US Patent 7807299 Lithium-ion battery

A lithium-ion battery includes a positive electrode including a positive current collector, a first active material, and a second active material. The battery also includes a negative electrode having a negative current collector and a third active material, the third active material including a lithium titanate material. The first active material, second active material, and third active materials are configured to allow doping and undoping of lithium ions. The second active material exhibits charging and discharging capacity below a corrosion potential of the negative current collector and above a decomposition potential of the first active material.