Patent ID: 7358001

Claim:
An electrochemical process for energy storage and/or power delivery comprising: (i) maintaining and circulating electrolyte flows in a liquid system in which the active constituents are soluble in a single cell or in an array of repeating cell structures, each cell with a positive (+ ve ) chamber containing a positive electrode and a negative (− ve ) chamber containing a negative electrode, the chambers being separated from one another by a cation exchange membrane, electrolyte 1 containing a sulfide circulating in the negative chamber of each cell during discharge, and electrolyte 2 containing bromine circulating in the positive chamber during discharge, (ii) restoring or replenishing the electrolytes in the positive and negative 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) controlling the distribution of water between the two electrolytes by a process including (a) discharging electrolyte 1 , or fractions thereof, and/or discharging electrolyte 2 , or fractions thereof, to such an extent that a difference in the ionic strengths of the electrolytes ensures that water will flow by osmosis from electrolyte 1 into electrolyte 2 when said electrolytes in a separate chamber are separated by a water permeable membrane and (b) circulating electrolytes 1 and 2 , or fractions thereof, through the first and second chambers respectively of a separate container which is divided by a water permeable membrane, under conditions wherein no current flows in said container between electrolytes 1 and 2 such that water flows from electrolyte 1 into electrolyte 2 by osmosis to redistribute water between the electrolytes.