软包锂离子电池热失控多维特征参数演变研究

Study on Multi-Dimensional Characteristic Parameters Evolution of the Pouch-Type Lithium-Ion Battery Thermal Runaway

摘要: 锂离子电池的安全性问题严重阻碍了新能源汽车的普及和发展，本文以软包三元锂电池为研究对象，通过高温加热热失控实验，分析研究了高温热失控期间软包电池温度、电压、电阻、产气膨胀四个多维参数的演变规律和耦合机制。结果表明：1) T1是电池早期温度最高的测点，可以作为热失控早期的温度监测点，而热失控时温度最高的T3测点能更好地反映整个热失控期间的电池温度变化。2) 电压随着温度升高缓慢降低，在190℃时突降0.27 V，随后骤降为0；而电阻随着温度的升高呈小幅度减小后增大再迅速减小的变化趋势。3) 电池中心是出现膨胀最早且膨胀量最大的位置，膨胀量能表征电池的产气、破裂排气、热失控喷射等现象，膨胀信号的首次出现和下跌比温度骤增分别早了约3500 s和1700 s。膨胀是比电压和温度更快、更准确的热失控早期预警信号。

Abstract: The safety of lithium-ion batteries has seriously hindered the popularity and development of new energy vehicles. This paper takes the pouch-type ternary lithium battery as the research object, and through the high-temperature heating thermal runaway experiment, analyses and researches the evolution law and coupled mechanism of the four multi-dimensional parameters of battery temperature, voltage, resistance, and gas-producing expansion during the high-temperature thermal runaway. The results indicate: 1) T1 is the highest temperature measurement point in the early stage of heating battery and can be taken as the temperature monitoring point in the early stage of thermal runaway. While temperature measurement point T3 with the highest temperature in thermal runaway can better reflect the battery temperature change during the whole thermal runaway process. 2) The voltage decreases slowly with rising temperature, drops suddenly by 0.27 V at 190˚C, and then plummets to 0. While the resistance shows a trend of slight decrease and then increase and then decrease with the temperature rises. 3) The battery center is the earliest and largest expansion position, and the expansion can characterize the gas production, rupture and venting, and injection phenomena of TR; the first occurrence and the decline of the expansion signal are earlier than the sudden rise in temperature by about 3500 s and 1700 s, respectively. Expansion is a faster and more accurate early warning signal of thermal runaway than voltage and temperature.