Hierarchical pipe-in-pipe carbon nitride with oxygen doping and carbon defects synergistically promotes solar-to-hydrogen conversion.

An artificial SEI consisting of an Na–Sn alloy and NaCl layer possesses high-uniformity and fast ion diffusion, stabilizing Na metal anodes.

Sodium (Na) metal anodes suffer from dendrite formation and inferior reversibility, mainly induced by the inhomogeneous nucleation/growth and fragile solid electrolyte interphase (SEI), which hinders their commercial application. Optimizing nucleation behavior or SEI features can improve Na deposition/ stripping process, as observed in most currently available approaches, but its long-term cyclic stability remains a great challenge because these issues are not fully optimized/solved in an individual method. Herein, a dual-role crown ether additive (CEA) is introduced into electrolytes to circumvent these challenges concurrently. As revealed by experiments and theoretical calculations, CEA possesses a strong affinity with Na + and effectively regulates desolvation kinetics, leading to the uniform Na nucleation/growth. On the other hand, the resultant Na + /CEA complexes with a strong Lewis acid feature easily attract anions, which enables an anion-abundant solvation sheath, resulting in a NaF-rich SEI. Consequently, Na|Cu cells deliver a high average Coulombic efficiency of 99.95% beyond one year and stable cyclic stability over 3000 h even under a high depth of discharge (75%), surpassing most previous studies. Furthermore, this concept is readily extended to zinc metal batteries, verifying that simultaneous nucleation control and interfacial chemistry regulation are promising ways to realize stable metal anodes.

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The practical application of Zn metal anodes in electronic devices is hindered by dendrite growth and parasitic reactions. Electrolyte optimization, particularly the introduction of organic co‐solvents, is widely used to circumvent these challenges. Various organic solvents in a wide range of concentrations have been reported; however, their influences and corresponding working mechanisms at different concentrations are largely unexplored in the same organic species. Herein, economical, low‐flammable ethylene glycol (EG) is used as a model co‐solvent in aqueous electrolytes to examine the relationship between its concentration, anode‐stabilizing effect, and mechanism. Two maximal values are observed for the lifetime of Zn/Zn symmetric batteries under EG concentrations from 0.05 vol% to 48 vol%. Zn metal anodes can stably run for over 1700 h at a low EG content (0.25 vol%) and high EG content (40 vol%). Based on the complementary experimental and theoretical calculations, the enhancements in low‐ and high‐content EG are ascribed to the specific surface adsorption for suppressed dendrite growth and the regulated solvation structure for inhibited side reactions, respectively. Intriguingly, a similar concentration‐reliant bimodal phenomenon is observed in other low‐flammable organic solvents (e.g., glycerol and dimethyl sulfoxide), thereby suggesting universality of this study and providing insight into electrolyte optimization.