Enhanced High-Temperature Capacitive Energy Storage in Polynorbornene Nanocomposites Enabled by Functional Side-Chain...

With the fast development of the electrical and electronic fields, there is an urgent need for polymer film capacitors with high energy storage density at extreme conditions‌. In this work, molecular engineering and nano-filler engineering are employed to address the contradictory relationship between the thermal stability and breakdown strength for polynorbornene dielectrics. The large-adamantine and rigid-biphenyl side-chains can endow the excellent heat resistance of ternary copolynorbornene film (A₈-T₁-B₁), reaching the glass transition temperature of 265°C. Further, the host hybrid nanofiller β-CD@TiO₂ (β-cyclodextrin, β-CD) can form deep traps and physical crossing points in the polynorbornene matrix via host-guest recognition, leading to sharply increasing the breakdown strength in the range of wide temperature. By introducing a small number of biphenyl and anhydride units, the arrangement distance between adamantine units is expanded, providing enough space for the host-guest complexation of hybrid β-CD@TiO₂ particles. As a results, 0.1% β-CD@TiO₂/A₈-T₁-B₁ composite film achieves the discharged energy densities of 5.0 and 4.3 J/cm³ at 150°C and 200°C, respectively, with corresponding efficiencies of above 90% and 80%. This work provides a completely new way to scalable high-temperature-resistant polymers dielectric with superior energy storage performance.