One-step in-situ synthesis of Sn-nanoconfined Ti3C2Tx MXene composites for Li-ion battery anode

Benefiting from the unique chemical properties and the adjustable layered spacing, MXenes have been paid more attention to the field of energy storage and conversation, especially towards constructing hybrid structure for the use of Li-ion battery anodes. However, most MXene-based composites are achieved by the ex-situ mixing method on the basis of acid-etched MXene, which makes it extremely hard to maintain a good structural stability in the service process. Herein, we proposed a novel one-step in-situ strategy, i.e. SnCl2 molten salt reaction with Ti3AlC2 for synthesizing Sn-nanoconfined Ti3C2Tx MXene composites. During the synthesis process, SnCl2 not only executed as the Lewis acid to etch Ti3AlC2 for obtaining Ti3C2Tx MXene, but could also be in-situ transformed to Sn nanoparticles confined between the Ti3C2Tx MXene layers. The 2D layer-confined effect inhibited the spontaneous coarsening of metal Sn at high temperature as well as the huge volume expansion during the electrochemical cycles. Meanwhile, the in-situ formed Sn nanoparticles as pillar played a decisive role in enlarging interlayered active spacing of Ti3C2Tx MXene for Li-storage. As a result, the surprising enhancement of electrochemical Li-storage performances could be achieved during long-term cycling. This work provides a novel route to explore the application of MXene based on the molten salt methods.