Lithium secondary battery

Abstract

The present invention relates to a lithium secondary battery including: an electrode assembly having a structure in which a stacked sheet including a positive electrode plate and a negative electrode plate stacked with a separator interposed therebetween is wound; an electrolyte; a can in which the electrode assembly and the electrolyte are accommodated; and a cap assembly configured to seal an opening of the can, wherein the positive electrode plate includes a positive electrode current collector, a positive electrode mixture layer disposed on at least one surface of the positive electrode current collector, a positive electrode tab electrically connected to the positive electrode current collector, and a positive electrode tab protection member configured to protect the positive electrode tab, and X defined by Equation (1) is 200 or less. Equation (1): X = A × B, wherein A is an expansion rate of the negative electrode plate, and B is a thickness of the positive electrode tab protection member measured in μm.

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