Tailoring Multi-Metallic Phosphide Heterostructures for High Energy Density Hybrid Supercapacitors

Abstract

Transition metal phosphides have emerged as a cost effective and resourceful materials that gained extreme attention in the energy sector due to deliverance of high capacitance as well as good redox ability comparable with other oxide materials, which makes them budding material for next-generation electrochemical energy storage (EES) systems. Thanks to the metal-phosphorous chelate in the structure which probes the storage mechanism in EES systems. The electrochemical performance can be enhanced by combining multi-metals in the phosphide to collectively utilize the individual features which will increase the charge efficiency. Herein, tri-metallic Ni-Co-Mo-P electrode on Ni-foam substrate was prepared using simplified hydrothermal-calcination-phosphorylation process. The introduction of Mo enhances the electronic conductivity in the trimetallic phosphide electrode which is reflected in the increased electrochemical performance in comparison to NiCoP electrode. Although, Ni-Co-Mo-P electrode delivers superior activity compared to oxide and precursor electrode, however, the capacity retention till 10 A/g was observed to be 60%, which is higher than other prepared electrodes. The enhanced charge storage performance can be attributed to increased number of electrochemical surface area facilitating more redox reactions. The asymmetric supercapacitor device is constructed with Ni-Co-Mo-P // rGO that delivered high energy and power density with satisfactory cyclic capability.