Nanoplatelets ammonium nickel-cobalt phosphate graphene foam composite as novel electrode material for hybrid supercapacitors

Nanoplatelets NH4(NiCo)PO4 center dot H2O and NH4(NiCo)PO4 center dot H2O/GF composites were synthesized through a hydrothermal approach and used as actively positive electrode for hybrid supercapacitor. Electrochemical performances of the samples were carried out in both the 3and 2-electrode measurements in 1 M KOH solution. The composite NH4(NiCo)PO4 center dot H2O/GF exhibited an improved specific capacity of 111 mAh g(-1) over the pristine NH4(NiCo)PO4 center dot H2O material with a 100 mAh g(-1), which was obtained at 0.5 Ag-1. Moreover, an assembled hybrid device NH4(NiCo)PO4 center dot H2O/GF//AC revealed maximum specific energy of 47 Wh kg(-1) and specific power of 468 W/kg at 0.5 Ag-1. The device was subjected to a long-term stability test of over 10,000 GCD cycles and could retain about 70% of its initial capacity and also proved a columbic efficiency of 99.8% at 10.0 A g(-1). Interestingly, the device could preserve a 1.14 V of its initial potential window of 1.4 V after being subjected to a 72 h self-discharge test, showing an efficiency of 81.4%. Based on the results discussed on this work, the NH4(NiCo)PO4 center dot H2O/GF composite could be an excellent candidate as future energy storage material, specifically supercapacitors. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The NH4(NiCo)PO4•H2O/GF composite exhibited improved electrochemical performance in hybrid supercapacitors, with higher specific capacity and specific energy. The device showed high columbic efficiency and self-discharge efficiency in long-term stability tests.