JPH0713898B2 - Non-aqueous solvent battery - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a non-aqueous solvent battery, and more particularly to a non-aqueous solvent battery having an improved electrolytic solution that also serves as a positive electrode active material.

[Technical background of the invention and its problems]

A non-aqueous solvent battery using at least one of light metals such as lithium, sodium, aluminum, potassium, and calcium as a negative electrode active material has high energy density, excellent storage characteristics, and a wide operating temperature range. It is often used as a backup power source for calculators, clocks, and memories. Among them, batteries using lithium for the negative electrode and sulfur oxyhalides such as thionyl chloride (SOCl ₂ ) and sulfuryl chloride (SO ₂ Cl ₂ ) as the positive electrode active material are attracting attention because of their particularly high energy density. . Such batteries have a positive electrode composed of carbon and a metal current collector, and generally dissolve a Lewis acid such as aluminum chloride (AlCl ₃ ) or aluminum bromide (AlBr ₃ ) and a Lewis base such as lithium chloride or lithium bromide. Liquid sulfur oxyhalide is used as the electrolyte. For this reason,
The liquid oxyhalide serves both as a positive electrode active material and an electrolytic solution, and by using a positive electrode having an appropriate shape, a battery having excellent high rate discharge characteristics can be expected.

By the way, in the battery described above, the oxyhalide of sulfur, which is the positive electrode active material, is in direct contact with lithium of the negative electrode, so that a LiCl film, which is a reaction product, is formed on the surface of the negative electrode lithium. This LiCl film has a function of preventing direct contact between the negative electrode lithium and the oxyhalide, and plays a role of preventing deterioration of the battery capacity during storage. But,
It acts as a resistance component during discharge and causes a voltage drop at the beginning of discharge. The degree of this voltage drop is so small that it can be ignored when the discharge current is as small as μA, but it cannot be ignored in the case of large current discharge, and especially when stored at high temperature for a long time.
After a considerable amount of LiCl film growth or during low-temperature discharge, a large voltage drop occurs at the start of discharge, and it takes a considerable time for the voltage to recover to a prescribed level, which is a so-called voltage delay phenomenon. there were. The extent of this voltage delay phenomenon varies greatly depending on the temperature and time during battery storage, the current during discharge, etc., but it is considered to be a practical problem if the voltage recovery time requires 15 seconds or more.

For this reason, some proposals have been made to solve the above problems. For example, in JP-A-56-7360, a homopolymer of vinyl chloride or vinylidene chloride or vinyl chloride and acetic acid is contained in an electrolytic solution. Dissolving a vinyl-based polymer such as a copolymer with vinyl is disclosed. Although the voltage delay phenomenon is certainly improved by dissolving the vinyl polymer having a chlorine substituent in the electrolytic solution in this manner, as a result of our research, we found that the degree of voltage recovery depends on the vinyl substituent having a chlorine substituent to be added. It has been found that the present invention largely depends on the amount of the chlorine substituent in the polymer, and thus the present invention has been accomplished.

[Object of the Invention]

An object of the present invention is to provide a non-aqueous solvent battery having a small voltage drop even in the initial stage of large current discharge, a short voltage recovery time, and excellent discharge characteristics.

[Outline of Invention]

The present invention provides a non-aqueous solvent battery composed of a negative electrode composed of a light metal such as lithium, a positive electrode containing carbon as a main constituent material, and an electrolytic solution containing sulfur oxyhalide as a main component and also serving as a positive electrode active material. , 57-70 wt% in the electrolyte
It is characterized in that a vinyl polymer having a chlorine substituent is added. As described above, the battery using the electrolytic solution containing the vinyl polymer having a chlorine substituent of 57 to 70% by weight does not show a large voltage drop at the start of discharge even if a large current discharge is performed after storage, and the voltage Recovery time is also short.

In this case, the degree of shortening the voltage recovery time is remarkably superior to the case where a vinyl-based polymer having the same chlorine substituent is added as compared with the case where a polymer having an amount of chlorine substituent outside the above range is added. Further, in addition to the above-mentioned effects, the battery of the present invention has advantages such as excellent discharge characteristics at low temperatures and less capacity deterioration due to long-term storage.

The vinyl-based polymer having a chlorine substituent in the present invention,
It refers to a homo- or copolymer and a mixture of polymers having a structure represented by the following general formula.

The content of these vinyl-based polymers in the electrolytic solution is preferably in the range of 0.2 to 10 g / l, particularly 0.3 to 5 g / l. This is because when the content of the copolymer is less than 0.2 g / l, the effect of suppressing the voltage drop cannot be sufficiently exerted,
On the other hand, if the amount exceeds 10 g / l, the effect is hardly increased and the discharge capacity of the battery may be decreased.

Example of Invention

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

Examples 1 to 6 FIG. 1 is a sectional view showing the structure of the non-aqueous solvent battery in this example and the comparative example.

