Patent ID: 7858232

Claim:
A non-aqueous electrolyte secondary battery comprising: a positive electrode capable of reversibly absorbing and desorbing Li; a negative electrode; and a non-aqueous electrolyte, said negative electrode comprising an alloying material that is 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, said at least one transition metal element being selected from the group consisting of Ti, Zr, Ni, Cu, and Fe, at least one of said A phase and said B phase comprising a microcrystalline or amorphous region, the weight percent of said A phase relative to the total weight of said A phase and said B phase being not less than 50% and not greater than 95%, and wherein said alloying material has a volume cumulative frequency as a function of particle size distribution in which the mean particle size (median diameter: D50) is 0.5 to 20 μm, the 10% diameter (D10) is 0.1 to 5 μm, and the 90% diameter (D90) is 5 to 80 μm.