Light-driven high-performance metal-air battery under extreme low pressure

Metal-air batteries are considered an efficient energy storage technology due to their high energy density, environmental friendliness, and potential for long-term cycle lifetime. However, current research on metal-air batteries is limited to ambient pressure with only several studies focusing on extreme environments specifically low-temperature scenarios. Considering the critical role of pressure on gas-involved reactions and potential applications of low-pressure metal-air batteries, herein, we studied the pressure-dependent catalytic process theoretically based on thermodynamics and found that light-generated carriers can compensate for the low-pressure-induced unfavorable reaction barrier by regulating absorption strength. Following the theoretical guidance, we propose a light and catalysis co-compensation (LCC) strategy for low-pressure Li-CO₂ batteries. As a demonstration, we designed and constructed the p-TiO₂/Pd@Graphene heterojunction serving as the bifunctional photocathode, where p-TiO₂ provides photo-generated carriers and Pd@Graphene accelerates the reaction catalytically thus facilitating the charging/discharging process jointly under low-pressure. Consistent with the theoretical prediction of pressure sensitivity and photoelectrocatalysis, the resulting light-assisted low-pressure Li-CO₂ batteries exhibit surprising performance that far exceeds that at low pressure and even higher than that operating at atmospheric pressure. Furthermore, multiple metal-air batteries, including Li, Na, Mg, and Al-based systems, have proven the feasibility and reliability of the photocatalysis compensated low-pressure reaction theory. This work provides a new pathway for developing high-energy batteries at extremely low pressures and extensively expands the pressure-dependent application fields of catalysis and energy storage devices.