Ultrahigh energy storage capacity in multilayer-structured cellulose-based dielectric capacitors caused by interfacial polarization-coupled Schottky barrier height

Polymer-based dielectric capacitors, which have two main branches of PVDF-based and PI-based systems, show the advantages of ease of processing and good energy storage capacity over bulk and epitaxy thin films. Nevertheless, both suffer from the drawbacks of being derived from petroleum-based materials and polluting the environment during the post-treatment process. As the most abundant natural polymer on earth, cellulose, which has eco-friendly characteristics and good voltage endurance, has been studied as the best candidate. Owing to the strong self-assembly behavior of the hydrogen bond network in cellulose chains, it is challenging to prepare multilayered cellulose-based films, which have caused a bottleneck in their development. Herein, using the strategy of hydrogen bond replacement, such behavior was weakened, and the sandwich-structured cellulose-based dielectric capacitors of BaTiO3@cellulose/PVDF were successfully fabricated through a modified tape-casting technology. The structure characterization revealed that the cellulose, PVDF, and BaTiO3 particles were bonded through hydrogen bonds, and an energy storage density as high as 27.2 J cm−3 was obtained. Both the band theory and finite element simulation were employed to reveal the excellent electric breakdown strength, which is thought to be the main reason for such a good performance. The reliability measurements showed great potential in practical application, and good power density was also achieved. Besides, the sandwich-structured BaTiO3@cellulose/PVDF has better mechanical properties than the single-layered one. Our study provides a solid theoretical basis for fabricating high-performance biomass-based dielectric capacitors.