Facile electrostatic assembly of Si@MXene superstructures for enhanced lithium-ion storage

Silicon (Si) has attracted much attention as anode materials for next-generation lithium-ion batteries (LIBs) due to its high theoretical capacity. To improve the electrical conductivity, it is critically important to realize the uniform distribution of Si nanoparticles (NPs) onto conductive substrates such as graphene and MXene. Herein, a simple and effective strategy through facile electrostatic assembly was reported, in which Si NPs can adhere onto few-layer MXene (Ti₃C₂) nanosheets uniformly to afford Si@MXene superstructures. Importantly, Ti₃C₂ nanosheets not only facilitates Li⁺ and electron transport of the electrode materials, but also buffer the notorious volume expansion of Si NPs during charge/discharge. Meanwhile, the assembly of Si NPs prevents the re-stacking of Ti₃C₂ nanosheets, while simultaneously offering additional active sites. The as-prepared Si@Ti₃C₂ anode exhibits an initial capacity of 3502.3 mAh g^-1 at 0.1 A g^-1, retaining a high capacity of 1342.8 mAh g^-1 at 1 A g^-1 with a Coulombic efficiency of 99.8% after 200 cycles. This work provides a new strategy for the scalable synthesis of Si@MXene composites containing uniformly distributed Si NPs, which show a great promise for being used as high-performance anode materials for LIBs.