JPS6182673A - Nonaqueous solvent battery - Google Patents

Abstract

PURPOSE:To minimize the voltage reduction of a nonaqueous solvent battery during its initial stage of large current electric discharge and shorten the time for voltage recovery by adding a vinyl chloride-vinylidene chloride copolymer to prepare the liquid electrolyte. CONSTITUTION:A can 1 contains a liquid electrolyte 13 poured through a pipe- like positive terminal 10. The liquid electrolyte 13 is prepared by adding 2.5g/l of vinyl chloride-vinylidene chloride copolymer to a solution prepared by dissolving 1.5mol/l of aluminum chloride and 1.5mol/l of lithium chloride in thionyl chloride. After a stainless steel needle 14 is inserted in the positive terminal 10, the needle 14 and the end of the terminal 10 are fused by laser welding to seal the terminal 10. Owing to the above structure, only a slight voltage decrease occurs during the initial stage of large current electric discharge. Furthermore, it is possible to reduce the time for voltage recovery.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a non-aqueous solvent battery, and more particularly to a non-aqueous solvent battery in which an electrolyte that also serves as a positive electrode active material is improved.

[Technical background of the invention and its problems]

Nonaqueous solvent batteries that use light metals such as lithium, sodium, and aluminum as negative electrode active materials have high energy density, excellent storage characteristics, and a wide operating temperature range. It is often used as a backup power source. Among them, lithium is used for the negative electrode, and thionyl chloride (SOCl2) is used as the positive electrode active material.
Batteries using sulfur oxyhalides, such as sulfuryl chloride (SO2C22), are attracting attention because of their particularly high energy density. Such cells have a positive electrode consisting of carbon and a metal current collector, typically a Lewis acid such as aluminum chloride (ktcL5), aluminum bromide (AtBrρ) and lithium chloride.

A liquid oxyhalide of sulfur obtained by bath-dissolving a Lewis base such as lithium bromide is used as the electrolyte. Therefore, the liquid oxyhalide serves both as a positive electrode active material and as an electrolyte, and by using a positive electrode with an appropriate shape, a battery with excellent high rate discharge characteristics can be expected.

By the way, in the above-mentioned battery, since the sulfur oxyhalide which is the positive electrode active material is in direct contact with the lithium of the negative electrode, a LIC1 film which is a reaction product is generated on the surface of the negative electrode lithium. This LiCt film has the function of preventing direct contact between the negative electrode lithium and the oxyhalide, and serves to prevent battery capacity deterioration during storage.

However, during discharge, it acts as a resistance component and causes a voltage drop in the early stage of discharge. The degree of this voltage drop is negligible when the discharge current is minute on the μA order, but
This cannot be ignored in the case of large current discharge, especially after storage at high temperature for a long time and considerable growth of the LiCL film has occurred, or when discharging at low temperature, a large voltage drop occurs at the beginning of discharge, and the voltage does not reach the specified voltage. There was a problem called the so-called voltage delay phenomenon, which required a considerable amount of time to recover.

For this reason, several proposals have been made to solve the above problems, such as: Kosho 57-3
7992 has a negative electrode surface made of vinyl chloride.

Coating with a vinyl/IJ polymer such as a homopolymer of vinylidene chloride or a copolymer of vinyl chloride and vinyl acetate has been disclosed. However, although this method does greatly improve the voltage delay phenomenon, it takes some time for the voltage to recover when a large current discharge is performed after the battery has been stored at a high temperature.

[Purpose of the invention]

The present invention aims to provide a non-aqueous solvent battery that has a small voltage drop even in the early stages of large current discharge, a short voltage recovery time, and excellent discharge characteristics.

[Summary of the invention]

The present invention provides a non-aqueous solvent battery comprising a negative electrode made of a metal such as lithium, a positive electrode mainly made of carbon, and an electrolyte that also serves as a positive electrode active material and whose main component is sulfur oxyhalide. , a copolymer of vinyl chloride and vinylidene chloride is added to the electrolytic solution. In this way, a battery in which a copolymer of vinyl chloride and vinylidene chloride is present in the electrolyte does not show a significant voltage drop even when discharged at a large current after storage, and also has a short voltage recovery time. In this case, the voltage recovery time is significantly shortened compared to batteries in which homopolymers such as vinyl chloride, vinyl chloride 7, etc., mixtures of both, or vinyl polymers such as vinyl chloride-vinyl acetate copolymer are added to the electrolyte. Excellent.

The content of the vinyl chloride-vinylidene chloride copolymer in the electrolytic solution is desirably in the range of 0.2 to 10 Vt. The reason for this is that if the content of the copolymer is less than 0.217, it will not be able to sufficiently exhibit the effect of suppressing voltage drop, etc., but if the amount exceeds 10 Vt, the effect will be negligible. Not only will it not increase, but there is a possibility that the discharge capacity of the battery will decrease on the contrary.

