High-Energy Density Flow Battery Validation

A zinc-alkaline flow cell was used to validate a new type of flow battery in which all reagents and products remain as solids on the electrodes. In every case, flow of electrolyte reduced overpotential losses when compared with operation without electrolyte flow. Large separation distances between the electrodes resulting from larger sections of separating tubing led to increased overpotential losses. A mass transfer mechanism is proposed that substantiates increasing overpotential with increasing electrode separation distances. Based on this mechanism, it was hypothesized that ion exchange packing would reduce the overpotential losses; this hypothesis was experimentally validated. (C) 2010 American Institute of Chemical Engineers AIChE J, 57: 1961-1967, 2011