Scaling up pullulan-based supercapacitors: A sustainable approach to binder and separator integration in EDLCs

Electrochemical double-layer capacitors (EDLCs) play a critical role in high-power energy storage, offering exceptional durability and longevity for diverse applications. EDLCs typically utilize activated carbon electrodes combined with organic electrolytes, produced through cost-effective roll-to-roll manufacturing, and achieving operating voltages of approximately 2.7 V. Replacing toxic materials in electrode fabrication is critical for transitioning towards sustainable manufacturing practices. A key component in their production is the binder, which must ensure uniform coating, thermal and mechanical stability, optimal microstructural properties, electrochemical inertness, and environmentally friendly processing. Pullulan (PUL), a water-soluble polysaccharide, emerges as a promising alternative, offering reduced environmental impact and cost benefits. Our recent studies demonstrated the feasibility of PUL as a binder for aqueous processed EDLCs at the laboratory-scale. However, scaling up this process and validating it for large-scale EDLC electrodes remain open challenges. Here, we present a comprehensive investigation into the optimization of low-binder-content, high-mass-loading electrode manufacturing at both laboratory and pre-industrial scales. Moreover, a PUL electrospun membrane has been also investigated as separator. The optimized electrode formulations are validated in pouch cells with 20 cm 2 electrodes, providing critical insights into the feasibility and scalability of the proposed supercapacitor configuration. • Water-processable pullulan as dual binder and separator in EDLCs. • Scaled pouch cells with ≥5 mg cm −2 electrodes, 8 wt% binder content. • Pouch cells (20 cm 2 , 4 F) validated with ACN and greener PC electrolytes. • PC-based cells outperform ACN at 60 °C, enabling safer high-T operation. • Fully water-processed EDLCs shown viable for sustainable large-scale production.