Non-Uniform Circumferential Expansion of Cylindrical Li-Ion Cells—The Potato Effect

This paper presents the non-uniform change in cell thickness of cylindrical Lithium (Li)-ion cells due to State Charge (SoC). Using optical measurement methods, with aid a laser light band micrometer, expansion and contraction are determined over complete charge discharge cycle. The is rotated around its own axis by an angle ?=10° each step, so that different positions can be compared other circumference. experimental data show that, contrary assumption based on physical properties electrode growth lithium intercalation graphite, does not expand uniformly. Depending position orientation coil, there zones contraction. In order confirm circumference 3D, X-ray computed tomography (CT) scans performed at low high SoC. Comparison resolution 3D reconstructed volumes clearly visualizes sinusoidal pattern for expansion. From volume, it confirmed variation vary significantly height battery observed mechanisms. However, slight decrease volume towards poles higher stiffness monitored.