Improved energy storage properties of polypropylene-based composite dielectrics by introducing surface-charged BaTiO3@chitisan ultrafine constructions

Dielectric capacitors with ultra-high power density and rapid charge–discharge rate are indispensable energy storage components in pulse power systems. However, the low intrinsic energy density of conventional dielectrics limits their application in modern electrical and electronic industries. To solve this problem, in this work, ultrafine BaTiO3 nanoparticles coated with a surface-charged chitosan (CS) shell were synthesized by combining hydrothermal and electrostatic self-assembly approaches. A tiny amount of BaTiO3@CS core–shell construction (∼0.2 vol%) endowed the polypropylene (PP)-based composite dielectrics with a significantly improved energy storage density (Ue) of 4.76 J cm−3, which is a 269% increase compared to that of neat PP (Ue ∼ 1.77 J cm−3). Meanwhile, a high discharging efficiency of 93.9% was also maintained. In addition, the breakdown strength of BaTiO3@CS/PP composite dielectrics (∼435 MV m−1) was effectively improved at an elevated temperature (105 °C), which is 16.9% higher than that of neat PP (∼372 MV m−1). Both the enhanced interfacial polarization and high electron affinity provided by the BaTiO3@CS ultrafine constructions are beneficial to the improvement of dielectric and insulating performances of the composites, which were also confirmed by finite element simulation. This study provides an effective and feasible strategy for preparing composite dielectrics with superior overall energy storage performance.