Cost‐Effective Synthesis of Electrodeposited NiCo₂O₄ Nanosheets with Induced Oxygen Vacancies: A Highly Efficient Electrode Material for Hybrid Supercapacitors

Abstract

Nanostructured transition metal oxide synthesis possessing high energy density and stability is desirable for supercapacitors. Herein, we synthesize three‐dimensional NiCo2O4 (NCO) nanosheets with oxygen vacancies induced by sustainable and environmentally benign electrodeposition assisted chemical reduction process. Oxygen vacancies increase the conductivity, adsorptivity, and the active surface area, thereby enhancing the charge storage capabilities. The binder‐free NCO delivers the highest specific capacitance (Csp) of 2065 F g−1 at 1 A g−1, retaining 89.30 % of its initial value at 10 A g−1 after 10,000 continuous charge‐discharge (CD) cycles. An asymmetric supercapacitor (ASC) fabricated shows remarkable electrochemical properties with high energy density (Emax) of 28.6 Wh kg−1 and power density (Pmax) of 7.5 kW kg−1. The assembled ASC reports exceptional cyclic retention of 90.6 % for 10,000 CD cycles with practical demonstration. The approach used herein is suitable for eco‐friendly supercapacitor electrode fabrication with large scale manufacturing capability and less capital investment.

N‐doped oxygen vacancy‐rich NiCo 2 O 4 nanoarrays for supercapacitor and non‐enzymatic glucose sensing

“…The incorporation of N-doping and oxygen vacancies, along with the mesoporous architecture, which synergistically boosts the electrochemical activity, is largely responsible for the remarkable enhancement in the current density response in the CV curves of N-Ov/NiCo 2 O 4 -350. 28,33 The CV curves of the N-Ov/NiCo 2 O 4 -350 electrode at different scan rates of 5-100 mV s À1 within the potential range of À0.2 to À0.6 V vs Hg/HgO is shown in Figure 4D. The N-Ov/NiCo 2 O 4 -350 electrodes all exhibit similar CV curves with high redox peaks, suggesting typical battery-like characteristics and a good rate capability.…”

A review on the advances in electrochemical capacitive charge storage in transition metal oxide electrodes for pseudocapacitors

“…Later, to improve the rate capability, a successful attempt to increase the O vacancies was made possible with sodium borohydride reduction. The end results were reported with excellent redox peaks and charge storage, but sodium borohydride is an expensive reducing agent 287,288 . Zhao et al were able to synthesize NiCo 2 O 4 @Ni 4.5 Co 4.5 S 8 via two‐step electrodepositions to deliver superior specific capacitance with remarkable retention.…”

“…The end results were reported with excellent redox peaks and charge storage, but sodium borohydride is an expensive reducing agent. 287,288 Zhao et al were able to synthesize NiCo 2 O 4 @Ni 4.5 Co 4.5 S 8 via two-step electrodepositions to deliver superior specific capacitance with remarkable retention. The electrode demonstrated great capacitive nature overcoming diffusion contribution in low scan speeds as shown in Figure 14B.…”

Nickel Cobaltite: A Positive Electrode Material for Hybrid Supercapacitors

“…Recently, 2D nanomaterials have largely been tested for the SCs applications due to their layered structure, high electrical conductivity, and large surface area. Pappu et al [46] . developed HSCs by using the 2D nanosheets‐composed NiCo 2 O 4 as a positive electrode.…”