JPH0254870A - Organic electrolyte battery - Google Patents

Abstract

PURPOSE:To elevate the heavy load discharge characteristics of a battery by putting the average grain diameter of electrolytic manganese dioxide in the specified value. CONSTITUTION:As positive electrode active material 1, for example, a positive compound consisting of electrolytic manganese dioxide with an average grain diameter of 73.5mum, graphite, and polytetrafluoroethylene is pressed and formed in disc-shape. Next, the material 1 is arranged in a positive electrode can 2, and a negative electrode active material 3 is force-bonded and held by a negative electrode can 4, and the space between the negative can 4 and the gasket 6 is compressed so as to maintain the sealing inside a battery. In this case, the average grain diameter of electrolytic manganese dioxide is determined within the range of 50-130mum.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an organic electrolyte battery using lithium or a lithium alloy as a negative electrode active material and electrolytic manganese dioxide as a positive electrode active material, and in particular, to This paper relates to improvements in heavy load discharge characteristics.

[Summary of the invention]

The present invention provides an organic electrolyte battery such as a lithium manganese battery using an organic electrolyte, in which the average particle diameter of electrolytic manganese dioxide used as a positive electrode active material is 50 to 130 μm.
More preferably, the thickness is 60 to 120 μm to improve the heavy load discharge characteristics of the battery.

[Conventional technology]

Organic electrolyte-based batteries that use lithium or a lithium alloy as a negative electrode active material and an organic electrolyte have excellent characteristics such as high energy density, good leakage resistance (and low self-discharge). Therefore, it has attracted particular attention in recent years.As positive electrode active materials for organic electrolyte-secondary batteries, MnO□, CFxXFe5z, CuO1Cu
Those using FeSz etc. have been put into practical use. Among these, MnO2 can provide high operating voltage, flat discharge voltage, and is inexpensive, making lithium-manganese batteries using MnO2 an excellent choice for use in calculators, watches, and memory. Demand for power supplies for various electronic devices such as backup devices is increasing year by year.

[Problem to be solved by the invention]

However, because organic electrolytes have lower conductivity than aqueous electrolytes, the use of organic electrolyte-secondary batteries is generally limited to light-load applications, such as card-type FM radios. relatively heavy loads such as (several m AC
For applications requiring discharge at a current density of s −' or higher,
It was not suitable.

Up until now, methods for improving the heavy load characteristics of organic electrolyte-secondary batteries have included expanding the facing area of the positive and negative electrodes, improving the conductivity of the electrolyte by examining the electrolyte solvent composition and salt concentration, and the composition of the positive electrode mixture. Attempts have been made to improve the charge mobility at the positive electrode by studying the above, but sufficient characteristics have not been obtained.

Conventionally, electrolytic manganese dioxide has been used as the positive electrode active material of this battery, but improvements to this positive electrode active material have also been made mainly for light load applications, as disclosed in Japanese Patent Publication No. 61-49790. The purpose was to improve the utilization rate of active materials during discharge. In order to improve this utilization rate, decreasing the average particle diameter of the positive electrode active material and increasing the total specific surface area increases the electrode reaction area and reduces the reaction amount per unit area, so the active material utilization rate decreases. It is an effective means for improvement. For this reason, the electrolytic manganese dioxide commonly used in lithium manganese batteries at present has an average particle diameter of 40 μm or less.

Previously, one of the inventors of the present application filed Japanese Patent Application No. 62-3;889.
In No. 3, an organic electrolyte battery with improved discharge characteristics during heavy load discharge by using chemically synthesized manganese dioxide produced by a predetermined method and having a predetermined particle specific surface area as a positive electrode active material was developed. Proposed together with the inventor. The chemically synthesized manganese dioxide in this case is very porous and has large pores, so the average particle size is 30
It has a very large specific surface area even around μm.

On the other hand, electrolytic manganese dioxide is generally used as manganese sulfate (I
I) Produced by electrolytically oxidizing the solution on an insoluble anode. In this case, since manganese dioxide is electrodeposited and deposited on the anode, it is peeled off and the flaky electrodeposit is mechanically crushed and other necessary steps are performed to obtain electrolytic manganese dioxide. There is. Although this electrolytic manganese dioxide is porous, its pores are small, so it has an excellent filling rate. However, on the other hand, when electrolytic manganese dioxide, which has a small average particle diameter of 40 μm or less, is used as a positive electrode active material, formations occur between particles inside a positive electrode mixture formed using this positive electrode active material under normal pressure. The individual gaps between the holes also become smaller, and the pores are so small that they are easily clogged. Therefore, the amount of electrolyte that permeates and is retained in the gap also decreases. For this reason, during heavy load discharge where a fast reaction rate is required, ion diffusion does not occur smoothly and the utilization rate decreases. For the above reasons,
Organic electrolyte secondary batteries using electrolytic manganese dioxide with a small average particle size as a positive electrode active material cannot be used under heavy loads.

