Designing FeCoP@NiCoP heterostructured nanosheets with superior electrochemical performance for hybrid supercapacitors

Abstract The precise preparation of transition metal phosphides-based battery-type electrode materials with well-defined morphology and nanostructure have shown great potential in supercapacitors, due to their high electrical conductivity and superior redox activity. Herein, a smart nanoarchitecture comprised of a FeCoP@NiCoP core-shell hybrid is designed via a two-step electrodeposition strategy together with a phosphorization treatment. The 3D FeCoP@NiCoP nanosheet arrays grown on a flexible carbon cloth substrate can provide an efficient nanoporous framework, facilitate the electron/ion transport, and generate the effective synergy of good conductivity from FeCoP and superior redox activity from NiCoP. As a result, the as-prepared FeCoP@NiCoP electrode exhibits a high specific capacity of 973.0 C g−1 at a low current density of 1 A g−1 and excellent rate capacibity with 84.3% retention at 20 A g−1, superior to those of bare FeCoP and NiCoP electrodes. Additionally, a hybrid supercapacitor is assembled with FeCoP@NiCoP as a cathode and a barley-derived hierarchical porous carbon BPC-800 as an anode, showing a high energy density of 75.9 Wh kg−1 at a power density of 827.8 W kg−1 and outstanding cycling stability of 89.7% retention of the initial capacitance after 10000 cycles.