Improvement in Insulation and Corona Resistance of PI by Incorporating SiO 2 and AlN

ABSTRACT The rapid advancement of new energy vehicles has exposed critical limitations in conventional enamelled wire insulation materials for drive motors, particularly in meeting escalating operational demands. Polyimide is widely adopted in the motor insulation systems, and its inherent corona resistance remains insufficient under extreme conditions. Herein, we propose a strategy to improve the corona resistance of PI films or PI polymer based on the integration of silicon dioxide (SiO 2 ) and aluminium nitride (AlN) nanoparticles. The results indicate that the excellent insulation of SiO 2 and the high thermal conductivity of AlN can lead to a strong effect in improving the corona resistance life of PI. The resultant polymer film (MPI/ASA3) exhibits an excellent corona resistance life of 184.7 min which is 23.38 times higher than that of the MPI/1.0 vol% AOC film. Meanwhile, it still maintains excellent thermal and mechanical properties. Hopefully, our work could promote the advancement of the drive motor for new energy vehicle technology.