Effect of Crystal Structures on Electrochemical Performance of Hierarchically Porous CoSe2 Spheres as Anodes for Sodium-Ion Batteries

摘要

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 CoSe2 (o-CoSe2) and cubic CoSe2 (c-CoSe2) spheres are prepared through a controllable selenization and subsequent annealing strategy. Both types of CoSe2 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-CoSe2 electrode delivers a higher rate capability of 244mAhg(-1) at 3000mAg(-1) and a better cyclability of 378mAhg(-1) after 100 cycles at 1000mAg(-1) compared to the c-CoSe2. From detailed microstructure characterization and kinetics behavior analysis, it is revealed that the o-CoSe2 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.