JPH0722019B2 - Organic electrolyte battery - Google Patents

Description

TECHNICAL FIELD The present invention relates to an organic electrolyte battery (so-called lithium battery) in which lithium is used for a negative electrode and an organic electrolytic solution is used as an electrolytic solution, and in particular, sulfuration of iron is used for a positive electrode. The present invention relates to improvement of an organic electrolyte battery using a product.

[Outline of Invention]

The present invention is intended to suppress the blistering of a battery due to discharge by using a mixture of iron sulfide and antimony trisulfide as a positive electrode material of an organic electrolyte battery.

[Conventional technology]

Compared to organic electrolyte batteries that use manganese disulfide or fluorocarbon as the positive electrode active material, organic electrolyte batteries that use metallic lithium as the negative electrode and iron sulfide as the positive electrode active material have an electric capacity per unit volume. It has excellent characteristics such as a large discharge voltage and a discharge voltage of about 1.5 V, which is compatible with silver oxide batteries and alkaline manganese batteries. Therefore, these batteries are used as power sources for various consumer electronic devices such as calculators, watches, hearing aids, and memory backups.

By the way, in many electronic devices, in order to make the overall size and shape of the device as compact as possible, it is usual to design the battery size and the battery storage case as small and thin as possible. In this case, when the battery expands in these electronic devices, the electronic device may be damaged or contact failure may occur. Therefore, it is desirable that the batteries used in these electronic devices have little battery expansion due to discharge and storage.

However, in an organic electrolyte battery that uses iron sulfide alone as a positive electrode active material, the expansion of the positive electrode due to discharge is greater than the volume reduction of the negative electrode lithium, causing the entire battery to expand and appear as a blistering of the battery. . As one method for reducing the expansion of the battery, it is conceivable to provide a void in the battery to accommodate the expanded portion of the positive electrode, but this reduces the battery capacity and is not a preferable method. Absent.

[Problems to be solved by the invention]

As described above, in the organic electrolyte battery in which iron sulfide is used alone as the positive electrode active material, the blistering of the battery is a serious problem.

Therefore, the present invention has been proposed in view of such conventional circumstances, and an object of the present invention is to provide an organic electrolyte battery having a small battery swelling and a good battery capacity.

[Means for solving problems]

The present inventors have developed an organic electrolyte battery with little battery swelling, and as a result of extensive research over a long period of time, they found that the addition of antimony trisulfide to a positive electrode was effective, and completed the present invention. In the organic electrolyte battery comprising a negative electrode mainly composed of lithium, a positive electrode mainly composed of a mixture of iron sulfide and antimony trisulfide, and an organic electrolyte, the mixed amount of antimony trisulfide is: It is characterized by being 20% by weight or more based on the total weight of the mixture.

As iron sulfide used as the positive electrode, iron sulfide, ferric sulfide, etc. can be used in addition to iron disulfide. Even if the amount of antimony trisulfide added to these iron sulfides is small, the effect of suppressing battery swelling can be obtained. For example, when iron disulfide is used in the positive electrode active material.
If it is 20% by weight or more, it is possible to suppress the blistering of the battery to be less than the allowable amount. Also, the larger the amount of antimony trisulfide added, the greater the effect of suppressing battery swelling, but if the amount of antimony trisulfide becomes too large, the capacity of the battery will decrease. It is preferable to set it appropriately according to

On the other hand, as the negative electrode active material, in addition to lithium, Li and Al, Pb, S
An alloy with one or more of n, Bi, Cd, etc. can be used.

A non-aqueous organic electrolyte prepared by dissolving a lithium salt in an electrolyte and dissolving it in an organic solvent is used as the electrolytic solution.

Here, as the organic solvent, esters, ethers, 3
Substituted-2-oxazolidinones and mixed solvents of two or more of these may be mentioned.

Examples of the esters include alkylene carbonate (ethylene carbonate, propylene carbonate, γ-butyrolactone, etc.) and the like.

The ethers include cyclic ethers, for example, ethers having a 5-membered ring [tetrahydrofuran; substituted (alkyl,
Alkoxy) tetrahydrofuran, for example 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, 2-
Ethyltetrahydrofuran, 2,2′-dimethyltetrahydrofuran, 2-methoxytetrahydrofuran, 2,5-dimethoxytetrahydrofuran, etc .; dioxolane, etc.], ether having a 6-membered ring [1,4-dioxane, pyran, dihydropyran, tetrahydropyran], Dimethoxyethane and the like can be mentioned.

The 3-substituted-2-oxazolidinones include 3-alkyl-2-oxazolidinone (3-methyl-2-oxazolidinone, 3-ethyl-2-oxazolidinone, etc.), 3-
Cycloalkyl-2-oxazolidinone (3-cyclohexyl-2-oxazolidinone, etc.), 3-aralkyl-2
Examples include -oxazolidinone (3-benzyl-2-oxazolidinone and the like) and 3-aryl-2-oxazolidinone (3-phenyl-2-oxazolidinone and the like).

