Ultrahigh-rate and high-density lithium-ion capacitors through hybriding nitrogen-enriched hierarchical porous carbon cathode with prelithiated microcrystalline graphite anode

Lithium-ion capacitors (LICs) are novel advanced electrochemical energy storage (EES) systems integrating both battery and capacitor functions. Most efforts for developing high-power LICs are currently dedicated to nanostructure design of battery-type anodes, which in general results in low packing densities and cannot fundamentally improve the slow Faradaic reaction. Up to now, little attention has been focused on the effects of porous carbon cathodes and the reasonable matching of cathode/anode on the power performance of LICs. Herein, a novel nitrogen-enriched mesoporous carbon nanospheres/graphene (N-GMCS) nanocomposite is demonstrated, which shows simultaneously hierarchical porous structure, 3D conductive network, as well as very high mass density. When such N-GMCS cathode is coupled with prelithiated microcrystalline graphite (PLMG) anode, the integrated device shows quite high packing density which is highly desirable in EES systems. In particular, the PLMG anode in N-GMCS//PLMG system breaks the limitation of slow Faradaic reaction and lithium-ion bulk diffusion, providing an ultrafast capacitor-like electrochemical response. Quite attractive maximum energy density (80Whkg^-1, 68.6WhL^-1) and state-of-the-art maximum power density (352kWkg^-1, 292kWL^-1) can be achieved in N-GMCS//PLMG, which are 5 and 2.8 times as large as those of the supercapacitor counterpart, respectively.