Nanocellulose is used to prepare sodium ion flexible batteries

In recent years, sodium ion batteries have attracted widespread attention due to their low cost and abundant sodium reserves. sib has a similar working principle as lib: Na+ migrates in the electrolyte between the cathode and the anode, while electrons are transmitted through external circuits. However, the radius of Na+ is about 55% higher than that of Li+, so some anode materials that are high-quality anodes in lib exhibit poor storage performance in sib. Generally speaking, the main frame of the SIBs electrode has a large gap Na+ for insertion/extraction material. In addition to the dynamics problem, the larger Na+ radius is also related to the possible structural changes of the electrode material during insertion or extraction. Therefore, developing suitable electrode materials is crucial to improve the performance of sib.

Nanocellulose can be combined with active materials to prepare sib flexible electrodes. Hu et al. have shown that using tempo-oxidized CNF as a dispersant can effectively disperse two-dimensional materials (such as MoS2) in aqueous solution and form hybridization with the two-dimensional materials. The optimized CNF/MoS2/CNTs composite film can be used as a flexible electrode for the SIB anode. Although the MoS2 content is low, the first cycle discharge capacity is 147 mAh g − 1, which is still higher than the capacity of the MoS2/CNTs anode. Nanocellulose can be combined with the active material and converted into functional sodium ion electrode material after further carbonization. For example, Yu and colleagues demonstrated a binder-free, independent carbon nanofiber electrode by simply carbonizing the BC film. The results show that sodium ions and solvents are adsorbed and co-intercalated in the ether-based electrolyte, and have long cycle life and high coulombic efficiency at high capacity.

Compared with Li+, Na+ is larger in size, hindering the kinetics of electrochemical reactions. Therefore, the nanocellulose- based composite materials used for reversible electrodes should have sufficient gap sites and/or large channels. The challenge for the future is to build and manufacture new with layered three-dimensional porous structures through advanced synthesis strategies nanocellulose- based composites that contain appropriate Na+ storage space, higher Na+ diffusion coefficient, and shorter ion diffusion distance. and fast electronic transmission.