Bacterial cellulose-derived carbon electrodes for supercapacitors: Fabrication strategies, electrochemical performance, and mechanical properties — A review

Bacterial cellulose-derived carbon (BCC) has emerged as a promising biomass-derived electrode platform for supercapacitors because of its high purity, three-dimensional nanofibrillar architecture, structural tunability, and ability to form porous conductive carbon networks after carbonization. This review systematically analyzes BCC electrodes by linking fabrication strategies, pore architecture, surface chemistry, electrochemical performance, mechanical properties, and techno-economic scalability. Based on 50 Scopus-indexed articles, freeze drying is identified as the dominant pre‑carbonization route for BCC electrodes, being used in 89.80% of the analyzed studies because of its ability to preserve the open nanofibrillar structure of BC before thermal conversion. Accordingly, the main performance analysis focuses on freeze-drying-assisted BCC systems and is organized according to material-engineering strategies, including direct carbonization into pristine BCC, activation, heteroatom doping, and composite formation. Non-freeze-drying routes are discussed separately as alternative fabrication pathways whose performance depends strongly on precursor design, activation, and electrode architecture. Electrochemical analysis shows that pristine BCC delivers 21–231 F g−1 at 1 A g−1, while activation increases the capacitance range to 234–369 F g−1 by improving pore accessibility. Heteroatom doping further broadens the range to 120–536 F g−1 through improved wettability, surface polarity, and additional active sites. Composite formation provides the widest capacitance range, 92–1949.5 F g−1, especially when BCC is integrated with pseudocapacitive metal oxides, hydroxides, or sulfides. However, high capacitance is not always accompanied by high cycling stability, indicating a trade-off between Faradaic charge storage and long-term structural durability. In two-electrode systems, BCC-based symmetric supercapacitors show competitive energy–power performance, and several systems surpass commercial YP-50F under comparable symmetric-device conditions. In contrast, BCC-based asymmetric devices represent a separate device category and achieve much higher energy densities, up to 131.6 Wh kg−1, particularly when redox-active electrolytes are involved. Beyond electrochemical performance, flexible BCC-based supercapacitors can maintain electrochemical stability under bending up to 180°, while BCC/graphene electrodes also show stable cyclic voltammetry profiles after 100 bending–release cycles at 90°. Further development of BCC-based supercapacitors requires more systematic control of BC precursor quality, more consistent paired three-electrode/two-electrode evaluation, standardized reporting of electrode parameters, and broader validation under practical operating environments. These advances are essential to translate the intrinsic advantages of BCC, including its porous carbon network, structural tunability, flexibility, and lightweight architecture, into reproducible and scalable supercapacitor devices.