A Synergistic Strategy for Highly Reversible Sodium Metal Anodes by Using ZnSe Nanoparticles-Decorated N-Doped Carbon Nanosheets as a Host

Sodium metal stands as one of the most promising anode materials for the upcoming generation of high-energy-density rechargeable batteries. Nevertheless, the intractable issues of dendrite growth and unstable solid electrolyte interphase (SEI) in sodium metal anodes (SMAs) have drastically impeded the practical applications of sodium metal batteries. Herein, nitrogen-doped carbon nanosheets uniformly decorated with ZnSe nanoparticles (ZnSe@NC) are designed as the SMA host, which efficiently facilitates a highly reversible Na plating/stripping behavior while stabilizing the SEI. Specifically, ZnSe can undergo in situ reactions with Na to generate NaZn₁₃ alloy with excellent sodiophilicity and a SEI enriched with inorganic Na₂Se components. On one hand, the sodiophilic NaZn₁₃ sites reduce the Na nucleation overpotential, enabling uniform Na deposition. On the other hand, the in situ formed Na₂Se increases the inorganic SEI fraction, stabilizing the interface and enhancing both ionic conductivity and mechanical resilience. As a result, the as-designed ZnSe@NC electrode stably cycles for over 200 times at 1.0 mA cm^-2 with an average Coulombic efficiency of 99.3% in half cells. Besides, the assembled symmetric cells demonstrate excellent performances with low nucleation overpotential and long cycle life of 1000 h at 2.0 mA cm^-2 under a 40% depth of discharge. More impressively, the practical feasibility of the SMA host is demonstrated by cycling Na@ZnSe@NC∥Na₃V₂(PO₄)₃ full cells for over 200 cycles at 2 C, achieving a high capacity retention rate of 97.1%.