High-Throughput Processing of Nanographite-Nanocellulose-Based Electrodes for Flexible Energy Devices

The current work aims at understanding factors that influence the processability of nanographite-nanocellulose suspensions onto flexible substrates for production of conductive electrodes. A custom-built slot-die was used in a continuous rollto-roll process to coat the nanomaterial suspension onto substrates with varying surface smoothness, thickness, pore structure, and wet strength. The influence of a carboxymethyl cellulose (CMC) additive on suspension rheology, water release properties, and coating quality was probed. CMC addition reduced the suspension yield stress by 2 orders of magnitude and the average pore diameter of the coated electrodes by 70%. Sheet resistances of 5-9 Omega sq(-1) were obtained for the conductive coatings with a coat weight of 12-24 g m(-2). Calendering reduced the sheet resistance to 1-3 Omega sq(-1) and resistivity to as low as 12 mu Omega m. The coated electrodes were used to demonstrate a metal-free aqueous-electrolyte supercapacitor with a specific capacitance of 63 F g(-1). The results increase our understanding of continuous processing of nanographite-nanocellulose suspensions into electrodes, with potential uses in flexible, lightweight, and environmentally friendly energy devices