JPS6164079A - Nonaqueous electrolyte battery - Google Patents

Abstract

PURPOSE:To improve the preservation characteristics of a nonaqueous electrolyte battery by using a solvent mixture containing propylene carbonate and tetrahydrofuran as the solvent of the nonaqueous liquid electrolyte and using lithium perchlorate as the solute. CONSTITUTION:A liquid electrolyte is prepared by dissolving, for example, 1mol/l of lithium perchlorate used as the solute in a solvent mixture prepared by combining propylene carbonate and tetrahydrofuran in a ratio of 1:1. A positive electrode is made by subjecting a mixture composed of manganese dioxide, carbon powder used as the conductive agent and fluorine resin powder to pressure molding before the molded mixture is thermally treated. A negative electrode with given dimensions is stamped out from a rolled lithium plate. Since the manganese dioxide of the positive electrode absorbs water of an amount at least that of water entering the battery during its storage, the content of water in the nonaqueous electrolyte decreases. Consequently, the preservation characteristics of the battery is improved.

Description

Detailed Description of the Invention (a) Industrial Application Field The present invention provides a negative electrode using light metals such as lithium cum or sodium chloride or their alloys as an active material, a positive electrode using manganese dioxide as an active material, and a solvent and a solute. The present invention relates to a non-aqueous electrolyte battery comprising a non-aqueous electrolyte comprising:

BACKGROUND ART This type of battery is disclosed in, for example, Japanese Patent Publication No. 57-4064, and has been put into practical use as a power source battery for calculators, watches, etc.

Now, in recent years, as the fields of application of this type of battery have expanded, there has been a demand for further improvements in battery characteristics, and one of these demands is an improvement in storage characteristics.

To improve this storage characteristic, it is necessary to reduce the moisture in the positive electrode and the moisture in the non-aqueous electrolyte as much as possible from the viewpoint that the negative electrode active material is highly reactive with moisture.

(c) Problems to be Solved by the Invention The object of the present invention is to further improve the storage characteristics of batteries by improving non-aqueous electrolytes.

Various solvents and solutes constituting the non-aqueous electrolyte have been proposed. For example, as disclosed in Japanese Patent Publication No. 57-52866, propylene carbonate, γ-butyrolactone, dimethquinethane, dioxocone, and tetrahydrofuran are used as solvents. In addition, as solutes, there are known to be chicums that react with perchlorine, and chicums that react with hock.

B) Alternative means for solving the problem The nonaqueous electrolyte of the battery of the present invention uses a mixed solvent containing propylene carbonate and tetrahydrofuran as a solvent, and lithium perchlorate as a solute.

(E) Function According to the dissolution into non-aqueous electrolyte according to the present invention, the water concentration in the non-aqueous electrolyte can be controlled when it is incorporated into a battery together with a positive electrode containing manganese dioxide as an active material.

(f) Example Examples of the present invention will be described in detail below.

A mixed solvent consisting of propylene carbonate and tetrahydroalane mixed at a mixing ratio of 1:1 is used as a solvent, and 1 mol/l of lithium perchlorate is added as a solute to this mixed solvent.
The dissolved material is used as an electrolyte.

Positive electrode t-i: Manganese dioxide heat-treated in a temperature range of 550 to 450°C is used as an active material, and this manganese dioxide, carbon powder as a conductive agent, and fluororesin powder as a binder are mixed in a weight ratio of 85:5 to 10:5. Using a mixture mixed in a ratio of 2 to 250°C and heat-treated at 250 to 350°C, the 8-pole was made by punching out a top plate to a specified size using lithium pressure. 5-1 Battery capacity IQ1
A 2QfnAH battery of the present invention is obtained. This battery is called A.

Next, in order to demonstrate the superiority of the battery A of the present invention, comparative batteries B to 0 were prepared using various solvents, solutes, and positive electrode active materials as shown in the table below.

In the table above, the mixing ratios of all mixed solvents are 1:1, and the concentrations of solutes are all 1 mol/l.

Figure 1 shows the discharge characteristics when batteries A, B, and O are assembled and immediately discharged at 25°C with a constant resistance of 12Ω, and Figure 2 shows the discharge characteristics after batteries A, B, and O are assembled. A discharge characteristic diagram is shown when the battery was stored at 60°C for 3 months and then discharged at 25°C with a constant resistance of 12Ω.

When comparing batteries A, B, and C from these characteristic diagrams, it can be seen that although the initial discharge characteristics are comparable, the battery A of the present invention is superior in the discharge characteristics after storage.

Figure 5 shows the change over time in the water concentration in the electrolyte when batteries A to G were stored at 60°C. It can be seen that, while it increases, in the battery A of the present invention, it decreases on the contrary.

Considering the reason for this, it is found that the increase in water content in batteries B to G is due to non-aqueous content: in addition to the water pre-contained in the decomposed solution, water outside the electrolyte oil is added to the battery during storage. This seems to be due to an intrusion inside.

On the other hand, according to studies conducted by the present inventors, when tetrahydrofuran is used as a solvent and manganese dioxide is used as a positive raking material, manganese dioxide seems to have the effect of adsorbing water. However, when tetrahydroalane is used alone as a solvent, there is a problem that the tetrahydroalane reacts with lithium as the negative electrode active material to generate hydrogen. Therefore, if propylene carbonate is added and used as a mixed solvent system, the reaction between propylene carbonate and lithium will form an extremely thin passive film on the lithium surface, which will prevent the reaction between tetrahydroalane and lithium chloride.

Also, by using lithium perchlorate as a solute,
Unlike the case with other solutes, the combination of the above mixed solvent, that is, the mixed solvent of propylene carbonate and tetrahydroalane, causes the water in the electrolyte to become unstable (in other words, it is easy to The amount of water adsorbed by manganese dioxide increases.

For the above reasons, it is thought that in the battery A of the present invention, the water concentration in the non-aqueous electrolyte decreases because more water is adsorbed by the manganese dioxide than the water that enters from outside the battery during storage. As a result, storage properties are improved.

(G) Effects of the Invention As mentioned above, a negative electrode whose active material is a light metal such as lithium or catholicum, or an alloy thereof.

In a non-aqueous electrolyte battery equipped with a positive electrode having manganese dioxide as an active material, a mixed solvent containing propylene carbonate and tetrahydrofuran as a solvent as the non-aqueous electrolyte;
Furthermore, by using lithium perchlorate as the solute, a non-aqueous electrolyte battery with excellent storage properties can be obtained, and its industrial value is extremely large.

[Brief explanation of the drawing]

Figure 1141 and Figure 2 are discharge characteristic diagrams, where Figure 1 shows the initial characteristics, Figure 2 shows the storage characteristics after storage for 3 months at 60"C, and Figure 3 shows the discharge characteristics when stored at 60"C. Fig. 3 shows the change in water concentration in the non-aqueous electrolyte over time. (4)...Battery of the present invention, a3) to (q... Comparative battery.

Claims (1)

[Claims] (1) A negative electrode comprising a light metal such as lithium or sodium or an alloy thereof as an active material, a positive electrode comprising manganese dioxide as an active material, and a non-aqueous electrolyte comprising a solvent and a solute, A non-aqueous electrolyte battery, wherein the solvent is a mixed solvent containing propylene carbonate and tetrahydrofuran, and the solute is lithium perchlorate.