Understanding the Reversible Reactions of Li‐N2 Battery Catalyzed With SnO2

Metal–N 2 battery can be applied in both energy storage and electrochemical nitrogen reduction reaction (NRR); however, there has been only extraordinarily little study on metal–N 2 battery since its electrochemical reversibility still needs further proofs. And its electrochemical performances also need to be enhanced. Herein, we investigated the discharge–charge reactions between Li anode and N 2 cathode via designing an efficient catalyst of nanosized SnO 2 particles dispersed on N‐doped carbon nanosheets (SnO 2 @NC) for the Li‐N 2 battery, with good cyclic stability and a high specific capacity of 0.25 mA h (~500 mA h g −1 ) at a large current density of 1000 mA g −1 . The electrochemical reversibility of both NRR in the discharge process and nitrogen extraction reaction in the charge process for Li‐N 2 battery is discussed. Time‐of‐flight secondary ion mass spectrometry results imply that the SnO 2 @NC can effectively promote the adsorption of N 2 and the activation of NRR in the discharge process. Furthermore, ex situ X‐ray photoelectron spectroscopy and Fourier transform infrared tests are performed to study the electrochemical reversibility of Li‐N 2 battery. It can be proved that the formation and decomposition of discharging product Li 3 N are electrochemical reversible during cycling in our deigned Li‐N 2 battery system with SnO 2 @NC catalyst.