Hybrid aqueous supercapacitors based on mesoporous spinel-analogous Zn-Ni-Co-O nanorods: Effect of Ni content on the structure and energy storage

• Published in: Journal of alloys and compounds 2021-11, Vol.882, p.160712, Article 160712
• Main Authors: Kumar, V., Gajraj, V., Gnanasekar, K.I., Dsoke, S., Indris, S., Ehrenberg, H., Roling, B., Mariappan, C.R.
• Format: Article
• Language: English
• Subjects: Activated carbon; Asymmetric supercapacitors; Cobalt; Electrochemical analysis; Energy storage; Energy storage materials; Energy storage mechanism; Light emitting diodes; Mesoporous metal oxides; Nanorods; Nickel; Spinel; Storage capacity; Supercapacitors; Surface charge; Zinc
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2021.160712

The structure and the electrochemical performance of mesoporous spinel-analogous Zn-Ni-Co-O (Zn1−xNixCo2O4; 0.2 ≤ x ≤ 0.8) nanorods are investigated. Cyclic voltammetry gives strong indication that the charge storage mechanism is governed by pore surface redox processes without significant contribution from the sub-surface charge storage. Since the size of the Zn1−xNixCo2O4 rods decreases with increasing Ni content x, the BET surface and thus the charge storage capacity increases with increasing x, namely from 266 C g−1 to 463 C g−1 at 3.12 A g−1 when increasing x from 0.2 to 0.8. Hybrid aqueous supercapacitors (HSC) are fabricated with Zn1−xNixCo2O4, activated carbon (AC) and 6 M KOH as positive electrode, negative electrode and electrolyte, respectively. The specific energy densities of HSC are in the range of 27–2 Wh kg−1 at the specific power densities range of 780–2240 W kg−1. Real-world usage of the aqueous HSC device is demonstrated by enlightening a red light-emitting diode. These outcomes show that the mesoporous spinel-analogous Zn-Ni-Co-O materials are potential candidates for next-generation electrochemical energy storage applications. [Display omitted] •Mesoporous spinel-analogous Zn1−xNixCo2O4; 0.2 ≤ x ≤ 0.8nanorods prepared by Solvothermal route.•The size of the Zn1−xNixCo2O4 rods decreases with increasing Ni content.•The ES,HSC of HSC are in the range of 27–2 Wh kg−1 at the PS,HSC of 780–2240 W kg−1.•Real-world usage of the aqueous ASC device is demonstrated by enlightening a red light-emitting diode.