A novel lithium-ion hybrid capacitor based on an aerogel-like MXene wrapped Fe2O3 nanosphere anode and a 3D nitrogen sulphur dual-doped porous carbon cathode

Abstract

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 Ti₃C₂T_x 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.