Dual Role of Dopant CO 2 /O 2 in C 4 F 7 N Insulating Gas Based on Density Functional Theory Calculation

High Resolution Image Download MS PowerPoint Slide Perfluoroisobutyronitrile (C 4 F 7 N) has emerged as a sustainable alternative to SF 6 in gas-insulated equipment (GIE). However, its high boiling point of −4.7 °C and fast thermal decomposition rate under extreme conditions impede its large-scale practical application. These limitations can be mitigated by doping with CO 2 and a low concentration of O 2 . Herein, we establish different mixtures of C 4 F 7 N and CO 2 to identify the optimal mixing ratio. Electronic structure analyses reveal the dipole-induced multiinteractions with blending of CO 2 with C 4 F 7 N, optimizing liquefaction behavior with the best ratio of 1/9. Simultaneously, to understand the mechanism by which introducing a low concentration of O 2 inhibits decomposition-derived carbon deposition at high temperatures, we analyze the effects of the different O 2 concentrations in the decomposition, based on the mixture model of C 4 F 7 N-CO 2 with the ratio of 1/9. This work establishes the first atomic-level framework connecting the electronic interactions of C 4 F 7 N and dopants CO 2 /O 2 to macroscopic insulation performance, providing high efficiency for designing or modifying eco-friendly insulating gases with structural stability and dielectric properties.