In-situ constructed MXene/Si@NiO heterojunction: Dual modification unlocks ultrahigh reversible capacity and extra capacity gain in silicon anodes

Silicon, the most promising anode material for ultra-high specific capacity lithium-ion batteries, has been impeded from widespread use due to its large volume effects and limited electrical conductivity during cycling. In this study, we employed a facile one-step hydrothermal method to in-situ grow a Si@NiO core-shell structure on an MXene substrate, with the aim of optimizing its performance. The MXene substrate provides excellent electrical conductivity and structural stability; Si serves as the primary source of capacity contribution; NiO acts as an interlayer, bridging the substrate and the active material while mitigating the volume expansion of Si. This dual modification strategy, which targets both structure and interface, endows the Si anode with superior electrochemical performance. After 175 cycles at 0.1 A g −1 and 900 cycles at 1 A g −1 , the capacity of the electrode rose to 1530 m Ah g −1 and 1608 m Ah g −1 , Benefiting from the core-shell structure and optimized porous architecture, the electrode exhibits a volume expansion as low as 34 % after 900 cycles, effectively suppressing electrode pulverization failure caused by Si anode volume expansion. This study holds significant importance, as the simple and cost-effective one-step hydrothermal method also provides a reliable strategy for the commercial application of silicon anodes.