Early warning of lithium-ion batteries thermal runaway using dimethyl carbonate gas sensor based on Co3O4-ZnO heterojunction

Early warning of thermal runaway in lithium-ion batteries (LIBs) is a critical challenge for ensuring operational safety. Conventional monitoring approaches based on temperature and voltage are often limited by delayed response and susceptibility to environmental interference. In contrast, gas monitoring presents a promising alternative. Key electrolyte components such as dimethyl carbonate (DMC) are released during the early stages of thermal runaway, preceding gases like hydrogen and carbon monoxide, offering a unique opportunity for early warning. However, current DMC gas sensors are often hampered by the high operating temperatures and the sluggish response/recovery dynamics. In this work, we developed a gas sensor based on a Co 3 O 4 -ZnO p-n heterojunction. Under the operating temperature of 160 °C, the sensor exhibits a high response value of ∼110 to 500 ppm DMC, along with rapid response and recovery times (2 s and 15 s, respectively), as well as excellent selectivity against interfering gases such as H 2 , CO, and so on. The sensor also demonstrates stable performance over 32 d. Material characterization and theoretical calculations reveal that the p-n heterojunction effectively enhances carrier density and oxygen vacancy concentration, thereby facilitating DMC adsorption and electron transfer. Through simulated battery electrolyte leakage experiments, the sensor's capability for real-time and rapid detection of DMC is validated, highlighting its potential as an effective solution for early warning of thermal runaway in LIBs.