MXene-Based Porous and Robust 2D/2D Hybrid Architectures with Dispersed Li3Ti2(PO4)3 as Superior Anodes for Lithium-ion Battery

Abstract Two-dimensional (2D) MXenes become the predominant choice of lithium-ion battery electrode materials owing to large surface-area-to-volume ratio and metallic conductivity, but severe restacking still remains the main obstruct. Herein, a new strategy of avoiding restacking and assuring structural stability is proposed. We demonstrate the fabrication of novel hierarchically porous and robust 2D/2D hybrid architectures consisting of a large thin Ti3C2 flake with many standing intersecting TiO2 nanosheets, followed by generation of well-dispersed Li3Ti2(PO4)3 nanocrystals. The resulting TiO2 sheets of 4∼5 nm thick inherit specific layered atomic structures of 2D MXene through in-situ ultrafast reactions in molten-salt, and thus are composed of few layers with ∼0.8 nm layer spacing. The MXene-based composite as an anode delivers high discharge capacity of 204 mAh g-1 at 50 mA g-1, rate capability (115 mAh g-1 at 1000 mA g-1) and remarkable cycling stability with 193 mAh g-1 after 500 cycles at 100 mA g-1. This are attributed to high surface capacitive contributions of the unique 2D/2D robust hybrid architecture that provides enough spaces to accelerate ionic transfer and favorable tolerance to volume variation. This work provides an effective route to rapid generation of MXene-based 2D/2D hierarchical composites for many applications.