Recent advancement of supercapacitors: A current era of supercapacitor devices through the development of electrical double layer, pseudo and their hybrid supercapacitor electrodes

Supercapacitors are promising energy devices for electrochemical energy storage, which play a significant role in the management of renewable electrical energy to meet the demand for global energy consumption. They represent an electrochemical energy storage system for electronic devices to transport extraordinary power within a very short period. The electrode materials are the critical components of the supercapacitors that regulate the electrochemical characteristics, mechanism of energy storage, and mechanical properties of the supercapacitor devices. Hence, many significant advances for a new generation of supercapacitors have been described in recent years through the progress of the electrodes and device designs. Currently, different flexible solid-state supercapacitors with planar, wire, fiber, or cable architectures and shape versatile devices are designed for smart electronics. Hence, this review summarizes the recent advancement in supercapacitors through the development of novel electrode materials and solid-state flexible device design. Firstly, the review provides a brief description of the fundamentals of supercapacitors. The article focuses on the state-of-the-art progress towards different architectural carbon materials, transition metal oxides, and chalcogenides, conducting polymers, and their novel hybrid materials. The review also introduces newly developed metal-organic frameworks and MXenes-based supercapacitors, metal ion-based battery-type hybrid supercapacitors, 2D-phosphorous & phosphorous doped supercapacitors, graphene aerogel-based supercapacitors, high entropy alloy, high entropy oxide and high entropy chalcogenides based supercapacitors, photo-supercapacitors, and photoelectrochemical supercapacitors. Moreover, this review provides recent advancements in the design of novel solid-state flexible supercapacitor devices of planar, fiber/wire shape, and shape versatile architectures. Finally, the benefits, challenges, applications, and future scope of the supercapacitor devices have been elaborated. Therefore, this review provides the readers with a comprehensive and composed idea about the basics of supercapacitors, recent progress in the electrode materials, and the design of their original flexible solid-state devices to assemble an energy storage device of practical interest.