Aqueous Mixed-Cation Semi-solid Hybrid-Flow Batteries

The development of efficient and cost-effective energy storage systems is of critical importance for the potential future application of renewable energy resources. Here, we report a new class of environmentally friendly aqueous hybrid-flow batteries which are based on coupling high-energy Zn metal electrodes with semi-solid flowable electrodes in a mixed-cation concept. The special features of this new class of hybrid-flow battery enables the use of one single reservoir for both anolyte (Zn2+) and catholyte (LiMn2O4 or LiFePO4) and size exclusion separators which allow low cost, i.e. 96 US$ kWh–1 (15 mA cm–2) of Zn–LiFePO4 flow battery vs 164 US$ kWh–1 (100 mA cm–2) for the all-vanadium flow battery for an energy/power ratio of 10 (10 h). As proof of concept, Zn–LiFePO4 flow batteries are demonstrated achieving an energy density of 50 Wh L–1 with >99% Coulombic efficiency under continuous flowing conditions.