Abstract: To address the issues of insufficient instantaneous cooling capacity and secondary temperature rise during the suppression of thermal runaway in lithium-ion batteries by perfluorohexanone (Novec 1230), this study designs composite agents comprising Novec 1230 and three fluorinated gases—R236fa, R227ea, and R116—based on the characteristics of thermal runaway propagation and intermolecular interaction theory. Suppression experiments were conducted on 18650-type lithium-ion batteries undergoing thermal runaway. The results indicate that all three composite agents outperform pure Novec 1230 in reducing peak temperatures and delaying thermal diffusion. Among them, the Novec 1230/R227ea combination exhibited the highest cooling rate (10.6 ℃/s), maintained stable temperatures in the later stages, and effectively avoided secondary temperature rise, demonstrating the best overall temperature control performance. Furthermore, density functional theory (DFT) calculations were performed using Gaussian 16 to investigate the intermolecular interactions and structural stability of the composite systems. The results show that the Novec 1230/R227ea system has the highest intermolecular interaction energy (-33.62 kJ/mol). Non-covalent interaction (NCI) analysis reveals pronounced van der Waals forces, indicating a stronger synergistic effect and greater structural stability, which provide a microscopic explanation for its superior fire suppression performance.

Key words: perfluorohexanone, lithium-ion battery, thermal runaway, intermolecular interaction energy, compound inhibitor