Abstract
Extensive attention has been given for the fabrication of stable and cost-effective electrolytes materials for wearable energy storage systems. Herein, glycerol (Gly) and H3PO4 (P) based bio-electrolyte for electrical double layer capacitance (EDLC) was produced and then converted to redox-mediated gel bio-electrolytes via doping with cobalt ions (Co) at various compositions to form glycerol-H3PO4-Co (GlyPCoX; X: 1%, 3%, 5%, 10% w/w). The gel electrolyte forms a hierarchical framework for effective ion conduction between the pores of the carbon composite electrodes that is triggered by bias during charging and discharging processes. The supercapacitors (SCs) were assembled with activated carbon-based composite electrodes and device performances were tested according to redox-mediated electrolyte compositions. Remarkable device performance was obtained from the Gly, which contained 5 M H3PO4 (P5) and 5% Co (Co5), (GlyP5Co5) and showed a specific capacitance of 349 F g(-1). The corresponding specific energy and specific power were calculated as 47 and 420 W kg(-1). Excellent operational stability (91%) was obtained after 15 000 charge/discharge cycles. In addition, the electrolyte is cost effective, retained extraordinary performance during galvanostatic charge-discharge (GCD), and successfully powered light-emitting diode (LED) device (1-4 cm) at various bending angles. Thus, the gel electrolyte has excellent stability and flexibility for use in wearable energy storage systems.