A First-Principles Study of BTA-Regulated Charge Distribution and Interfacial Potential Barrier at the Oil-Paper Interface

Benzotriazole (BTA) is an effective insulating oil additive that shows great promise in suppressing oil flow electrification in oil-paper insulation systems and regulating charge distribution at the oil-paper interface. However, the microscopic mechanism by which BTA influences the electrical properties and potential barriers at the oil-paper interface remains unclear at the molecular level. To investigate this fundamental issue, this study employed first-principles computational methods to systematically elucidate the influence of BTA molecules on the interfacial potential and barrier between cellulose (paper) and mineral oil. By constructing oilpaper interface models with BTA molecules positioned at different locations, we first calculated the charge density differences and DDEC6 charge for each model, with results indicating that the introduction of BTA alters the direction of charge transfer at the interface. Subsequently, using PBE and PBE0 hybrid functionals, we calculated the interface potential barriers for different models. The study found that there is an increase in the electronic potential barrier by 0.5 eV when the added BTA molecule is located at the interface, and a decrease of 0.1 eV when the BTA molecule is in the oil bulk region. These findings elucidate the microscopic mechanism by which BTA regulates the interface potential barrier, providing a theoretical basis for the selection of insulating oil additives, which may also contribute to improving the electrical performance of oil-paper insulation systems.