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

Li-N-2 batteries have received widespread attention for their potential to integrate N-2 fixation, energy storage, and conversion. However, because of the low activity and poor stability of cathode catalysts, the electrochemical performance of Li-N-2 batteries is suboptimal, and their electrochemical reversibility has rarely been proven. In this study, a novel bifunctional photo-assisted Li-N-2 battery system was established by employing a plasmonic Au nanoparticles (NPs)-modified defective carbon nitride (Au-N-v-C3N4) photocathode. The Au-N-v-C3N4 exhibits strong light-harvesting, N-2 adsorption, and N-2 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-N-2 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 (approximate to 500 h). Remarkably, a combination of theoretical and experimental results demonstrates the high reversibility of the photo-assisted Li-N-2 battery. The proposed novel strategy for developing efficient cathode catalysts and fabricating photo-assisted battery systems breaks through the overpotential bottleneck of Li-N-2 batteries, providing important insights into the mechanism underlying N-2 fixation and storage.