A novel lithium-ion hybrid capacitor based on an aerogel-like MXene wrapped Fe<inf>2</inf>O<inf>3</inf> nanosphere anode and a 3D nitrogen sulphur dual-doped porous carbon cathode

© 2018 the Partner Organisations. Lithium-ion capacitors (LICs) have emerged as promising energy storage devices with both high energy density and high power density. However, due to the mismatch of charge-storage capacity and electrode kinetics between battery-type anodes and capacitor-type cathodes, the application of lithium-ion capacitors has been limited. In this work, interconnected aerogel-like MXene wrapped Fe2O3 nanospheres have been prepared and investigated as battery-type anode materials for lithium-ion capacitors. In this rationally designed hybrid electrode, the Ti3C2Tx MXene matrix is capable of providing fast transport of electrons and suppressing the volume change of Fe2O3. Simultaneously, Fe2O3 hollow nanospheres offer large specific capacity and prevent restacking of the MXene layers, synergizing to boost the electrochemical performances of such hybrid electrodes. Meanwhile, the three-dimensional (3-D) nitrogen and sulphur dual-doped porous carbon (NS-DPC) derived from biomass has also been fabricated as a capacitor-type cathode material for lithium-ion capacitors. Consequently, the lithium-ion capacitors can demonstrate a high energy density of 216 W h kg-1 at a power density of 400 W kg-1 and a high power density of 20 kW kg-1 at an energy density of 96.5 W h kg-1. This work elucidates that both high energy density and power density can be achieved in hybrid lithium-ion capacitors