The surge in demand for sustainable energy conversion and storage solutions pushes the development of rechargeable electro-chemical devices. As part of the EMPHASIS project, which targets sustainable supercapacitor design for applications in electromobility and smart clothing requiring high energy/power densities, our research focuses on the development of bio-based activated carbons for supercapacitors. A distinctive strategy within EMPHASIS involves the creation of high-specific-surface-area activated carbons derived from novel bio-based precursors. Specifically, our approach leverages doped cellulose fibers as precursors for activated carbon fibers (ACF) manufacturing. CANOE, a French RTO, has developed an expertise in cellulose spinning from H3PO4 solutions and subsequent carbonization into fibers at both laboratory and semi-industrial scales. WOOD K PLUS, an Austrian RTO in biomass materials, performs the thermal-chemical conversion process to transform these fibers into microporous ACF. In the EMPHASIS project, CANOE undertakes the spinning of doped cellulose solutions, incorporating heteroatom compounds and carbon nano-additives to tailor ACF properties, including surface chemistry, morphology, pore size distribution, and electrical conductivity. The activation of bio-based carbon fibers occurs at WOOD K PLUS in a two-step process combining chemical and physical activation . Supercapacitor test cells incorporating these innovative ACF-based electrodes demonstrate remarkable capacities and cycle stability. This research received support from the European Union under Horizon Europe as part of the EMPHASIS Project (https://www.emphasis-supercaps.eu/) under Grant 101091997