Polyimide (PI) is widely used in the insulation of variable frequency motors due to its excellent thermal stability and insulation performance. However

its poor corona resistance under high-frequency voltage significantly affects the lifespan of equipment. In this study

a two-dimensional MXene material with high thermal conductivity and high electrical conductivity were selected

and MXene/PI composite films with 0%

1%

2%

and 5% doping mass percentages were prepared by in-situ polymerization. Surface functional groups

elemental distribution

and microscopic morphology of undoped and different doping ratio composite films were characterized

followed by measurements of trap distribution characteristics

surface conductivity

thermal conductivity

and corona resistance. The experimental results showed that

with the increase of MXene doping content

the corona resistance time of MXene/PI composite film gradually increased. The average corona resistance time of 5% MXene/PI composite film increased by 443.75% compared to PI

reaching 142 minutes. A comprehensive analysis was conducted on the electrical and thermal factors affecting the corona resistance of composite films. With the increase of MXene content

the density of deep traps significantly decreases

while the overall changes in deep trap energy levels and shallow trap distribution are relatively small. At the same time

the surface conductivity of the composite film gradually increases. Analysis suggests that MXene overlaps with each other within the thin film to form a conductive network

promoting the dissipation of surface charges and suppressing electric field distortion. For composite films containing MXene

their thermal conductivity and heat dissipation characteristics are significantly higher than those of PI

reducing the damage to the molecular structure of the film caused by long-term corona heat accumulation. For the corona discharge phenomenon of composite films

the dominant mechanism in a short period of time is the rapid destruction process formed by the impact of high-energy charged particles and the accumulation of surface charges. As the corona resistance time increases

the corona discharge gradually turns into an electric thermal synergistic destruction effect.