Rational design of 3D hierarchical MXene@AlF3/Ni(OH)2 nanohybrid for high-performance lithium-sulfur batteries

Some challenges of lithium sulfur battery which result in unexpected capacity degradation and unsatisfactory rate performance are in urgent need to be resolved to bring Li-S battery into intensive practical use. Herein, the novel and facile methods are employed to fabricate 3D hierarchical Ti3C2Tx@AlF3 /Ni(OH)2 via one-step conversion of Ti3AlC2 to layered Ti3C2Tx@AlF3, followed by the decoration of Ni(OH)2 nanosheets. The stable layered Ti3C2Tx substrate boosts the electron conductivity upon cycling, while the produced polar AlF3 nanoparticles which are dispersed on the surface and in the interlayer of Ti3C2Tx show strong chemisorption with polysulfides. Moreover, the package of Ni(OH)2 nanosheets can serve as the physical baffle and play the critical role in effectively inhibiting the migration of soluble polysulfides and enhancing the redox kinetic of adsorbed polysulfides. Therefore, the Ti3C2Tx@AlF3 -S /Ni(OH)2 hybrid as cathode materials of Li-S battery exhibits high discharge capacity of 1184 mAh·g−1 at 0.2C, improved rate capability of 854 mAh·g−1 at 1C and 635 mAh·g−1 at 4C, as well as remarkable cycling stability of low capacity decay rate of 0.048% per cycle after 1000 cycles at 1C. The developed strategy of nanomaterials offers a new angle of rationally designing the multifunctional nanomaterials of composite structure for lithium sulfur battery.