Ultra-rapid electrolyte leakage diagnosis for lithium-ion batteries based on ultrasonic guided waves

Electrolyte leakage is one of the most important factors contributing to battery safety. Traditional battery electrolyte leakage diagnosis methods are mainly based on the electrical characteristic model parameters and volatile gas conditions of the battery. These methods have the disadvantages of low reliability and time consumption. We introduce an ultra-rapid electrolyte leakage diagnosis method for lithium-ion batteries that is based on ultrasonic guided waves. The evolution of the ultrasonic transmission characteristics inside the battery is used to diagnose battery leakage. A finite element model of the acoustic characteristics of a battery is constructed on the basis of the ultrasonic propagation mechanism in multilayer and porous structures. The causes of ultrasonic changes due to battery electrolyte leakage are investigated from three aspects, namely, the change in the guided wave transmission medium, the influence of boundary defects, and the internal pressure of the battery. The ultrasonic guided waves before and after electrolyte leakage and during normal charge and discharge cycles were obtained experimentally, and a large increase in the signal intensity of the guided wave after electrolyte leakage was detected. Finally, a fault detection method is carried out via principal component analysis (PCA) and the 3 Sigma principle, and the results show that battery electrolyte leakage can be diagnosed within 5 s on the basis of ultrasonic guided wave signals and the fault detection method. The method provides a new solution path for battery system safety management.