Pouch cell dilatometry
While the CompreDrive can measure the sample thickness, the most accurate way of measuring the thickness of a pouch cell in operando is to use the confocal sensor based Distance Add-on as seen to the left. As an auxiliary no-contact distance sensor, it is ideal for turning the CompreCell Pouch into a pouch cell dilatometer.
In the application note below, we showcase this functionality for a multilayer lithium-ion battery pouch cell. A detailed investigation of the electrochemical impedance spectra can be found here.
Performing three cycles each at succesively higher pressures, the pouch cell thickness (red curve) could be monitored on-line. The CompreDrive makes this kind of testing convenient since it can easily be automated.
The overall compression of the pouch cell under higher pressure over several hours and multiple cycles was evident, as well as the cell expension during charge, and contraction during discharge. Also the two-stage swelling due to graphite lithium intercalation on the anode could be clearly seen.
To cite this application note, please use: “Karlsson et al, rhd instruments GmbH & Co. KG, Application Note: In Operando Pouch Cell Thickness Monitoring during Cycling under Controlled Temperature and Pressure”, November 2022, https://docs.rhd-instruments.de/appnotes/application-note_CompreDrive_Pouch_Cell_Thickness.pdf”.