Synthesis of three-dimensional Sn@Ti₃C₂ by layer-by-layer self-assembly for high-performance lithium-ion storage

Powerful yet orderly nanostructure lithium-ion batteries (LIBs) are eagerly desired to satisfy the practical application of portable electronics and smart grids. However, the surface re-stacking and surface functionalization on the MXenes in the anode electrode severely restrict the accessibility to electrolyte ions, hindering the full utilization of their intrinsic properties. To address this challenge, we rationally design three-dimensional (3D) Sn@Ti₃C₂ materials and fabricate them in a unique layer-by-layer manner through self-assembly for boosting LIBs. In this design system for fast lithium-ion storage, the Ti₃C₂ MXene nanosheets serving as 3D scaffolds buffer the severe volume expansion and agglomeration of Sn nanoparticles (NPs) and enhance electrode conductivity at the interface. Furthermore, Sn NPs are embedded as interlayer spacers to prevent nanosheet re-stacking and provide outstanding electrochemical performance. The nanostructure can increase the lithium-ion diffusion coefficient and create additional active sites. As a result, the Sn@Ti₃C₂ anode exhibits a superior specific capacity up to 666 mA∙h∙g^-1 at 0.5 A∙g^-1 after 250 cycles. Compared with pure Sn NPs, the improved electrochemical performance of Sn@Ti₃C₂ can be ascribed to the high electronic conductivity of Ti₃C₂ MXene nanosheets. The 3D Sn@Ti₃C₂ materials prepared in a layer-by-layer manner through self-assembly display promising performances for LIBs.