High-voltage power transmission in electrical grids requires reliable and durable dielectric polymers for wire insulation^1,2. Electrical treeing caused by high, local electric fields is a damaging process that leads to structure degradation and electrical conduction of dielectric materials, and ultimately, to catastrophic failure of the devices^3,4,5. Here, we demonstrate that the addition of less than 0.1 volume per cent of superparamagnetic nanoparticles into a thermoplastic polymer enables the repair of regions damaged by electrical treeing and the restoration of the insulating properties. Under the application of an oscillating magnetic field, the embedded nanoparticles migrate to the electrical trees and generate a higher local temperature, which heals the electrical tree channels in the polymer. Our method allows us to regenerate the dielectric strength and electrical resistivity over multiple cycles of tree formation and healing, which could be used to increase the lifespan and sustainability of power cables for electronics and energy applications.

电网中的高压输电需要可靠且耐用的介电聚合物来进行电线绝缘^1,2。高局部电场引起的电树现象是一个破坏性过程，导致结构退化和介电材料的电导通，最终导致设备^3,4,5发生灾难性故障。在这里，我们证明，将小于0.1％（体积）的超顺磁性纳米粒子添加到热塑性聚合物中，可以修复因电树损坏的区域并恢复绝缘性能。在振荡磁场的作用下，嵌入的纳米粒子迁移到电树并产生较高的局部温度，从而修复了聚合物中的电树通道。我们的方法使我们能够在树的形成和愈合的多个循环中再生介电强度和电阻率，这可用于延长电子和能源应用中电缆的使用寿命和可持续性。