Functional cellulose-derived materials for energy storage

The biopolymer cellulose is an inexhaustible source for the synthesis of various functional materials for energy storage. It should be accounted as an alternative to the currently most used precursors (coal tar pitch and synthetic polymers) of carbon nanostructures. In this work, cellulose-based carbon nanofibers (CNF) with high mechanical strength and electrochemical stability were nitrogen-doped and functionalized with carbon nanotubes (CNT) via two different methods in order to obtain electrode materials for energy storage devices.Amorphous granular carbon nanofibers were produced by three consecutive steps of cellulose acetate electrospinning, cellulose regeneration and carbonization. Carbonization of pure cellulose samples resulted in the formation of 25-40 μm thick carbon sheets consisting of fibers with 20-180 nm diameter, and electrical capacitance of 10.8\ub10.5 F/g. Functionalization of CNF led to the composite materials with higher capacitance values. Impregnation of cellulose samples with NH4Cl before carbonization allowed obtaining N-doped CNF with higher carbon yield and electrical capacitance of 20.0\ub10.5 F/g. Impregnation of cellulose with double-walled CNT before carbonization resulted in CNF/CNT composite material with the capacitance of 34.9\ub10.5 F/g, and CNF covered with CNT deposited by chemical vapor after carbonization resulted in the composite material with the capacitance of 38.4\ub10.5 F/g. As a conclusion, functional cellulose-based materials are prospective electrode materials for energy storage devices