Patent ID: 7682742

Claim:
A lithium ion battery comprising: a cathode; an anode; and an electrolyte, wherein, the anode includes an anode current collector and an anode active material layer on the anode current collector, and said anode active material layer includes oxygen (O) and silicon (Si), said anode current collector has a surface roughness Ra value of 0.2 μm or more, said anode active material layer is alloyed with said anode current collector at least in part of the interface with the anode current collector, when said anode is fully charged a lithium (Li) insertion amount per unit area is A, a lithium amount capable of being electrochemically inserted per unit area of the anode is B, and the maximum utilization ratio C % of said anode is (A/B)×100, the maximum utilization ratio C % is in the range from 40 to 80.