Rational design of three-dimensional branched NiCo-P@CoNiMo-P core/shell nanowire heterostructures for high-performance hybrid supercapacitor

Owing to the dramatically enhanced charge-mass transport and abundant electrochemically active sites, transition metal compound electrodes are increasingly attractive for achieving high-performance supercapacitors (SCs). Here, we report the fabrication of nickel foam supported three-dimensional (3D) branched nickel–cobalt phosphides@tri-metal cobalt–nickel-molybdenum phosphides core/shell nanowire heterostructures (denoted as NiCo-P@CoNiMo-P) as high-performance electrode materials for hybrid supercapacitors. The presence of multiple valences of the cations in such NiCo-P@CoNiMo-P enables rich redox reactions and promoted synergy effects. Benefiting from their collective effects, the resulting electrode demonstrates high specific capacity of 1366 C g⁻¹ at 2 A g⁻¹ (2.03 C cm⁻² at 2 mA cm⁻²) and 922 C g⁻¹ at 10 A g⁻¹, as well as good cycling stability (retaining ~ 94% of the initial capacity after 6000 cycles at 15 A g⁻¹). A hybrid SC using the NiCo-P@CoNiMo-P as the positive electrode and N-doped rGOs as the negative electrode exhibits a high energy density of 81.4 Wh kg⁻¹ at a power density of 1213 W kg⁻¹ and a capacity retention of 132% even after 6000 cycles at 10 A g⁻¹. Our findings can facilitate the material design for boosting the performance of transition metal compounds based materials for fast energy storage.