All-Iron Hybrid Flow Batteries with In-Tank Rebalancing

Principles of sealed iron flow batteries are introduced and a semi-empirical model that incorporates the hydrogen evolution reaction and electrolyte rebalancing is developed. Hydrogen generation rates are measured using pressure measurements in sealed vessels. Electrolyte dynamics with and without electrolyte rebalancing are simulated and discussed, and a good agreement is found between measured and simulated pressure responses. The sealed battery system with in-tank rebalancing demonstrates stable operation at low hydrogen partial pressure during 10 days and 100 cycles at ± 100 mA cm−2 at room temperature.