JPS5920971A - Secondary battery with organic electrolyte - Google Patents

Abstract

PURPOSE:To prevent deterioration in the battery performance due to decrease in the amount of organic electrolyte or breakdown of the battery due to abnormal increase in gas pressure, by adding polyphenelene or its derivertive to the anode. CONSTITUTION:The cathode 1 produced by punching into a predetermined size from lithium plate is pressed and attached to the internal bottom face of the cathode can 10. And the anode 2 produced by pressure forming of mixed powder composed of 80% by weight of molybdenum trioxide as the active material for the anode, 6% by weight of acetylene black as conductive material, 4% by weight of fluororesin powder as binding agent, and 10% by weight of polyphenelene powder is arranged on the internal bottom face of the anode can 20. Reference numeral 3 denotes a separator of nonwoven fabric of polypropylene impregnated with organic electrolyte prepared by dissolving 1mol/1 of lithium perchlorate as solute in the mixed solvent composed of propylene cabonate and 1.2 dimethoxyethane. By adding polyphnelene to the anode as described above, the charging voltage becomes constant in the vicinity of about 4.0V and the charging voltage does not rise anymore as shown by the curve A in the adjoining graph.

Description

[Detailed description of the invention] Industrial applications The present invention relates to an organic electrolyte secondary battery.

Conventional technology This type of battery uses a negative electrode that uses a light metal such as lithium or sodium as an active material, and an organic electrolyte that has a solute such as lithium perchlorate or difluoride dissolved in an organic solvent such as propylene carbonate or r-butyl lactone. , a positive electrode whose active material is molybdenum trioxide, panadicum pentoxide, titanium sulfide, etc.

Problems to be Solved by the Invention When charging this type of secondary battery, there are new problems compared to the case where an aqueous solution is used as an electrolyte like a normal nickel-power domicium battery. That is, when an aqueous solution is used as the electrolyte, a water decomposition reaction occurs during overcharging, producing hydrogen gas and oxygen gas, but a second chemical reaction or electrochemical reaction causes water to become inside the battery, resulting in depletion of the electrolyte amount or generation of gas. On the other hand, when an organic electrolyte is used, once the solvent decomposes, it decomposes into hydrocarbons and other components, and cannot be regenerated within the battery. This is impossible, and there is a problem of deterioration of battery performance due to a reduction in the amount of organic electrolyte or destruction of the battery due to an abnormal increase in gas pressure.

As a way to solve this problem, during charging, the charging voltage is set to the decomposition voltage of the solvent that makes up the electrolyte (usually about 5.OV).
It is conceivable to terminate charging when the battery reaches 100%, but this method requires a complicated charging circuit and the charging voltage changes as the battery charge/discharge cycle progresses, so the above method is practically impossible. Accurate control is difficult.

Means for Solving the Problems The present invention was made to solve the above problems, and includes a negative electrode made of a light metal such as lithium or sodium,
The present invention proposes an organic electrolyte secondary battery comprising an organic electrolyte comprising at least one solvent and at least one solute, and a positive electrode containing polyphenylene or a derivative thereof.

Example An embodiment of the present invention will be described below based on the drawings.

In FIG. 1, m is a negative electrode made by punching out a lithium plate to a predetermined size, and is press-bonded to the inner bottom surface of the negative electrode (IQI).

(2) is a positive electrode, which contains 80% by weight of molybdenum trioxide as an active material, 6% by weight of acetylene black as a conductive agent, 4% by weight of fluororesin powder as a binder, and polyphenylene. This is a mixture of 10% by weight and 10% by weight of powder, which is press-molded, and is placed on the inner bottom surface of the positive electrode can holder.

(3) is a separator made of polypropylene nonwoven fabric, which is impregnated with an organic electrolyte solution made by dissolving 1 mole of lithium perchlorate as a solute in a mixed solvent of propylene carbonate and 1.2 dimethoxyethane. . (4
) is an insulating backing that isolates the positive and negative electrodes.

Effects Figure 2 shows the charging characteristics when charged at a charging current of 2 mA/cJ, in which (5) is the case of the battery of the present invention and (B) is the case of the conventional battery using a positive electrode doped with polyphenylene. .

As is clear from FIG. 2, in the conventional battery, the charging voltage increases with the passage of charging time and reaches the decomposition voltage of the solvent constituting the electrolyte (usually about 5.0'V).

On the other hand, in the battery of the present invention, about 4. It can be seen that in the vicinity of OV, the charging voltage increases with the passage of time, but the charging voltage becomes constant near about 4° Ov, and the charging voltage is unlikely to rise any further.

Considering the effects of the present invention, when the battery is charged, LiMoOs, which is a discharge product, is charged as shown in the following equation 0, similar to the conventional battery, up to about 4.0μ, and on the positive electrode side, LiMoOs is charged, and on the positive electrode side, LiMoOs is generated, and on the negative electrode side, L generated by equation 0
A reaction progresses in which i+ is reduced and deposited as lithium metal on the negative electrode.

LiMoO3→MoO3+L+ +++・++++
In conventional batteries, the reaction of equation 0 continues to progress, and as the end of charging approaches, the concentration of LiMoOs decreases and Mo53 increases, causing the voltage to rise and reach the decomposition voltage of the solvent that makes up the electrolyte. be.

,,In contrast, in the battery of the present invention, it is about 4. Near Ov, the anion (C
Since the reaction in which ω4-) is doped into the polyphenylene in the positive electrode proceeds as the main reaction compared to the above equation 0, the charging voltage does not increase any further and does not reach the decomposition voltage of the solvent that makes up the electrolyte. 0 (C6H4)x+yct04+(C6H4)x(C2O
4) y+ye-...■ Note that in the above examples, only the case where polyphenylene was used as the additive was described, but in addition, for example, polyparaphenylene vinylene, polyparaphenylene sulfide, polymetaphenylene sulfide, or polyparaphenylene may be used. Polyphenylene derivatives such as oxides can also be applied.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of the battery of the present invention, and Figure 2 is a comparison diagram of charging characteristics between the battery of the present invention and a conventional battery. (1)...Negative electrode, (2)...Positive electrode, (3)...Separator, (4)...Insulating backing, 11...Negative electrode color, Kanji...Positive electrode can.

Claims (1)

[Claims] ■ A negative electrode made of light metals such as lithium and sodium,
An organic electrolyte secondary battery comprising an organic electrolyte comprising at least one solvent and at least one solute, and a positive electrode containing polyphenylene or a derivative thereof.