Batteries, Vol. seven, Pages 61: Non-Uniform Circular Expansion of Cylindrical Li-Ion Cells—The Potato Effect
Batteries doi: 10. 3390/batteries7030061
Authors: Jessica Hemmerling Jajnabalkya Guhathakurta Falk Dettinger Alexander Fill Kai Peter Birke
This paper presents the non-uniform change in cell thickness of cylindrical Li (symbol) (Li)-ion cells due to the change of Condition of Charge (SoC). Using optical measurement methods, along with the aid of the laser light band micrometer, the expansion and contraction are determined over the complete charge and release cycle. The cell will be rotated around its own axis by an position of α=10° in each step, so that the different positions can be compared with each various other over the circumference. The fresh data show that, in contrast to the assumption structured on the physical properties of electrode growth due to lithium intercalation in the particular graphite, the cell does not expand uniformly. Based on the position and orientation of the cellular coil, there are different zones of expansion plus contraction. In order to confirm the particular non-uniform expansion around the circumference of the cell in 3D, X-ray calculated tomography (CT) scans of the cells are performed on low and at large SoC. Comparison of the high resolution 3D reconstructed volumes clearly visualizes the sinusoidal pattern for non-uniform expansion. From the 3D volume, it can become confirmed which the thickness version does not vary considerably over the height from the battery cell due in order to the observed mechanisms. Nevertheless, a slight reduction in the volume change towards the poles of the electric battery cells because of the higher tightness can be monitored.