Cell resistance is an important factor affecting cell power output. For this section, the threechamber two-membrane cell used Fe 2+ /Fe 3+ (negolyte) and Fe(CN)6 4-/ Fe(CN)6 3-(posolyte) each at 0.1 M concentration, 50% SOC, with 1 M NaCl supporting salt. Tests were conducted in a 2.5 cm 2 cell. If not specified, the center chamber electrolyte was 1 M NaCl, tested at room temperature.