Direct solar energy charging of metal||air batteries enabled by photo-coupled electrodes

The realization of solar-charging within rechargeable batteries has been a dream of several generations of scientists, marking a transformation in sustainable energy storage. The key challenge is that the photo-rechargeable electrodes need to simultaneously possess high photovoltaic efficiency and cycling stability. Herein, through dynamic reconfiguration of sp-hybridized carbon networks via direct photoexcitation, we present nitrogen-substituted graphdiyne as a metal-free photoelectrode for integrated solar-charging in rechargeable batteries. Nitrogen-substituted graphdiyne accelerates oxygen evolution reaction kinetics by the synergistic effect of improved intermediate adsorption and hole-mediated oxidation under light excitation. Nitrogen-substituted graphdiyne-based photo-coupled positive electrodes are applicable to multiple metal||air batteries (Zn||air, Li||O₂, Mg||air, Fe||air, and Al||air), including a low charging voltage of 1.33 V and 96.9% energy efficiency in Zn||air batteries, along with stability over 230 cycles at 100 mA cm^-2. The Li||O₂ battery achieved an efficiency of 96.3%, while Mg||air, Fe||air, and Al||air systems exhibited reduced charging voltages. This research has pioneered a class of photoelectrodes whose active sites are directly and dynamically defined by light, opening avenues for high-efficiency solar-driven energy conversion and storage.