Constructing Robust Interfaces in CoSe₂/Nitrogen-Doped Carbon for Superior Long-Life Sodium-Ion Storage

Robust interfaces in anodes play a crucial role in boosting sodium-ion battery (SIB) performance. However, the fragile interfaces constructed by a two-step synthesis or artificial stack are prone to be destroyed during the charging/discharging processes, which significantly reduces the lifetime of SIBs. Here, a facile construction strategy is developed to produce robust interfaces in hollow sphere-like CoSe₂/nitrogen-doped carbon (HS-CoSe₂/NC) using intrinsic Co, N, C in metal-organic framework as precursors, which enhance the electron/ion diffusion kinetics. In parallel, the hollow sphere structure of CoSe₂/NC contributes to shortening the sodium-ion diffusion distance and guaranteeing structure stability. Benefiting from the unique design, ultrahigh reversible specific capacity (456.6 mAh g^-1 at 5 A g^-1) is maintained even after 7250 cycles with a supreme capacity retention (96.6%). The sodium-ion storage mechanism is clarified by combining theoretical calculations and in situ/ex situ experimental characterizations. This work provides a new pathway to build robust interfaces in anodes for boosting SIBs performance.