Ammonia-free soft urea‐derived nickel cobalt nitride integrated with carbon nanotubes as battery-type electrode for asymmetric supercapacitors

초록

Transition Metal Nitrides (TMNs) offer excellent redox properties and conductivity as supercapacitor electrodes. However, their ammonia-based synthesis approach is problematic against the environment. Here, we present an ammonia-free, soft urea-derived Nickel Cobalt Nitrides (NiCoN) integrated with Carbon Nanotubes (CNTs) as next-generation supercapacitor electrodes. The Nickel Cobalt Nitride synthesis solely via the soft urea-derived approach has not been reported to the best of our knowledge. We synthesize samples with different ratios between Nickel and Cobalt (i.e., NiCoN(1:1)/CNTs, NiCoN(1:2)/CNTs, and NiCoN(2:1)/CNTs). Several morphological and structural characterization techniques have been used to confirm the successful synthesis of the electrode material. The electrochemical performance of the samples has been tested using a three-electrode system, where NiCoN(1:1)/CNTs show 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 battery-like behavior has been assessed using Dunn's method. Furthermore, an Asymmetric Supercapacitor (ASC) is fabricated using NiCoN(1:1)/CNTs as the positive electrode and Activated Carbon (AC) as the negative electrode material. The NiCoN(1:1)/CNTs//AC device demonstrates 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. The device retains 101.8 % capacity with a coulombic efficiency of 98 % even after 10,000 cycles.

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