Various multiscale examination methods for Li plating

The aim of InOPlaBat is the spatially and temporally resolved detection of lithium plating (accumulation of metallic lithium) in lithium-ion batteries. Lithium plating is a safety-critical phenomenon, especially in the fast charging processes of electric vehicles, caused by the anode by the limited capacity of lithium ions to be absorbed in the desired rate. To optimize battery lifetime and safety for all requirement profiles, it is central to detect the formation of metallic lithium and dendrites at an early stage. Reversible and irreversible plating can be accompanied by the formation of dendrites and lead to safety-critical short circuits. Irreversible plating additionally leads to a significant capacity loss due to the loss of cyclable lithium.

In order to capture the structure of electrode materials and their changes, in particular, the plating of lithium on the anode during charging, across scales from nanometer to centimeter dimensions, various optical, electron microscopic (FIB, SEM, and TEM), and X-ray (micro-CT, nano-CT) techniques in combination with spectroscopic techniques (NMR, EPR, EIS) will be used in the project. Based on results from post-mortem investigations, suitable in situ/operando experimental cells will be set up for the respective methods to investigate the charging/discharging processes directly in a battery cell under operating conditions. This should make it possible to analyze plating processes with high resolution in situ in the cell and thus correlate structural changes with spectroscopically detected dynamic processes.

To understand the processes taking place and their fundamental causes, the measurements will be closely linked to coupled atomistic simulations and macroscopic modeling. A bidirectional flow of information is central since a deeper physical understanding can only be achieved through successful multiscale simulation of the processes taking place. At the same time, experimental data provide the basis for the formulation, parameterization, and validation of the simulation systems. Modeling at the macroscopic level subsequently provides a transfer path towards commercial cells and ensures direct feasibility of the results in industrial applications.

The knowledge thus gained should provide both rapid and accurate feedback on the impact of process and material changes in cell production. In addition, the further development of electrical tests will enable better random testing of cells. This will improve the sustainability of cells developed and produced in this way by increasing cell life and reducing safety risks and thus potential containment measures in the battery pack.