Polymethyl Methacrylate Substrate-Inducing Highly Ordered Regenerated Cellulose Films toward Ultra-High Breakdown Strength and Charge–Discharge Efficiency

Polymer-based dielectrics, ascribed to their brilliant flexibility and easy processing, have been extensively explored in applications for electronics and electric power devices. However, fabricating full organic polymer dielectrics in a feasible way without introducing any other components is still a long-standing challenge, especially for the polymers produced from natural resources. Here, the dielectric performance-microstructure relationships of the cellulose dielectric films are declared. We demonstrate that the substrate used for supporting the dielectric film exhibits a great role in tailoring the microstructures of the dielectric film. The polar substrate [poly(methyl methacrylate), PMMA] promotes the highly ordered stacking of macromolecules in the regenerated cellulose film (HO-RC), enhancing the intermolecular interaction and reducing or even eliminating defects. Owing to the densely compact and well-aligned chain arrangement, a biodegradable-cellulose (HO-RC)-film fabricated in this work possesses a high transmittance (91%), which is better than many other commercial transparent materials. Moreover, the highly ordered and compact inner structure restrains polarized-inducing-electrostriction and impedes charge injection and transportation under an external electric field, benefiting in preventing electromechanical breakdown and electric breakdown. Consequently, the cellulose film with 8 μm thickness (A8) exhibit a high energy density of 10.39 J cm–3 at 750 MV m–1 and ultrahigh efficiency exceeding 93% and survives in 10,000 times cyclic charge–discharge measurements at 600 MV m–1. The deterministic control of the macromolecular alignment by substrate–dielectric interaction, revealed in this work, opens a novel path for high-performance polymer-based dielectrics industries on one hand. On the other hand, this work also confirms the great potential of cellulose in dielectric energy storage and application.