Synchronous Hetero‐Interface and Vacancy Engineering for Construction of Pitaya‐Like CoSe1‐x/C@NC@ZnSe Nanosphere Toward Ultrastable Sodium‐Ion Half/Full Batteries

Abstract Transition metal selenides have attracted extensive attention as promising anode materials for sodium‐ion batteries (SIBs) due to their fascinating physical chemistry characteristics. However, its cycling performance especially at high currents, is still unsatisfactory owing to the intrinsic limited conductivity. Herein, N‐doped carbon shell coated and ZnSe bonded Se‐vacancy enriched CoSe 1‐x (CoSe 1‐x /C@NC@ZnSe, CZSCV) nanospheres with abundant hetero‐interfaces are designed through an in situ Se transfer strategy. Owing to the ingenious structure, as an anode material in SIBs, CZSCV demonstrates superior cycling stability (363.5 mAh g −1 at 10 A g −1 after 1000 cycles) and high‐rate sodium storage capability (193.9 mAh g −1 at 20 A g −1 after 5000 cycles). Meanwhile, in the CZSCV//Na 3 V 2 (PO 4 ) 3 @C full cell, it also delivers a stable capacity of 201.4 mAh g −1 at 1.0 A g −1 and provides a high energy density of 397.4 Wh kg −1 with a power density of 231.6 W kg −1 . Based on the kinetics analysis and the density functional theory calculation, the hetero‐interfaces and enriched Se‐vacancies can synergistically accelerate the Na + /electron transfer, owing to the charge redistribution, the decreased diffusion barrier of Na + and increased pseudo‐capacitive capacity contribution. As a result, excellent high‐rate anode material can be achieved for the SIBs.