Ni3S2 nanosheet-anchored carbon submicron tube arrays as high-performance binder-free anodes for Na-ion batteries

Abstract

Owing to the increasing concerns regarding limited lithium reserves, sodium-ion batteries (SIBs) have attained worldwide attention in recent years. However, there is still a challenge to find suitable anodes for SIBs with high capacity and a long cycle life. In this work, we propose a unique feather-like array-type anode composed of thin Ni₃S₂ nanosheets anchored on cracked carbon submicron tubes (CSTs) on a porous Ni foam substrate. The porous structure of the Ni foam facilitates electrode wetting by the electrolyte. The voids in between the Ni₃S₂/CST arrays provide free space for buffering volume changes upon sodiation/desodiation. The CSTs not only act as the support for Ni₃S₂ growth but also uniformly disperse the Ni₃S₂ nanosheets, leading to high capacity and good capacity retention. The Ni-supported Ni₃S₂/CSTs can deliver a high initial reversible capacity of 887 mA h g⁻¹ at 50 mA g⁻¹. The reversible capacity can be kept at 212 mA h g⁻¹ after 260 cycles. This work will shed light on the design of high-performance SIB anodes.