Abstract:
To meet the rising global energy demands, there has been significant interest in developing
efficient and sustainable energy storage devices. Supercapacitors (SCs), renowned for their
rapid charge-discharge capabilities and long cycle life, effectively bridge the energy-power
gap between batteries and traditional capacitors. Transition Metal Nitrides (TMNs) have
emerged as promising electrode candidates for SCs due to their excellent redox properties
and high electrical conductivity. However, challenges related to their electrochemical
stability considerably hinder their commercialization potential. Additionally, the toxic
ammonia-based synthesis methods commonly employed for fabricating metal nitrides raise
environmental and safety concerns. This study presents an ammonia-free, urea-based
synthesis of Nickel Cobalt Nitrides (NiCoN) integrated with Carbon Nanotubes (CNTs) as
next-generation supercapacitor electrodes. Different compositions of nickel and cobaltbased nitrides were synthesized with CNTs. The proper synthesis of the materials was
validated through various morphological and structural characterizations. The
electrochemical performance of the samples with different metallic ratios i.e.
NiCoN(1:1)/CNTs, NiCoN(1:2)/CNTs, and NiCoN(2:1)/CNTs was tested in threeelectrode system, where NiCoN(1:1)/CNTs showed the best performance, exhibiting a
remarkable specific capacitance of 1146.5 F g⁻¹ at a current density of 0.5 A g⁻¹. Its batterylike behavior was assessed using Dunn’s method. Furthermore, an Asymmetric
Supercapacitor (ASC) was assembled with NiCoN(1:1)/CNTs as the cathode and Activated
Carbon (AC) as an anode. The NiCoN(1:1)/CNTs // AC device achieved a high energy
density of 79.7 Wh kg⁻¹ and a power density of 243.75 W kg⁻¹ at 0.35 A g⁻¹. Notably, the
device demonstrated 101.8 % capacity retention and an average coulombic efficiency of
98 % after 10,000 continuous cycles, indicating excellent cyclic reversibility.
