Efficient synergy of MOF-derived CoTe2 polyhedron anchoring on CNTs as anode materials for Na-ion storages

Abstract

The transition metal chalcogenides (TMCs) are promising anode materials with excellent theoretical capacity and controllable synthesis approaches for Sodium ion batteries. However, the obvious volume effects and sluggish kinetics in the long-term sodiation/desodiation reaction limit the stability and high-capacity. Herein, the CoTe2 @carbon nanocomposite electrodes (CoTe2 @CNTs) are designed by ZIF-67 derived to conquer the volume expansion, synchronously, and CNTs anchored strategy are adopted to promote Na+ diffusion dynamics, and ensure cyclic stability and long cycle life of anode materials. Specifically, the as prepared nanocomposite constructed by CoTe2 and CNT has displayed efficient Na+ storage mechanism by providing multiple adsorption sites, interconnected conductive network and abundant ions transport pathways, which are revealed by the density functional theory calculations. Furthermore, the in-situ CNTs anchored of CoTe2 polyhedron have significantly enhanced the charge transfer capacity for Na+/electron and metallic properties of CoTe2 @CNT composites, which exhibit outstanding electrochemical capacities (112.7 mAh g−1 at 2 A g−1 after 500 cycles) and pseudocapacitive-dominated behaviors when used as anodes. This work is expected to provide a legitimate and convenient approach with the controllable preparation of nanocomposite in energy storge devices.