Li-N2 Batteries: A Reversible Energy Storage System?

Tremendous energy consumption is required for traditional artificial N-2 fixation, leading to additional environmental pollution. Recently, new Li-N-2 batteries have inextricably integrated energy storage with N-2 fixation. In this work, graphene is introduced into Li-N-2 batteries and enhances the cycling stability. However, the instability and hygroscopicity of the discharge product Li3N lead to a rechargeable but irreversible system. Moreover, strong nonpolar N equivalent to N covalent triple bonds with high ionization energies also cause low efficiency and irreversibility of Li-N-2 batteries. In contrast, the modification with in situ generated Li3N and LiOH restrained the loss and volume change of Li metal anodes during stripping and plating, thereby promoting the rechargeability of the Li-N-2 batteries. The mechanistic study here will assist in the design of more stable Li-N-2 batteries and create more versatile methods for N-2 fixation.