A Cost-Effective Mixed Matrix Polyethylene Porous Membrane for Long-Cycle High Power Density Alkaline Zinc-Based Flow Batteries

Alkaline zinc-based flow batteries (ZFBs) have received considerable interest for renewable energy storage due to their attractive features of low cost and high energy density. However, a membrane with high stability, high selectivity, and high ion conductivity is in urgent need. Herein, an economical mixed matrix membrane with highly anti-alkali microporous hollow spheres (denoted as DM-HM) is developed in this work. With excellent chemical and mechanical stability, DM-HM can achieve a high area capacity of 100 mA h cm(-2) for carbon felt (CF)||Zn@CF symmetrical flow battery, and thereby exhibits 500 stable cycles with a coulombic efficiency of 98.6% and an energy efficiency of 88.3% at 80 mA cm(-2) for alkaline zinc-iron flow battery. Additionally, with 44 wt% of hollow spheres inside matrix, DM-HM can dramatically shorten the ion transport pathway and results in a very high power density battery. A kilowatt stack assembled with DM-HM shows a very impressive performance, further confirming the practicability of this scalable mixed matrix membrane for alkaline ZFBs.