A novel dimethyl carbonate gas sensor for early warning of lithium battery thermal runaway

During the thermal runaway process of lithium-ion batteries (LIBs), signals such as pressure, gases, and temperature are generated. Traditional pressure and temperature monitoring methods have limited capability to capture localized early-stage signals. Insufficient response time can be provided for thermal runaway early warning. In contrast, gas monitoring provides clear advantages, with gas signals appearing far sooner than temperature and pressure signals at the initial phase of thermal runaway. This paper proposes a gas-sensing detection scheme for dimethyl carbonate (DMC) based on In₂O₃-ZnO composite materials. DMC is the primary component of LIBs electrolytes whose release precedes that of H₂ and CO, making it a more suitable early warning marker. ZnO and In₂O₃ nanosheets were first prepared separately via the hydrothermal method. These were then ground and calcined at high temperatures to form a composite material featuring an n-n heterojunction. Characterization confirms that the heterojunction in this composite material effectively enhances the surface adsorbed oxygen content and carrier density. Gas response testing indicates that the In₂O₃-ZnO sensor exhibits a lower operating temperature (160 °C), high response, rapid response, and excellent selectivity toward DMC. By integrating density functional theory (DFT) calculations with in situ Fourier transform infrared spectroscopy (FTIR) analysis, we reveal that the heterojunction enhances gas sensing performance by improving DMC adsorption capacity and charge transfer efficiency. This sensor not only responds rapidly (<15 s) in simulations of electrolyte leakage caused by puncture but also demonstrates excellent early-warning capabilities in thermal runaway experiments induced by overheating and overcharging, proving its broad applicability in complex electrochemical abuse scenarios.