Achieving High Energy Density and Low Loss in PVDF/BST Nanodielectrics with Enhanced Structural Homogeneity

Authors: Yunchuan Xie, Wanrong Jiang, Tao Fu, Jingjing Liu, Zhicheng Zhang*, Shengnan Wang

ACS Applied Materials & Interfaces, DOI: 10.1021/acsami.8b10354. 

ABSTRACT: Poor compatibility of polymer/ceramic composites used as high-pulse capacitors with high permittivity suffers from the reduced breakdown strength (Eb) and lowered energy density (Ue). Herein, mussels-inspired poly(dopamine) (PDA) modified BaSrTiO3 nanoparticle (mBST) and PVDF matrix are bonded together to fabricate nanocomposites with crosslinked network and enhanced compatibility. The significantly improved Eb of 466 MV/m and the highest Ue of 11.0 J/cm3 for PVDF-based polymer/BST composites have been obtained. By comparing the properties of three series of composites with different structure, the contribution of ferroelectric relaxation, interface polarization and leakage conduction to the dielectric loss has been well addressed. Notably, the surface modification of BST with PDA could remarkably enhance the compatibility of the two components and structural homogeneity of the composite. The improved bonding between polymer matrix and filler chemically or physically is responsible for the reduced dielectric loss from both conduction loss and interfacial polarization, which is the key to improve the Eb, Ue and  of the composite. It has been revealed that enhancing the homogeneity of the composites by modifying ceramics and constructing crosslinked networks between polymer matrix and filler might be a facile strategy to achieve high energy storage performance in polymer composite.