Cycle Issue and Failure Analysis of Li–N₂ Batteries

Li–N2 is a subset of Li–air batteries, without a testing protocol. Porous graphene was employed as the cathode to study the cycling of Li–N2. The nitrogen reduction mechanism was revised to an electrochemical interaction between lithium and nitrogen. The role of the Li3N interface during cycling was discovered. Using in situ electrochemical impedance, the study discerns the instability of the interface formed during the initial cycles. An abnormal phenomenon that the discharge voltage platform rose after cycling prompts a detailed characterization of the interface evolution during the initial and subsequent cycles. In the later stage of the Li–N2 battery, it seems that N2 fixation no longer occurs due to the occurrence of side reactions. Finally, the study proposes preforming the cathode interface to improve cycling performance. The article sheds light on the challenges and opportunities for metal–N2 batteries.