Research on the fabrication process of DMC sensors based on RF magnetron sputtered SnO2 thin films

Lithium-ion battery thermal runaway poses significant safety risks, necessitating effective early monitoring via characteristic gas detection. This study focuses on developing highly selective and sensitive SnO₂-based gas sensors for detecting dimethyl carbonate (DMC), a key early warning gas during thermal runaway. Using radio frequency magnetron sputtering, single-layer SnO₂ and stacked SnO₂/TiO₂ sensors were fabricated and optimized for process parameters (sputtering power, time, vacuum, Ar/O₂ ratio, and annealing). Experimental results show that the optimal single-layer SnO₂ sensor (60 W power, 6 h sputtering, 1 Pa vacuum, 30:5 Ar/O₂ ratio, and 500°C annealing) exhibits a detection limit of 50 ppb for DMC, with rapid response (7 s) and superior selectivity against H₂ and CO interference. The stacked SnO₂/TiO₂ structure further enhances performance, achieving a resistance baseline stability of 30–40 Ω and a response to DMC 2–14 times higher than other gases. Characterization via SEM and XRD confirms the formation of porous, crystalline SnO₂ and heterojunction structures, explaining improved gas adsorption and electron transfer efficiency. This work demonstrates that magnetron sputtering enables precise control of sensor microstructure, offering a viable solution for early thermal runaway detection in lithium-ion batteries.