Patent ID: 7771876

Claim:
An anode active material comprising: an alloy material including an element M capable of being alloyed with lithium selected from metal elements and metalloid elements and at least one kind of element R selected from elements with an atomic number of 20 or less, except for hydrogen, lithium and a noble gas, wherein as the element M, tin and at least one kind selected from the group consisting of nickel, copper, iron, cobalt, manganese, zinc, indium and silver are included, the content of the element R ranges from about 10 wt % to about 50 wt %; the alloy material has a median particle size of about 50 μm or less, the alloy material includes a reactive phase with lithium, and a half-width of a diffraction peak obtained by X-ray diffraction analysis of the reactive phase is about 5° or more.