Hydrogen Sensor for LIB Thermal Runaway Based on Ag-Bi-Modified Co₃O₄ Nanosheets: Experimental and DFT Calculation

Hydrogen (H2) is a typical gas generated by the thermal runaway (TR) fault of lithium-ion batteries (LIBs) and a typical gas for TR fault diagnosis. Fast detection and high sensitivity of hydrogen sensors have practical significance. In this article, the hydrothermal method was used to prepare Co3O4 nanosheets, and Ag- and Bi-modified Co3O4 composite was also successfully prepared. X-ray diffraction (XRD), scanning electron microscopy (SEM), TEM, and X-ray photoelectron spectroscopy (XPS) were used to characterize and analyze the crystalline phase structure, micromorphology, and physical equality properties of the material. Then the gas sensing properties of AgBi/Co3O4 composite on H2 were investigated. The experimental results showed that the optimum operating temperature of the AgBi/Co3O4 sensor for H2 is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$160~^{\circ }$ </tex-math></inline-formula>C. At this temperature, the AgBi/Co3O4 sensor has the best hydrogen sensing performance, with a response value of 2.6–400 ppm H2 and a response recovery time of 19/13 s, in addition, it has good stability and selectivity. Through first-principles calculation, the sensing mechanism of AgBi/Co3O4 was further explored. The results showed that the enhancement of AgBi/Co3O4 hydrogen sensing performance was the result of the synergistic catalytic action of Ag and Bi bimetals.