Silicon oxide powder is a negative electrode material used in lithium ion secondary battery. It helps to increase the initial capacity of the cell. However, it also reduces the charge/discharge capacity. So it is expensive. The present invention is intended to provide a silicon oxide powder that is inexpensive and yet effective.

Silicon dioxide is a natural material found in the earth and in human bodies. It is used in a variety of applications, including adhesives, paper, food packaging and filter aid.

SiO2 has high stability and a small loose density. However, its surface is prone to oxidation. Consequently, silicon oxide particles are prone to a decline in productivity.

In order to improve the productivity, a larger amount of metal silicon powder can be added to the raw material powder mixture. Ideally, the molar ratio of the silicon dioxide powder and metal silicon powder is 1.1.

Alternatively, the raw material powder mixture can be heated at a lower temperature. At lower substrate surface temperatures, the BET specific surface area of the silicon oxide particles may be higher. This may result in a lower charge/discharge capacity of the deposited material.

Moreover, the particle size of silicon dioxide and metal silicon powder is not limited. Typical particle sizes are 0.05 to 30 mm. Higher particle diameters tend to decrease the reaction speed, which results in a lower productivity.

In addition to higher reactivity, the presence of a metal layer on the metal silicon surface can increase the reactivity of the silicon oxide powder. The present invention was developed in the view of the above situation.

tags: semiconductor semiconductor material