Metal-Iodine and Metal-Bromine Batteries: A Review

Rechargeable metal-iodine and metal-bromine batteries have been pursued as potentially effective, low-cost, and mass-producible alternatives to current transition-metal-based batteries due to highly reversible redox and abundant resource. However, several challenges, such as low operability caused by thermodynamic instability of cathode and unsatisfactory cycling stability from shuttle effect, must be overcome before a real breakthrough and their widespread application. This review summarizes the state-of-the-art progress of their energy storage mechanisms and discusses the emerging metal-iodine/ bromine batteries including Zn-I-2 and Zn-Br-2 batteries, Li-I-2 and Li-BrCl batteries and other metal-I-2 batteries. We show the key issues that current metal-iodine/bromine batteries are facing and, furthermore, some promising solutions proposed during the past few years are highlighted to outline key perspectives for future research in this thriving field.