JPH03252064A - Inorganic nonaqueous electrolytic battery and manufacture thereof - Google Patents

Abstract

PURPOSE:To prevent a reduction in operating voltage by long-term storage and stabilize discharge characteristic by conducting a fixed quantity of pre- discharge at a low current such that a negative electrode can uniformly discharge after battery assembling. CONSTITUTION:An inorganic nonaqueous electrolytic battery is formed of a negative electrode 1, a batter vessel 2, a positive electrode 3, a separator 5, an electrolyte 5, a positive electrode collector 6, a battery cap 7, a body, a glass layer 9, and a positive electrode terminal 10. After battery assembling, a slight quantity of electricity is pre-discharged at a low current. The current at the time of pre-discharge is less than 0.6mA per unit area of lithium. As the discharge quantity in the pre-discharge, 10% or more of the theoretical electric capacity of lithium of the negative electrode 1 is proper in the view of stability of effect. Hence, a reduction in operating voltage by a long-term storage can be prevented, and discharge characteristic can be stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inorganic nonaqueous electrolyte battery in which an oxyhalide as a positive electrode active material also serves as a solvent for an electrolyte, and a method for manufacturing the same.

[Conventional technology]

Oxyhalides that are liquid at room temperature, such as thionyl chloride, sulfuryl chloride, and phosphoryl chloride, are used as positive electrode active materials.
An inorganic nonaqueous electrolyte battery uses an alkali metal such as lithium, sodium, or potassium for the negative electrode and a porous carbon material for the positive electrode, and the oxyhalide of the positive electrode active material also serves as the solvent for the electrolyte. Although it has excellent properties such as being able to operate at high temperatures and at low temperatures, the oxyhalide in the positive electrode active material and the alkali metal in the negative electrode are in contact with each other, so if stored for a long period of time, alkali halides will form on the negative electrode. A film is formed and this film grows into a dense and strong film that inhibits the battery reaction and causes a significant drop in the battery's operating voltage.

Therefore, as measures to prevent this, a method of adding vinyl polymer to the electrolyte (Japanese Patent Laid-Open No. 62-128454), a method of storing the battery at high temperature after assembly (Japanese Patent Laid-Open No. 62-128454),
-198056) and a method of coating the negative electrode with cyanoacrylate (U.S. Pat. No. 4,402.995), but methods such as adding or coating an organic substance such as vinyl polymer or cyanoacrylate have been proposed. If the separator is stored at high temperatures, the binder in the separator may elute into the electrolyte and react with the electrolyte, reducing the strength of the separator. There are problems such as letting

[Problem to be solved by the invention]

The present invention solves the problem that the conventional inorganic non-aqueous electrolyte battery has, in which the operating voltage of the battery decreases due to long-term storage, and the operating voltage does not significantly decrease even after long-term storage. The purpose of the present invention is to provide an inorganic non-aqueous electrolyte battery.

[Means to solve the problem]

The present invention achieves the above object by discharging a small amount of electricity at a low current after battery assembly.

As mentioned above, by discharging a small amount of electricity at a low current after battery assembly (hereinafter, this discharge after battery assembly is referred to as pre-discharge), there will be no significant drop in operating voltage even when stored for a long time. To explain why a battery can be obtained, using a lithium-thionyl chloride battery, which is a typical inorganic non-aqueous electrolyte battery, as an example, the negative electrode surface becomes a clean lithium surface through preliminary discharge, and then chloride containing no impurities is formed. Once a lithium film is formed, this lithium chloride film acts as a protective film and does not cause a significant drop in operating voltage even after long-term storage.In other words, even without pre-discharging as described above, chloride remains on the surface of the negative electrode. A lithium film is formed, but the lithium chloride film contains impurities,
This causes the growth of a dense and strong film, which inhibits the battery reaction and lowers the operating voltage. When a lithium film is formed, the lithium chloride film does not contain impurities and does not become a dense and strong film even after long-term storage, so it does not inhibit battery reactions and therefore causes a significant drop in operating voltage. Therefore, the discharge characteristics of the battery are stabilized.

In the preliminary discharge, if the negative electrode is gradually discharged at a low current, the entire surface of the negative electrode will be uniformly discharged, so that a uniformly clean lithium surface will be obtained. The current during this preliminary discharge is 0.6 per unit area of lithium.
It is appropriate to keep it below mA. The smaller the current, the more uniformly the lithium surface will be cleaned, but if the current is too small, the cleaning effect on the lithium surface will be insufficient. It is preferable to use less than .6 mA.

