MoS2 encapsulated in N-doped mesoporous carbon nanowires as high-rate anode for K-ion capacitors

Abstract

The main challenge for the emerging K-ion capacitors (KICs) is designing high-rate performance anode to match the fast kinetics of the cathode. In this work, we encapsulated MoS2 nanosheets in N-doped mesoporous carbon nanowires (MoS2@MCNWs) by dual-templating method as high-rate anode. After the performance was optimized with respect to MoS2 content, the preferred MoS2@MCNWs-2 (25 wt% MoS2) electrode shows a superior rate capability (89.2 mAh g−1 at 10 A g−1). Furthermore, the constructed KIC demonstrates superior energy/power density (Max. 106.5 Wh kg−1/9703.9 W kg−1) with excellent cycling stability (97.6% of initial capacitance after 6000 cycles at 1 A g−1). The good electrochemical properties arise mainly from the one-dimensional (1D) nanostructure that can facilitate the transportation of electrons, the opened ordered mesopores on the carbon nanowires that can endow the rapid K-ion/electrolyte diffusion, and the ultrafine MoS2 nanosheets embedded in carbon nanowires that can offer a lot of active sites. Furthermore, the doped N in carbon can afford additional adsorption sites for discharge products, promoting the durability of the electrode, which is confirmed by density function theory (DFT) calculations. This delicate design could offer a new avenue for the development of 1D-based anode with high-rate performance in metal-ion capacitors.