JPH0763014B2 - 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]

Non-aqueous solvent batteries that use light metals such as lithium, sodium, and aluminum as the negative electrode active material have the characteristics of high energy density, excellent storage characteristics, and a wide operating temperature range. It is often used as a backup power source. Of these, batteries using lithium as 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 a battery has a positive electrode composed of carbonic acid and a metal current collector, and is generally made of aluminum chloride (AlCl ₃ ),
A liquid oxyhalide of sulfur in which a Lewis acid such as aluminum bromide (AlBr ₃ ) and a Lewis base such as lithium chloride or lithium bromide are dissolved is used as an electrolytic solution.
Therefore, the liquid oxyhalide serves as both the positive electrode active material and the 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 very small on the order of μA, but it cannot be ignored in the case of large current discharge, and especially when stored at high temperature for a long time, Li
There is a problem called the voltage delay phenomenon, in which after a considerable amount of Cl film growth or during low-temperature discharge, a large voltage drop occurs with the start of discharge, and it takes a considerable amount of time to recover to the specified voltage. It was 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 the electrolytic solution. Dissolving vinyl polymers such as copolymers with vinyl is disclosed. Although such a method surely improves the voltage delay phenomenon significantly, as a result of research, we found that the degree of voltage recovery largely depends on the degree of polymerization of the vinyl polymer to be added, and completed the present invention. .

[Object of the Invention]

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

[Outline of Invention]

The present invention comprises a negative electrode composed of at least one light metal selected from lithium, sodium, and aluminum, 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 material. In the non-aqueous solvent battery, the average degree of polymerization in the electrolytic solution is 700
It is a non-aqueous solvent battery characterized by adding vinyl polymer of not less than 2000 and not more than 700 in this way 2
A battery using an electrolyte solution containing less than 000 vinyl polymers does not show a large voltage drop even after a large current discharge after storage, and the voltage recovery time is short.

In this case, the average degree of polymerization is 2000 when the voltage recovery time is shortened.
Although it is markedly higher than that of a battery in which a vinyl polymer having an average polymerization degree of more than 700 is added to the electrolytic solution, it is more preferable to use a vinyl polymer having an average degree of polymerization of 700 to 1700.

The amount of vinyl polymer added to the electrolytic solution is 0.2 to 10 g /
It is desirable to set the range to. The reason for this is that when the vinyl polymer content is less than 0.2 g /, the effect of suppressing the voltage drop cannot be sufficiently exerted, and when the amount exceeds 10 g, not only does the effect increase little, but This is because the discharge capacity of the battery may be reduced.

Example of Invention

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

Example 1 in the drawings is a bottomed cylindrical can body made of, for example, stainless steel, the upper surface of which also serves as a negative electrode terminal is opened. A cylindrical load 2 made of metallic lithium is pressure-bonded to the inner surface of the can body 1. Inside the can body 1 inside the load 2, a positive electrode 5 having a structure in which a cylindrical porous carbon layer 4 is pressure-bonded to the outside of a metal current collector 3 made of a cylindrical stainless steel net is a separator made of a glass nonwoven fabric.
It is provided via 6 ₁ , 6 ₂ . The positive electrode 5 is
For example, a commercially available acetylene black polyetrafluoroethylene is mixed, and this kneaded material is molded into a cylindrical shape with the metal net 3 of the stainless steel net so that the current collector is on the inside, and then the vacuum at 150 ° C. It is prepared by drying below and forming 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 provided in a central hole 9 of the metal top 8 via a glass sealing material 11 to form a metal top. It is electrically insulated and fixed to 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.

Commercially available batteries with different average degrees of polymerization are used as electrolytes for batteries with this structure, in which thionyl chloride (SOCl ₂ ) contains aluminum chloride (AlCl ₃ ) and lithium chloride (LiCl) in an amount of 1.5 mol / mol. Five kinds of batteries were prepared using the electrolyte solutions to which each of the polyvinyl chlorides (average degree of polymerization 700, 1100, 1400, 1700) was added.

Comparative Example 1 Same structure as in Example 1 except that a commercially available polyvinyl chloride having an average degree of polymerization of 2500 was added to an electrolytic solution in which AlCl ₃ and LiCl were dissolved in SOCl ₂ at 1.5 mol / mol, respectively. I assembled the battery.

Comparative Example 2 The same structure as that of Example except that a commercially available polyvinyl chloride having an average degree of polymerization of 3000 was added to an electrolyte solution in which AlCl ₃ and LiCl were dissolved in SOCl ₂ at 1.5 mol / mol, respectively. I assembled the battery.

Comparative Example 3 The same structure as in Example except that a commercially available polyvinyl chloride having an average degree of polymerization of 400 was added to an electrolyte solution in which AlCl ₃ and LiCl were dissolved in SOCl ₂ at 1.5 mol / mol. I assembled the battery.

With respect to the batteries of this example and Comparative Examples 1, 2, and 3 thus created, after the assembly was stored at 60 ° C. for 20 days, constant resistance discharge of 30Ω was performed, and the time until the voltage returned to 2.5 V, and the average The working voltage and the discharge capacity were measured. The results are shown in Fig. 2 and the table below.

As is clear from FIG. 2 and the table above, the battery with the vinyl polymer having an average degree of polymerization of 700 to 2000 added to the electrolyte has a voltage recovery time at the start of discharge as compared to the batteries with other vinyl polymers added. It can be seen that the discharge capacity is short and the discharge capacity is improved.

In the examples, polyvinyl chloride was used as the vinyl polymer, but polyvinylidene chloride, vinyl acetate, polyacrylonitrile vinyl chloride, vinylidene chloride copolymer, vinyl chloride / vinyl acetate copolymer, etc. A similar tendency was obtained when a vinyl polymer other than vinyl chloride was used, due to the difference in the degree of polymerization.

〔The invention's effect〕

As described in detail above, 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 of a non-aqueous solvent battery showing an embodiment of the present invention, and FIG. 2 is a discharge characteristic diagram of the non-aqueous solvent battery of 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 and aluminum, a positive electrode containing carbon as a main constituent, and an electrolytic solution containing sulfur oxyhalide as a main component and also serving as a positive electrode material. In the constituted non-aqueous solvent battery, the average degree of polymerization in the electrolytic solution 70
A non-aqueous solvent battery comprising 0 to 2000 vinyl polymer added.