JPH0630259B2 - Non-aqueous electrolyte battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention provides a non-aqueous electrolytic solution including a negative electrode using lithium or a lithium alloy as an active material, a positive electrode, and a non-aqueous electrolytic solution containing a solvent and a solute. The present invention relates to a primary or secondary battery.

(B) Conventional technology For non-aqueous electrolyte primary batteries using lithium as the negative electrode active material, it is typical to use manganese dioxide or carbon fluoride as the positive electrode active material, and these have already been put to practical use. Has been done.

A non-aqueous electrolyte secondary battery using lithium as a negative electrode active material is disclosed in, for example, Japanese Patent Publication No. 59-11189, and sulfides and selenides of titanium, zirconium, niobium, tantalum, and vanadium are used as positive electrode active materials. Alternatively, telluride and the like have been proposed.

On the other hand, as an electrolytic solution for this type of battery, a common one has been proposed regardless of whether it is a primary battery system or a secondary battery system, and it is composed of at least one solvent and at least one solute. Propylene carbonate, γ-butyrolactone, dimethoxyethane and the like are generally used as the solvent, and lithium perchlorate, lithium borofluoride, lithium chloride and the like are generally used as the solute.

Thus, in recent years, as a solvent, for example, Japanese Patent Publication No.
As disclosed in Japanese Patent No. 11890 or Japanese Patent Publication No. 58-56466, dioxolane has attracted attention. Since dioxolane has the advantages that the solute has a higher solubility than other solvents and that the viscosity at low temperatures is low, a non-aqueous electrolyte battery having excellent low-temperature characteristics can be obtained.

However, the dioxolane single solvent, which reacts with active lithium to ring-opening polymerize to cause deterioration of the electrolytic solution, has a particular problem in battery storage characteristics.

(C) Problems to be Solved by the Invention An object of the present invention is to improve the storage characteristics of a non-aqueous electrolyte battery using dioxolane as a solvent.

(D) Means for Solving the Problems The battery of the present invention is characterized by using a mixed solvent containing dioxolane and trimethoxymethane as a solvent constituting the non-aqueous electrolyte.

(E) Operation According to the battery of the present invention, the reaction of dioxolane and lithium is suppressed by the addition of trimethoxymethane, and deterioration of the electrolytic solution is suppressed.

(F) Examples Hereinafter, examples of the present invention will be described with reference to the drawings, taking a non-aqueous electrolyte secondary battery as an example. FIG. 1 shows a half cross-sectional view of a battery. (1) and (2) are stainless steel positive and negative electrode cans, which are isolated by an insulating packing (3) made of polypropylene.

(4) is a positive electrode, which is a positive electrode mixture prepared by mixing titanium disulfide active material with acetylene black as a conductive agent and fluorine resin powder as a binder at a weight ratio of 80:10:10. It is a molded product and is pressed against the positive electrode current collector (5) fixed to the inner bottom surface of the positive electrode can (1). (6) is a negative electrode, which consists of a rolled lithium plate punched to a specified size
It is pressure-bonded to the negative electrode current collector (7) fixed to the inner bottom surface of (2).

(8) is a separator made of polypropylene nonwoven fabric, which is impregnated with an electrolytic solution having the following composition. That is, a mixed solvent containing dioxolane (DOXL) and trimethoxymethane (TMM) was used as a solvent, and 1 mol / mol of lithium perchlorate was dissolved in this mixed solvent.

Then, the volume ratio of the mixed solvent is DOXL: TMM is 1
Inventive batteries A, B, C and D having a ratio of 0: 1, 7: 3, 5: 5 and 3: 7 were prepared, and a comparative battery E was prepared using a single solvent of dioxolane. The table below shows the storage characteristics of these batteries (discharge conditions; 5 mA discharge, discharge end voltage 1.5 V).

It can be seen from the above table that the batteries (A) to (D) of the present invention have excellent storage characteristics as compared with the comparative battery (E).

Further, FIG. 2 shows a charge-discharge cycle characteristic diagram, and the charge-discharge conditions were a charge cutoff voltage of 10 mA, a charge cutoff voltage of 4.0 V, and a discharge discharge flow of 5 mA, a discharge cutoff voltage of 1.5 V. From FIG. 2, it can be seen that the battery of the present invention has dramatically improved cycle characteristics.

Considering the reason for this, lithium, which is the negative electrode active material, has a high activity and a high electron supply property, and therefore attacks an electron-accepting atom or group.

In the structural formula of dioxolane (DOXL), a carbon atom sandwiched by two oxygen atoms is in an electron-deficient state, that is, an electron-accepting property, and thus lithium attacks carbon.
As a result, the bond between carbon and oxygen is broken to open the ring, causing decomposition or polymerization and deteriorating the electrolytic solution.

On the other hand, trimethoxymethane (TMM) has an electron-donating methoxy group in its structural formula, and a carbon atom has an excess of electrons. Therefore, in a mixed solvent of dioxolane and trimethoxymethane, the carbon atoms of the dioxolane are attracted to each other, so that the carbon atoms of dioxolane are less susceptible to the attack of lithium and the ring-opening /
Polymerization is suppressed and deterioration of the electrolytic solution is suppressed.

(G) Effect of the invention As described above, the present invention uses a mixed solvent containing dioxolane and trimethoxymethane as a solvent that constitutes the non-aqueous electrolyte, and therefore has the advantage of dioxolane, that is, good low-temperature characteristics. It is possible to obtain a non-aqueous electrolyte battery that maintains and has excellent storage characteristics.

In particular, as shown in the examples, the secondary battery system has an effect of further improving the charge / discharge cycle characteristics, and its industrial value is extremely large.

[Brief description of drawings]

FIG. 1 is a half sectional view of the battery of the present invention, and FIG. 2 is a charge / discharge cycle characteristic diagram. (1) …… positive electrode can, (2) …… negative electrode can, (3) …… insulating packing, (4) …… positive electrode, (6) …… negative electrode, (8) …… separator.

Claims (1)

[Claims] 1. A negative electrode using lithium or an alloy containing lithium as an active material, a positive electrode, and a nonaqueous electrolytic solution containing a solvent and a solute, and containing dioxolane and trimethoxymethane as the solvent. A non-aqueous electrolyte battery characterized by using a mixed solvent for