Highly conductive carbon–CoO nanowire array electrodes on 3D nickel foam were designed with ultrahigh specific capacitance (3282.2 F g−1), approaching the CoO theoretical value. Assembled into an asymmetric supercapacitor, the energy density is ∼58.9 W h kg−1, a record among Co-based supercapacitors.

A three dimensional (3D) porous framework-like N-doped carbon (PFNC) with a high specific surface area was successfully fabricated through ammonia doping and graphitization based on pomelo peel. The obtained PFNC exhibits an enhanced specific capacitance (260 F g(-1) at 1 A g(-1)) and superior cycling performance (capacitance retention of 84.2% after 10000 cycles at 10 A g(-1)) on account of numerous voids and pores which supply sufficient pathways for ion diffusion during cycling. Furthermore, a fabricated asymmetric PFNC//PFN device based on PFNC and porous flake-like NiO (PFN) arrays achieves a specific capacitance of 88.8 F g(-1) at 0.4 A g(-1) and an energy density of 27.75 Wh kg(-1) at a power density of 300 W kg(-1) and still retains 44 F g(-1) at 10 A g(-1) and 13.75 Wh kg(-1) at power density of 7500 W kg(-1). It is important that the device is able to supply two light-emitting diodes for 25 min, which demonstrates great application potential.

Redox-active covalent organic frameworks (COFs) are an emerging class of energy storage materials due to their notably abundant active sites, well-defined channels and highly surface areas. However, their poor electrical...

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