Improved lithium ion storage performance of TiCT MXene@S composite with carboxymethyl cellulose binder.

MXenes are regarded as promising electrode materials for lithium-ion batteries owing to their high electrical conductivity and two-dimensional structure but suffer from low intrinsic specific capacities. In this study, we fabricate sulphur-doped multilayer TiCT MXenes via calcination and annealing using sublimed sulphur as the sulphur source. After sulphur doping, the interlayer spacing of TiCT increases, which is favourable for Li-ion insertion. The TiCT MXene@S composite exhibits excellent electrochemical performance. A high reversible specific capacity of 393.8 mAh g at a current density of 100 mA g after 100 cycles is obtained. Additionally, a negative fading phenomenon is observed when the specific capacity increases to 858.9 mAh g after 2550 cycles at 1 A g and to 322.2 mA h g after 3600 cycles at 5 A g from the initial 267.3 mAh g. We systematically investigate the effects of two different binders (polyvinylidene difluoride and carboxymethyl cellulose, hereinafter abbreviated as PVDF and CMC, respectively) on the electrochemical performance of the TiCT MXene@S composite and discovered that the electrode using the CMC binder exhibits better lithium-ion storage performance than that using the PVDF binder, which is attributed to the lower charge transfer resistance, higher ion diffusivity, and enhanced adhesion force.