JPS61288374A - Organic electrolyte cell - Google Patents

Abstract

PURPOSE:To improve preserving property of a cell, by using an alkaline metal including silicone dioxide or a silicate compound as a negative electrode active substance. CONSTITUTION:To remove impurities in an organic electrolyte, such as peroxide compounds typically, and impurities melted from a positive electrode composite 4, an alkaline metal including silicone dioxide or a silicate compound is used as a negative electrode active substance. Therefore, the impurities in the organic electrolyte, peroxide compounds as a typical one, and the impurities melted from the positive electrode composite are absorbed or decomposed to make a stable compound by the silicone dioxide or the silicate compound, and so a lithium 2 surface, which is a negative electrode active substance, is not contaminated, whose active condition is maintained. Consequently, the preserving property can be improved.

Description

[Detailed description of the invention] Industrial applications The present invention relates to improvements in organic electrolyte batteries.

Conventional technology Organic electrolyte batteries have high energy density and storage performance that is much superior to other battery systems, so in recent years, with the development of the electronics field, they have become popular as power sources for various electronic devices. It is attracting attention, especially as a memory backup power supply. To this end, there is a need for further reliability in long-term storage and reduction of variations between batteries.

In batteries that use alkali metals as negative electrode active materials, if moisture, oxygen, or other impurities are present inside the battery, gas generation,
This causes voltage deterioration, capacity reduction, increase in internal resistance (large variation in internal resistance), and deterioration in storage performance. Therefore, it is desired that the impurities and the like be sufficiently removed.

Taking the example of a lithium battery, in which battery materials are conventionally pretreated in the following manner in order to remove the impurities, etc.: ■ Purification of organic electrolytes and organic solvents (dimethoxyethane is used as an organic solvent) , propylene carbonate, tetrahydrofuran,
Solvents with high dielectric constants such as γ-butyrolactone, jetoxyethane, and dioquinrane are mainly used.
+LiCρ4 t LIA8F6 p LiBF4, etc.) Dehydration by vacuum drying ■ Various parts (case, sealing plate, gasket, separator) Moisture removal by vacuum drying Moisture removal by high humidity drying ■ Active material, lithium - melt purification, positive electrode mixture (mainly (composed of cathode active material, conductive material, and binder) - Moisture removal by vacuum drying Despite this pretreatment, moisture, oxygen, and other moisture in the atmosphere are removed by the end of battery assembly. Foreign matter gets inside the battery. Furthermore, impurities that cannot be removed by the above-mentioned pretreatment also enter the battery. Therefore, the battery characteristics could not be sufficiently improved.0 Problems to be Solved by the Invention Organic electrolyte batteries, compared to aqueous batteries, require the purification of various materials, especially the positive electrode mixture and electrolyte solution. It is difficult to purify
Various impurities are present within batteries. Furthermore, as described above, moisture, oxygen, and other impurities in the atmosphere also enter the battery.

Furthermore, organic electrolyte batteries use active alkali metals such as lithium as negative electrode active materials. Therefore,
Impurities present inside the battery react with active lithium metal to form a passive film, resulting in problems such as an increase in internal resistance, a decrease in battery capacity, and a decrease in voltage.

Organic electrolytes are usually prepared by mixing two or three types of organic solvents and dissolving the electrolyte in the mixture. The preparation step includes a stirring step,
Impurities in the atmosphere mix into the electrolyte. Further, the organic solvent is purified by distillation and molecular sieve treatment, but both treatments are performed in the atmosphere, and oxygen is dissolved in the solvent. Furthermore, oxygen is dissolved during the stirring step as well. It is generally known that oxygen dissolved in an organic electrolyte reacts with the organic solvent, particularly the organic solvent having an ether bond, to produce a peroxide compound.

Furthermore, since peroxide compounds easily combine with alkali metals, they react with lithium, which is a battery negative electrode active material, and a passive film of an organic compound is formed on the lithium surface. This causes an increase in the internal resistance of the battery, a decrease in voltage, and a decrease in battery capacity.

On the other hand, the positive electrode mixture is made by kneading the positive electrode active material, conductive material, and binding material, forming it into a pellet shape after drying, and then vacuum drying it before battery assembly. impurities contained in the material, which only includes processes;
In particular, organic compounds are eluted during removal, react with active lithium, form a passive film on the lithium surface, and there is a problem in that the internal resistance increases during storage of the battery.

An object of the present invention is to solve the above-mentioned conventional problems and provide an organic electrolyte battery with excellent storage performance and excellent battery characteristics.

Means for Solving the Problem In order to solve this problem, the present invention uses silicon dioxide to remove impurities in the organic electrolyte represented by peroxide compounds and impurities eluted from the positive electrode mixture. Alternatively, an alkali metal containing a silicate compound is used as a negative electrode active material.

