Enhanced high-temperature energy storage density of polypropylene-based materials by micro-crosslinked structure design with N-type organic semiconductor

In this study, the authors proposed a promising structure design, the micro-crosslinked polypropylene (PP), to enhance the high-temperature energy storage density. With the grafting of 1,6,7,12-tetrachlorinated perylene-N-2-aminoethyl acrylate-N′-dodecylamine-3,4,9,10-tetracarboxylic bisimide (PTCDA) onto PP molecules, the obtained PP-g-PTCDA achieved a superior energy storage density of 2.34 J/cm³ at 120°C with the discharge efficiency above 90%, which was 585% higher than that of neat PP. The great enhancement, on the one hand, originated from the micro-crosslinked structure, since the restricted molecular motion can lead to the suppression of electrons' hopping across the molecular chains. On the other hand, deep traps were also introduced in PP-g-PTCDA, which restricted the electrons' hopping along the molecular chains simultaneously. This work provided an orientation to enhance the energy storage density at an elevated temperature of 120°C.