A study on performance characterization considering six-degree-of-freedom vibration stress and aging stress for electric vehicle battery under driving conditions

The battery degradation tests under various stress are critical to understand the relationship between the battery lifespan and the external factors. This paper establishes a battery test bench, which can provide not only the 6-six degree of freedom (DOF) vibration stress but also the charge-discharge stress. By conducting lithium-ion batteries under 6-DOF vibration stress and other reference experiments, the electrochemical impedance spectroscopy (EIS), internal resistances, thermal measurement, open circuit voltage (OCV) recovery and capacity of the cells are compared to determine the impact of the 6-DOF vibration stress on the cells. The experimental results show that the vibration stress increases the ohmic resistance, and also causes a higher heat release. In addition, the cells under vibration stress exhibit a higher capacity fade and a lower OCV recovery rate, while the internal impedance is also changed with vibration stress. In order to quantize the effect of the vibration stress on battery degradation, the analysis of variance (ANOVA) is calculated. The conclusion is that the vibration stress has little impact on the cell polarization resistance, while it significantly affects the ohmic resistance, OCV recovery, thermal measurement, and capacity of cells, respectively.