Design of voltage stabilizers for high breakdown strength materials

High breakdown strength material in the cable insulation layer is a key enabler for high voltage power transmission. In this work, we seek to design high-performance voltage stabilizers to be compounded into polyethylene to improve its breakdown strength. We hypothesize that electron affinity (EA) and HOMO-LUMO gap are two key factors that affect the performance of voltage stabilizers. To achieve larger EA and smaller HOMO-LUMO gap, we propose to use aromatic molecules decorated with electron acceptors and donors. A search of an internal chemical database narrows down to 529 molecules using structure, ClogP, and H-phrases (hazard statement) as criteria. The EA and HOMO-LUMO gap of these molecules are then calculated and experiments are carried out to measure the performance of 20 molecules. The performance improvement does not show a significant correlation with either EA or HOMO-LUMO gap. However, the best performers have an EA of 1.3–2.3 eV and HOMO-LUMO gap of 3.2–5.2 eV. The experimental study shows that adding side groups to voltage stabilizers will typically degrade their performance because side groups will generally increase the distance between the HOMO-LUMO orbitals and polyethylene backbone, and therefore decrease the electron/hole tunneling effectiveness.