It is appropriate for the amount of discharge in the preliminary discharge to be 10% or more of the theoretical electric capacity of lithium in the negative electrode, from the viewpoint of stabilizing the effect. The reason for this is not clear at present, but by pre-discharging 10% or more of the theoretical capacity of the lithium in the negative electrode, the lithium surface in the negative electrode becomes a sufficiently uniform and clean surface, and the lithium in the electrolyte becomes The discharge reaction product concentration is
It is considered that when the amount exceeds a certain level, the lithium chloride film formed on the lithium surface of the negative electrode no longer contains impurities.

The amount of discharge during preliminary discharge may be large from the viewpoint of cleaning the lithium surface, but as the amount of discharge during preliminary discharge increases, the discharge capacity of the battery decreases.
Normally, it is preferable to set the value to 15% or less of the theoretical electric capacity of lithium. In the present invention, the theoretical electric capacity of lithium in the negative electrode refers to the theoretical electric capacity of the lithium used in battery assembly. It means the theoretical electric capacity.

In addition, if the battery is aged for 2 to 7 days at 45 to 80°C after the above pre-discharge, a suitable film of lithium chloride will be formed during that time, and it will remain stable even during subsequent storage, preventing a significant drop in operating voltage. can do. If the temperature at the time of aging is lower than 45℃, there is little effect, and 80"
When it exceeds C, the binder in the separator dissolves into the electrolyte and reacts with the electrolyte, weakening the strength of the separator.

In the above explanation, a lithium-thionyl chloride battery was explained using thionyl chloride as the oxyhalide and lithium as the alkali metal. In an inorganic non-aqueous electrolyte battery using , potassium, or the like, the same effect of preliminary discharge as described above can be obtained.

Therefore, in the present invention, in addition to thionyl chloride, oxyhalides that are liquid at room temperature, such as sulfuryl chloride and phosphoryl chloride, can be used as the positive electrode active material. These oxyhalides are active materials for the positive electrode and are also used as a solvent in the electrolyte, and the electrolyte contains these oxyhalides as well as LiAlC1n and LiAlBr.
4, prepared by melting a supporting electrolyte such as LiGac14, LiAlC1+o. In preparing the electrolyte, supporting electrolytes such as LiAlC1 are present in the form of LiAlC1 in the electrolyte by adding LiC1 and AlCl to oxyhalides (however, they are ionized to form Li- ions and AlCl4+ ions). In addition to lithium, the negative electrode may also contain
Alkali metals such as sodium and potassium can be used.

〔Example] Next, the present invention will be further explained with reference to Examples.

A glass fiber non-woven fabric with a porosity of 95% by volume and a thickness of 200 μm was used as a separator, lithium was used for the negative electrode, thionyl chloride was used for the positive electrode active material, and the electrolyte contained Li A I CI g in this thionyl chloride. 1゜2wol/
j! Using the dissolved material, an AA-sized inorganic non-aqueous electrolyte battery based on lithium thionyl chloride and having the structure shown in FIG. 1 was fabricated.

To explain the battery shown in Fig. 1, (1) is a negative electrode, and this negative electrode (1) is made of lithium, and a lithium sheet is placed in a bottomed cylindrical battery container (2) made of stainless steel.
) is formed into a cylindrical shape by being crimped onto the inner peripheral surface of the cylinder. (3) is a positive electrode, and this positive electrode (3) is made of a cylindrical porous carbon molded body whose main constituent material is carbon made by adding a small amount of polytetrafluoroethylene as a binder to acetylene black. (1) and separator (
4). The separator (4) is made of glass fiber nonwoven fabric, has a cylindrical shape, and separates the cylindrical negative electrode (1) and the cylindrical positive electrode (3).

