Silicon oxide material for nonaqueous electrolyte secondary battery negative electrode material, making method, negative electrode, lithium ion secondary battery, and electrochemical capacitor
A silicon oxide material is obtained by cooling and precipitating a gaseous mixture of SiO gas and silicon-containing gas and has an oxygen content of 20-35 wt %. Using the silicon oxide material as a negative electrode active material, a nonaqueous electrolyte secondary battery is constructed that exhibits a high 1st cycle charge/discharge efficiency and improved cycle performance while maintaining the high battery capacity and low volume expansion of silicon oxide.