Based on durable,but highly redox-active property of organic radicals,we have developed "radical polymers",aliphatic polymers densely populated with pendant radical groups such as nitroxides and galvinoxyls.Radical polymers were employed as electrode-active,charge-storage materials in a rechargeable battery,which was characterized by its extremely high power-rate capability (10 sec.for charging) and cycle stability (＞1000 cycles).