sultone deteriorates the storage characteristics in a high-temperature atmosphere. I will. As a result of detailed studies by the present inventors, the discharge characteristics after storage depend on the value of the open circuit voltage before storage, and when the value is 3.5 V or less, good characteristics are obtained. It has been found that when the voltage exceeds 0.5 V, the performance is deteriorated.
Further, these phenomena are caused by the fact that when the component on the positive electrode side is at a potential exceeding 3.5 V with respect to metallic lithium and is exposed to a high-temperature atmosphere, particularly an atmosphere of 60 ° C. or higher, the positive electrode side by propane sultone is used. The knowledge resulting from corrosion of the component was also obtained. Based on these findings, after assembling a battery using an electrolyte solution containing propane sultone, the open circuit voltage of the battery is reduced to 3.5 V or less by preliminary discharge, so that a positive electrode current collector, a positive electrode can, etc. It allows the use of inexpensive materials such as austenitic stainless steel and iron. The amount of electricity discharged in the pre-discharge process is about 1% of the discharge capacity immediately after assembly, and the effect on battery characteristics is extremely small.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below.

The carbon material as the starting material of the fluorocarbon according to the nonaqueous electrolyte battery of the present invention has a structure close to graphite, in which the degree of crystallinity of the graphitizable carbon is increased by heat treatment. 002) Natural graphite and artificial graphite having a plane spacing of 3.50 ° or less are preferable, and those having a plane spacing of 3.50 to 3.35 ° are more preferable. Examples of the graphitizable carbon include petroleum coke, coal coke, mesocarbon microbeads, mesophase pitch-based carbon fiber, and the like, and when these are heat-treated at 1000 ° C. or more, the value of the (002) plane spacing becomes 3. A carbon material of 50 ° or less can be obtained. In addition, artificial graphite reduces coke by two.
It is obtained by heat treatment at 800 ° C. or higher.

Further, the shape of the starting carbon material may be spherical coke such as flue coke or Gilsonite coke, or spherical material such as mesocarbon microbeads made from mesophase small spheres generated in the carbonization process of pitch. preferable.

In the case of carbon fluoride using a graphitizable carbon as a starting carbon material, the value of the (002) plane spacing is larger than 3.50 °, the surface spacing of the carbon fluoride increases as the spacing increases. The effect of adding propane sultone, which forms a dense organic film, is undesirably reduced. In addition, the fluorination degree (x) of the fluorocarbon (CFx) n of the present invention is x = 0.4 to
1.0 is preferable, and more preferably x = 0.5 to
1.0.

[0013] The battery of the present invention is pre-discharged after assembly to reduce the battery voltage to 3.5 V or less, preferably from 3.5 V to
In the range of 3.4 V, the amount of preliminary discharge electricity is preferably in the range of 1 to 5% of the positive electrode design capacity. Note that the open circuit voltage is set to 3.
When the voltage is set to 4 V or less, a sufficient effect for suppressing corrosion is recognized, but a pre-discharge of 5% or more is required, and the battery capacity is undesirably reduced. The battery according to this embodiment uses metallic lithium or a lithium alloy for the negative electrode, and it is considered that the battery voltage and the positive electrode potential show almost the same value.

The content of propane sultone in the organic electrolyte is preferably 0.1 to 15% by mass. Even if the content is less than 0.1%, the effect is recognized, but the surface of the fluorocarbon cannot be completely covered, and there is a danger that a large voltage drop will occur during discharge after storage at a high temperature. On the other hand, when the content is more than 15% by mass, the thickness of the organic film is increased, and although the organic film has good conductivity, the resistance increases, and a voltage drop due to the thickness of the organic film starts to be seen.

On the other hand, materials used for the negative electrode include metallic lithium or Li-Al, Li-Si, Li-Sn,
Lithium alloys such as i-NiSi and Li-Pb can be given.

