Effect of Crystal Structures on Electrochemical Performance of Hierarchically Porous CoSe <sub>2</sub> Spheres as Anodes for Sodium‐Ion Batteries
Xin Liu, Guo B. Xu, Ting Cheng, L. W. Yang, Juexian Cao
Abstract
Abstract Metal selenides with controllable crystal structures and hierarchically porous architectures have recently attracted great attention as the advanced electrode materials for sodium‐ion batteries. In present study, hierarchically porous orthogonal CoSe 2 (o‐CoSe 2 ) and cubic CoSe 2 (c‐CoSe 2 ) spheres are prepared through a controllable selenization and subsequent annealing strategy. Both types of CoSe 2 spheres exhibit superior electrochemical properties resulting from hierarchical architecture, which can alleviate of the structural strain, the accelerated electron transmission and shorten the diffusion pathway of Na + . As anode materials for SIBs, the o‐CoSe 2 electrode delivers a higher rate capability of 244 mAh g −1 at 3000 mA g −1 and a better cyclability of 378 mAh g −1 after 100 cycles at 1000 mA g −1 compared to the c‐CoSe 2 . From detailed microstructure characterization and kinetics behavior analysis, it is revealed that the o‐CoSe 2 spheres exhibits larger specific surface, optimized porous nature, higher pseudocapacitive contribution, and more powerful Na + ‐ions mobility. Our studies can pave the way for rational design and development of selenides electrode materials in rechargeable batteries.