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 (4), a negative electrode (6) comprising a collector and carbon fibers held to the collector for absorbing and desorbing lithium ions, a separator (5) arranged between the positive electrode (4) and the negative electrode (6), 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.