Nano-Silica/Polydimethyl(methylvinyl)siloxane dielectric elastomer generator with high generating energy density, high efficiency and long fatigue life

Dielectric elastomer generator (DEG) can easily realize the energy harvesting from nature motion sources such as waves and human movements. Up to now, the bottleneck of the development of DEG is the lack of dielectric elastomer (DE) material with excellent dielectric properties and long fatigue life, restricting the practical application of DEG. In this study, a kind of nano-silica (SiO2) with strong interfacial polarizability was introduced into polydimethyl(methylvinyl)siloxane (PMVS) matrix to enhance its permittivity. The results show that the increase of permittivity of PMVS by adding SiO2 is five times that by adding traditional ceramic filler, and all these composites maintain high insulation. After the grafting of a coupling agent (CA) on SiO2 (CA@SiO2), the co-crosslinking reaction between CA@SiO2 and PMVS can occur, leading to the large enhancement of the interfacial interaction and thus the improvement of both breakdown strength and fatigue life of the CA@SiO2/ PMVS composites. The as-prepared unprestretched DE composite was then used as DE substrate for cone DEG, and an up-to-date highest generating energy density (47.9 mJ/g) and conversion efficiency (32.3%) were achieved. More importantly, the as-prepared DEG exhibits long fatigue life of over 50,000 cycles and its full-life generating energy density reaches over 2,000 J/g, approximately 290 times higher than that using the most widely used VHB material based DEG. By combining atomic force microscopy, the finite element analysis and experimental results, the mechanism why enhancing the interface interaction can improve the energy harvesting performance and fatigue life of DEG is revealed.