Effect of interparticle electrostatic interactions on the dielectric response of 0–3 connectivity particle/polymer composites for high energy density storage

Abstract

Polymer composites with high energy density have been of great interest to scientists for a long time, and this accounts for a great wealth of experimental data that are available for interpretation. One of the important phenomena is the variation rate of the permittivity of composites, which always deviates from the linear increase and rises steeply toward the high concentration. Interestingly, the critical transition concentration is always located in the range of 20 vol. %–25 vol. %, but still far less than the common percolation threshold of composites. Through the analysis of the local electric field distribution and surface polarized charges distribution, the phenomenon is successfully interpreted as the effect of the electrostatic interactions between the adjacent polarized particles. Two specified composite configurations (BCC and FCC) are designed, and their dielectric properties have been systematically studied with the help of the finite element method and the phase field method. The simulation results indicate that the strength of the particles’ interaction is short-range effective and depends closely on the gap distance between adjacent particles. When the gap distance is smaller than 0.8 times the radius of the particles, which is tantamount to the concentration larger than 20 vol. % and 25 vol. % for BCC and FCC, respectively, the electrostatic interaction of the particles is rather significant, resulting in an additional contribution on the variation of the dielectric properties of composites and vice versa. The synchronous variation tendency between the simulation results and experimental measurements demonstrates the effect of electrostatic interaction on the dielectric properties of composites.