Fabrication of high value cellulose nanofibers@Ni foam by non carbonization: various application developed during the preparation

Bulk cellulose nanofibers (CNF)-based foam materials have attracted more and more attention in the field of energy storage and sensing because of their advantages of environmental protection, flexibility and cross-linked porous structure. However, the poor conductivity and low utilization efficiency of bulk CNF foam limit their wide application. Although some researchers have improved the conductivity of bulk CNF foam by carbonization, bulk CNF foam material will become fragile powders, not to mention flexibility, which seriously affects its application in energy and sensing fields. Herein, an attempt was made to fabricate a kind of non-carbonized bulk CNF@Ni foam hybrid by a combination of liquid reduction and freeze drying. During the process of the CNF@Ni foam preparation, the intermediate product CNF@NiCl₂ shows good water storage and monitoring sensing characteristics, as well as it can be used as home decoration. What’s more, the final CNF@Ni foam product can be directly assembled into a symmetrical supercapacitor that not only presents a good cycle stability, but also exhibits high gravimetric and volumetric energy densities of 38 Wh kg^− 1 and 58 Wh L^− 1, and simultaneously retains high power densities of 56 kW kg^− 1 and 39 kW L^− 1. Additionally, the hybrid also shows outstanding sensing properties. All in all, from the beginning to the end of the CNF@Ni foam preparation, various potential applications are explored in the whole process, which not only improves the utilization efficiency of CNF-based composites, but also explores more application scenarios of CNF-based composites.