Bio-Based Poly(hydroxy urethane)s for Efficient Organic High-Power Energy Storage.

Fast, low-cost, and efficient energy storage technologies are urgently needed to balance the intermittence of sustainable energy sources. High-power capacitors using organic polymers offer a green and scalable answer. They require dielectrics with high permittivity ( ε r ) and breakdown strength ( E B ), which bio-based poly(hydroxy urethane)s (PHUs) can provide. PHUs combine high concentrations of hydroxyl and carbamate groups, thus enhancing their ε r , and a highly tunable glass transition ( T g ), which dictates the regions of low dielectric losses. By reacting erythritol dicarbonate with bio-based diamines, fully bio-based PHUs were synthesized with T g ∼ 50 °C, ε r > 8, E B > 400 MV·m -1 , and low losses (tan δ < 0.03). This results in energy storage performance comparable with the flagship petrochemical materials (discharge energy density, U e > 6 J·cm -3 ) combined with a remarkably high discharge efficiency, with η = 85% at E B and up to 91% at 0.5 E B . These bio-based PHUs thus represent a highly promising route to green and sustainable energy storage.