Largely improved generating energy density, efficiency, and fatigue life of DEG by designing TiO₂/LNBR/SiR DE composites with a self-assembled structure

Dielectric elastomer generators (DEGs) can easily harvest electrical energy from mechanical energy including ocean waves and human motion. A key bottleneck restricting the development of DEG is the lack of dielectric elastomer (DE) materials with simultaneously good dielectric, elasticity and mechanical properties. In this study, silicone rubber (SiR) DE composites for DEG with high energy density (w), high power conversion efficiency (PCE) and high fatigue life (N_FL) were designed and prepared by simultaneously introducing low content of liquid acrylonitrile-butadiene rubber (LNBR) and titanium dioxide (TiO₂) into SiR. The hydrogen bonding interaction between LNBR and TiO₂ results in the self-assembly of LNBR on TiO₂ particles (LNBR@TiO₂). The as-prepared TiO₂/LNBR/SiR DE composites with a self-assembled structure show the following advantages: maintaining high electrical insulation and breakdown strength (E_b) and high elasticity, significantly increasing the dielectric constant (ϵ_r) by both strong dipole polarizability of LNBR and interfacial polarizability of LNBR@TiO₂, and largely increasing the elongation at break and tensile toughness by the strong interfacial interaction and the “plasticizing effect” of LNBR. Using TiO₂/LNBR/SiR DE composites as the substrate of DEG, an up-to-date highest w (62.1 mJ cm⁻³) of DEG using an unprestretched DE film was obtained, and the fatigue life (N_FL) of our DEG (42 000 times) is much higher than that of the VHB DEG (approximately 500 times). The high w and long N_FL result in a high full-life energy density of approximately 1083 J cm⁻³, 361 times that of the VHB DEG. In addition, the PCE of our DEG (28.6%) is much higher than that of the VHB DEG (13.7%). The relationship between microstructure and energy harvesting performance was revealed.