Thermal Equilibrium Composition of C4F7N/CO2 Gas Mixtures During Arc-Interruption

C
4
F
7
N/CO
2
gas mixtures have been proposed as an eco-friendly insulator with a low global warming potential to replace SF6 in the power grid. However, recent studies revealed that these gas mixtures may decompose in complicated pathways, raising concerns about their scaling-up adoption. In this work, we performed computations aimed at probing the thermal equilibrium composition of C
4
F
7
N/CO
2
gas mixtures during arc-interruption based on density functional theory (DFT) and Gibbs free energy minimization. The computations demonstrated that C4F7N stays stable until 1000 K. Above 1000 K, C4F7N rapidly decomposes into CF3, CN, and F free radicals, and the C free radicals released from C4F7N recombine with the O free radicals released from CO
2
to generate CO. Above 10000 K, CO starts to decompose into C free radicals and O free radicals. Above 20000 K, all molecules and free radicals fully decompose into monatomic free radicals, including C, F, N, and O. The computations aid the future mitigation of C
4
F
7
N/CO
2
decomposition products and promote the adoption of C
4
F
7
N/CO
2
gas mixtures in an SF
6
-free green power network.