Chemical Pre-lithiation Compensates for Capacity Loss in Lithium Ion Batteries

Experimental Considerations Provide Insights into the Use of Lithium Arene Complex Solutions on Silicon Anodes

Lithium ion batteries (LIB) are currently the state-of-the-art electrochemical energy storage systems. In order to further succeed, its specific energy and energy density must be further increased. A research group from Frontier Research Laboratory from LG Energy Solutions in Münster – a cooperation of MEET Battery Research Center, the Helmholtz Institute Münster of Forschungszentrum Jülich and Advanced Cell Research Center (LG Energy Solution) − has now systematically investigated the effect of chemical pre-lithiation of silicon anodes in LIBs. Silicon is currently considered a “next generation material” for the use as a negative electrode because it has a higher specific and volumetric capacity than conventional graphite. However, a still unsolved problem when using the semi-metal is the strong volume change of up to 280% during (de-)lithiation. This leads to fragmentation of the silicon particles and thus to continuous decomposition of the electrolyte and continuous (re)formation of the passivation layer, the so-called solid electrolyte interphase (SEI). The cycle life of the battery is thus considerably shortened due to continuous active lithium and capacity losses.

Chemical pre-lithiation via LAC as a fast, easy and most important scalable method to effectively enhance the electrochemical performance of Si-based LIBs.
© Advanced Energy & Sustainability Research

Chemical Prelithiation as a Practical Approach

In their study, the scientists examined the application of a lithium arene complex solution, which is used to compensate for the active loss of lithium during the manufacturing process of the Li cells. “This process, in which the silicon is immersed in the solution, is considered a promising approach to compensate for future capacity losses while controlling the degree of lithiation and enabling a homogeneous lithium distribution. In addition, it is technically comparatively easy to implement,” says MEET scientist Lars Frankenstein, explaining the series of investigations. “In our experiments, we focused on extreme conditions in order to be able to draw conclusions about chemical limitations and to gain insights into the interaction of the various parameters,” Frankenstein continued. The scientists were able to analyze that not only the pre-lithiation degree, but also the previously applied pre-lithiation conditions such as time and temperature affect the performance of the cell. However, the reactivity of the solution, particularly its chemical instability, as well as its ability to decompose solvents and binders, remains a challenge. The scientists were able to demonstrate suitable solvents and binders to effectively implement the pre-lithiation technique in laboratory scale. Thus, although chemical pre-lithiation remains theoretically promising and easy to implement in laboratory scale, it is still challenging in its practical application and up-scaling.

Pre-lithiation with varied capacity excess of LAC solution relative to active mass of anode.
© Advanced Energy & Sustainability Research

Complete Study Online Available

The detailed results of their study have been published by the authors Lars Frankenstein, Christoph Peschel, Dr Lukas Stolz, Dr Aurora Gomez-Martin, Dr Tobias Placke, Dr Johannes Kasnatscheew (MEET Battery Research Center) and Hyuck Hur (Advanced Cell Research Center, LG Energy Solution), Marvin Mohrhardt (Helmholtz Institute Münster) und Prof. Dr Martin Winter (MEET Battery Research Center and Helmholtz Institute Münster) in the journal "Advanced Energy & Sustainability Research".