2.4.4 Impregnation
The excellent porous structure and large specific surface area of cellulose paper are considered suitable carriers for loading active materials. Among them, bacterial cellulose (BC) has an excellent length-to-diameter ratio and a network of interwoven fibers. However, after impregnation, the conductive substance and the paper-based film made of pure BC have poor mechanical properties. As shown in Figure 15D, Wu et al. [126] prepared a flexible and strong paper-based substrate by mixing cellulose fibers with BC. It is then impregnated in CNT solution. Due to the surface modification of BC by polyimide, a large number of amine groups are generated on the BC surface. The adsorption of this CNT provides excellent prerequisites. From the SEM image of the paper-based electrode, it is clear that the cellulose fibers provide the skeleton of the composite, and the CNT is uniformly loaded inside the material. The results show that the electrode has a conductivity of 0.59S cm-1 and a specific capacitance of 77.5F g-1. It is worth mentioning that after 15,000 ultra-long cycles, its electrochemical performance is still maintained at 98.4% of the initial state, showing excellent durability and stability.