An object of the present invention is to provide an organic electrolyte battery that has excellent discharge characteristics during heavy load use even when electrolytic manganese dioxide is used as the positive electrode active material.

[Means to solve the problem]

The present invention provides an organic electrolyte battery using lithium or lithium alloy as a negative electrode active material and electrolytic manganese dioxide as a positive electrode active material, wherein the average particle diameter of the electrolytic manganese dioxide is 50 to 130 μm, more preferably 60 to 130 μm. The present invention relates to an organic electrolyte battery characterized in that the thickness is in the range of 120 μm.

In the present invention, lithium or a lithium alloy is used as the negative electrode active material, and in the latter case, A1, p b
It is possible to use one or more of SS n , B i , Cd SCu SF e, etc. added as an alloying element. Note that these metals are preferably added to an extent that does not significantly change the potential of lithium.

As the electrolytic solution, it is preferable to use a non-aqueous organic electrolytic solution in which a lithium salt is used as an electrolyte and the electrolyte is dissolved in an organic solvent.

Here, as the organic solvent, for example, esters,
Examples include ethers, 3-substituted-2-oxazolidinones, and mixed solvents of two or more of these.

Examples of the above esters include ethylene carbonate, propylene carbonate, γ-butyl lactone, 2
-Methyl-γ-butyl lactone and other alkylene carbonates can be mentioned.

Examples of the above ethers include diethyl ether,
Examples include cyclic ethers (for example, ethers having a 5-membered ring and ethers having a 6-membered ring), dimethoxyethane, and the like. In this case, specific examples of ethers having a 5-membered ring include tetrahydrofuran; substituted (alkyl,
alkoxy)tetrahydrofuran (e.g., 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, 2-ethyltetrahydrofuran, 2-2'-dimethyltetrahydrofuran, 2-methoxytetrahydrofuran, 2,5-dimethoxytetrahydrofuran, etc.),
Examples include dioxolane. Further, specific examples of the ether having a 6-membered ring include 1,4-dioxane, pyran, dihydrobyran, and tetrahydropyran.

Examples of the above-mentioned 3-substituted-2-oxazolidinones include 3-alkyl-2-oxazolidinones (e.g., 3-
methyl-2-oxazolidinone, 3-ethyl-2-oxazolidinone, etc.), 3-cycloalkyl-2-oxazolidinone (e.g., 3-cyclohexyl-2-oxazolidinone, etc.), 3-aralkyl-2-oxazolidinone (e.g., 3-cyclohexyl-2-oxazolidinone, etc.), (benzyl-2-oxazolidinone, etc.), 3-aryl-2-oxazolidinone (eg, 3-phenyl-2-oxazolidinone, etc.).

Among these, organic solvents include propylene carbonate, ethers having a 5-membered ring (especially tetrahydrofuran, 2-methyltetrahydrofuran, 2-ethyltetrahydrofuran, 25-dimethoxytetrahydrofuran, 2-methquintetrahydrofuran), 3-methyl- 2-oxazolidinone and the like are preferred.

Examples of the electrolyte include lithium perchlorate, lithium borofluoride, lithium phosphorus fluoride, lithium chloride aluminate, lithium halide, lithium trifluoromethanesulfonate, and in particular, lithium perchlorate, lithium borofluoride, and the like. Lithium and the like are preferred.

[Effect]

When the average particle diameter of electrolytic manganese dioxide used as a positive electrode active material is increased to the above range compared to conventional ones,
Since the gaps between the particles in the positive electrode mixture that are formed after pressure molding this manganese dioxide become larger without significantly reducing the filling rate of the active material, the amount of electrolyte retained in these gaps can be increased. Can be done. In this way, if the amount of electrolyte that can be included in the positive electrode mixture can be increased, rapid reaction between the active material and the electrolyte becomes possible during heavy load discharge. Therefore, the active material utilization rate increases more than when the average particle diameter is small.

〔Example〕

An embodiment in which the present invention is applied to a coin-shaped CR2016 type lithium manganese battery will be described with reference to the drawings.

FIG. 1 shows a longitudinal cross-sectional view of a CR2016 type lithium manganese battery, which was manufactured as described below.

As the positive electrode active material 1, for example, 88.9 parts by weight of electrolytic manganese dioxide with an average particle diameter of 73.5 μm and 9.9 parts by weight of graphite.
0.36 g of a positive electrode mixture consisting of 3 parts by weight and 1.8 parts by weight of polytetrafluoroethylene was heated to a diameter of 14.5 m++,
It was pressure molded into a disc shape with a height of 0.64 W.

