Extremely high energy density and long fatigue life of nano-silica/polymethylvinylsiloxane dielectric elastomer generator by interfacial design

Dielectric elastomer generator (DEG) can harvest electrical energy from various movement in nature such as human walking and ocean waves. To achieve high energy harvesting performance of DEG, dielectric elastomer (DE) composite with strong interfacial interaction, and thus high electrical breakdown strength (E_b) and long fatigue life (N_FL) at high strain is a key. In this study, nano-silica (SiO₂)/polymethylvinylsiloxane (PMVS) DE composite with strong interfacial interaction for DEG with extremely high energy density (w), high power conversion efficiency (PCE) and long N_FL was prepared by designing and synthesizing a new polar macromolecule coupling agent (MCA), ester group grafted liquid butadiene rubber using a photoinitiated thiol-ene click reaction. Compared with the common small molecule coupling agent (SCA) modified SiO₂ (SCA@SiO₂)/PMVS composite, the new MCA modified SiO₂ (MCA@SiO₂)/PMVS composite shows much stronger interfacial interaction owing to the largely increased co-crosslinking junction and chain entanglement, resulting in the significantly improved elongation at break and E_b at high strain (400%). As a result, MCA@SiO₂/PMVS DEG exhibits an up-to-date highest w (92.2 mJ/cm³) and PCE (35.8%) among the previously reported DEG using unprestretched DE film, and its N_FL reaches 141000 times, 3.9 times that of SCA@SiO₂/PMVS DEG (36000 times). Thus, MCA@SiO₂/PMVS DEG shows the highest full-life generating energy density (9710 J/cm³), 4.8 times and 2427 times that of SCA@SiO₂/PMVS DEG and commercial VHB DEG, respectively.