Influence of Matrix, Filler, and structural design on the dielectric and energy storage properties of cellulose composites

Cellulose is a renewable, biodegradable, cost-effective, and easy-to-process natural biopolymer. Because of its dielectric, piezoelectric, and mechanical performance, cellulose and its composites are often used as a matrix, filler, substrate, gel electrolyte, and dielectric layer for flexible energy storage devices. They offer easy fabrication strategies and excellent mechanical properties. In this mini-review, we summarized the principles of dielectric and energy storage features of cellulose composites and factors affecting their dielectric properties, mainly exploring the incorporation of various filler materials in the cellulose matrices and cellulose materials acting as different types of fillers. Moreover, the fabrication strategies, structural design, and matrix-filler interactions of cellulose composites enhance their dielectric properties as systematically reviewed. This review summarizes the current state-of-the-art progress of cellulose dielectric composites, challenges, and future outlook for green dielectric and energy storage devices. The review suggests that optimizing the filler type, cellulose fiber content, fabrication techniques, and structural design can significantly enhance the dielectric properties and energy storage capacity of cellulose composites.