Enhanced physical and chemical binding of MXene/CNT composite and Ni catalytic conversion to boost the performance of Li–S battery

Abstract

A unique three-dimensional (3D) porous MXene/CNTs-Ni composite was fabricated as host material for the cathode of lithium–sulfur battery. One-dimensional carbon nanotubes (CNTs) were interspersed with two-dimensional MXene nanosheets to establish a porous network structure for fast charge transfer and efficient active site exposure. Meanwhile, the introduction of catalytically active zero-dimensional nickel oxide can catalyze the creation of more active sites, which can further inhibit the shuttle effect and enhance the redox kinetics. The hosts of MXene/CNTs-Ni with a unique 3D porous structure of point-line-sheet interconnection shape not only improve the sulfur loading and slow down the volume expansion of cathodes but also effectively inhibit the shuttle effect of lithium polysulfides through the synergistic effect of physical confinement and chemical adsorption. Among the composites, the cell with S@MXene/CNT-1Ni as a cathode had an initial discharge specific capacity of 1078.2 mAh g−1 at 0.5 C and a capacity of 470.8 mAh g−1 after 1000 cycles. The capacity decay was as low as 0.056% per cycle. Even with a sulfur loading of 4.0 mg cm−2 and a current of 2.0 C, the S@MXene/CNT-1Ni composite provides a high first-cycle specific capacity of 808.2 mAh g−1 and a capacity of 370.6 mAh g−1 after 300 cycles, with a capacity decay of 0.18% per cycle.