Constructing Hierarchical Hollow Microspheres with Cos/Co9s8 Heterostructured Nanosheets for High-Performance Sodium Storage

Abstract

Transition metal sulfides with high theoretical capacities have drawn increasing attention as anode materials for sodium-ion batteries (SIBs). Unfortunately, their practical application is still limited by the rapid decay of capacity and severe volume variation during cycling. Herein, we constructed a hollow microspheres material composed of CoS/Co9S8 heterostructured nanosheets through a one-step solvothermal method. When applied as the anode for SIBs, CoS/Co9S8 exhibited a superior specific capacity of 600 mAh g−1 after 100 cycles at 0.5 A g−1, and a remarkable cycling performance of 530 mAh g−1 after 800 cycles at 5 A g−1. The outstanding electrochemical performance can be ascribed to the alleviated volume expansion during cycling due to the unique three-dimensional hollow hierarchical structure. Moreover, the density functional theory calculation results revealed the enhancement of electronic conductivity, Na+ diffusion and structural stability due to the CoS/Co9S8 heterostructure.

Keywords: Sodium-ion battery, heterostructure, Three-dimensional hierarchical structure, Cobalt sulfides, Anode material