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

Metal–N2 battery can be applied in both energy storage and electrochemical nitrogen reduction reaction (NRR); however, there has been only extraordinarily little study on metal–N2 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 N2 cathode via designing an efficient catalyst of nanosized SnO2 particles dispersed on N‐doped carbon nanosheets (SnO2@NC) for the Li‐N2 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‐N2 battery is discussed. Time‐of‐flight secondary ion mass spectrometry results imply that the SnO2@NC can effectively promote the adsorption of N2 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‐N2 battery. It can be proved that the formation and decomposition of discharging product Li3N are electrochemical reversible during cycling in our deigned Li‐N2 battery system with SnO2@NC catalyst. The electrochemical reversibility of both nitrogen reduction reaction in discharge process and nitrogen extraction reaction in charge process for a stable cycling Li‐N2 battery with nanosized SnO2 catalyst is discussed based on time‐of‐flight secondary ion mass spectrometry, X‐ray photoelectron spectroscopy, and Fourier transform infrared investigations.