JPS6166363A - Nonaqueous electrolyte cell - Google Patents

Abstract

PURPOSE:To improve a characteristic of discharge voltage at the latter period of discharging for nonaqueous electrolyte cell with lithium on a negative electrode by adding a certain amount of copper sulfide to a positive polar active material consisting of iron disulfide to form a positive electrode. CONSTITUTION:A positive electrode 1 is formed by pressing, molding, and firing a black mix consisting of iron disulfide blended with cuprous sulfide of 1-20wt% together with acetylene black and graphite added as conductive materials, and fluoro-resin powder added as bonding agent. A negative electrode 2 of lithium acting as a negative polar active material, a separator 6 and nonaqueous electrolyte, are composed between a positive polar can 8 and negative one 4, then sealed to form an nonaqueous electrolyte cell. On discharge of the cell, copper sulfide reacts with lithium while iron disulfide is reacting with it, and copper of high conductivity is produced on the positive electrode 1, which inhibits a rise of internal resistance. Hence, a characteristic of discharge voltage can be maintained flat even at the latter period of discharging.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention relates to an improvement in a nonaqueous electrolyte battery that uses lithium or a lithium alloy as a negative electrode active material and iron disulfide as a positive electrode active material.

〉 Conventional technology A negative electrode using light metals such as lithium and sodium 24 or their alloys as active materials, and a positive electrode using metal oxides, chlorides, halogen carbon compounds, etc. as active materials, Organic solvents such as propylene carbonate, γ-butyrolactone, 12-dimethoxyecune, etc.
;・Nonaqueous electrolyte batteries equipped with an electrolyte in which inorganic salts such as lithium chloride are dissolved have high energy density and are attracting attention because of their low self-discharge. A 3V type non-aqueous electrolyte battery using C as a positive electrode active material has been put into practical use.

In recent years, there has been a great deal of interest and research into 1.5V nonaqueous electrolyte batteries and secondary battery type nonaqueous electrolyte batteries. In particular, 1.5V nonaqueous electrolyte batteries that are compatible with existing batteries as source batteries for small electronic devices are attracting attention, and their positive electrode active materials are disclosed in, for example, Japanese Patent Laid-Open No. 58-57262. Iron disulfide (FeS2) is known as disclosed in .

By the way, nonaqueous electrolyte batteries that use lithium or lithium alloy as a negative electrode active material and iron disulfide as a positive electrode active material have a problem in that internal resistance increases rapidly in the late stage of discharge, making it impossible to maintain flat discharge pressure characteristics. there were.

(c) Problems to be Solved by the Invention The present invention aims to improve the discharge voltage characteristics in the late stage of discharge in a non-aqueous electrolyte battery that uses lithium or a lithium alloy as a negative electrode active material and iron disulfide as a positive electrode active material. purpose.

(d) Means for Solving the Problems The present invention is characterized in that copper sulfide is added to the positive electrode whose active material is iron disulfide. Note that the amount of copper sulfide added is preferably in the range of 1 to 20% by weight based on the positive electrode active material.

(e) Effect When the battery of the present invention is discharged, a reaction occurs between copper sulfide and the rib ram in parallel with the reaction between iron disulfide and lithium, which are living materials, and the latter reaction causes a high conductivity in the positive electrode. Copper is produced.

Kube) Example Embodiments of the present invention will be described in detail below with reference to the drawings.

Creation of positive electrode: Commercially available iron disulfide (FeSz) was replaced with steel sulfide (Cu).
85% by weight of a mixture of 10:IJt% of aS), 10% by weight of acetylene black and graphite) as a conductive agent
After adding 5% by weight of fluororesin powder as a stone agent and mixing thoroughly, this mixture was press-molded at a pressure of about 2 tons/cm'' to form a stone with a diameter of 15.0 m/m and a thickness of 1.1 m/m. A molded body is obtained, and this molded body is fired at a temperature of 200 to 300°C to form a positive electrode (1).

Creating a battery: Rolled lithium plate with a thickness of about 0.6 m/m and a diameter of 15.0 m/m.
An insulating backing (3) is placed around the negative electrode (2) punched out at a+
) on the inner bottom surface of each negative electrode (4) where a negative electrode current collector (5) is placed.
At the same time, a separator is impregnated onto the negative electrode (2) with an electrolytic solution in which 1 mol/2 of lithium perchlorate is dissolved in a mixed solvent of propylene carbonate and 1,2 dimethoxyethane (6) and the positive electrode (6). 1) and then cover the positive electrode can (8) with the positive electrode current collector (7) fixed on the inner bottom surface.
) to make a completed battery. This battery is referred to as (A).

In addition, for comparison, a comparative battery was prepared using iron disulfide as the positive electrode active material and a positive electrode prepared without adding copper sulfide.
B) was assembled. Note that the comparative battery (B) was the same as the battery of the present invention except for the positive electrode. Figure 2 shows two of these batteries.
The discharge characteristics when discharged at a constant load of 5.6 Ω at 0°C are shown, and the figure shows that the Honyoshimei battery (A) has a
It can be seen that the increase in internal resistance can be suppressed and flat discharge voltage characteristics are exhibited.

Considering the reason for this, when the battery of the present invention is discharged, a reaction between copper sulfide and lithium occurs concurrently with a reaction between iron disulfide and lithium, and the latter reaction causes highly conductive copper to be deposited in the positive electrode. This is thought to be because the electroconductivity of the positive electrode is improved due to the formation of hydrogen, suppressing the increase in internal resistance, and improving the profit margin of the positive electrode.

It should be noted that the amount of copper sulfide added must be at least 1% by weight or more based on iron disulfide to be effective; on the other hand, if the amount added is too large, the filling amount of iron disulfide, which is the original active material, will decrease. The amount is preferably 20% by weight or less, and although cuprous sulfide is used as the copper sulfide in the examples, the same effect can be obtained by using cupric sulfide without being limited thereto.

(G) Effects of the Invention As mentioned above, according to the present invention, it is possible to obtain a 1.5V non-aqueous electrolyte battery that exhibits flat discharge voltage characteristics even in the late stage of discharge, and its industrial value is extremely high. It's large.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the battery of the present invention, and FIG. 2 is a comparison diagram of discharge characteristics between the battery of the present invention and a comparison battery. (1)...Positive electrode, (2)...Negative electrode, (3)...Insulating backing, (4>...Each negative electrode, (6)...Separator, (8)...Positive electrode can , (A)...Battery of the present invention, (B)...Comparison battery.

Claims (1)

[Claims] (1) A device comprising a negative electrode using lithium or a lithium alloy as an active material, a non-aqueous electrolyte, and a positive electrode using iron disulfide as an active material, characterized in that copper sulfide is added to the positive electrode. Non-aqueous electrolyte battery.