Life Cycle Assessment of Supercapacitor Electrodes Based on Activated Carbon from Coconut Shells

Abstract

Coconut shells can be used to produce high-performance activated carbon (AC) electrodes for energy storage supercapacitors. An incentive to promote this manufacturing route is sought through its anticipated positive impact on the environment and the substitution of non-renewable resources. The present study sets out to assess the environmental performance of a recently developed route for AC manufacturing through a simple activation process using steam. The analysis was carried out using the life cycle assessment (LCA) approach to investigate the production of AC material and resulting electrodes for a broad range of environmental impact categories and energy use. The study was conducted for a hypothetical optimized industrial-scale scenario drawing on experimental observations, literature, and energy and material balance calculations. Impact assessment results were presented both for the functional unit of electrode’s capacitance and mass of AC and electrode, and interpreted through comparative analyses with coal-derived AC, reduced graphene oxide, and algae-derived biochar aerogel electrodes. The impact assessment results of the new AC electrode show competitive performance across most of the investigated impact categories and indicators. Larger impacts are mostly only observed for the land and water use categories stemming from the agriculturally intensive practice of coconut production. A total of 5.68 kg of CO₂ and 34.4 MJ of CED kg^–1 AC are reported, with AC constituting roughly 60% of the total impacts arising in the production of supercapacitor electrodes. The results have to be interpreted with present limitations to data especially considering the potentially high variability of carbon content in coconut shell species.