Enhancing the electrochemical performance of a nickel molybdenum nitride for an energy storage device using cobalt nitride and phosphorus doping

Abstract

Compared to traditional energy storage devices, hybrid solid-state supercapacitors have gained a lot of attention because of their exceptional power, energy density and outstanding cyclic stability. Transition metal nitrides are eminent candidates with high-performance electrochemical properties for energy storage devices. In this work, a high-performance CoN/NiMoN interface with P-doping was prepared by a simple feasible strategy for the positive electrode of a supercapacitor. The electrochemical performance in a 2 M KOH electrolyte revealed a specific capacity of 2070C·g−1 at a 5 A·g−1, which is exceptional compared to recently reported literature. Encapsulating NiMoN with CoN and its P-doping, resulting in a three-dimensional structure with desirable textural properties and easy permeation of electrolyte, enhances the electrochemical performances prepared electrode. Further, a hybrid solid-state supercapacitor was prepared with P-CoN/NiMoN (positive) and activated carbon (negative) as a electrodes. The prepared P-CoN/NiMoN//activated carbon supercapacitor showed an operating potential window of 1.7 V with an admirable specific capacity of 573.99C·g−1, for 135.5 Wh·kg−1 energy and 850 W·kg−1 power density at a 1 A·g−1. The results provide a feasible strategy to prepare and modify the electrochemical properties of NiMoN by CoN encapsulation and P-doping. The method gives insights for the preparation of other transition metal nitrides for high-density energy storage without much change in the power density.