Among them, propylene carbonate, ether having a 5-membered ring (particularly tetrahydrofuran, 2-methyltetrahydrofuran, 2-ethyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, 2-methoxytetrahydrofuran) and 3-methyl-2-oxazolidinone are preferable.

As the electrolyte, lithium perchlorate, lithium borofluoride, lithium phosphofluoride, lithium chloroaluminate, lithium halide, lithium trifluoromethanesulfonate and the like can be used, and lithium perchlorate and lithium borofluoride are preferable.

[Action]

By mixing 20% by weight or more of antimony trisulfide with iron sulfide, which is the positive electrode material of an organic electrolyte battery, the blistering of the battery due to discharge is significantly suppressed. Furthermore, by adjusting the amount of antimony trisulfide mixed, the reduction in discharge capacity is also suppressed.

〔Example〕

Hereinafter, specific examples of the present invention will be described, but it goes without saying that the present invention is not limited to these examples.

Iron disulfide and antimony trisulfide were used as the positive electrode active material, graphite was used as the conductive agent, and polytetrafluoroethylene was used as the binder, and they were mixed with the composition shown in the following table to obtain a positive electrode mixture. These anode mix, diameter 4mm, thickness 0.85mm,
A positive electrode pellet (Sample 1 to Sample 7) was produced by pressure molding to a weight of 33 mg.

Next, as shown in FIG. 1, a metal lithium foil (2) having a diameter of 4 mm and a thickness of 0.85 mm was pressure-bonded to the anode cup (1) as a negative electrode material, and a separator (3) containing an electrolytic solution was further formed thereon. ) Is placed and the plastic gasket (4) is fitted, the prepared anode pellet (5) is placed on the separator (3) and the cathode can (6) is covered, and the end is caulked to seal the organic electrolyte. I assembled the battery.

The prepared battery had a diameter of 6.8 mm and a total height of 2.1 mm. In addition, in the anode cup (1) and the cathode can (6),
A nickel-plated stainless steel was used, and as the electrolyte, 1 mol / l of lithium perchlorate was dissolved in a solvent in which propylene carbonate and 1,2-dimethoxyethane were mixed at a volume ratio of 1: 1. A water electrolyte was used.

The amount of swelling and the discharge capacity of the batteries in the height direction were measured when these batteries were discharged to 1.2 V with a load resistance of 15 kΩ. The results are shown in FIGS. 2 and 3. In FIGS. 2 and 3, the horizontal axis represents the weight mixing ratio of antimony trisulfide to the total weight of the positive electrode active materials iron disulfide and antimony trisulfide, and the vertical axis represents the battery. The amount of swelling (Fig. 2) or the discharge capacity (Fig. 3) is plotted. Therefore, the battery using Sample 1 as a positive electrode pellet corresponds to a case where the weight mixing ratio of antimony trisulfide is 0% by weight, and the battery using Sample 2 as a positive electrode pellet has a weight mixing ratio of antimony trisulfide of 20% by weight. Corresponds to the case. The same applies hereinafter to a battery in which sample 7 is a positive electrode pellet corresponds to a case where the weight mixing ratio of antimony trisulfide is 100% by weight.

As is clear from the results shown in FIG. 2, the swelling of the battery due to discharge is significantly suppressed by mixing iron disulfide with antimony trisulfide. Further, as is clear from the results shown in FIG. 3, by adjusting the mixing amount of antimony trisulfide to an appropriate amount, the decrease in discharge capacity can be suppressed. For example, if the mixing ratio of antimony trisulfide is set to 20% by weight, the amount of blistering of the battery is reduced to less than half, and the battery capacity remains almost unchanged.

〔The invention's effect〕

As is clear from the above description, in the present invention, since the sulfide of iron is used as the positive electrode active material of the organic electrolyte battery, and 20% by weight or more of antimony trisulfide is mixed,
Blistering of the battery caused by discharge is greatly suppressed.
Further, by appropriately setting the mixing amount of antimony trisulfide, the decrease in battery capacity can be suppressed to the minimum.

Therefore, it is possible to provide an organic electrolyte battery having a long battery life and a high practicality without fear of damaging an electronic device or causing a contact failure.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view showing an example of the structure of the organic electrolyte battery. FIG. 2 is a characteristic diagram showing the relationship between the mixture ratio of antimony trisulfide and the amount of swelling of the battery due to discharge, and FIG. 3 is a characteristic diagram showing the relationship between the mixture ratio of antimony trisulfide and the discharge capacity. 2 …… Metallic lithium foil (cathode) 3 …… Separator 5 …… Anode pellet

Claims (1)

[Claims] 1. An organic electrolyte battery comprising a negative electrode containing lithium as a main component, a positive electrode containing a mixture of iron sulfide and antimony trisulfide as a main component, and an organic electrolyte. , 20 based on the total weight of the mixture
An organic electrolyte battery, characterized in that the content is at least wt%.