SECONDARY BATTERY AND ITS OPERATION METHOD

摘要

PROBLEM TO BE SOLVED: To provide a secondary battery operable with high load regardless of a discharge state in a normal operation and to provide its operation method. SOLUTION: This secondary battery is provided with first tanks 31 and 32 for storing an electrolyte in a normal operation and second tanks 33 and 34 for storing an electrolyte in an emergency operation. The electrolyte in the first tanks 31 and 32 and the electrolyte in the second tanks 33 and 34 are circulated to a cell stack 100 by changing over them by opening and closing valves 41-48. For the electrolyte in the second tanks 33 and 34, the ratio of the quantity of an active material produced by its charge reaction to the quantity of the whole active material is 50% or more.