Patent ID: 7897284
Filing Date: 2011-03-01
Classification: H01M,Y02E,Y02P

Abstract:
1. A lithium secondary battery comprising: a negative electrode comprising a negative electrode current collector and negative electrode active material layers formed on respective surfaces of the negative electrode current collector, said negative electrode active material layers including a negative electrode active material layer disposed inward relative to the negative electrode current collector and another negative electrode active material layer disposed outward relative to the negative electrode current collector and each of the negative electrode active material layers comprising an alloy containing a negative electrode active material that intercalates and deintercalates lithium and an additive metal that does not intercalate or deintercalate lithium; a positive electrode; a separator interposed between the positive and negative electrodes; and an electrode assembly comprising the negative electrode, the positive electrode, and the separator, wherein: at least a portion of the electrode assembly has a curved portion, and in the curved portion, the inward negative electrode active material layer contains a higher concentration of the additive metal than the outward negative electrode active material layer, wherein the curved portion has a concentration difference of the additive metal of from 5 atomic % to 15 atomic % between the negative electrode active material layer disposed inward relative to the negative electrode current collector and the negative electrode active material layer disposed outward relative to the negative electrode current collector.