Graphene-like nanocomposites anchored by Ni3S2 slices for Li-ion storage

Abstract

Metal sulfide has received considerable interest for electrochemical energy storage and conversion. However, its inherent poor conductivity and structural instability limit its practical application in energy conversion and storage devices. In this work, Ni₃S₂ nanoslices anchored on reduced graphene oxide (denoted as Ni₃S₂@C-RGO) were designed and synthesized through a facile hydrothermal step and a subsequent heating treatment process. Glucose and graphene oxide (GO) both possess abundant oxygenated functional groups, and their strong synergetic effects help to restrict the growth of Ni₃S₂ to form a nanoslice structure. Meanwhile, the redundant glucose can be transformed into a thin carbon layer coating on the surface of the Ni₃S₂ slices through the subsequent thermal treatment. When evaluated as the anode of a lithium ion battery (LIB), the synthesized Ni₃S₂@C-RGO nanocomposite showed an initial capacity of 608.4 mA h g⁻¹, a specific discharge capacity of 560 mA h g⁻¹ remained after the 100th cycle, and improved rate capability, which is much better than that of the Ni₃S₂ and Ni₃S₂-RGO nanostructures. The enhanced electrochemical performance can be attributed to the synergetic effects between Ni₃S₂ nanoslices and the 2D C-RGO nanostructures, such as increasing conductivity, shortening Li⁺ ion diffusion path, and accommodating huge volume changes through the cycles.