Iron-doped cobalt copper phosphide/phosphate composite with 3D hierarchical flower-like structures as electrodes for hybrid supercapacitors

Transition two-metal and tri-metal phosphides are promising candidate materials for supercapacitors' performance. Here, FeCoCuP with 3D hierarchical structures is successfully synthesized and phosphorized using hydrothermal method. By examining the amount of Fe doped in the CoCuP lattice structure, an optimal FeCoCuP nanoarrays with 3D hierarchical nanoneedles is obtained, which improves the charge transport during the redox reactions. The flower-like FeCoCuP nanoarrays with unique designs create appropriate specific surface area and large electrical conductivity, which have good supercapacitor performance by supplying abundant active sites for redox reactions and reducing the penetration path of ions and electrons. Therefore, the prepared FeCoCuP nanoarrays material shows a specific capacity of 1290 C g−1 at a current density of 1.0 A g−1 with a 64% retention capacity after enlarging the current density to 10.0 A g−1. Also, the FeCoCuP asymmetric supercapacitor (FeCoCuP//AC) has an energy density of 61.5 Wh kg−1 at a power density of 1201.7 W kg−1 with good cyclic stability of 88.7% after 5000 cycles at a current density of 7 A g−1. These encouraging findings indicate that the FeCoCuP nanocomposites are a suitable electrode material for supercapacitor applications.