Damage analysis of cylindrical lithium-ion cells under three-points bending using acoustic emission

Lithium-ion cells are vulnerable to various types of deformations due to the influence of external forces. Failure to detect the damage degree of lithium-ion cells affects the cell use and can be dangerous. In this paper, the failure process of cylindrical lithium-ion cells under three-points bending was studied using acoustic emission (AE). A real time in situ experimental platform was built based on voltage and AE monitoring. The AE signals of three 18650 lithium-ion cells were obtained, and the wavelet transformation was used to analyze the signals. The load-displacement curves and the AE signals in time domain of the lithium-ion cells were divided into four stages, which corresponded to different failure modes of the lithium-ion cells. The time-frequency analysis was performed, and the corresponding frequency and energy of the signals in different failure stages were obtained, which verified the time domain results. The results showed that the AE technique was an effective tool for failure monitoring of the lithium-ion cells, and the different failure modes were recognized by the AE signal characteristics.