JPS61190864A - Nonaqueous solvent battery - Google Patents

Abstract

PURPOSE:To reduce voltage drop in the initial stage of high rate discharge by forming a negative electrode comprising lithium of nonaqueous solvent battery by covering at least part of the surface of the negative electrode with polyethylene oxide. CONSTITUTION:A cylindrical negative electrode 2 comprising metallic lithium whose surface is covered with polyethylene oxide is pressed against the inner surface of container 1 which also serves as a negative terminal, and a positive electrode 5 comprising a carbon porous layer 4 which is pressed against a current collector 3 made of stainless steel net is arranged with separators 61, 62 comprising glass nonwoven fabric interposed between the negative electrode 2 and the positive electrode 5. An electrolyte 13 mainly comprising sulfur oxyhalide which also serves as positive active material is pored into the container 1 for forming a nonaqueous solvent battery. By properly specifying the film thickness of polyethylene oxide, voltage drop in the initial stage of discharge is reduced, and the recovery time of voltage is shortened without increase in internal resistance.

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 electrolytic solution 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 R storage characteristics, and a wide operating temperature range, so they are used in calculators, watches, and memories. It is often used as a backup power source. Among them, 'lithium' is used for the negative electrode, and thionyl chloride (socz,
), batteries using sulfur oxyhalides such as sulfuryl chloride (80*CJt) are attracting attention because of their particularly high energy density. These batteries have positive electrodes consisting of carbon and metal current collectors, typically aluminum chloride A (J), aluminum bromide (Ajiro), etc.
A liquid oxyhalide of sulfur is used as an electrolyte, which is a solution of a Lewis acid such as lithium chloride or a Lewis base such as lithium chloride or lithium bromide. Therefore, the liquid oxyhalide can be used as both the positive electrode active material and the electrolyte.
By using an appropriately shaped positive electrode, 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, which is the negative electrode, an LICJ skin, which is a reaction product, is generated on the surface of the negative electrode lithium. This LIC 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 moves as a resistive component, causing a voltage drop in the early stages of discharge. The extent of this voltage drop is radiant! 1
When the lCvIL current is minute on the μA order, it is negligible, but it cannot be ignored when it is a large current discharge, especially after storage at high temperatures for a long time and significant growth of LiCj skin occurs, or at low temperatures. When discharging, there is a problem in that a significant voltage drop occurs at the start of discharge, and it takes a considerable amount of time to recover to a predetermined voltage.

Several proposals have been made to solve the above problems.
The voltage delay phenomenon was reduced by using a complex salt obtained by reacting ionic compounds such as i1S, Li1O, CaO, BaO, etc. with AlCl, and in JP-A-56-7360, chloride was added to the electrolyte. It has been disclosed that a polymer such as vinyl and a sulfur compound such as lithium sulfide are added to reduce the voltage delay phenomenon due to the mutual effect of the two. Although this method does significantly improve the voltage delay phenomenon, it has drawbacks such as low conductivity of the electrolyte and troublesome storage, handling, and dehydration of hygroscopic lithium sulfide.

[Purpose of the invention]

The present invention aims to eliminate such drawbacks and provide a non-aqueous solvent battery which has a small voltage drop even in the early stages of large current discharge and a short voltage recovery time.

[Summary of the invention]

The present invention provides a non-aqueous solvent battery comprising a negative electrode made of a light metal such as lithium, a positive electrode mainly made of carbon, and an electrolyte that also serves as an active material and made of a sulfur oxyhalide. , characterized in that at least a portion of the surface of the negative electrode is coated with polyethylene oxide.

In this way, a battery in which at least a portion of the negative electrode surface is coated with a copolymer of vinyl chloride and vinylidene chloride does not show a significant voltage drop even when discharged at a large current after storage, and also has a short voltage recovery time. short.

The method for coating at least a portion of the negative electrode with polyethylene oxide includes, for example, dissolving the polyethylene oxide in a non-aqueous solvent that does not react with negative electrode gold, applying the solution to the surface of the negative electrode, and drying it; There is a method of immersing the negative electrode in it and then pulling it up and drying it. In particular, the latter method is simple. The thickness of the copolymer coating the negative electrode surface can be changed by controlling the 1:1 degree of the solution. If the film is thick, the effect of preventing passivation of the negative electrode will not be sufficient, and on the other hand, if the film is made thicker than necessary, not only will the initial discharge characteristics not increase as described above, On the contrary, it becomes a factor that increases the internal resistance of the battery. Therefore, the a degree of the solution is 0.1 to 10% by weight.
It is appropriate to do so.

