Hierarchical MoS2/C@MXene composite as an anode for high-performance lithium-ion capacitors

The battery-type anodes and capacitor-type cathodes enable lithium-ion capacitors (LICs) to achieve high energy density and high power density concurrently. Nonetheless, the gap in capacity and electrochemical reaction dynamics between anodes and cathodes remains a grand challenge. In this work, we report the synthesis of hierarchical MoS2/C@MXene composite with uniform MoS2/C nanosheets grown on few MXene flakes by electrostatic flocculation and hydrothermal reaction. As a result, the restacking of MXene flakes is inhibited effectively by electrostatic flocculation, and the few-layer MXene provides abundant sites for the uniform growth of MoS2 nanosheets. Meanwhile, the amorphous carbon matrix derived from diethylenetriamine can further enhance the conductivity of MoS2 and mitigate the oxidation of MXene. Due to the desirable coupling effect between MoS2/C and MXene conductive networks, MoS2/C@MXene electrode demonstrates superior Li storage capacity. It delivers a reversible capacity of 600 mAh g(-1) at 1.0 A g(-1) after 700 cycles, along with excellent rate performance. Moreover, the assembled LIC device using MoS2/C@MXene as anode and three-dimensional porous carbon as cathode exhibits a high energy density of 164.5 Wh kg(-1) at the power density of 225 W kg(-1), and an energy density of 53.1 Wh kg(-1) even at a high power density of 11.3 kW kg(-1), as well as good cycling stability with capacity retention of 77.2% after 5000 cycles at 1.0 A g(-1). These results indicate that MoS2/C@MXene might be promising anode materials for high-performance LICs.