Shallow trap mediated charge transport in polymer dielectrics for HVDC by incorporating 2D nanoclay

In this letter, we report a new space charge suppression solution for polymer dielectrics by a manner of incorporating 2D Talc nanoclay particles to enhance shallow trap mediated charge transport. This approach was verified in both semi-crystalline cross-liked polyethylene (XLPE) and amorphous cross-linked ethylene propylene rubber (EPR), with large performance improvement independent of the crystalline morphology of polymers. The introduction of 2D Talc nanoclay modifies the distribution of the traps in polymer with enlarged number of shallow states, effectively increasing the charge carrier mobility while significantly reducing the macroscopic activation energies for XLPE from 0.88 to 0.66 eV and for EPR from 0.97 to 0.54 eV, as indicated by the quasi steady-state conduction measurement. The shallow trap mediated charge transport was further investigated by the Thermally Stimulated Depolarization Current (TSDC) measurement, confirming the decrease in the activation energy from 0.99 to 0.54 eV for XLPE and from 1.02 to 0.52 eV for EPR. The resulting higher mobility of charge carriers in the nanocomposite samples with 2D Talc nanoclay contributes to a notable suppression of the hetero-polar space charge, and consequently, a huge reduction of the local electric field enhancement, from 60 to 15% for XLPE and 31.5–11% for EPR, when tested at 50 °C with the presence of a thermal gradient. This trap-mediated charge transport study unveils a new approach for HVDC cabling with high scalability for future renewable energies.