Process for manufacture of negative electrode material for a non-aqueous electrolyte secondary battery

摘要

A negative electrode material for a nonaqueous electrolyte secondary battery having a high discharge capacity and a good cycle life is made from alloy particles having an average particle diameter of 0.1-50 mum and including Si phase grains 40 and a phase of a solid solution or an intermetallic compound of Si and other element selected from Group 2A elements, transition elements, Group 3B elements, and Group 4B elements from the long form periodic table (for example, an NiSi2 phase 42 and an [NiSi2+NiSi] phase 41) at least partially enveloping the Si phase grains. 5-99 wt % of this material is Si phase grains. The alloy particles can be manufactured by rapid solidification (such as atomization or roller quenching) of a melt including Si and the other element, or by adhering the other element to Si powder by electroless plating or mechanical alloying and then performing heat treatment. Even if rapid solidification is carried out, a negative electrode material having a good discharge capacity and cycle life is obtained without heat treatment.