US Patent 8367240 Lithium secondary battery with wound electrodes

A battery comprising a first electrode, a second electrode, a separator interposed between the first electrode and the second electrode, and an electrolyte having lithium ion conductivity. The first electrode and the second electrode are wound with the separator interposed therebetween to form an electrode assembly. The first electrode includes a current collector and an active material layer carried on one face of the current collector. The active material layer includes columnar particles having a bottom and a head, the bottom of the columnar particles being adhered to the current collector. The head of the columnar particles is positioned at an outer round side of the electrode assembly than the bottom.