Germanium‐Functionalized 3D Microporous, Nanostructured Nickel–Nickel Oxides for Application in Asymmetric Supercapacitors

Abstract

Limited fossil fuels, increasing population and pollution, environmental/climate change, and ever‐increasing demand for energy are motivating society to use renewable and clean energy for all needs in the domestic and industrial sectors. However, the intermittent nature of renewable sources hinders their continuous availability and utilization. Subsequently, energy storage devices, such as supercapacitors and batteries, are becoming popular for the sustainable development of future generations. But, the bottleneck is the associated high cost, which limits the bulk use of batteries and supercapacitors. In this context, and realizing that the cost of energy storage devices mainly depends on materials, synthesis processes/procedures and device fabrication, we made an effort to rationally design and develop novel low‐cost electrode materials with enhanced electrochemical performance in asymmetric supercapacitors. In this work, we adopted the surface functionalization approach to design low‐cost 3‐D mesoporous and nanostructured nickel (Ni) ‐ nickel oxide (NiO) electrode materials using facile synthesis for application in supercapacitors. We demonstrate that the 3‐D mesoporous Ni provides a high surface area and enhanced ionic conductivity, while germanium (Ge) functionalization improves the electrical conductivity and reduces the charge transfer resistance of NiO. Surface functionalization with Ge demonstrates a significant improvement in the specific capacitance of NiO. The asymmetric supercapacitor using these Ge‐functionalized NiO‐Ni electrodes provides a specific capacitance of 304 Fg‐1 (94 mFcm‐2), energy density of 23.8 Whkg‐1 (7.35 µWhcm‐2), and power density of 6.8 kWkg‐1 (2.1 mWcm‐2) with excellent cyclic stability of 92 % after 10000 cycles. Finally, powering the digital watch using the asymmetric supercapacitors in laboratory conditions is demonstrated to validate their practical applications.This article is protected by copyright. All rights reserved.

Morphology-controllable synthesis of rod-shaped CuO@Co3O4 derived from CuCo-MOF-74 for supercapacitors

“…Among TMOs, Co 3 O 4 and CuO stand out as ideal materials for electrochemical studies because of their abundance, low toxicity, and diverse physicochemical and optical properties. [23][24][25] The combination of Co 3 O 4 and CuO exhibits increased oxygen vacancies, which can favor the development of SCs. Thus, synergistic utilization of Co 3 O 4 and CuO holds tremendous potential for advancements in the realm of SCs.…”