High-power and long-life lithium-ion capacitors constructed from N-doped hierarchical carbon nanolayer cathode and mesoporous graphene anode

For current lithium-ion capacitors (LICs), high energy storage is usually accompanied with the sacrificing of high power density due to the mismatched kinetics between capacitor-type cathode and battery-type anode. In this work, N-doped hierarchical carbon nanolayer (NHCN) is fabricated by a facile one-step templated carbonization/activation from naturally abundant and renewable chitosan biomass, which is employed as cathode materials of LICs for the first time. Encouragingly, due to the high specific surface area of 2350 m(2) g(-1), high nitrogen doping of 4.26 at. % and hierarchical porosity, NHCN exhibits a high capacity of 125 mAh g(-1) together with excellent rate capability and long cyclability. Furthermore, a LIC cell is constructed by coupling the NHCN cathode with mesoporous graphene anode to leverage synergetic kinetics in both electrodes. The NHCN-based LIC can delivers a high energy density of 146 Wh kg(-1) at the power density of 650 W kg(-1) and a well-retained energy density of 103 Wh kg(-1) at an ultra-high power density of 52 kW kg(-1). Moreover, the capacity retention of NHCN-based LIC can reach 91% after 40000 cycles. The strategy developed here opens a new avenue for the utilization and application of commercially available chitosan in high-performance LICs. (C) 2018 Elsevier Ltd. All rights reserved.