Recent Advancements on Carbon Fibers-Based Sustainable Electrodes for Flexible and Wearable Supercapacitors

Abstract

Electrochemical energy storage devices such as rechargeable batteries and supercapacitors have replaced conventional batteries and dielectric capacitors due to their excellent charge storage abilities and other electrochemical performances. Supercapacitors are high-power devices that can deliver high-power on demand. These devices utilize water-based electrolytes hence are safe and reliable energy storage devices for application in portable and wearable electronic devices to power them. A major challenge in fabricating the wearable supercapacitors lie in the rigidity of electrodes due to the rigid metallic current collectors used in it, which hinders their successful implementation. The flexibility to the devices is mainly imparted by the electrodes hence the preparation of electrodes is utmost important in determining their flexibility. In this review, we report the facile fabrication of supercapacitors using carbon fibers (CFs). CF is a sustainable and the most reliable environment-friendly electrode material for supercapacitors but their low specific capacitance is a bottle-neck. The specific capacitance can be enhanced by preparing hybrid or nanocomposite electrodes of CF with high-performing electrode-active materials such as electronically conducting polymers, nanocarbons, MXenes, transition metal oxides, etc is a promising choice. The various strategies adopted for the synthesis of CF-based hybrid/nanocomposite flexible electrodes is discussed in detail. The electrochemical performance evaluation of CF-based electrodes is reviewed and emphasis is given to their flexible and wearable features. This article helps to get an in-depth insight about the preparation of CF-based flexible electrodes for the next-generation wearable supercapacitors.