Examples of the solvent for the organic electrolyte include well-known solvents (high-dielectric solvents and low-viscosity solvents) used in batteries of this type. Examples of the high dielectric constant solvent include ethylene carbonate (EC), propylene carbonate (PC), and butylene carbonate (B
C) and cyclic esters such as γ-butyrolactone (GBL). As the low viscosity solvent, 1,2 dimethoxyethane (DME), 1,2 diethoxyethane (DE
E) Chain ethers such as 1,3 dioxolane (DOL), and chain esters such as dimethyl carbonate (DMC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC). The high dielectric constant solvent and the low viscosity solvent may be used alone or in combination of a plurality of solvents, but when a low viscosity solvent is used, the low conductivity of the low viscosity solvent is used. It is preferable to use in combination with a high dielectric constant solvent in order to supplement the above.
Examples of the combination of the high dielectric constant solvent and the low viscosity solvent include two-component solvent systems such as EC-DME, PC-DME, and GBL-DME, EC-PC-DME, EC-GBL-
DME, GBL-BC-DME, PC-GBL-DME
And a three-component solvent system. The ratio between the high dielectric constant solvent and the low viscosity solvent is, for example, 40:
60-70: 30 is preferred.

Further, propylene carbonate (PC)
And γ-butyrolactone (GBL) have a freezing point of −40 ° C.
Ethylene carbonate (EC) has high solubility of lithium salt, and 1,2 dimethoxyethane (DME) has relatively high solubility of lithium salt among low viscosity ethers. From these three
PC-DME, GBL-DME, E combining components
-20 ° C for C-PC-DME, EC-GBL-DME, etc.
This is advantageous in that it can be used in a wide range of use environments of up to 85 ° C. The mixing ratio in these two-component or three-component solvent systems is such that propylene carbonate (PC) or γ-butyrolactone (GBL) is 5 to 6 in volume ratio.
It is particularly preferable to include 0.

The solute of the organic electrolyte is LiCl
O ₄ , LiPF ₆ , LiBF ₄ , LiCF ₃ SO ₃ , LiB
BB or a lithium salt having an imide bond, for example, Li
N (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiN
(CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ) and the like. These lithium salts may be used alone or in combination. Among them, LiPF ₆ or LiBF ₄ is preferable.
The salt concentration of the solute is preferably in the range of 0.1 to 2 mol / l, more preferably in the range of 0.3 to 1.5 mol / l.

[0019]

The present invention will be described below in detail with reference to examples.

Example 1 FIG. 1 is a sectional view of a coin-type battery used in this example. Positive case 1, negative case 2
Is ferritic stainless steel (SUS444)
The power generation element is hermetically sealed through an insulating packing 3 made of polypropylene. The positive electrode 4 and the negative electrode 5 made of metallic lithium are opposed to each other via a separator 6 made of a nonwoven fabric made of polypropylene. The electrolyte is lithium borofluoride (LiBF ₄ ) as a solute in a single solvent of propylene carbonate (PC), which is a cyclic ester.
Was dissolved at a ratio of 1 mol / l. Further, 3% by mass of propane sultone (PS) was added to the adjusted electrolyte.
The ratio is added. The dimensions of the obtained battery were 20 mm in diameter and 2.0 mm in thickness. Hereinafter, the configuration of the positive electrode 4 will be described in detail.

A petroleum pitch was used as a starting carbon, and this was calcined at 2000 ° C. in a nitrogen atmosphere to obtain (002).
A scale-like graphitizable carbon having a plane spacing of 3.40 ° was obtained. Furthermore, this graphitizable carbon was fluorinated at 400 ° C. to obtain carbon fluoride. This fluorocarbon was mixed with carbon black as a conductive agent and a fluorine-based resin as a binder at a weight ratio of 85: 8: 7 to obtain a positive electrode mixture. This positive electrode mixture is ² ton / cm ² and 16 mm in diameter.
110 ° C in a dry atmosphere
To obtain a positive electrode having a weight of 190 mg. The design capacity of this positive electrode is 100 mAh. Using this positive electrode, 160 μl of an electrolytic solution having the above composition was injected to prepare a battery A of the present invention.

