Engineering a Low-Cost and Sustainable Electrochemical Cell Using Sericin as a Bio-Electrolyte

Abstract

Sericin, a water-soluble protein derived as a byproduct of silk processing, was investigated as a bio electrolyte in a single chambered cell. As a byproduct of silk processing, sericin is a natural, biodegradable, and sustainable biopolymer. Sericin extracted from Bombyx mori cocoons was dispersed in water at concentrations ranging from 0.5% to 8% and the homogeneous solution was used as an electrolyte with graphite serving as both cathode and anode. The performance of the electrolyte (sericin) in the electrochemical cell (SEC) was evaluated by varying the applied voltage, charging time, and electrolyte concentration. Further, the ability of the electrolyte to store and release electrical energy was studied. Sericin contains both positively and negatively charged amino acids and exhibited a maximum voltage retention of 2.8 V. The performance of the SEC was strongly dependent on the operating parameters, particularly sericin concentration and applied voltage. A sericin concentration of 2% and applied voltage of 15 V for 60 min provided the maximum potential. A maximum discharge time of approximately 7 min was obtained when the SEC was fully charged and connected to a standard LED (forward voltage ∼1.8–2 V, current ∼20 mA). Electrochemical studies confirmed that the performance of the battery was mainly dependent on the sericin concentration, attributed to ionizable amino acid residues that facilitate ionic conduction through hydrogen-bonded networks within the protein matrix. The SEC could be charged and discharged multiple times without loss of potential. In addition, ionic properties of the SEC were investigated using impedance studies, dielectric analysis, and transport number measurements. Sericin-based electrochemical systems show promise as sustainable energy sources for low powered electronics, such as medical devices and personal care devices.