Patent ID: 7879495

Claim:
A medical device comprising: a rechargeable lithium-ion battery for providing power to the medical device, the lithium-ion battery comprising: a positive electrode comprising a current collector and a first active material; and a negative electrode comprising a current collector, a first layer comprising a second active material, and a second layer separate and different from the first layer comprising a third active material, the second active material comprising a lithium titanate material and the third active material selected from the group consisting of LiMn 2 O 4 , Li x VO 2 where x is between approximately 0 and 1, LiM x Mn (2-x) O 4 (where M is a metal and x is between approximately 0.05 and 0.4), V 6 O 13 , V 2 O 5 , V 3 O 8 , MoO 3 , TiS 2 , WO 2 , MoO 2 , RuO 2 , and combinations thereof; wherein the third active material exhibits charging and discharging capacity below a corrosion potential of the current collector of the negative electrode and above a decomposition potential of the first active material.