Battery B of the present invention is a battery having the same structure as that of battery A, except that γ-butyrolactone (GBL) was used instead of propylene carbonate as the solvent of the electrolytic solution.

A battery having the same structure as that of the battery A of the present invention except that the solvent of the electrolytic solution was changed to propylene carbonate and a mixed solvent of propylene carbonate and 1,2-dimethoxyethane (DME) at a volume ratio of 50:50 was used. Battery C.

A battery D having the same structure as the battery A of the present invention was prepared except that flaky graphitizable carbon having a (002) plane spacing of 3.50 ° was used as a starting carbon source of fluorocarbon. And

Using a mesophase microsphere (MCMB) obtained by subjecting a starting carbon source of fluorocarbon to baking treatment at 2200 ° C. and having a (002) plane spacing of 3.40 °, an electrolytic solution was used. A battery having the same configuration as the battery A is referred to as a battery E of the present invention, except that the solvent of the above is changed to propylene carbonate and a mixed solvent of propylene carbonate and 1,2-dimethoxyethane in a volume ratio of 50:50 is used.

Except that natural graphite was used as the starting carbon source of fluorocarbon, the solvent of the electrolytic solution was changed to propylene carbonate, and a mixed solvent of propylene carbonate and 1,2-dimethoxyethane at a volume ratio of 50:50 was used. A battery having the same configuration as battery A is referred to as battery F of the present invention.

Instead of using the organic electrolyte solution of the battery A of the present invention, only 1 mol / l of lithium borofluoride was dissolved as a solute in a single solvent of propylene carbonate, and an electrolyte solution to which propane sultone was not added was used. Is a comparative battery 1 having the same configuration as the battery A.

A battery having the same structure as Battery A was compared with Comparative Battery 2 except that Fluorinated carbon obtained by fluorinating acetylene black at 400 ° C. was used instead of Fluorocarbon of Battery A of the present invention. I do.

Instead of the fluorocarbon of Invention Battery A, (00
2) Battery A except that fluorinated carbon was used as a starting carbon source, with flake-like graphitizable carbon having a surface spacing of 3.51 °.
A battery having the same configuration as that of Comparative Battery 3 is used.

The batteries A, B, C, D, E and F of the present invention described above.
The comparative batteries 1 to 3 were each subjected to a preliminary discharge of 1 mA at 2 mA for 2 hours (2% of the designed capacity) and a measurement of the open circuit voltage.
Each of the five samples was stored at 85 ° C. for 20 days, and the remaining five samples were subjected to a 10 kΩ resistance (high load) at room temperature and a discharge cutoff voltage of 1.
The discharge capacity up to 0 V was examined. 5 batteries each after storage at 85 ° C
Each battery was discharged under the same conditions as above, and the minimum value of the drop voltage at the start of discharge (hereinafter referred to as the initial discharge voltage) and the discharge sustaining voltage were measured. Further, the discharge capacity ratio (%) (discharge capacity of storage battery / discharge capacity of unstored battery × 100) was calculated. Table 1 shows the results.

[0031]

[Table 1]

As is clear from Table 1, the batteries A, B, C, D, E and F of the present invention all have an initial discharge voltage of 2.
At 0 V or higher, the voltage is equivalent to the sustaining voltage, and the voltage drop is small.
The discharge capacity ratio also shows a high value of 90% or more. Batteries C, E, and F using a mixed solvent in which cyclic ester was mixed with 1,2-dimethoxyethane of a low-viscosity ether were better than batteries A, B, and D in which the solvent of the organic electrolyte was only cyclic ester. Good results were obtained. The battery E using spherical graphitizable carbon as the starting carbon material had the best high-load discharge characteristics.

