Electrical Appliance

Abstract

An object is to increase the conductivity of an electrode including active material particles and the like, which is used for a battery. Two-dimensional carbon including 1 to 10 graphenes is used as a conduction auxiliary agent, instead of a conventionally used conduction auxiliary agent extending only one-dimensionally at most, such as graphite particles, acetylene black, or carbon fibers. A conduction auxiliary agent extending two-dimensionally has higher probability of being in contact with active material particles or other conduction auxiliary agents, so that the conductivity can be improved.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a variety of electrical appliances, particularly a battery, including a particulate material.[0003]2. Description of the Related Art[0004]In a manganese battery, an alkaline battery, a nickel-hydride battery, a lithium ion secondary battery, and the like, a particulate material is used as an active material for storing electricity. In some cases where the particulate material (active material particles) has low conductivity, a conduction auxiliary agent such as acetylene black, graphite particles, or carbon fibers is mixed into the material so as to increase the conductivity (see Patent Document 1).[0005]Specifically, the active material particles, the conduction auxiliary agent, and a binder are mixed, and the mixture is applied onto a current collector, molded, and then dried to be used as an electrode such as a positive electrode or a negative electrode.[0006]A procedure similar to th...

AI Technical Summary

Benefits of technology

[0012]Further, when graphite is used as a conduction auxiliary agent for a positive electrode of a battery, such as a lithium ion battery, in which charge and discharge are performed by transfer of alkali ions, there is a problem in that graphite particles absorb the alkali ions, thereby decreasing the use efficiency of current.

[0032]FIG. 3B illustrates the carbon fibers observed in a direction indicated by an arrow “a” in FIG. 3A. In FIG. 3B, an arrow “b” indicates a direction in which the carbon fibers are observed in FIG. 3A. The case is considered where the carbon fibers 101 are in contact with upper carbon fibers 102. For example, with an arrangement illustrated in FIG. 3C, it seems that the carbon fibers 101 are in close contact with the upper carbon fibers 102, so that the resistance therebetween can be minimum.

Problems solved by technology

In addition, natural graphite has poor electrolyte retention characteristics.

These factors cause a problem of reduction in use efficiency of the active material.

Further, when graphite is used as a conduction auxiliary agent for a positive electrode of a battery, such as a lithium ion battery, in which charge and discharge are performed by transfer of alkali ions, there is a problem in that graphite particles absorb the alkali ions, thereby decreasing the use efficiency of current.

However, a battery including acetylene black as a conduction auxiliary agent has a disadvantage that the potential and discharge capacitance are greatly reduced, since a functional group having a high reducing property with respect to an active material exists on a surface of acetylene black.

The above problem is also caused in the case where graphite particles are used.

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