[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. The inner surface of the can body 1 is coated with gold [I] whose surface is coated with polyethylene oxide.
A cylindrical negative electrode 2 made of J-thium is crimped. The negative electrode 2 was prepared by pressing metallic lithium onto the inner surface of the can body 1, injecting 2 volumes of a tetrahydrofuran solution of the copolymer up to the upper end of the metal lithium, then removing the solution and drying.

Inside the can body 1 inside the negative electrode 2, a separator 6h made of glass nonwoven fabric is placed between the positive electrodes, which has a structure in which cylindrical porous carbon #4 is crimped onto the outside of a metal current collector 3 made of a cylindrical stainless steel net.
6! It is provided through.

The positive electrode 5 is made by, for example, mixing commercially available acetylene black and polytetrafluoroethylene, and forming the mixture together with a stainless steel mesh metal current collector 3 into a cylindrical shape so that the current collector is on the inside. After molding, it is dried under vacuum at 150° C. to form the porous carbon layer 4 from the mixed wire.

Further, in the can body 1 above the positive electrode 5, an insulating paper 7 supported by the separator 6 and having a hole in the center is disposed. A metal top 8 is sealed at the upper opening of the can body 1 by laser welding or the like, and a pipe-shaped positive electrode terminal 10 is inserted into a hole 91 at the center of the metal top 8 through a glass sealing material 11. The metal top 8 is electrically insulated and fixed to the metal top 8. The lower end of the positive electrode terminal 10 is connected to the metal current collector 3 of the positive electrode 5 via a lead wire 12. The electrolytic solution 13 injected from the pipe-shaped positive electrode terminal 10 is housed in the can body l. This electrolyte 13 contains aluminum chloride (AJej, ) and lithium chloride (Lic) in thionyl chloride (8QCl!v).
z> and 1.5 mol/! It is dissolved. A trunk body 14 made of stainless steel, for example, is inserted into the pipe-shaped positive electrode terminal 10, and the nuclear positive electrode terminal 10 is sealed by laser welding the tip of the terminal 10 and the inserted trunk body 14.

Comparative Example A battery having the same structure as the example was assembled except that a negative electrode made of only metallic lithium was used.

Therefore, for the batteries of this example and comparative example, the assembly fl.
After storing R for 3 months at 25℃, perform a constant resistance discharge of 30Ω and release it! When the initial characteristics of It were investigated, the characteristic diagram shown in FIG. 2 was obtained. In addition, in FIG. 2, A is the discharge curve of the battery of the example, and B is the discharge curve of the battery of the comparative example. Second
As is clear from the figure, the battery whose surface is coated with polyethylene oxide has a smaller initial voltage drop and a shorter voltage recovery time than the conventional battery.

It was also confirmed that the battery of this example had a larger discharge capacity than the battery of the comparative example.

〔Effect of the invention〕

As detailed above, according to the present invention, a non-aqueous solvent battery with excellent discharge characteristics can suppress voltage drop even in the early stage of large current discharge, shorten voltage recovery time, and improve discharge capacity. can be provided.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a non-aqueous solvent battery showing an embodiment of the present invention, and FIG. 2 is a curve diagram showing the discharge characteristics at the initial stage of large current discharge in the battery of the embodiment of the present invention and the battery of a comparative example. be. 1.-Can body, 2.. Negative electrode, 3.. Metal current collector, 4.
- Porous carbon layer, 5... Positive electrode, 61e61... Separator, 8... Metal top, lO... Pipe-shaped positive electrode terminal, 13... Electrolyte solution. Representative Patent Attorney Noriyuki Chika (and 1 other person) Figure 1 Figure 2 Figure 1-B Zate f own] (Second procedure amendment (self-motivated) September 35, 1932)

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 at least a portion of the surface of the negative electrode is coated with polyethylene oxide.