Reference numeral 1 in the figure denotes a bottomed cylindrical can body made of, for example, stainless steel, the top surface of which also serves as a negative electrode terminal is opened. A cylindrical negative electrode 2 made of metallic lithium is pressure-bonded to the inner surface of the can body 1. The negative electrode 2 inside of the can body 1, the separator 6 ₁ tubular porous positive electrode 5 having a structure in which crimp the carbon layer 4 on the outer side of the metal current collector 3 of the tubular stainless meshes body is made of glass nonwoven , 6 ₂ are provided. The positive electrode 5 is formed by, for example, mixing commercially available acetylene black and polytetrafluoroethylene, and molding the kneaded material together with the metal current collector 3 made of a stainless steel net into a cylindrical shape so that the current collector is inside. After that, it is dried under vacuum at 150 ° C. to form the kneaded material into the porous carbon layer 4.

In addition, in the can body 1 above the positive electrode 5 , the separator
Insulating paper 7 is provided with a hole in supported center 6 _1. A metal top 8 is sealed by laser welding or the like in the upper opening of the can body 1, and a pipe-shaped positive electrode terminal 10 is inserted in a central hole 9 of the metal top 8 via a glass sealing material 11. And is electrically insulated and fixed to the metal top 8. The lower end of the positive electrode terminal 10 is a lead wire 12
It is connected to the metal current collector 3 of the positive electrode 5 via.
Then, the electrolytic solution 13 injected from the pipe-shaped positive electrode terminal 10 is accommodated in the can body 1.

Further, a needle body 14 made of, for example, stainless steel is inserted in the pipe-shaped positive electrode terminal 10, and the needle body 14 inserted into the tip of the terminal 10 is inserted.
The positive electrode terminal 10 is sealed by laser welding of and.

As Examples 1 to 6, 57.5 and 58. 5 respectively were added to an electrolytic solution prepared by dissolving 1.5 mol / l of aluminum chloride (AlCl ₃ ) and lithium chloride (LiCl) in thionyl chloride (SOCl ₂ ), respectively.
Six types of batteries were prepared using an electrolyte solution containing 6,60,64.5,67.5,69.5% by weight of a vinyl polymer (2 g / l) having a chlorine substituent.

Comparative Example 1. An electrolyte solution in which 40 wt% of a vinyl polymer having a chlorine substituent (a kind of chlorinated polyethylene) was added to an electrolyte solution in which AlCl ₃ and LiCl were dissolved in SOCl ₂ at 1.5 mol / l each. A battery having the same structure as that of the example except that the above was used was assembled.

Comparative Example 2. An electrolytic solution in which 56.7% by weight of a vinyl polymer having a chlorine substituent (polyvinyl chloride) was added to an electrolytic solution in which AlCl ₃ and LiCl were dissolved in SOCl ₂ at 1.5 mol / l respectively. A battery having the same structure as that of the example except that it was used was assembled.

Comparative Example 3. AlCl ₃ and LiCl in SOCl ₂ were dissolved in an amount of 1.5 mol / l each, and an electrolytic solution containing 73.1% by weight of a vinyl polymer having a chlorine substituent (polyvinylidene chloride) was prepared. A battery having the same structure as that of the example except that it was used was assembled. Then,
After assembling the batteries of Examples 1 to 6 and Comparative Examples 1 to 3
After storing at 60 ℃ for 40 days, carry out constant resistance discharge of 30Ω,
The time required for the voltage to return to 2.5 V, the average operating voltage and the discharge capacity were measured.

The results are shown in FIG. 2 and Table 1.

As is clear from FIG. 2 and Table 1, 57 to 70
Batteries to which vinyl polymer with a chlorine substituent of wt% was added have a shorter voltage recovery time at the start of discharge of less than 15 seconds compared to batteries to which vinyl polymer with chlorine content outside the above range was added, and It can be seen that the capacity is also large. In addition, it was confirmed that the battery according to the present invention has excellent discharge characteristics at low temperature and less capacity deterioration due to long-term storage, as compared with the battery of Comparative Example.

〔The invention's effect〕

As described above in detail, according to the present invention, it is possible to provide a non-aqueous solvent battery having excellent discharge characteristics such that the voltage recovery time at the initial stage of large current discharge is shortened and the discharge voltage and discharge capacity are improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of the structure of a non-aqueous solvent battery, and FIG. 2 is a discharge characteristic diagram of the non-aqueous solvent battery according to the present invention. 1 ... Can body, 2 ... Negative electrode, 3 ... Metal current collector, 4 ... Porous carbon layer, 5 ... Positive electrode, 6 ₁ , 6 ₂ ... Separator, 8 ...
… Metal top, 10 …… Pipe-shaped positive electrode terminal, 13 …… Electrolyte.

Claims (1)

[Claims] 1. A negative electrode composed of at least one light metal selected from lithium, sodium, aluminum, potassium, and calcium, a positive electrode containing carbon as a main constituent, and a positive electrode active material containing sulfur oxyhalide as a main component. A non-aqueous solvent battery comprising an electrolytic solution, wherein a vinyl polymer having a chlorine substituent of 57 to 70% by weight is added to the electrolytic solution.