LITHIUM SECONDARY BATTERY

摘要

PROBLEM TO BE SOLVED: To provide a lithium secondary battery having high charge and discharge capacity and excellent charge and discharge characteristic by preventing deterioration of capacity due to strain of negative electrode active material generated in initial cycles and generation of wrinkles or deflection caused by uneven plastic deformation of a negative electrode.

SOLUTION: The lithium secondary battery has an electrode group comprising: a negative electrode 1 constituted by forming negative electrode active material layers 12 and 13 consisting of alloy including silicon which occludes and emits lithium and iron which does not occlude and does not emit lithium on both sides of a negative electrode collector 11; a positive electrode; and a separator arranged between the positive electrode and the negative electrode. The electrode group has at least a part bent. In the part bent, the density of the above-mentioned iron in the negative electrode active material layer 13 inside the negative electrode collector is higher than that in the negative electrode active material layer 12 outside the negative electrode collector.

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