In the text, the average particle diameter of electrolytic manganese dioxide was determined by volume weighted average. Moreover, electrolytic manganese dioxide was used after being subjected to dehydration treatment at 420° C. for 4 hours. Next, this positive electrode active material 1 was placed in a positive electrode can 2 made of stainless steel whose outside was nickel plated.

The negative electrode active material 3 was a disk-shaped metal lithium with a diameter of 16 m1 and a thickness of 0.22+n, and was supported by pressure in a negative electrode can 4 made of nickel-plated stainless steel as described below.

electrolytic? As fl, propylene carbonate and 1.2
- Lithium perchlorate was dissolved at a ratio of 1 mole/1 in a mixed solvent with dimethoxyethane at a volume ratio of 1:1.

After making the positive electrode active material 1 and the negative electrode active material 3 face each other with a polypropylene separator 5 interposed therebetween,
By caulking the positive electrode can 2, the space between the negative electrode can 4 and the gasket 6 made of polypropylene whose surface was coated with asphalt was compressed, and the airtightness of the inside of the battery was maintained.

As described above, a coin-shaped CR2016 type lithium manganese battery with a diameter of 201 m and a height of 1.6 m was produced.

Next, the average particle diameter of the electrolytic manganese dioxide was changed to 6 types, and 6 more types of lithium manganese batteries were produced in exactly the same manner as in the above case.

As a result, as shown in the following table, a total of seven types of lithium manganese batteries using electrolytic manganese dioxide having seven types of average particle diameters were obtained.

In this table, electrolytic manganese dioxide D, E, and F have average particle diameters in the range of 50 to 130xJm, so batteries made using these are as follows:
This is an example of the present invention. Furthermore, since the average particle diameters of electrolytic manganese dioxide A, B, C, and G are outside the above range, batteries made using these are reference examples of the present invention.

For these seven types of batteries, the current density was 5 m at 20°C.
Acm-'' constant current continuous discharge test was conducted.

This current density was based on the area of the positive electrode facing the negative electrode on the facing surfaces of the positive and negative electrode active materials facing each other. Figure 2 shows a discharge characteristic diagram showing this result. A to G in the same figure
shows the discharge characteristic curves of each lithium manganese battery using the electrolytic manganese dioxide described in A to G of the table as the positive electrode active material.

As is clear from Figure 2, the average particle size is 50 to 130p.
The battery of the present invention using electrolytic manganese dioxide in the range of m (curves E and F in the figure) has an average particle size of 40
The constant current discharge time at a current density of 5 mAcm is longer than those with an average particle diameter of less than 130 μm (curves A, B, and C) or those with an average particle diameter of more than 130 μm (curve mG). Comparing the discharge time up to a voltage of 2.0 μm, the discharge time of the battery using (C) with an average particle size of 36.5 μm is 3.0 hours, whereas the discharge time of the battery with an average particle size of 51.5 μm is 3.0 hours. Since the discharge time of the battery using the material (D) is 3.7 hours, the latter is improved by more than 20% compared to the former.Furthermore, the battery using the material (E) with an average particle diameter of 73.5 μm and the battery with an average particle size of 73.5 μm The discharge time of each battery using the battery (F) with a diameter of 116.3 μm is 4.0 hours and 3.95 hours, which is an improvement of more than 30%. Therefore, from Fig. 2, It is clear that it is more preferable that the average particle diameter of the electrolytic manganese dioxide is in the range of 60 to 120 μm.

As explained above, in the above embodiment, CR2
Although the present invention was applied to a 016 type lithium manganese battery, the present invention can also be applied to other types of organic electrolyte secondary batteries, and can also be applied to organic electrolyte secondary batteries.

〔Effect of the invention〕

The S-containing electrolyte battery according to the present invention uses electrolytic manganese dioxide having an excellent filling rate as the positive electrode active material, and has an average particle diameter of 50 to 130%.
μm, preferably in the range of 60 to 120 μm,
The amount of electrolyte that can be held inside the positive electrode can be increased without significantly reducing the filling rate of the positive electrode active material.
Therefore, the heavy load discharge characteristics of the battery can be improved. For example, in a constant current continuous discharge test at a current density of 5 mAc+n-2 on a CR2016 type lithium manganese battery, the discharge time of the battery according to the present invention to 2.0 V is approximately 20 to 30% longer than that of conventional products.

2−・−・・−・−・−−−−−−−m−Positive electrode can 3−
・・・・・−・−1−−−−−−・Negative electrode active material 4−・
−−−−−1・−・−・−・・Negative electrode can 5−−−−−・−
...---------Separator.

Claims (1)

[Scope of Claims] An organic electrolyte battery using lithium or a lithium alloy as a negative electrode active material and electrolytic manganese dioxide as a positive electrode active material, wherein the average particle diameter of the electrolytic manganese dioxide is 50 to 130μ.
An organic electrolyte battery characterized in that the electrolyte is in the range of m.