Rechargeable Hydrogen–Chlorine Battery Operates in a Wide Temperature Range

Hydrogen–chlorine (H 2 –Cl 2 ) fuel cells have distinct merits due to fast electrochemical kinetics but are afflicted by high cost, low efficiency, and poor reversibility. The development of a rechargeable H 2 –Cl 2 battery is highly desirable yet challenging. Here, we report a rechargeable H 2 –Cl 2 battery operating statically in a wide temperature ranging from −70 to 40 °C, which is enabled by a reversible Cl 2 /Cl – redox cathode and an electrocatalytic H 2 anode. A hierarchically porous carbon cathode is designed to achieve effective Cl 2 gas confinement and activate the discharge plateau of Cl 2 /Cl – redox at room temperature, with a discharge plateau at ∼1.15 V and steady cycling for over 500 cycles without capacity decay. Furthermore, the battery operation at an ultralow temperature is successfully achieved in a phosphoric acid-based antifreezing electrolyte, with a reversible discharge capacity of 282 mAh g –1 provided by the highly porous carbon at −70 °C and an average Coulombic efficiency of 91% for more than 300 cycles at −40 °C. This work offers a new strategy to enhance the reversibility of aqueous chlorine batteries for energy storage applications in a wide temperature range.