The rapid development of new energy vehicles has drawn widespread attention to battery safety. Overcharging, as an important source of thermal runaway, may occur instantaneously without obvious signs, and any corresponding fire will be difficult to extinguish. This study is an investigation of overcharging thermal runaway and thermal runaway warnings for lithium-ion batteries. A stress-type early warning system is proposed, which has faster respo. The rapid development of new energy vehicles has drawn widespread attention to battery safety. Overcharging, as an important source of thermal runaway, may occur instantaneously without obvious signs, and any corresponding fire will be difficult to extinguish. This study is an investigation of overcharging thermal runaway and thermal runaway warnings for lithium-ion batteries. A stress-type early warning system is proposed, which has faster response time and more distinctive characteristics compared with other parameters. Through the association rule mining method, a multi-parameter coupled thermal runaway early warning strategy based on voltage, temperature, and pressure parameters was designed. A hierarchical early warning model including feature extraction, data processing and early warning evaluation modules was established. On this basis, a remaining time prediction module was added to achieve an alarm escape time of up to 474 s and shortest of 65 s, meeting safety standards. In the thermal runaway experiment at 705.2 °C, the early warning level system was triggered respectively. The maximum battery temperatures were 28.4 °C, 41.5°Cand 60.3 °C. The escape time errors were 16.56 s, 11.52 s, and 11.88 s respectively, all within 20 s for each level. Corresponding to different experimental results, the significant level classification simultaneously verifies the accuracy and effectiveness of the classification strategy.••••A multiparameter coupling thermal runaway early warning strategy••Quick response pressure••Hierarchical warning modelBattery safetyOvercharge-thermal runawayPressure-type warningMultiparameter warning strategyThe scarcity of nonrenewable resources, such as oil, has led to a rapid increase in the development of new energy vehicles. Lithium-ion batteries, with advantages including high energy density, high power density, and a long cycle life, are preferred by an increasing number of manufacturers [,,,,,,, ] and are widely used in commercial electric vehicles (EVs) [,,, ]. Vehicles that use new types of energy and lithium-ion batteries are thus rapidly developing; however, concerns about safety remain. The electrochemical reactions that occur during charging and discharging cause changes in the internal impedance and temperature, leading to a continual decline in performance. When the temperature exceeds the optimal working range of 15–35 °C. If the temperature continues to rise, a cascade of and side reactions, such as solid electrolyte interface (SEI), film decomposition, reactions between the negative electrode and electrolyte, and reactions between the positive electrode and electrolyte can occur, resulting in short-circuiting, the release of a large amount of heat, and significant risk of thermal runaway [,, ]. In recent years, several studies have been conducted on lithium-ion battery abuse [,,,, ], with electrical, thermal, and mechanical abuse considered the main causes of thermal runaway [,,,,,,,,, ]. Conventional fire extinguishing methods, such as carbon dioxide, dry powder, and water, are often used i. 2.1. Research subjectsCommercial soft pack lithium-cobalt acid lithium-ion batteries were used in this study. A list of the product specifications and parameters is provided in Table 1.Table 1. Battery characteristic parameters.2.2. Experiment equipmentCharging was performed using the CT-4008-5V100A tester manufactured by NEWARE, Shenzhen, China, with a current accuracy of 0.5 %, insulation layer provided by a high temperature glass fiber k thermocouple wire, and a temperature range of −73 °C to 700 °C. Voltage and temperature data were acquired and recorded using a HIOKI LR8450 manufactured in Shanghai, China. A FLUKE TI400 (USA), which allows temperature measurements ranging from −20 °C to 1200 °C with an error of <±2 °C, was used for thermal imaging during battery failure. The kcut MY2802 and DF9-40, which were independently developed by Huishang, Shenzhen, China, were adopted as the pressure sensor and collector, respectively. A schematic of the experimental setup is given in Fig. 1.2.3. Overcharge thermal runaway experiment using a lithium-ion battery.