Inter-overlapped MoS2/C composites with large-interlayer-spacing for high-performance sodium-ion batteries

Abstract

As a two-dimensional layered material with a structure analogous to that of graphene, molybdenum disulfide (MoS₂) holds great promise in sodium-ion batteries (SIBs). However, recent research findings have revealed some disadvantages in two-dimensional (2D) materials such as poor interlayer conductivity and structural instability, resulting in poor rate performance and short cycle life for SIBs. Herein, we designed MoS₂ nanoflowers with an ultra-wide spacing interlayer (W-MoS₂/C) anchored on special double carbon tubes to construct three-dimensional (3D) nanostructures. When tested as an anode material in a SIB, the as-prepared CNT@NCT@W-MoS₂/C sample achieves high capacities (530 and 230 mA h g⁻¹ at current densities of 0.1 and 2 A g⁻¹, respectively). Density functional theory (DFT) calculations demonstrate that the ultra-wide spacing MoS₂/C structure is beneficial for the chemical adsorption of sodium ions and facilitates redox reactions. The wide interlayer spacing and the presence of an intermediate carbon layer provide a rapid diffusion channel for ions and offer a free space for volume expansion of the electrode material.