On the other hand, the comparative battery 1 to which propane sultone was not added had a large voltage drop at the initial stage of discharge, and also had a severe capacity deterioration. In addition, even when propane sultone was added, the comparative battery 2 of acetylene black having amorphous carbon as a starting material and the comparative battery 3 of graphitizable carbon having an interplanar spacing of (002) of 3.51 ° In any case, all the characteristics are inferior to the battery of the present invention. As described above, when the specific surface area of the starting material is very large, or when the (002) plane spacing exceeds 3.50 °,
The effect of adding propane sultone cannot be obtained. The open-circuit voltage of the comparative batteries 2 and 3 was 3.5 V or less, and no corrosion of the constituent members was observed.

Example 2 As Example 2, the amount of propane sultone added to the organic electrolyte was changed and the effect was examined. Propane Sultone (P
Batteries G to K of the present invention having the same configuration as the battery A of the present invention of Example 1 were prepared except that the addition amount of S) was changed in the range of 0.05 to 18% by mass. Table 2 shows the results of the evaluation.

[0035]

[Table 2]

As is clear from Table 2, 0.1 to 15 watts
The batteries H, A, I, and J in the range of t% are excellent in both voltage and storage characteristics. On the other hand, the battery G can suppress an increase in internal resistance due to high-temperature storage, but is inferior in characteristics to other batteries in terms of initial discharge voltage and capacity ratio, and the battery K shows the same tendency. From this, 0.1w
When the content is less than t% or more than 15 wt%, improvement by addition is recognized, but the effect is insufficient. From this, it is understood that the content of propane sultone is preferably in the range of 0.1 to 15 wt% with respect to the electrolytic solution.

Example 3 As Example 3, the effect of the solvent composition was examined. In the electrolyte according to the third embodiment, propylene carbonate (P
C) and ethylene carbonate (EC), using 1,2 dimethoxyethane (DME) as a low-viscosity solvent, and preparing a binary or ternary solvent selected from these, and using lithium fluoride as a solvent for each. (LiBF ₄ )
Was used so as to be 1 mol / l.
Further, propane sultone was added to each of the electrolytes, and
It was added at a ratio of mass%. Batteries L to R having the same configuration as the battery A of Example 1 were produced except that these electrolytic solutions were used, and the same evaluation as in Example 1 was performed. Example 3
In order to clarify the influence of high-temperature storage on low-temperature discharge characteristics after storage, discharge conditions after storage were performed at an ambient temperature of −20 ° C. and a load resistance of 30 kΩ. Table 3 shows the results.

[0038]

[Table 3]

As is clear from Table 3, batteries N to Q in which the volume ratio of propylene carbonate as a high dielectric constant solvent is 5 to 60% are all excellent. On the other hand, the batteries L and M in which the ratio of PC in the solvent is less than 5%,
In addition, in the battery R having a PC ratio of 70% or more, the discharge voltage and the discharge capacity ratio are significantly reduced. Although the increase in internal resistance during high-temperature storage can be suppressed by the addition of propane sultone, the discharge characteristics at low temperatures are inferior to those of other batteries. This is because the effect of the conductivity of the electrolytic solution at a low temperature of −20 ° C. becomes remarkable, and when the proportion of propylene carbonate having a low freezing point is less than 5%, or when propylene carbonate is added at a high rate of 70%. Nevertheless, 1,2 dimethoxyethane (D
When the ratio of (ME) is low, it is considered that the conductivity of the electrolytic solution is lowered, which causes deterioration of the discharge characteristics at low temperatures. Therefore, in any of the two-component system and the three-component system having a solvent composition, propylene carbonate preferably has a volume ratio of 5 to 60%. In this example, propylene carbonate was used as the high dielectric constant solvent. However, similar results can be obtained in the case of γ-butyrolactone (GBL).

