Ultrahigh Energy Storage Density in Poly(vinylidene fluoride)-Based Composite Dielectrics via Constructing the Electric Potential Well

摘要

Dielectric capacitors are fundamental energy storage components inelectronics and electric power systems due to their unique ultrahighpower density. However, their relatively low energy storage density is along-standing challenge which greatly limits their practical applicationrange. Chitosan (CS) and montmorillonite (MMT) are two kinds of materialsthat exist abundantly on the earth with natural surface charges. Thepositively charged CS and negatively charged MMT can be self-assembledinto the typical sandwich-structured CS/MMT/CS 2D structure throughan electrostatic attraction. Loading these surface-charged sandwichstructurednanosheets into poly(vinylidene fluoride)-based composite witha weight fraction as tiny as 0.3 wt., an ultrahigh energy storage densityof 32.5 J cm~(?3) accompanied with a high efficiency of 64 are concurrentlyachieved with a very low cost and scalable process. Guided by finite elementsimulation, it is revealed that a number of electric potential wellsthat exist in the charged sandwich nanosheets impede the acceleration ofinternal charges and hinder the growth of electrical trees. The results offera novel paradigm for exploring ultrahigh energy storage density capacitorsin an economical way.