(5) is an electrolytic solution, and this electrolytic solution (5) uses thionyl chloride, which is a positive electrode active material, as an electrolyte solvent, and this thionyl chloride has LiAlCl as a supporting electrolyte,
It is prepared by dissolving. Because the positive electrode active material thionyl chloride also serves as the electrolyte solvent, this battery differs from other batteries in that a large amount of electrolyte (5) is injected into the battery, and thionyl chloride As can be seen from the fact that thionyl is the positive electrode active material, the positive electrode (3) does not react with itself, but lithium ions ionized and eluted from the positive electrode active material thionyl chloride and the negative electrode (1). This is the place where the reaction takes place. (6) is a positive electrode current collector made of stainless steel.
('7) is the battery cover, and this battery cover (7) is the body (
8), a glass layer (9), and a positive terminal (10), the body (8) is made of stainless steel, and its raised outer periphery is welded to the open end of the battery container (2). It is joined. The glass layer (9) is provided on the inner circumferential side of the body (8), and this glass layer (9) insulates the body (8) and the positive electrode terminal 00), and the constituent glass on the outer circumferential surface of the body (8) is fused to the inner circumferential surface of the body (8), and the constituent glass is fused to the outer circumferential surface of the positive terminal 0■ on the inner circumferential surface to seal between the body (8) and the positive terminal (10). There is. The positive electrode terminal 00) is made of stainless steel, and part of it is shaped like a pipe and is used as an electrolyte inlet when the battery is assembled, and its upper end is used as the positive electrode current collector inserted into the hollow part after the electrolyte is injected. It is sealed by welding to the upper part of (6).

00 is a bottom insulating material, and this bottom insulating material 00 is made of glass fiber nonwoven fabric and insulates the positive electrode (3) and the battery container (2) which also serves as the negative electrode terminal. 0 is the upper insulation material,
This upper insulating material 0 is made of the same glass fiber nonwoven fabric as the bottom insulating material θ0, and is insulated to prevent direct contact between the positive electrode (3) and the body (8) of the battery lid (7), which also serves as the negative electrode terminal. There is. An air chamber a2 is provided in the upper part of the battery to absorb the volumetric expansion of the electrolytic solution when the temperature rises.

The above battery was assembled as shown below.

First, a lithium sheet is pressure-bonded to the inner peripheral surface of a cylindrical battery container (2) with a bottom to form a negative electrode (1).
A separator (4) is placed along the inner circumferential surface of the cell, then a bottom insulating material 0θ is placed at the bottom of the battery container (2), and a cylindrical positive electrode (3) is inserted into the inner circumferential side of the separator (4). Then, place the upper insulating material surface on the positive electrode (3), fit the battery lid (7) into the opening of the battery container (2), and connect the outer periphery of the body (8) of the battery lid (7) with the battery. The open end of the container (2) is welded and joined with a carbon dioxide laser, the electrolyte is injected into the battery through the pipe part of the battery lid (7), and after the electrolyte is injected, the positive electrode current collector is inserted into the pipe part. (6), pass the lower end of the positive electrode current collector (6) through the upper insulating material 02) and reach the inside of the positive electrode (3), and insert the upper part of the positive electrode current collector (6) into the upper end of the pipe section. The battery was assembled in the state shown in FIG. 1 by welding and sealing and forming the positive electrode terminal 0(1).

The batteries assembled as described above were charged at 0.05 mA, 0.2 mA, 0.6 mA per unit area of negative electrode lithium, and 1
．． Each flow was pre-discharged to 4%, 7%, 10%, and 15% of the theoretical capacitance of lithium at currents of 0 mA and 3 mA.

These batteries were stored at room temperature for 300 days, and after storage, 20
The closed circuit voltage was measured by discharging at 100Ω for 5 seconds at °C. The results are shown in FIG.

In addition, a battery pre-discharged to 10% of the theoretical capacitance of lithium with a current of 0.6 mA was immediately discharged at 30°C, 45°C, 160°C, 80°C, and 100°C for 1 hour each. Aging was performed by storing for 1 day, 2 days, 3 days, 7 days, and 14 days.

These batteries also have a lifespan of 300°C at room temperature, as described above.
After storage, the battery was discharged at 20° C. and 100Ω for 5 seconds, and the closed circuit voltage was measured. The results are shown in FIG.

In Figure 2, the current during pre-discharge is plotted on the horizontal axis, and the closed-circuit voltage is plotted on the vertical axis, and the relationship between the current during pre-discharge and the closed-circuit voltage is shown for each amount of discharge during pre-discharge. As shown in Figure 2, 0.6 mA per unit area of lithium
When 10% or more of the theoretical electric capacity of lithium was predischarged at the following current, the closed circuit voltage was 3.0 V or more even after 300 days of storage, indicating that the operating voltage did not decrease much. The closed circuit voltage after storage without any pre-discharge is 2.55V, and if 10% or more of the theoretical capacitance of lithium is pre-discharged with a current of 0.6 mA or less per unit area of lithium. In comparison, the closed-circuit voltage was low, indicating that the drop in operating voltage due to storage was large.

