LAUSR

Dielectric elastomer generators (DEGs) with high generated energy density and high conversion efficiency are of great interest. Among several dielectric elastomers (DEs), silicone elastomer filled with ceramic fillers have been extensively studied for their high elasticity, insulation, and permittivity. However, the stretched breakdown strength (Ebs) of such composites decreases significantly under large strain, thus sharply reduces its energy harvesting performances. In this study, a polar rubber‐based dielectric (GNBR) is synthetized and creatively used as “soft filler” for silicone elastomer. Benefiting from the deformability under stretching and its inherent strong interface bonding with silicone elastomer, this soft filler effectively avoids the formation of weak interface under large strain and reduces the local field strength of interface area. As expected, the composite filled with soft filler (GNBR/PMVS) shows enhanced Ebs of 2.8 times that of composite with traditional hard filler (TiO2/PMVS) under equibiaxial strain of 200%. As a result, GNBR/PMVS composite exhibits maximum energy density of 130.5 mJ g−1 with up‐to‐date highest power conversion efficiency of reported DEG (44.5%). The findings will provide new insights in the rational design of DE composites characterized by high stretched breakdown strength for advanced energy harvesting system.