Rechargeable Hydrogen–Chlorine Battery Operates in a Wide Temperature Range

Hydrogen-chlorine (H₂-Cl₂) 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 H₂-Cl₂ battery is highly desirable yet challenging. Here, we report a rechargeable H₂-Cl₂ battery operating statically in a wide temperature ranging from -70 to 40 °C, which is enabled by a reversible Cl₂/Cl^- redox cathode and an electrocatalytic H₂ anode. A hierarchically porous carbon cathode is designed to achieve effective Cl₂ gas confinement and activate the discharge plateau of Cl₂/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.