Regulating crystal face of SnO₂ films for selective detection of H₂ and DMC

With the widespread use of rechargeable lithium-ion batteries in portable electronic devices and electric vehicles, battery safety has become an increasingly important issue. During the thermal runaway (TR) of lithium-ion batteries, hydrogen (H₂) and dimethyl carbonate (DMC) are released as characteristic products. However, there is a lack of high-performance sensors capable of accurately and effectively detecting the concentrations of these two gases during TR. In this study, magnetron sputtering was used to fabricate SnO₂ film sensors with different exposed crystal faces, which exhibit high sensitivity and selectivity for DMC and H₂, respectively. The results show that SnO₂ with (110) exposed faces demonstrates a response of 808 % to 100 ppm H₂, with a much lower response of only 209 % to DMC. In contrast, SnO₂ with (101) exposed faces shows a response of 752 % to 100 ppm DMC, but only 216 % to H₂. By adjusting the ratio of exposed crystal faces, this study significantly enhanced the selectivity of SnO₂ sensors towards DMC and H₂. Experimental and simulation calculations further revealed that the gas selectivity differences induced by different exposed crystal faces are due to variations in surface atomic arrangements and the number of adsorption sites. In actual TR experiments of lithium-ion batteries, the sensors were able to accurately detect DMC and H₂ concentrations, providing an early warning of TR up to 434 s (>7 min) in advance.