Lithium ion secondary battery

摘要

A lithium ion secondary battery improved in large-current discharge characteristics, discharge capacity, and cycle life is disclosed. This lithium ion secondary battery includes a positive electrode, a negative electrode comprising a collector and carbon fibers held to the collector for absorbing and desorbing lithium ions, a separator arranged between the positive electrode and the negative electrode, and a nonaqueous electrolyte. The carbon fibers have a radial orientation from an axis of the fibers, and 50 vol % or more of all carbon fibers are arranged such that an angle between an axis of each carbon fiber and a surface of the collector is 45 DEG or less.