(Invited) Green Materials for Sustainable Supercapacitors

Abstract

The exponential increase of energy storage systems like batteries and supercapacitors is paralleled by the growing need of minimizing the environmental and economic impact of disassembly and recycling of waste devices. Today, electrode and separator processing greatly contribute to device cost and environmental footprint. The use of water-processable, biodegradable electrodes and separators is a viable approach to develop green and easy-to-dispose devices. Natural polymers processed by aqueous solutions are a very promising alternative to fluorinated polymers like polyvinylidene difluoride that also requires the use of the toxic N-Methyl-2-pyrrolidone solvent. Electrospinning is an emerging technology for the preparation of free-standing fiber mats to be used as electrode materials and separators in supercapacitors. Here, the strategies to develop green supercapacitors making use of natural binders and separators and bio-derived electrodes are presented. In particular, the performance of supercapacitors making use of cellulose and pullulan membranes prepared by electrospinning are reported and compared to those of devices featuring cellulose separators produced by bacteria. Acknowledgments The research has been carried out under the Italy-South Africa joint Research Programme 2018-2020 and the Executive Bilateral Program Italy-Quebec 2017-2019, Italian Ministers of Foreign Affairs and of the Environment.