3D frame-like architecture of N-C-incorporated mixed metal phosphide boosting ultrahigh energy density pouch-type supercapacitors

Abstract The multi-compositional adjustment and distinctively architectural control have been challenging to modulate the electrochemical performance of favorable supercapacitor electrodes. Herein, three-dimensional hollow open frame-like architectures nickel cobalt phosphate with nitrogen doped carbon (Co2−xNixP-N-C-2) converted from a metal-organic framework precursor is utilized as the functional electrode for supercapacitor, which delivers remarkable electrochemical performance in terms of exceptional capacitance reaching ~1374.7 C g−1 (specific capacitance of ~3054.9 F g−1) and ultra-long cycling longevity (a retention of ~91.7% after 10,000 cycles at 5 A g−1). Furthermore, the assembled hybrid supercapacitor (HSC) device displays ultrahigh energy density of ~86 Wh kg−1 at a maximum power density of ~800 W kg−1. The superior performance can be attributed to: (I) 3D hollow open nanostructures provide sufficient electroactive sites and ion-diffusion “short-cuts”; (II) The introduction of phosphorus can adjust the band structure and gain a small band gap; (III) Bimetals enhance rich redox reactions; (IV) Nitrogen doped carbon ensures high conductivity and charge storage kinetics.