Single-Crystal Copper Sulfide Anode with Fast Ion Diffusion for High-Rate Sodium-Ion Batteries
Xiao Pei, Youqi Zhu, Changliang Du, Hui Peng, Zhitao Wang, Xilan Ma, Jianhua Hou, Chuanbao Cao
Abstract
Copper sulfide has been considered the promising alternative anode material due to the high theoretical capacity and weak Cu–S bonds for sodium-ion batteries (SIBs). However, conversion-type copper sulfide anode materials undergo huge volume expansion, sluggish sodium-ion diffusion kinetics, and low conductivity. Herein, the single-crystal Cu 9 S 5 nanorods fabricated via an efficient microwave-assisted synthesis method are demonstrated with fast ion diffusion, favorable long-term stability, and exceptional rate performance in SIBs. The optimized single-crystalline Cu 9 S 5 nanorods can realize high rate capability, including a specific discharge capacity of 670.2 mAh g –1 at 100 mA g –1 and 519.1 mAh g –1 at 3000 mA g –1, which is equivalent to 77.5% of the capacity at 100 mA g –1 . More importantly, the single-crystalline microrods greatly alleviate the structure degradation during repeated sodiation–desodiation reactions, offering 95% capacity retention at 1 A g –1 current density and a slight decay of 0.0099% per cycle. The microwave-induced crystallographic and morphologic transformations of copper sulfide are confirmed for the first time under prolonged irradiation time. This work provides a insight to develop high-rate anode materials for sodium-ion batteries.