Abstract: The safety problem of lithium-ion batteries (LIBs) has become an urgent bottleneck technical problem to be solved in the large-scale promotion and application of energy storage technology, and the identification of thermal runaway characteristics and the extraction of key parameters of LIBs are the basis for realizing the safety early warning of energy storage batteries. The thermal runaway process is usually accompanied by changes in battery temperature, voltage, current, deformation, gas composition and concentration. The existing gas sensors can not meet the early warning requirements of low cost, low power consumption, high selectivity and high stability of lithium-ion batteries. Aiming at the problems of high working temperature and poor selectivity of semiconductor metal oxides in gas sensing, Co₃O₄ and NiO nanosheets were in-situ doped on graphene aerogel by solvothermal method, and Co₃O₄-NiO/rGO nanoflower composites with multi-porosity, multi-fold and large specific surface area were obtained. The gas sensor made of Co₃O₄-NiO/rGO composites has high sensitivity to H₂ (86.8%@100 ppm) and short response time (T₉₀=69 s). The lithium-ion battery heating triggered thermal runaway experiment was carried out. During the thermal runaway experiment, the changes of key characteristic parameters of temperature, voltage, gas type and concentration of soft packet battery were monitored. The critical-time of thermal runaway and early warning time was obtained. By comparing the experimental results of the commercial hydrogen sensor and the Co₃O₄-NiO/rGO hydrogen sensor in the battery thermal runaway experiment, it is shown that the Co₃O₄-NiO/rGO hydrogen sensor can detect the leakage of small concentration of H₂ faster and with higher response, and it is expected to achieve more than 30 minutes of advance warning.