Flexible supercapacitors powering sustainable future: fundamentals, emerging low dimensional materials and current-prospective applications

At present, flexible, wearable and implantable electronic devices (FWIEDs), renewable energy (RE) systems and Net Zero platforms are predominantly powered by rechargeable batteries (RBs) specifically lithium-ion batteries (LiBs). This can potentially limit advancements of these systems in terms of cyclability, miniaturization and flexibility. In addition, RBs contain sizable quantities of toxic and flammable active materials posing threat to human health when used in some of the above cited applications. Therefore, it is vital to investigate innovative energy materials, design and experiment new devices to fulfil power requirements of current and prospective applications. This review discusses the fundamentals, followed by conventional and state of the art low-dimensional active materials and finally, market potential of flexible supercapacitors (FSCs). Pivotal segment of this study is the extensive level of emphasis on the existing and potential applications of FSCs including implantable medical devices, wearable electronics, soft robotics, Internet of Things/Everything and RE/Net Zero platforms. Finally, insights are provided of the challenges presently faced by FSCs for broader commercialisation and outlook in the form of potential as energy storage devices (ESDs) in next generation applications in short, medium and long term.