Systematic evaluation of a low-cost membrane-free single-chamber zinc-bromine battery for energy storage

Abstract

Energy storage has become the pivotal issue with the current clean-tech revolution, since energy generated by intermittent energy sources like solar and wind must be stored to be usable. However, current battery solutions are too expensive, too dangerous, or don’t have a significant enough capacity life for utility-scale energy projects. The zinc-bromine battery cell is studied as a solution to this energy storage issue. I present a simple, low-cost, membrane-free, non-flowing, single-chamber Zn-Br\(_{2}\) system with a maximum specific capacity of 76 mAh/g and energy density over 152 Wh/kg (calculated using the mass of ZnBr\(_{2}\) salt in the electrolyte). Including passive components, each cell costs $94/kWh, with coulombic and energy efficiencies of up to 95% and 75%, respectively, for over 500 cycles. These cost and performance metrics make the system cost-competitive with the most popular energy storage devices and makes this system attractive for large area grid-scale applications. In this work, I discuss a simple design for such a Zn-Br\(_{2}\) cell and include our research on the battery performance, measured by the metrics of cycle life, energy efficiency, and coulombic efficiency. I then leverage our ability to tune the characteristics of the cell by varying electrode geometry design, electrolyte pH, and compositional chemistry. Future works would leverage this research to optimize for the best performing battery with the longest cycle life.