摘要：

開展鋰離子電池熱失控研究，可為提升電池熱安全、減少新能源汽車熱災害等提供重要幫助。針對高比能21700型NCM811鋰離子電池熱濫用、老化等因素引起的熱失控問題，通過實驗研究了電池健康狀態(tài)（state of health，SOH）對電池充放電特性及自身熱失控行為的作用機制，量化分析了電池老化特性與熱失控觸發(fā)時間、表面溫度、工作電壓、燃爆特性、能量、TNT當量及破壞半徑等特征參數(shù)。發(fā)現(xiàn)能量效率隨著老化循環(huán)次數(shù)的增加而降低，電池熱失控的溫升幅度隨SOH的減小而下降，同時其自產熱起始溫度、熱失控觸發(fā)溫度與安全閥脫落溫度均減小，這表明老化電池熱失控觸發(fā)所需的時間更短，60%SOH電池在608 s觸發(fā)熱失控，相比于100% SOH縮短了64.8%。SOH越小，電池熱失控劇烈程度越弱，熱失控后的質量損失也越小。電池熱失控過程的峰值溫度、釋放的能量、TNT當量與破壞半徑隨SOH的減小而降低，表明老化電池較新鮮電池熱失控破壞性降低。研究結果可為全生命周期21700電池熱失控的行為特征分析、預警與火災防控等提供參考。

關鍵詞: 21700三元鋰電池, 健康狀態(tài), 熱失控, 溫度, 能量, 破壞半徑

Abstract:

Research on the thermal runaway of lithium-ion batteries is crucial for enhancing battery thermal safety and reducing thermal incidents in new energy vehicles. This study focuses on thermal abuse and aging-induced thermal runaway issues in high-specific-energy 21700-type NCM811 lithium-ion batteries. Experimental research was conducted to explore the state of health (SOH) impacts on battery charging and discharging characteristics, and the mechanism underlying thermal runaway. The quantitative analysis covered battery aging characteristics and thermal runaway parameters, including triggering time, surface temperature, operating voltage, combustion characteristics, energy, TNT equivalent, and damage radius. The findings reveal that energy efficiency decreases with increasing aging cycles, and temperature rise during thermal runaway decreases with decreasing SOH. Notably, time required for thermal runaway triggering in aged batteries is substantially shorter. For example, a battery with 60% SOH triggered thermal runaway in 608 s, a 64.8% reduction compared to 100% SOH. Moreover, smaller SOH values correspond to weaker thermal runaway intensity and reduced mass loss after thermal runaway. During the thermal runaway process, peak temperature, released energy, TNT equivalent, and damage radius decrease with decreasing SOH. This indicates that thermal runaway damage in aged batteries is lower than in fresh batteries. The study results offer valuable insights for characterizing behavior, early warning systems, fire prevention, and control in the thermal runaway of full-lifecycle 21700 batteries.

Key words: 21700 ternary lithium battery, SOH, thermal runaway, temperature, energy, failure radius

中圖分類號: 

X 932

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