Patent ID: 7635540
Filing Date: 2009-12-22
Classification: H01M,Y02E

Abstract:
1. A negative electrode for a non-aqueous electrolyte secondary battery, comprising graphite and an alloying material capable of electrochemically absorbing and desorbing Li, said alloying material comprising an A phase composed mainly of Si and a B phase comprising an intermetallic compound of at least one transition metal element and Si, at least one of said A phase and said B phase comprising a microcrystalline or amorphous region, the weight percentage of said A phase relative to the total weight of said A phase and said B phase being greater than 40% and not greater than 95%, the weight percentage of said graphite relative to the total weight of said alloy material and said graphite being not less than 65% and not greater than 85%, wherein: said alloying material exists in gaps between particles of said graphite, said alloying material has a maximum particle size of 10 μm or less, and the ratio of the mean particle size of said alloying material to the mean particle size of said graphite is in the range of 0.15 to 0.90.