Online monitoring of vented gases released by lithium-ion batteries (LIBs) during the early stages of thermal runaway is a potential method for ensuring the operational state of LIBs. Using the density functional theory method, the adsorption and sensing performances of transition-metal (TM) (Rh, Au, Pd, and Ag)-doped GeTe monolayers toward vented gases from LIBs were analyzed by calculating the adsorption energy, charge transfer, deformation charge density, density of states, work function, sensitivity, and recovery time. Results demonstrate that TM-doped GeTe monolayers have superior adsorption properties and sensitivity for CO 2 , CO, C 2 H 2 , and C 2 H 4 compared with pure GeTe. This study provides theoretical guidance for designing a new gas nanosensor to detect the vented gases emitted from LIBs during thermal runaway.