A practical zinc-bromine pouch cell enabled by electrolyte dynamic stabilizer

Abstract

The next-generation high-performance batteries for large-scale energy storage should meet the requirements of low cost, high safety, long life and reasonable energy density. Here, we report a practical Ah-level zinc-bromine (Zn-Br₂) pouch cell, which operates stably over 3400 h at 100 % depth of discharge and shows an attractive energy density of 76 Wh kg⁻¹. The Zn-Br₂ battery is achieved by in-situ electrolyte dynamic stabilizer (EDS) regulation using quaternary ammonium salts on both solid bromine cathode and Zn anode chemistries, whose energy storage mechanisms are comprehensively revealed through in-situ optical microscopy, electrochemical analyses, and simulations. The EDS prevents bromine cathodes from dissolution and diffusion into electrolyte while regulating uniform Zn nucleation and plating through electrostatic shielding. Benefiting from the EDS regulation, the bromine cathode displays a high areal capacity of 40 mAh cm⁻² and can stably operate for 1200 cycles at an areal capacity of 15 mAh cm⁻². The Zn anode exhibits excellent performance with dendrite-free Zn plating/stripping at a high areal capacity of 100 mAh cm⁻² for 400 h and at 10 mAh cm⁻² over 1500 h in an anode-free electrode design. The excellent performance of our Zn-Br₂ batteries opens up new opportunities for practical large-scale energy storage applications.