Negative-electrode active material for electrical device, and electrical device using same

Abstract

The invention provides a means capable of improving the cycle durability of an electrical device such as a lithium-ion secondary battery. [Solution] Using, for an electrical device, a negative-electrode active material made of a silicon-containing alloy that has a predetermined composition and has a structure in which silicide phases including a silicide of a transition metal are dispersed in a matrix phase including amorphous or low-crystalline silicon as a main component, wherein, in an X-ray diffraction measurement of said silicon-containing alloy using a CuKalpha1 beam, the value of the ratio (B / A) of the diffraction peak intensity B of the transition metal silicide in the range 2 [theta] = 37 to 45 degrees to the diffraction peak intensity A of the (111) plane of Si in the range 2 [theta] = 24 to 33 degrees is 0.41 or greater.

Description

technical field [0001] The present invention relates to a negative electrode active material for electric equipment, and an electric equipment using the negative electrode active material. The negative electrode active material for electrical equipment of the present invention and the electrical equipment using it can be used, for example, as secondary batteries, capacitors, etc., as power sources for driving engines of vehicles such as electric vehicles, fuel cell vehicles, and hybrid electric vehicles, and auxiliary power supplies. power supply. Background technique [0002] In recent years, in order to cope with air pollution and global warming, the reduction of the amount of carbon dioxide has been strongly desired. In the automotive industry, the reduction of carbon dioxide emissions due to the introduction of electric vehicles (EV) and hybrid electric vehicles (HEV) is expected, and electrical equipment such as secondary batteries for driving engines is the key to gra...

AI Technical Summary

Problems solved by technology

However, in carbon / graphite-based negative electrode materials, charge and discharge are performed by the storage / release of lithium ions into graphite crystals, so there is a disadvantage that LiC, which is the compound with the largest lithium introduction, cannot be obtained. 6 The obtained charge and discharge capacity has a theoretical capacity of 372mAh / g or more

[0008] However, for a lithium ion secondary battery using a material alloyed with Li for the negative electrode, the expansion and contraction of the negative electrode during charge and discharge are large.

For example, the volume expansion when absorbing Li ions is about 1.2 times for graphite materials, while for Si materials, a large volume change will be caused by the transition from amorphous state to crystalline state when Si and Li are alloyed ( about 4 times), so there is a problem that the cycle life of the electrode is reduced

In addition, in the case of the Si negative electrode active material, capacity and cycle durability are in a trade-off relationship, and there is a problem that it is difficult to improve cycle durability while exhibiting high capacity.

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