Laser-based surface modification of high energy graphite anodes for lithium-ion batteries to improve the wettability and rate capability


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Many battery applications require both, a high energy and a high power density. Reflecting electric vehicles, that represents a high driving range with a fast charging option. To increase the energy density of lithium-ion batteries, it is common practice to reduce passive material of the battery by producing electrodes with high active material layer thickness and high compaction[1]. However, such thick and compact electrodes exhibit a poor rate capability and impede the wetting with liquid electrolyte[2,3]. 3D laser structuring such as trenching or perforation with a deep ablation of the active material layer is a promising approach to partially overcome the rate performance issues of high energy electrodes[4–6] as well as to improve the wettability[7]. However, ablation of the active material leads to a noticeable loss of capacity. Bolsinger et al. and Enderle et al. reported a “2D”-laser-based surface modification of NCM-based cathodes that enables selective ablation of the surface near binder-additive compound – which in turn reduces the Li-ion transport resistance and enhances the rate capability of the cathodes[8,9].

In this study, this “2D”-process is applied to graphite anodes. To do so, we did an extensive study on adjusting the laser parameters accordingly. As a result, we will show that it is possible to increase the anodes surface roughness without significantly ablating the active material. The surface-near microstructural changes, evaluated by microscopic analysis and white light interferometry are shown and correlated with the electrolyte wetting which can be improved significantly. Additionally, we will present a rate capability test comparing differently modified and pristine anodes indicating that the kinetics of the electrodes benefits at the same time.

[1] L. S. Kremer, A. Hoffmann, T. Danner, S. Hein, B. Prifling, D. Westhoff, C. Dreer, A. Latz, V. Schmidt, M. Wohlfahrt-Mehrens, Energy Technology 2020, 8, 1900167.
[2] Hilmi Buqa, Dietrich Goers, Michael Holzapfel, Michael E. Spahr, Petr Nova\’k, Journal of The Electrochemical Society 2005, 152, A474.
[3] S. G. Lee, D. H. Jeon, Journal of Power Sources 2014, 265, 363.
[4] J. B. Habedank, J. Kriegler, M. F. Zaeh, Journal of The Electrochemical Society 2019, 166, A3940.
[5] K.-H. Chen, M. J. Namkoong, V. Goel, C. Yang, S. Kazemiabnavi, S. M. Mortuza, E. Kazyak, J. Mazumder, K. Thornton, J. Sakamoto, others, Journal of Power Sources 2020, 471, 228475.
[6] W. Pfleging, Nanophotonics 2018, 7, 549.
[7] J. B. Habedank, F. J. Günter, N. Billot, R. Gilles, T. Neuwirth, G. Reinhart, M. F. Zaeh, The International Journal of Advanced Manufacturing Technology 2019, 102, 2769.
[8] S. Enderle, M. Bolsinger, S. Ruck, V. Knoblauch, H. Riegel, Journal of Laser Applications 2020, 32, 42008.
[9] M. Bolsinger, M. Weller, S. Ruck, P. Kaya, H. Riegel, V. Knoblauch, Electrochimica Acta 2020, 330, 135163.

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