Ru-Based Dual-AtomActive Sites Supported on g-CNMonolayer for Early Detection of Lithium-Ion Battery Thermal RunawayGases: A Density Functional Theory Investigation

Abstract Accurate detection of thermal runaway gases (TRGs) released from lithium-ion batteries can effectively monitor battery operating states and mitigate the spread of accidents. In this article, the density functional theory method was used to investigate the sensing potential of six TRGs (C2H2, H2, C2H4, CO2, CH4, and CO) on the g-CN nanosheets modified with Ru–M (RuMN, M = B, C, Si). The results show that Ru–C, Ru–B, and Ru–Si codoping substantially reduces the bandgap of g-CN, thereby enhancing its electronic conductivity. Simultaneously, the introduction of Ru–M dual-atom pairs provides highly active sites that significantly improve the gas adsorption activity toward specific TRGs. In particular, RuCN and RuSiN exhibit strong chemisorption toward CO, C2H2, and C2H4, with adsorption energies all exceeding −1.31 eV. This strong adsorption effect is mainly attributed to pronounced hybridization between the Ru-4d orbitals and the C-2p orbitals of gas molecules. Moreover, RuCN shows a bandgap change rate exceeding 52% upon the adsorption of C2H4 and C2H2, while RuSiN shows bandgap change rates all exceeding 24% after adsorption of C2H4, CO, and C2H2. Furthermore, the work-function change rates of RuCN and RuSiN upon adsorption of C2H2 and C2H4 are all greater than 10%. At high temperatures, the recovery times of RuCN for C2H2 and C2H4 are 17.91 and 45.48 s, respectively, indicating fast response and good reusability for these two gases. This work lays down the essential scientific foundation for designing a high-performance g-CN-based gas sensor for TRGs detection.