Interface engineering of MoS2-based ternary hybrids towards reversible conversion of sodium storage

Abstract

Sodium-ion batteries (SIBs) using conversion-type metal sulfides as anode materials have received a lot of attention. However, the irreversible conversion reaction is the major challenge for achieving long-life cycling performance. Herein, taking MoS2 as a representative material, conductive Co9S8 and three-dimensional porous nitrogen-doped graphene-like carbon are selected to promote its reaction kinetics through engineered interface. In the designed MoS2-based hybrids, MoS2 and Co9S8 form two-dimensional (2D) Mott-Schottky heterostructure via in-plane interface, lying on the surface of graphene-like carbon through horizontal interface. The 2D in-plane Mott-Schottky interface not only improves the electrical conductivity but also facilitates the Na+ adsorption and diffusion. The horizontal interface is beneficial for adsorbing and dispersing the discharged products. They lead to highly reversible conversion reaction. Therefore, the resultant hybrids show an excellent long-term cycling stability of 1,500 cycles at a high rate of 1 A/g. This work suggests that rational design of interface in conversion-type hybrids is a promising way for preparing highly reversible anodes of SIBs and provides a new approach to construct 2D metal sulfide-based heterostructures.