Multi-axis vibration durability testing of lithium ion 18650 NCA cylindrical cells

This paper presents new research to determine if the electromechanical attributes of Nickel Cobalt Aluminium Oxide (NCA) 18650 battery cells are adversely affected by exposure to vibration commensurate with that experienced by electric vehicles (EVs) through road induced excitation. This investigation applied vibration to a set of commercially available cells in six degrees of freedom (6-DOF) using a multi-axis shaker table. This method of mechanical testing is known to be more representative of the vibration experienced by automotive components, as 6 motions of vibration (X, Y, Z, roll, pitch and yaw) are applied simultaneously. Within the context of this study, cell characterisation within the electrical domain is performed via quantification of the cell's impedance, the open-circuit potential and the cell's energy capacity. Conversely, the mechanical properties of the cell are inferred through measurement of the cell's natural frequency. Experimental results are presented that highlight that the electromechanical performances of the 18650 NCA cells do not, in the main, display statistically significant degradation when subject to vibration representative of a typical 10-year European vehicle life. However, a statistically significant increase in DC resistance of the cells was observed.