Structural design on microporous cellulose-derived carbon via freeze-drying and carbonization for enhancing energy storage performances

Generating micropores of carbon electrode materials with pore sizes matching the size of transport ions plays a crucial role in improving the energy density of carbon-based supercapacitors. Herein, a biomass-derived carbon with a tailored three-dimensional (3D) porous structure was developed using TEMPO-oxidized cellulose nano-fibrils (CNF). The specific surface area and micropore volume were controlled by fine-tuning via freeze-drying and carbonization-activation processes, yielding a carbonized CNF aerogel (CCA) with micropores dominant structure. Benefiting from the elaborate porous architecture and high conductivity, a CCA electrode delivers good capacitive performance, e.g., a high capacitance of 174 F/g. In particular, the electrode has good cyclic durability after long-term cycles (97.22% capacitance retention after 100,000 cycles). This work not only provides a reference for the fine-regulation of the porous structure of CNF-derived carbon but also promotes the application of biomass resources in the field of energy storage.