Microbial cellulose-derived interconnected carbon nanotube networks as binder- and metal-free electrodes for electrochemical capacitor

Microplastic and metal waste from electronic industries are now a major global problem due to high demand in smart technology. This work aims to fabricate a green electrical double-layer capacitor (EDLC) using natural resources. An eco-friendly electrodes film are produced by the presence of green polymers called microbial cellulose from symbiotic culture of bacteria and yeast (SCOBY) via harmless, inexpensive and simple procedures. The microbial cellulose electrodes (MCE) are paired with a thin layer of green polymer electrolyte (GPE). Glycerol serves as the plasticization agent for alternative pathways for ionic migration. The most optimum GPE possesses good ionic conductivity of ~ 10"^ S/cm. From transference number analysis (TNM), ions have found to be the dominant charge carrier in the GPE as the TNM number of ions is close to unity. Linear sweep voltammetry (LSV) analysis illustrated that the GPE is electrochemically stable up to 2.4 V. The GPE is sandwiched between two identical MCE to form an EDLC. Cyclic voltammetry (CV) analysis showed that the green EDLC stores energy through non-Faradaic mechanism and the specific capacitance is influenced by the sweep rates. The EDLC can be charged and discharged up to 2 V and it showed a great cyclability.