Halogen-enabled rechargeable batteries: Current advances and future perspectives

The state-of-the-art battery technologies appear in various fields ranging from stationary electric stations to mobile electronics and vehicles. The subsequent development of batteries mainly relies on the following aspects: high-performance electrode/electrolyte materials and innovative battery designs. Studies on halogen species for battery applications have been conducted in recent decades due to their attractive advantages, such as the high redox potentials, low cost, and source abundance for massive applications. Halogen species utilized in battery chemistries mainly obey two different concepts: (i) participating redox reactions for charging/discharging and (ii) serving as a crucial redox-free component for other specific functions, such as promoting charge transfer and composing electrode or electrolyte compounds. In this review article, we extensively outlined the utilization of halogen and halogen compounds in various rechargeable batteries from the two perspectives above, with the focus on how the halogen species function during battery operation. The remaining challenges and potential opportunities for the adoption of halogen and halogen compounds in secondary batteries have been highlighted. The widely covered review article aims to provide a comprehensive understanding for the halogen chemistry in batteries, which differs from the enormous articles with deep study on a branch. We hope to stimulate more future research efforts on halogen-enabled batteries