Function: According to this configuration, the silicon dioxide or silicate compound adsorbs or decomposes impurities represented by peroxide compounds contained in the organic electrolyte and impurities leached from the positive electrode mixture, thereby converting them into stable compounds. Therefore, the surface of lithium, which is the negative electrode active material, is not contaminated and remains active.

Therefore, the increase in internal resistance and drop in voltage are eliminated, and the storage characteristics are dramatically improved.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to FIG. 1st
The figure shows a lithium-fluorocarbon type flat organic electrolyte battery, and its capacity is 250 m1.

In the figure, 1 is a sealing plate made by punching a stainless steel plate with a thickness of 0.30 ffll to an outer diameter of 22.7 fflll, and 2 is a sealing plate made of lithium containing 100 ppm of silicon dioxide of the present invention, with a diameter of 20 jrj! , thickness o, 5 oarz and press-bonded to the sealing plate 1. Reference numeral 3 denotes a separator made of polypropylene reed, which was punched out from a sheet with a thickness of 0.40 ffl to an outer diameter of 23.5 mm, formed into a pot shape, and inserted into the sealing plate.

4 is a positive electrode mixture pellet, 100 parts by weight of fluorocarbon, 10 parts by weight of acetylene black, fluororesin, 14
Parts by weight were kneaded, dried and pulverized, and then molded into a pellet shape, and the weight was 450 Da.

5 is an insulating backing, after molding polypropylene into a cross-sectional shape, a sealing agent mainly made of blown asphalt is applied to the inside, and it is fitted to the periphery of the sealing plate. 6 is a positive electrode case which also serves as a positive electrode terminal, and the outer mold is 24.4fl made of stainless steel plate.

It is punched into a shoulder with a height of 3.2M. The positive electrode current collector is a titanium sheet with a width of 12.0 ff* and a thickness of 0.1 mm. Off1l! It is cut out into corners, bent to form a spring shape, and welded to the positive electrode case. Further, a carbon film is formed on the surface of the electrode for the purpose of improving contact with the positive electrode pellet. The electrolytic solution used is one in which lithium borofluoride is dissolved in a volumetric mixed solvent such as 1,2-jethoxyethane and globylene carbonate at a ratio of 1 mol/l.

In this example, carbon fluoride was used as the positive electrode active material, but other materials known as active materials for organic electrolyte batteries, such as copper oxide, iron sulfide, manganese dioxide, and silver chromate, were also used. It can be similarly applied to battery systems.

Next, the battery of this embodiment is designated as A, and the conventional example is designated as B, and the battery characteristics immediately after assembly and after storage in SO'C for 6 months are shown in Table 1 below.

Table 1: 50 units each for n types As is clear from Table 1, immediately after assembly, the battery of this example has more stable static characteristics than the conventional example, and the discharge capacity is also higher than that of the conventional example. are doing.

Furthermore, even after storage at 60° C. for 6 months, the battery of this example shows superior characteristics compared to the conventional example.

Figure 2 shows battery A of this embodiment and battery B of a conventional example.
It shows the changes in internal resistance and open circuit voltage during storage at ℃.

As is clear from the figure, the actual product A is stable with little increase and variation in internal resistance during storage. The same applies to the open circuit voltage.

In this example, lithium containing silicon dioxide was used, but even if lithium containing a silicate compound was used, the P1
Similar effects can be obtained.

In order to determine the optimal content of the silicon dioxide or silicate compound of the present invention in the negative electrode active material, the content was varied and variations in internal resistance and discharge capacity were confirmed. The results were as shown in Table 2. In the table, XX indicates extremely poor, × indicates poor, ○ indicates good, and Δ indicates slightly poor.

From the results shown in Table 2 and above, it can be seen that the optimum content of silicon dioxide or silicate compound is 50 ppm to 800 ppm.

As is clear from the explanation beyond the effects of the invention, 50 ppm to 800
The battery of the present invention uses an alkali metal as a negative electrode active material containing ppm of silicon dioxide or a silicate compound because the silicon dioxide or silicate compound has the effect of adsorbing or decomposing impurities mixed inside the battery. , the increase in internal resistance, the decrease in voltage, and the decrease in battery capacity are eliminated, and the storage characteristics are improved.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-section of a flat organic electrolyte battery according to an example of the present invention, and FIG. 2 is a diagram showing changes in open circuit voltage and internal resistance of the same battery when stored at 60'C. 1...Sealing plate, 2-...--Lithium negative electrode,
3... Separator, 4... Positive electrode mixture pellet.

Claims (2)

[Claims] (1) An organic material comprising a positive electrode active material made of any one of a metal oxide, a halide, or a chalcogen compound, an organic electrolyte, and a negative electrode active material made of an alkali metal containing silicon dioxide or a silicate compound. electrolyte battery. (2) The organic electrolyte battery according to claim 1, wherein the amount of silicon dioxide or silicate compound contained in the alkali metal is 50 ppm to 800 ppm.