Monitoring real-world battery degradation is crucial for the widespread application of batteries in different scenarios. However, acquiring quantitative degradation information in operating commercial cells is challenging due to the complex, embedded, and/or qualitative nature of most existing sensing techniques. This process is essentially limited by the type of signals used for detection. Here, we report the use of effective battery thermal conductivity (k_eff) as a quantitative indicator of battery degradation by leveraging the strong dependence of k_eff on battery-structure changes. A measurement scheme based on attachable thermal-wave sensors is developed for non-embedded detection and quantitative assessment. A proof-of-concept study of battery degradation during fast charging demonstrates that the amount of lithium plating and electrolyte consumption associated with the side reactions on the graphite anode and deposited lithium can be quantitatively distinguished using our method. Therefore, this work opens the door to the quantitative evaluation of battery degradation using simple non-embedded thermal-wave sensors.

监测现实世界中的电池退化对于电池在不同场景中的广泛应用至关重要。然而，由于大多数现有传感技术的复杂性、嵌入式和/或定性性质，在商业电池运行中获取定量降解信息具有挑战性。该过程本质上受到用于检测的信号类型的限制。在这里，我们报告了利用有效电池热导率（ k _eff ）作为电池退化的定量指标，利用k _eff对电池结构变化的强烈依赖性。开发了一种基于可附加热波传感器的测量方案，用于非嵌入式检测和定量评估。快速充电过程中电池退化的概念验证研究表明，使用我们的方法可以定量地区分与石墨阳极和沉积锂上的副反应相关的锂电镀量和电解液消耗量。因此，这项工作为使用简单的非嵌入式热波传感器定量评估电池退化打开了大门。