In situ chamber for studying battery failure using high-speed synchrotron radiography

Abstract

The investigation of lithium-ion battery failures is a major challenge for personnel and equipment due to the associated hazards (thermal reaction, toxic gases and explosions). To perform such experiments safely, a battery abuse-test chamber has been developed and installed at the microtomography beamline ID19 of the European Synchrotron Radiation Facility (ESRF). The chamber provides the capability to robustly perform in situ abuse tests through the heat-resistant and gas-tight design for flexible battery geometries and configurations, including single-cell and multi-cell assemblies. High-speed X-ray imaging can be complemented by supplementary equipment, including additional probes (voltage, pressure and temperature) and thermal imaging. Together with the test chamber, a synchronization graphical user interface was developed, which allows an initial interpretation by time-synchronous visualization of the acquired data. Enabled by this setup, new meaningful insights can be gained into the internal processes of a thermal runaway of current and future energy-storage devices such as lithium-ion cells.

Keywords: Li-ion batteries; X-ray imaging; abuse tests; in situ studies; propagation; safety; thermal runaway.

Figure 1

Sketch of the battery abuse-test chamber installed at the ESRF beamline ID19 including an overview of the setup at the beamline and a detailed description of the chamber.

Figure 2

Pictures of the battery testing chamber, showing in (a) the outside of the chamber, with the extraction tube and valve visible, as well as the polished X-ray aluminium windows, and the opening for the thermal camera. In (b) the inside of the chamber with the sample table and nail piston is visible. The cell holder which is placed on top of the sample table is depicted in (c) with the nail going through the guiding hole and the cells mounted inside the cell holder.

Figure 3

Image of the sample table including the sample holder. The dummy cells are shown in (a) a horizontal configuration and (b) a vertical configuration. The current setup includes variable positioning of the cell holder, height adjustment of the sample table and different configurable cell holders as well as two different positions for the nail devices: a flexible positioning of the initiation mechanism and high-speed X-ray radiography with cell configurations of up to four cylindrical cells.

Figure 4

Thermal image of nail-triggered TR of a Molicel P42A cell with another cell mounted below it (Exp.2). The images show the venting process of the first cell and the heat-induced TR of the second cell. The time-synchronous recording of the different data sets enables a comparison with the temperature data of the thermocouple and the pressure differential recorded by the pressure sensor, among other examples.

Figure 5

Example images from the high-speed X-ray recording. In Exp.1 (a) the cell was punctured directly with the nail, Exp.2 (b) and Exp.3 (c) show the cells directly under a punctured cell, which also entered a TR due to the temperature rise of the first TR. The setup of the images in (c) differs from that of (a) and (b) by a larger magnification factor (5×), resulting in a pixel size of approximately 4 µm. The images demonstrate the effects of a TR on the internal cell structure. To time the high-speed X-ray images in the abuse process, the images from Exp.1 and Exp.2 are plotted with the temperature data in (d). This facilitates the extraction of complex interrelationships across the entire process.