Lithium Plating and Stripping in the Framework of a 3D Electrochemical Model

Tuesday, October 13, 2015: 09:00
101-B (Phoenix Convention Center)
S. Hein (Helmholtz Institute Ulm (HIU), German Aerospace Center (DLR)) and A. Latz (German Aerospace Center (DLR), Helmholtz Institute Ulm (HIU))
The range of application of lithium-ion-batteries (LIB) is vast. It ranges from consumer electronics, like smartphones, to battery packs inside of electric vehicles. While cell size and geometry may differ, the electrodes are subject to the same degradation mechanisms. One of these processes is known as “lithium plating”. While charging a lithium-ion-battery with high currents or during operation at low ambient temperatures ( T < 0 °C), lithium ions can deposit on the surface of the negative electrode. The resulting metallic film can lead to increased solid electrolyte interphase growth, and may even create an electrical short-circuit, potentially causing a thermal runaway of the whole battery. Therefore it is desirable to hinder or, if possible, prevent the deposition of metallic lithium on the electrode surface.
To pursue this objective, a better understanding of which operating conditions, at which spatial locations inside the electrode microstructure and which material most parameters influence the deposition is vital. Since it is not convenient to measure the exact electrochemical situation at the electrode surface during operation, theoretical modeling and simulation is the tool of choice.
We present a model describing the initialization, growth and dissolution of a metallic lithium phase. This model is incorporated into the framework of a 3D microstructure resolved model [1, 2]. This is achieved by extending the mathematical description of the interfaces to consider the governing differential equations of surface species. These surface modifications allow for the simulation of the electrode surfaces, on which metallic lithium nucleates and grows. In the presented model, a complete coverage of the surface with a metallic lithium film results in the blockage of the direct intercalation pathway.
The influence of the geometry of the negative electrode and operating conditions on the cell performance and electrochemical conditions is investigated. The cell voltage plateau during discharge of a LIB, which contains plated lithium, [3, 4] can be attributed to chemical intercalation of metallic lithium into the supporting active material, as well to electrochemical dissolution.

[1] Battery and Electrochemical Simulation Tool, http://www.itwm.fraunhofer.de/best
[2] A. Latz and J. Zausch, J. Power Sources, 196 (2011), pp. 3296–3302.
[3] M. Petzl and M. A. Danzer, J. Power Sources, 254 (2014), pp. 80-87.
[4] B.V. Ratnakumar, M.C. Smart, J. Electrochem. Soc. Trans. 25 (2010), pp. 241-252.