Example 4 As Example 4, the effect of the open circuit voltage before high-temperature storage on the storage characteristics was examined using the battery A of the present invention. By using the battery prepared in Example 1 and performing preliminary discharge (partial discharge) on the assembled battery of about 3.6 V, batteries having different open-circuit voltages were obtained. Specifically, by changing the time at a constant current discharge of 1 mA, the preliminary discharge depth is set in the range of 0 to 5% of the positive electrode design capacity (100 mAh), and the open circuit voltage becomes 3.6 to 3.4 V. Ten batteries were produced for each. These batteries were evaluated in the same manner as in Example 1, and the resulting discharge capacity ratios are shown in Table 4.

[0041]

[Table 4]

As is clear from Table 4, batteries having an open circuit voltage of 3.46 V or less have the effect of adding propane sultone without capacity deterioration due to high-temperature storage. on the other hand,
In the case of the battery of 3.51 V or more, the capacity was significantly deteriorated, and when the battery was disassembled and examined, deposition of stainless steel as the material of the positive electrode case was observed on the lithium surface. From the above, it can be seen that by setting the open circuit voltage to 3.5 to 3.4 V, the effect of adding ethylene sulphie can be sufficiently exerted.
In order to obtain this voltage value, 1 to 5% of the positive electrode design capacity is required.
Is preferably pre-discharged.

In this embodiment, coin type batteries have been described. However, the present invention can provide similar results for batteries of various shapes such as cylindrical types.

[0044]

As is clear from the above description, (00)
2) A positive electrode made of graphitizable carbon or a graphitic material having a plane distance of 3.50 ° or less as a starting carbon material, a positive electrode made of carbon fluoride, a negative electrode capable of releasing lithium ions, and an organic material containing propane sultone. By forming the battery by combining the electrolytes and setting the open circuit voltage to 3.5 V or less, the non-aqueous solution which is excellent in high temperature storage characteristics, does not cause a voltage drop even under high load discharge after storage, and is excellent in intermittent discharge characteristics. An electrolyte battery is obtained. At the same time, even if stainless steel or the like is used for the battery components, the characteristics are not degraded, and its industrial value is great.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a nonaqueous electrolyte battery according to an embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Positive electrode can 2 Negative electrode can 3 Gasket 4 Positive electrode 5 Negative electrode 6 Separator

Continued on the front page (72) Inventor Nobuharu Koshiba 1006 Kadoma, Kazuma, Osaka Pref. F-term (reference) in Matsushita Electric Industrial Co., Ltd. EA22 HA01 HA04 HA18

Claims (8)

[Claims] 1. A non-aqueous electrolyte battery comprising a negative electrode made of metallic lithium or a lithium alloy, a positive electrode made of fluorocarbon, and an organic electrolyte, wherein the fluorocarbon is:
A graphitizable carbon or a graphitic material having a (002) plane spacing of 3.50 ° or less is used as a starting carbon material, the organic electrolytic solution contains propane sultone, and the open circuit voltage after preliminary discharge. Is 3.5V or less. 2. The non-aqueous electrolyte battery according to claim 1, wherein propane sultone is contained in the organic electrolyte at a ratio of 0.1 to 15% by mass. 3. The non-aqueous electrolyte battery according to claim 2, wherein the organic solvent constituting the organic electrolyte comprises a cyclic ester. 4. The method according to claim 1, wherein the organic solvent is ethylene carbonate,
Propylene carbonate, butylene carbonate, γ-
The non-aqueous electrolyte battery according to claim 3, which is at least one cyclic ester selected from butyrolactone. 5. The non-aqueous electrolyte battery according to claim 2, wherein the organic electrolyte comprises a mixed solvent of a low-viscosity ether or chain ester and a cyclic ester. 6. The non-aqueous electrolyte battery according to claim 5, wherein the low-viscosity ether is 1,2 dimethoxyethane. 7. The non-aqueous electrolyte battery according to claim 5, wherein the cyclic ester of the mixed solvent is at least one of γ-butyrolactone and propylene carbonate, and the cyclic ester is contained at a ratio of 5 to 60% by volume. 8. The non-aqueous electrolyte battery according to claim 3, wherein the graphitizable carbon has a spherical shape.