Pullulan-ionic liquid-based supercapacitor: A novel, smart combination of components for an easy-to-dispose device

Abstract

Strategies that simultaneously target energy/power performance, sustainable manufacturing processes, valorization of green raw materials, and easy recycling of supercapacitors are urgently needed. Today, efforts have to be devoted not only to improve system performance but also to address the sustainability of materials and devices manufacturing and recyclability. Specifically, pullulan is herein proposed as a novel bio-degradable binder and separator for green supercapacitors. It is processed by electrospinning from aqueous solutions, therefore overcoming issues related to conventional membrane processing by organic solvents. Furthermore, combining the water-soluble, biodegradable pullulan with a hydrophobic ionic liquid electrolyte brings about a novel approach for end-of-life management of devices. The use of pullulan is demonstrated in a supercapacitor with carbon electrodes obtained from pepper-seeds waste and 1-Ethyl-3-methylimidazoliumbis(trifluoromethylsulfonyl)imide as the electrolyte. The supercapacitor delivers up to 5 kW kg−1 specific power and 27.8 Wh kg−1 specific energy at 3.2 V, that well compare with conventional electrical double-layer capacitor performance with the added value of being eco-friendly and cheap.