Real-time monitoring of internal temperature evolution of the lithium-ion coin cell battery during the charge and discharge process

The internal temperature is the most effective parameter to determine whether the battery is entering the danger zone. However, it is also the most difficult to be monitored in real time. This paper focuses on the real-time monitor of internal temperature evolution of the lithium-ion coin cell battery during charge and discharge. First, the experimental set-up is introduced, which consists of four parts: the embedded sensor, incubator, data transmission and collection. This shows that the internal temperatures rise rapidly at the end of the discharge process while the difference between internal temperature and surface temperature is insignificant during the 0.5 C rate charge process. With the increasing C-rate, the heat generation rate increases correspondingly. Secondly, the influence of the embedded sensor on electrochemical performance is evaluated at different C-rates. It is found that the capacity difference is about 8.28% for the 0.1 C-rate charge process between the cases with and without the embedded sensor. With the increase of the charge rate, the capacity difference becomes larger and even approached 50% under 2 C-rate. Finally, a novel thermal model is developed to determine the heat transfer parameters for the coin cell based on the monitoring data. The heat flow during 1 C and 2 C discharge tests is calculated by the thermal model and temperature curves, which has the same tendency with the experimental results using the micro-calorimeter technique.