The vinyl chloride-vinylidene chloride copolymer used in the present invention has a weight ratio of vinyl chloride to vinylidene chloride of 95=5 to 1.
It is desirable that the ratio be in the range of 0 to 90, more preferably 95:5 to 50:50.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

Reference numeral 1 in the drawings indicates a bottomed cylindrical can made of, for example, stainless steel and having an open top which also serves as a negative electrode terminal.

A cylindrical negative electrode 2 made of metallic lithium is pressure-bonded to the inner surface of the can 1. Inside the can body I inside the negative electrode 2, a separator made of lath nonwoven fabric is placed over the positive electrode, which has a structure in which a cylindrical porous carbon layer 4 is crimped to the outside of the body 3 to a metal collection τ of a cylindrical stainless steel mesh body. 61, 6□. Note that on the positive electrode, for example, commercially available acetylene black and polytetrafluoroethylene are mixed, and this kneaded mixture is placed in a cylinder together with a metal current collector 3 made of stainless steel mesh so that the current collector is on the inside. The porous carbon layer 4 is produced by forming the kneaded product into a porous carbon layer 4 by drying it under vacuum at 150°C.

Further, in the can body 1 above the positive electrode, an insulating paper 7 supported by the cell taro 1 and having a hole in the center is disposed. A metal dog 8 is sealed to the upper opening of the can body by laser bath welding or the like, and a pipe-shaped positive electrode terminal 10 is attached to a hole 9 in the center of the metal dog 8 with a sealing material 11 made of glass. It is electrically insulated and fixed to the metal dog 8 via the metal dog 8. The lower end of the positive electrode terminal 10 is connected to the metal current collector 3 of the positive electrode king via a lead wire 12. The can body 1 accommodates an electrolytic solution 13 injected from the nozzle-shaped positive electrode terminal 10.

This electrolyte 13 contains aluminum chloride (AtC43) and lithium chloride (t, tc) in thionyl chloride (socz2).
z) and a commercially available vinyl chloride-vinyl chloride lyso y copolymer (copolymerization ratio 80:2).
0) was added at 2.5 g/.

A seal 14 made of stainless steel, for example, is inserted into the pipe-shaped positive electrode terminal 10, and the positive electrode terminal 10 is sealed by laser welding the tip of the terminal IQ and the inserted seal 14.

Comparative Example 1 A battery having the same structure as in Example was assembled, except that a ktct3/LiC4-based electrolyte having a concentration of 1.5 mol/mole to which no vinyl chloride-vinylidene chloride copolymer was added was used as the electrolyte.

Comparative Example 2 Vinyl chloride homopolymer was used as an electrolyte at 2.5 Vt.
A battery having the same structure as in the example was assembled except that an Atct3/LIC4 type with a concentration of 1.5 mol/mole was used.

Comparative Example 3 Vinylidene chloride homopolymer was used as an electrolyte at 2.5
g/added to a concentration of 1.5 mol/A1. Cts/
A battery having the same structure as the example was assembled except that a LiC2 type battery was used.

Comparative example 4? ! ! As a solution, 2.5 g of a mixed polymer prepared by mixing vinyl chloride homopolymer and vinylidene chloride homopolymer at a ratio of 80:20 was added to give a concentration of 1.5 mol/Atct/LIC1 system. A battery having the same structure as in the example was assembled except that the same material was used.

Comparative Example 5 As an electrolytic solution, a fi, tct, / Li CL type electrolyte with a concentration of 1.5 molar μ to which 2.5 g of vinyl chloride-vinyl acetate copolymer (copolymerization ratio 86:14) was added was used. A battery having the same structure as the example was assembled except that the battery was used.

Therefore, regarding the batteries of this example and comparative examples 1 to 5,
After assembling and storing at 60℃ for 20 days, a constant resistance discharge of 30Ω was performed, and the minimum voltage at the start of discharge and the voltage were 2.
．． The time taken to return to 5V, as well as the average operating voltage and discharge capacity were measured. The results are shown in the table below.

As is clear from the above table, the battery made of vinyl chloride-vinyl chloride lyso-y copolymer has a smaller initial voltage drop and a shorter voltage recovery time than conventional batteries. Furthermore, it can be seen that the discharge capacity is also improved.

〔Effect of the invention〕

As detailed above, the present invention provides a nonaqueous solvent battery with excellent discharge characteristics, such as suppressing voltage drop even in the early stage of large current discharge, shortening voltage recovery time, and improving discharge capacity. Can be provided.

[Brief explanation of drawings]

The figure is a sectional view of a non-aqueous solvent battery showing one embodiment of the present invention. 1... Can body, 2... Negative electrode, 3... Metal current collector, 4
... Porous carbon layer, Σ... Positive electrode, 61.62...
Separator, 8...Metal top, 10.../arm-shaped positive electrode terminal, 13... Electrolyte solution.

Claims (1)

[Claims] In a non-aqueous solvent battery that is composed of a negative electrode made of light metals such as lithium, sodium, and aluminum, a positive electrode mainly made of carbon, and an electrolyte that also serves as a positive electrode active material and mainly made of sulfur oxyhalide, A non-aqueous solvent battery, characterized in that a copolymer of vinyl chloride and vinylidene chloride is added to the electrolyte.