Approaching High-Performance Supercapacitors via Enhancing Pseudocapacitive Nickel Oxide-Based Materials

Nickel oxide, as a typical pseudocapacitive material, holds great promise for boosting the energy storage capability of supercapacitors (SCs) owing to its great advantages, such as high theoretical capacitance value, low-cost, good stability, and environmentally benign nature. Nevertheless, many obstacles, including low intrinsic conductivity and limited surfice electrochemically active sites, need to be overcome before its practical implementation. In this review, the recent advances on nickel oxide-based electrode materials are outlined with particular attention paid to strategies for enhancing their SC performance. To begin, an introduction to the physical and chemical properties of nickel oxide and its charge storage mechanisms is presented, followed by a discussion of the obstacles to its widespread implementation and the corresponding strategies for constructing high-performance nickel oxide-based electrode materials. After that, recent progress in the use of organic electrolyte systems to achieve improvements in integrated device performance is highlighted. To conclude, a detailed discussion on future trends and opportunities associated with NiO-based electrode materials for future SCs is provided. © 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim