ALLOY POWDER FOR NEGATIVE ELECTRODE OF NONAQUEOUS ELECTROLYTE SECONDARY BATTERY AND METHOD FOR MANUFACTURING THE ALLOY POWDER

摘要

PROBLEM TO BE SOLVED: To provide a negative electrode material for nonaqueous electrolyte secondary battery excellent in the discharge capacity and cyclic lifetime. SOLUTION: A powder of Si-X alloy (X is one or more elements to form an inter-metal compound or solid solution together with Si) whose structure includes an Si-phase having a large Li-occluding ability is manufactured by a rapid cooling solidification method with a cooling speed of 100 deg.C/sec (gas atomizing method, rapid cool rolling method, etc.). One or more easy-to-oxidize elements selected among Li elements and those oxidized easier than Li (for example, Ca, Mg, rare earth elements) is included in an amount: 0.01-1 wt.% in the alloy so that a drop of the discharge capacity due to oxygen inclusion is precluded. It may also be accepted that the solidification is followed by a heat treatment at a temperature lower than the solid phase line temperature of the alloy.