JPH09129239A - Organic electrolytic battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic electrolytic battery having large capacity as well as a stable battery function by improving the conductive agent of the positive electrode thereof. SOLUTION: Expanded graphite having apparent bulk specific gravity between 0.02 and 0.08g/cc is used as the conductive agent of a positive electrode for an organic electrolytic battery. The mixing ratio of the expanded graphite and manganese dioxide is maintained within the range of 3 to 100 and 10 to 100 by weight, thereby improving the moldability of a positive electrode mix and conductivity. As a result, the added amount of a bonding agent in the positive electrode mix can be reduced, and the conductivity of the positive electrode can be maintained with the addition of the small amount of the conductive agent. Thus, the liquid absorption function of an increased active material in a positive electrode with an electrolyte is remarkably improved, thereby providing an organic electrolytic battery having a high battery function.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to improvement of discharge characteristics of an organic electrolyte battery.

[0002]

2. Description of the Related Art In a positive electrode of an organic electrolyte battery, 10 to 12 parts by weight of scaly graphite as a conductive agent was added to 100 parts by weight of a positive electrode active material of manganese dioxide, but a positive electrode active material and a conductive agent were mixed. Since the positive electrode mixture is processed into pellets or sheets to form a positive electrode, 3 to 4 parts by weight of a binder is added to the positive electrode mixture in order to improve moldability and increase the filling amount of the molded body. A fluororesin was added and molding was performed to assemble the battery.

[0003]

However, in the above technique, since the amount of the binder added is large in order to stabilize the moldability, the electrolyte absorbability with the positive electrode pellets is deteriorated and the battery sealing At times, the electrolyte leaked, which was a cause of variations in battery characteristics. In order to obtain conductivity, 100 parts by weight of manganese dioxide positive electrode active material is used as a conductive agent for flake graphite 1
Since 0 to 12 parts by weight was added, it was difficult to increase the filling amount of the positive electrode active material within a certain volume, and therefore there was a limit in improving the battery capacity.

The present invention solves the above problems. By using expanded graphite having an apparent bulk specific gravity in a specific range as a conductive agent, moldability and conductivity are improved, battery capacity is improved and battery performance is improved. The purpose is to stabilize.

[0005]

In order to solve these problems, the present invention uses expanded graphite having an apparent bulk specific gravity of 0.02 to 0.08 g / cc as a conductive agent for a positive electrode.

In the expanded graphite according to the present invention, a compound such as sulfuric acid is usually inserted between layers of natural scaly graphite treated with a strong oxidizing agent such as concentrated sulfuric acid to thermally expand it, and the apparent bulk specific gravity is 0.02. Graphite treated to ~ 0.08 g / cc.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION By using the expanded graphite of the present invention as a conductive agent for a positive electrode, the moldability and conductivity of the positive electrode mixture are significantly improved. Therefore, the addition ratios of the binder and graphite can be greatly reduced, the amount of active material in the positive electrode pellets is increased, and the liquid absorbability with the electrolytic solution is improved, so that a high-capacity and stable battery can be provided.

[0008]

EXAMPLES Examples of the present invention will be shown in Example 1 below. An example of a flat type organic electrolyte battery will be described.

7 parts by weight of the expanded graphite of the present invention was mixed with 100 parts by weight of manganese dioxide heat-treated at 400 ° C. as a positive electrode active material for 5 minutes according to the bulk specific gravity in a V blender to obtain a positive electrode mixture having a specific resistance, The results of moldability and breaking strength of molded pellets are shown in (Table 1).

[0010]

[Table 1]

About 1 g of the positive electrode mixture is used as a method for measuring the specific resistance.
Weighed, put in a mold with a diameter of about 13 mm, and measured the specific resistance of the mixture when applying a pressure of about 50 kg. Moldability was evaluated by weighing 715 mg of each positive electrode mixture and molding pressure 4 using a molding die having a diameter of 15.15 mm.
Molding was performed 50 times at t / cm ² , and the molded body was evaluated for chipping, cracking and the like. The method for measuring the breaking strength of the molded pellet was as follows. The pellet was set upright, compressed with a load cell, and the values at which the pellet was broken were measured. Apparent bulk specific gravity of 0.08 g /
When it is cc or more, cracks and chips frequently occur in the molded body, and when the apparent bulk specific gravity is 0.08 g / cc or less, specific resistance, moldability,
The strength is stable. Also apparent bulk specific gravity of 0.02 g / c
Expanded graphite of c or less cannot be tested because it is difficult to manufacture with the current manufacturing technology.

Next, a comparison was made of battery performance depending on the addition ratio of manganese dioxide in the apparent bulk specific gravity of expanded graphite. The compounding ratio of the materials of the positive electrode mixture prepared according to the apparent bulk specific gravity of expanded graphite is shown in (Table 2).

[0013]

[Table 2]

The mixing method was carried out under the same conditions as described above. As molding conditions, 715 mg of each positive electrode mixture prepared by expanding graphite having different apparent bulk specific gravity according to the compounding ratio was weighed, and molding pressure was 4 t / cm using a molding die having a diameter of 15.15 mm.
Molded in ² and mold the molded positive electrode pellets at 250 ℃ about 8
After being dried for a period of time, the positive electrode pellet was used to form a flat organic electrolyte battery (C with a height of 2.5 mm and a diameter of 20 mm (C
R2025) is constituted, discharge is carried out at 20 ° C. 2.7 kΩ 2.5 V termination and n = 10 average values are shown on the right side of Table 2.
In the results, the reason why the discharge duration of the expanded graphite is 3% or less is short because the conductivity of the positive electrode mixture is insufficient and the internal resistance is increased. Further, the reason why the discharge duration is short at the addition rate of 10% or more is that the amount of manganese dioxide in a certain volume is decreased due to the large amount of graphite added. From the above, the addition ratio of expanded graphite to manganese dioxide is 3: 3 by weight ratio.
The range of 100 to 10: 100 can maximize the utilization rate of manganese dioxide.

[0015]

As is apparent from the above description, the apparent bulk specific gravity of the positive electrode conductive agent is 0.02 to 0.08 g /
cc of expanded graphite is used, and when the mixing ratio of the expanded graphite and manganese dioxide is in the range of 3: 100 to 10: 100 by weight, the moldability and conductivity of the positive electrode mixture are improved, so that the binding It is possible to significantly reduce the addition rate of the agent and graphite. From the above, it is possible to provide an organic electrolyte battery having a high capacity and stable characteristics by increasing the amount of active material in the positive electrode pellet and improving the liquid absorbability with the electrolytic solution.

Continued on the front page (72) Inventor Fumio Oo 1006 Odakadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (1)

[Claims] 1. An organic electrolyte battery comprising a negative electrode using a light metal as an active material, a positive electrode using a positive electrode mixture containing a manganese dioxide positive electrode active material, a conductive agent and a binder, and an organic electrolyte electrolytic solution containing an organic solvent. Further, expanded graphite having an apparent bulk specific gravity of 0.02 to 0.08 g / cc is used as the conductive agent of the positive electrode, and the mixing ratio of the expanded graphite and manganese dioxide is 3: 100 to 10: 100 by weight. The organic electrolyte battery is characterized in that