3D flexible N-doped carbonaceous materials/PVDF-HFP composite frameworks for quasi-solid-state 4.5 V Li-ion capacitors

3D nitrogen-doped carbonaceous foams containing carbon nanotubes, graphene and hollow carbon sphere are synthesized by chemical vapor deposition, and the assembled quasi-solid-state lithium-ion capacitors possess both high energy densities and power densities. [Display omitted] •3D N-doped carbon was synthesized by CVD method using melamine as the raw material.•The carbonaceous foams performed good flexibility after integrating with PVDF-HFP.•The quasi-solid-state LIC retains 72.2% capacity after 2000 cycles at high power.•The LIC delivers an energy density of 209.3 Wh/kg at a power density of 342.5 W/kg. Lithium-ion capacitors (LICs) possess high energy density and power density simultaneously. However, for balancing electrochemical performance, mechanical properties and safety issues, the development of high-performance electrodes and electrolytes is still a challenge in this field. Herein, a 3D nitrogen-doped carbonaceous foam (NC) was synthesized by chemical vapor deposition (CVD), and the covering of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) dramatically increase its flexibility without decreasing the electrochemical performance. The complete quasi-solid-state LICs using NC/PVDF-HFP as anode, NC/activated carbon (AC)/PVDF-HFP as cathode and PVDF-HFP as the skeleton of gel electrolyte are fabricated and shows good cycle stability (72.2 % after 2000 cycles). Meanwhile, the power density of the LIC can reach up to 342.5 W/kg when the energy density is 209.3 Wh/kg, and the power density can reach as high as 7632.2 W/kg at energy density of 77.6 Wh/kg, which is higher than many other dual-carbon and quasi-solid-state LICs.