In addition, even when pre-discharging 10% or 15% of the theoretical capacity of lithium, or pre-discharging at a current of 1.0 mA or 3.0 mA, there was no significant decrease in the closed circuit voltage, but the battery could be disassembled. As a result, the lithium surface was consumed unevenly, and it was predicted that the current density would be uneven when the pre-discharged battery was used, which was not desirable as a pretreatment.

In Figure 3, the horizontal axis represents the number of storage days during aging, and the closed circuit voltage represents the vertical axis, and the relationship between the number of storage days and the closed circuit voltage is shown for each temperature during aging. , aging temperature is 45-80℃ and 2-7
When aging was performed by storing for days, the closed circuit voltage was high and the effect was found to be further improved.

〔Effect of the invention〕

As explained above, in the present invention, after the battery is assembled, pre-discharge is carried out at a constant amount at a low current that can uniformly discharge the surface of the negative electrode. We were able to provide a water electrolyte battery.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of an inorganic non-aqueous electrolyte battery according to the present invention. FIG. 2 is a diagram showing the relationship between current and closed circuit voltage during preliminary discharge for each amount of discharge during preliminary discharge. Third
The figure is a diagram showing the relationship between storage days and closed circuit voltage during aging for each temperature during aging. (1)...Negative electrode, (3)...Positive electrode, (4)...
・Separator, (5)...Electrolyte solution 1 Diagram o, Qric! 6 1θ L(-A)

Claims (10)

[Claims] (1) An oxyhalide that is liquid at room temperature is used as a solvent for a positive electrode active material and an electrolytic solution, and a negative electrode (1) made of an alkali metal, a positive electrode (3) made of a carbon porous molded body, and a separator (4), Electrolyte (
5), and the separator (4) has the negative electrode (1) and the positive electrode (
3) In the inorganic non-aqueous electrolyte battery placed between An inorganic nonaqueous electrolyte battery characterized by undergoing stabilization treatment. (2) The oxyhalide is thionyl chloride, the alkali metal is lithium, and the negative electrode (1) is stable enough to discharge 10% or more of the theoretical electric capacity of lithium at a current of 0.6 mA or less per unit area of lithium. The inorganic non-aqueous electrolyte battery according to claim 1, which has been subjected to a chemical treatment. (3) The inorganic nonaqueous electrolyte battery according to claim 1 or 2, wherein the inorganic nonaqueous electrolyte battery is aged by being stored in an atmosphere at 45 to 80°C for 2 to 7 days immediately after the stabilization treatment. (4) An oxyhalide that is liquid at room temperature is used as a positive electrode active material and an electrolyte solvent, and a negative electrode (1) made of an alkali metal, a positive electrode (3) made of a carbon porous molded body, and a separator (4), Electrolyte (
5), wherein the separator (4) is the negative electrode (1) and the positive electrode (3).
) When manufacturing an inorganic non-aqueous electrolyte battery placed between 1. A method for producing an inorganic non-aqueous electrolyte battery, which comprises performing a stabilization treatment. (5) 0.05 to 0.6 mA per unit area of negative electrode (1)
5. The method for manufacturing an inorganic non-aqueous electrolyte battery according to claim 4, wherein the battery is discharged at a current of . (6) The method for manufacturing an inorganic non-aqueous electrolyte battery according to claim 4 or 5, wherein 10 to 15% of the theoretical electric capacity of the negative electrode (1) is discharged. (7) The oxyhalide is thionyl chloride, the alkali metal is lithium, and 10% or more of the theoretical electric capacity of the lithium is discharged at a current of 0.6 mA or less per unit area of the lithium of the negative electrode (1). 5. The method for manufacturing an inorganic non-aqueous electrolyte battery according to claim 4, wherein a stabilization treatment is performed. (8) 0.05 to 0.05 per unit area of lithium in negative electrode (1)
0. 8. The method for manufacturing an inorganic non-aqueous electrolyte battery according to claim 7, wherein the battery is discharged with a current of 6 mA. (9) The method for manufacturing an inorganic nonaqueous electrolyte battery according to claim 7 or 8, wherein 10 to 15% of the theoretical electric capacity of lithium is discharged. (10) The inorganic non-water according to claim 4, 5, 6, 7, 8 or 9, wherein after the stabilization treatment, the inorganic non-water is immediately stored in an atmosphere of 45 to 80°C for 2 to 7 days to carry out aging. A method of manufacturing an electrolyte battery.