Sustain Sustainable technology: biodegradable batteries from chitosan as a bio-entrepreneurship

Abstract

This case study evaluates the feasibility of producing biopolymers as an environmentally friendly component for batteries, using chitosan obtained from shrimp shells, an abundant agro-industrial waste product, as a sustainable bio-enterprise proposal. The raw material was extracted, and its physicochemical characterization was performed, yielding the following contents: moisture (3,38%), crude protein (40,77%), ash (33,21%), calcium carbonate (24,91%), chitin (22,00%), and chitosan (18,70%). Chitosan production was estimated to be 10 kg and 3 tons of raw material, resulting in 1,17 kg and 352,3 kg, respectively. An electrochemical cell with a zinc anode, MnO₂ cathode, and a chitosan gel as the electrolyte was theoretically modeled, evaluating parameters such as voltage, current, lifespan, and stability. Using standard potentials, a voltage of approximately 0.8 V was estimated, with a current in the range of 0,1 to 2 mA, a lifetime between 30 minutes and 2 hours, and gel stability of up to 5 days. The biodegradability of the system exceeded 60% over a three-week period, as determined by material mass loss. Additionally, key chitosan characterization parameters were considered, such as the degree of deacetylation (DD%), viscosity, molecular weight, and impurity content (ash and residual salts), as well as gel properties (thickness, crosslinking, and hydration), which directly influence the ionic conductivity and stability of the electrolyte. Biodegradability was evaluated using a mass loss assay under controlled composting conditions, considering temperature, relative humidity, and exposure time. This study demonstrates the potential of chitosan as an electrolyte in sustainable electrochemical systems, promoting the circular economy and the reduction of marine debris.