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Na‐O2 batteries are attractive for energy storage due to their high theoretical energy density. In order to alleviate Na dendrite formation, artificial protective coatings have been widely investigated in Na‐metal batteries (NMBs). Although it can be intuitive to expect transferable Na protection methodologies from NMBs to Na‐O2 batteries, the performance of anode protection coatings in Na‐O2 batteries remains obscure, because Na‐O2 batteries undergo a unique reaction mechanism involving superoxide. Here, the effect of superoxide crossover on the polymeric Na protection layer in Na‐O2 batteries is revealed, and an effective strategy to eliminate the implications of a superoxide‐sensitive protecting layer is proposed. Using polymeric alucone protected Na anode as an example, the alucone layer actually decomposes under superoxide attack and is incapable of facilitating long‐term cycling of Na‐O2 batteries in sharp contrast to its stable performance in NMBs. By blocking superoxide crossover with solid‐state electrolytes (SSEs), significantly improved Na‐O2 cell performance is demonstrated, recovering the Na dendrite suppressing effect of the alucone film. Benefiting from the synergistic effect of SSE and alucone layer, Na‐O2 batteries can achieve a long life of 325 cycles at 0.2 mA cm−2. This work indicates that the stability of the Na protection layer against superoxide should be taken into serious consideration. [ABSTRACT FROM AUTHOR]

Lithium–sulfur batteries are deemed as optimal energy devices for the next generation of high‐energy‐density energy storage. However, several problems such as low energy density and short cycle life hinder their application in industry. Here, MoS2–MoN heterostructure nanosheets grown on carbon nanotube arrays as free‐standing cathodes are reported. In this heterostructure, MoN works as a promoter to provide coupled electrons to accelerate the redox reaction of polysulfides while the MoS2, with a two‐dimensional layered structure, provides smooth Li+ diffusion pathways. Through their respective advantages, both MoN and MoS2 could mutually boost the process of "adsorption‐diffusion‐conversion" of polysulfides, which have a synergy enhancement effect to restrain the lithium polysulfides from shuttling. The designed cathodes show excellent long‐term cycling performances of 1000 cycles at 1C with a low decay rate of 0.039% per cycle and a high rate capability up to 6C. A high initial areal capacity of 13.3 mAh cm−2 is also achieved under a low electrolyte volume/sulfur loading (E/S) ratio of 6.3 mL g−1. This strategy of promoting polysulfide conversion by heterostructure MoS2–MoN as presented in this work can provide a more structured design strategy for future advanced Li–S energy storage systems. [ABSTRACT FROM AUTHOR]