Novel nano-C@BaTiO3 fibers/polar trans-cyclohexane modified polyimide composite films with enhanced dielectric properties and energy storage density†

Polyimide (PI), a kind of polymer with excellent heat resistance, processing, mechanical and electrical insulation performance, stands out as a prime candidate for advanced dielectric energy storage materials. However, the low dielectric constant of PI has hindered its broader development, requiring dielectric modification. In order to increase the dielectric constant of PI, PI with a polar trans-cyclohexane structure was synthesized and characterized and then reinforced with nano-C@BT-fibers to produce a novel nanofiber reinforced PI film. Experimental results demonstrate that polar trans-cyclohexane enables pure PI films to achieve a dielectric constant of 8.89 at 100 Hz. Meanwhile, the dielectric constant of C@BT-fibers/modified PI composite films was indeed increased up to 39.48 at 100 Hz and the energy storage density increases to 1.028 J cm⁻³ with only 1.0 wt% addition content of C@BT-fibers, increased by 117.3% compared with that of pure PI (0.473 J cm⁻³).