Photo-Assisted Li-N₂ Batteries with Enhanced Nitrogen Fixation and Energy Conversion

Li-N₂ batteries have received widespread attention for their potential to integrate N₂ fixation, energy storage, and conversion. However, because of the low activity and poor stability of cathode catalysts, the electrochemical performance of Li-N₂ batteries is suboptimal, and their electrochemical reversibility has rarely been proven. In this study, a novel bifunctional photo-assisted Li-N₂ battery system was established by employing a plasmonic Au nanoparticles (NPs)-modified defective carbon nitride (Au-N_v -C₃ N₄ ) photocathode. The Au-N_v -C₃ N₄ exhibits strong light-harvesting, N₂ adsorption, and N₂ activation abilities, and the photogenerated electrons and hot electrons are remarkably beneficial for accelerating the discharge and charge reaction kinetics. These advantages enable the photo-assisted Li-N₂ battery to achieve a low overpotential of 1.32 V, which is the lowest overpotential reported to date, as well as superior rate capability and prolonged cycle stability (≈500 h). Remarkably, a combination of theoretical and experimental results demonstrates the high reversibility of the photo-assisted Li-N₂ battery. The proposed novel strategy for developing efficient cathode catalysts and fabricating photo-assisted battery systems breaks through the overpotential bottleneck of Li-N₂ batteries, providing important insights into the mechanism underlying N₂ fixation and storage.