Patent ID: 6764789
Filing Date: 2004-07-20
Classification: H01M,Y02E

Abstract:
A redox flow type secondary battery which is a liquid-circulating battery comprising a battery cell and storage tanks for positive and negative electrolytes, wherein the battery cell is separated by a membrane to provide a positive cell and a negative cell, each cell having a liquid-permeable porous electrode disposed therein, and the positive and negative electrolytes are passed and circulated from the storage tanks for the positive and negative electrolytes to the positive and negative cells, respectively, to conduct an oxidation-reduction reaction to charge and discharge the battery, characterized in that the amount of the liquid in the storage tank where the liquid decreases over cycles of charge and discharge is set greater than that of the liquid in the other storage tank beforehand, and the positive and negative electrolytes are sulfuric acid aqueous solutions with vanadium ion concentrations of 0.5 mol/l to 8 mol/l and the electrolyte which migrates through the membrane over cycles of charge and discharge is returned from the storage tank where the liquid increases to the storage tank where the liquid decreases in order to keep the change in the amounts of the positive and negative electrolytes in a certain range while charge and discharge are carried out.