High energy density and high efficiency all-organic polymers with enhanced dipolar polarization†
Advanced polymers with high energy density and high efficiency are urgently needed in pulse power capacitor applications. Here, we present a practical design approach towards all-organic polymers with high energy density and high efficiency by enhancing dipolar polarization at the molecular level. Flexible segments were introduced into the backbones of rigid polar aromatic polymers to increase the flexibility of dipoles. Dielectric spectroscopy measurements of designed polymers revealed multiple strong sub-glass transition (sub-Tg) relaxation peaks with low activation energies, which indicated the enhanced movement freedom of dipoles below the glass transition temperature. As a result, dielectric constants were increased up to 46% when compared with their base polymers and D–E loop measurements showed that all these designed polymers had high energy densities above 11 J cm−3 with efficiencies above 90%. These results unveiled a novel approach towards high dielectric constant organic polymers for electrical energy storage.