Structural and chemical interplay between nano-active and encapsulation materials in a core–shell SnO2@MXene lithium ion anode system

Rational engineering of the microstructure and interfacial properties of nano-metal oxides materials is critical to realize their practical use in batteries. This work reports a detailed study on how structural and chemical interplay in a robust 3D crumpled MXene protected SnO2 core–shell system contributes to performance as an anode in lithium-ion batteries. Our results show that the compact conductive MXene shell can provide robust protection against the large volume change and aggregation of SnO2, providing excellent structural stability. Further analyses show that rich surface groups on the MXene can not only enable strong interfacial interactions through Sn–O–Ti bonds to grant electrical contacts, but also provide a pseudocapacitive contribution for fast and stable lithium storage. Furthermore, a conformal SEI formed outside the MXene can build a stable protective interface and prevent further consumption of electrolyte simultaneously. As a result, the SnO2@MXene composite delivered a high specific capacity of 829.4 mAh g−1 at a current density of 0.2 A g−1, and exhibited an excellent cycling stability (533.9 mAh g−1 after 500 cycles at 1 A g−1). The strategy reported here for synthesizing a core–shell MXene based material can be promising for the development of high-performance anode materials for next-generation LIBs.