Internal short circuit diagnosis method based on discharge curve of lithium-ion battery

The internal short circuit (ISC) of lithium-ion battery is one of the common causes of thermal runaway. Therefore, it is necessary to find an effective method to diagnose ISC to avoid thermal runaway and improve battery safety. In this paper, it is found from the battery long-term cycling data set that some batteries are short-circuited during the cycle or after standing that the terminal voltage is 0. In this paper, the ISC diagnosis method is proposed by observing the cycle data of the ISC battery. It is found that due to the polarization of the battery, the area of the discharge curve of the battery at high current rates (1C) and low current rates (1/25C) is different. In this paper, the area of the discharge voltage curve of the battery at high rate and law rate is featured, and ISC diagnosis method is proposed. Specifically, it was found that the decay rate of the area of the discharge curve at law current rates was slower than that at high current rates during battery cycle. The decay rate of the area of ISC cells discharge curve at law current rates is faster than that at high current rates during battery cycle. ISC diagnosis method is proposed based on the results. In the process of battery cycling, if the fitting curve of the area of the discharge curve at high current rates and low current rates has a tendency of "crossing", it can be judged that the battery has occurred ISC.