Largely enhanced energy harvesting performances of DEGs by constructing all-organic dielectric composites with a soft and deformable filler

Abstract

Dielectric elastomer generators (DEGs) based on silicone rubber composites have received considerable attention in recent years. However, the addition of traditional rigid dielectric fillers not only increases the modulus of composites but also leads to interface debonding between the filler and elastomer matrix under high stretching conditions, thereby limiting the energy harvesting performance. Here, gel-like ester group grafted butadiene rubber (GEBR) with a relatively low modulus was synthesized and used as a “soft filler” to enhance energy harvesting performance of PMVS-based DE composites. The GEBR filler with a high concentration of polar groups could lead to an increase in the dielectric constant of GEBR/PMVS composites by the introduction of interfacial polarizability and the improvement of dipole polarizability. Most notably, compared with TiO₂ as the rigid filler, the combination of GEBR's deformability under stretching and strong interfacial interaction between the GEBR filler and PMVS matrix could effectively prevent weak interface formation under high strain conditions, and thus hinder the propagation of electrical treeing. As a result, benefiting from the GEBR filler with a low modulus, 5 vol% GEBR/PMVS DEG exhibits an excellent maximal energy density (65.4 mJ g⁻¹) and outstanding power conversion efficiency (38.4%), achieving a high energy density at relatively low input mechanical force. This study presents a pioneering methodology to fabricate high-performance all-organic DE composites for DEGs through designing a soft dielectric filler with exceptional deformability under stretching.