LITHIUM SECONDARY BATTERY

摘要

PROBLEM TO BE SOLVED: To provide a long-service-life lithium secondary battery having little unevenness in battery capacity. SOLUTION: This cylindrical lithium-ion secondary battery has a positive electrode wherein a positive electrode mix layer containing lithium manganate is formed on aluminum foil, and a negative electrode wherein a negative electrode mix layer containing amorphous carbon is formed on electrolytic copper foil. A negative electrode current collector uses the electrolytic copper foil of <=2% weight unevenness per area and of <=5% elongation percentage when pressing the negative electrode mix layer. Unevenness in the thickness of the negative electrode current collector is suppressed, and train of the electrolytic copper foil is small to prevent generation of a micro short-circuit.