Patent ID: 6841294

Claim:
An electrochemical process for energy storage and/or power delivery comprising: (i) maintaining and circulating electrolyte flows in a fully liquid system in which the active constituents are fully soluble in a single cell or in an array of repeating cell structures, each cell with a positive (+ ve ) chamber containing an inert + ve electrode and a negative (− ve ) chamber containing an inert − ve electrode, the chambers being separated from one another by a cation exchange membrane, the electrolyte circulating in the − ve chamber of each cell during power is delivery containing a sulfide (electrolyte 1 ), and the electrolyte circulating in the + ve chamber during power delivery containing bromine (electrolyte 2 ), (ii) restoring or replenishing the electrolytes in the + ve and − ve chambers by circulating the electrolyte from each chamber to storage means comprising a volume of electrolyte greater than the cell volume for extended delivery of power over a longer discharge cycle than the cell volume alone would permit, and (iii) rebalancing the electrolytes by circulating a fraction of electrolyte 1 or electrolyte 2 through the + ve chamber of ant auxiliary cell, said auxiliary cell comprising a + ve chamber containing an inert + ve electrode and a −ve chamber containing an inert − ve electrode, the chambers being separated from one another by a cation exchange membrane, the electrolyte circulating through the − ve chamber of the auxiliary cell containing water and being free from polysulfide and free from bromine during rebalancing, the auxiliary cell operating so as to oxidise sulfide ions to sulfur or bromide ions to bromine in the + ve chamber and so as to reduce water to hydrogen and hydroxide ions in the − ve chamber.