Redox flow type battery

A liquid-circulating type redox flow battery which comprises:

• a positive cell;
• a negative cell;
• a permeable membrane interposed therebetween;
• two porous carbon electrodes disposed in said positive and negative cells, respectively;
• and
• two, positive and negative, electrolytic solutions, said electrolytic solutions being circulated in said positive and negative cells, respectively, so as to cause an oxidation-reduction reaction to take place and hence lead to charge and discharge;
• (a) said battery being defined by a ratio (H/L) where (H) is the average height of each of said porous electrodes in a flow direction of each of said electrolytic solutions, and (L) is the length of each of said porous electrodes in a direction perpendicular to the flow direction of each of said electrolytic solutions, the ratio (H/L) being in the range of 0.18 to 1.95;
• and
• (b) said battery being defined by ratios (.SIGMA.s.sub.ai /S.sub.a) and (.SIGMA.s.sub.ci /S.sub.c) where (.SIGMA.s.sub.ai) is the sum of the cross-sectional area of an inlet for introducing said positive electrolytic solution into said positive cell, (.SIGMA.s.sub.ci) is the sum of the cross-sectional area of an inlet for introducing said negative electrolytic solution into said negative cell, (S.sub.a) is the average of the cross-sectional area of said porous electrode in a direction perpendicular to the flow direction of said positive electrolytic solution, and (S.sub.c) is the average of the cross-sectional area of said porous electrode in a direction perpendicular to the flow direction of said negative electrolytic solution, each of the ratios (.SIGMA.s.sub.ai /S.sub.a) and (.SIGMA.s.sub.ci /S.sub.c) being in the range of 0.001 to 0.04, and said battery being further defined by ratios (.SIGMA.s.sub.ao /S.sub.a) and (.SIGMA.s.sub.co /S.sub.c) where (.SIGMA.s.sub.ao) is the sum of the cross-sectional area of an outlet for discharging said positive electrolytic solution out of said positive cell, (.SIGMA.s.sub.co) is the sum of the cross-sectional area of an outlet for discharging said negative electrolytic solution out of said negative cell, and (S.sub.a) and (S.sub.c) are as denoted above, each of the ratios (.SIGMA.s.sub.ao /S.sub.a) and (.SIGMA.s.sub.co /S.sub.c) being in the range of 0.001 to 0.04.