Constructing metal telluride-grafted MXene as electron “donor–acceptor” heterostructure for accelerating redox kinetics of high-efficiency Li–S batteries

Abstract

The emergence of three-dimensional (3D) porous heterostructure that integrates the advantages of two materials offers prospects to resolve the serious shuttle effect and slow reaction kinetics in lithium sulfur (Li–S) batteries. In this work, an electron modulation strategy of “donor–acceptor” is constructed by uniformly grafting NiTe₂ onto MXene (denoted as NiTe₂@MXene) to inhibit the restacking of MXene and the aggregation of NiTe₂ nanoparticles, serving as a functional heterostructure catalyst for shuttling blockers and kinetics promoters. The as-obtained 3D porous NiTe₂@MXene heterostructure provides highly-exposed active interfaces, fast electron transfer channels, abundant defect sites, and rapid stepwise sulfur conversion, as fully demonstrated by the optical images, theoretical calculations, and pouch cell. Consequently, the batteries with NiTe₂@MXene-modified separator deliver a remarkable cycling performance at 1C (with a capacity decreasing rate of only 0.0287% per cycle) over 500 cycles. Even under a high sulfur loading (8.31 mg cm⁻²) and a limited electrolyte/sulfur ratio (E/S = 6.52 μL mg⁻¹), an outstanding areal capacity of 7.3 mA h cm⁻² is achieved. The above results indicate that the electronic modulation of the NiTe₂@MXene heterostructure achieves the best electrocatalytic activities for polysulfides conversion and practical application, providing unique insights into the design of 3D porous MXene-based heterostructures.