Biomass Derived Flexible Free-Standing Electrodes for a High Performance Supercapacitor

Abstract

Global energy demand, the depletion of fossil fuels, and environmental deterioration have spurred a search for significant improvements in energy conversion and storage. The need for efficient methods of electrical energy storage for on-demand use is critical. Batteries and supercapacitors (SCs) are two of the main energy-storing technologies. SCs and batteries are frequently used in everyday items like smartphones, wearable electronics, electric cars, and portable electronic devices. Supercapacitors (SCs) continue to generate a lot of attention due to their higher energy storage capacity than conventional capacitors and faster rate performance than rechargeable batteries. Supercapacitors, on the other hand, have a high-power density (>10 kWkg-1), extended cycle stability, and an increased capacity for charging and discharging quickly. Supercapacitors are divided into two major categories: EDLC and pseudo-capacitors, depending on the charge storage mechanism. At the electrode-electrolyte contact in EDLC, a double layer of charge is created. Charge transfer reactions between the electrode and electrolyte cause pseudo-capacitance to arise. Compared to EDLCs, pseudocapacitive materials have a greater capacitance. Materials that are pseudo-capacitative include transition metal oxides (TMOs) like, Fe2O3, CoO, NiO, ZnO2, TiO2, and V2O5. which are good candidates for high-performance supercapacitors. Herein, we have proposed a pseudocapacitive material functionalized carbon fabrics produced from cellulosic-based biomass material as a free-standing electrode for supercapacitor application. The fibrous electrode not only provides good mechanical flexibility but also a large surface area for electron transportation in the charging-discharging process. An excellent specific capacitance of ~ 1024 Fg-1 was exhibited in the three-electrode system. An electrochemical study for a full-cell asymmetric supercapacitor was also carried out which showed that the electrodes have an appreciable energy density of ~ 32 Wh kg-1 at a power density of ~ 120 W kg-1. In addition, a flexible asymmetric supercapacitor was also fabricated. A specific capacitance of ~ 40 Fg-1 was achieved in the device. Also, after bending at different angles there was no change in the cyclic voltammetric curve, suggesting that functionalized carbon fabric has good flexibility. Keywords : Supercapacitor, Cellulosic material, Free-standing, Carbon fibre