(Invited) Enabling Fast Charging of Lithium-Ion Batteries without Lithium Plating

Abstract

Today’s Li-ion technology is highly optimized for performance at relatively slow charging operation. However, significant challenges still present for fast charging conditions (> 4C). In state-of-the-art Li-ion batteries (LIBs) with high energy densities, the electrodes are relatively thick (> 100 μm), which leads to a tradeoff between energy density and high-power performance. In addition, the electrochemical potential of the anode can easily become more negative than Li/Li + during fast charging, resulting in Li plating [1]. Therefore, new approaches are needed to overcome these energy/power tradeoffs in LIBs In this talk, I will introduce three strategies to enable fast charging LIBs, using industrially-relevant pouch cells with thick (>3 mAh/cm 2 ) electrode loadings. In the first strategy, vertical channels are introduced into post-calendared electrodes using laser ablation patterning [2]. The resulting 3-D anode architecture consists of a hexagonal close-packed array of vertical channels that serve as linear pathways for rapid ionic diffusion through the electrode thickness. This allows for a more homogeneous flux of Li throughout the volume of the electrode. As a result, the accessible capacity of the electrode during fast charging increases, and Li plating is eliminated. In the second strategy, the energy/power tradeoffs in carbonaceous anode materials are overcome by forming hybrid blends of graphite and hard carbon [3]. This allows for a balance between the higher energy density of graphite with the faster rate performance of hard carbon. By controlling the graphite/hard carbon ratio, we identify an optimal blend for fast charging. In the third strategy, we demonstrate the potential to eliminate Li plating and enabling 4C fast charging purely through interfacial control. This is achieved by coating the surface of graphite with a solid-state electrolyte material using Atomic Layer Deposition (ALD) [4]. These coatings eliminate electrolyte decomposition during the formation cycle, resulting in an “artificial SEI” with a resistance that is 75% lower than the natural SEI that forms in carbonate electrolytes. This challenges the fundamental assumption that fast charging of thick graphite anodes must be solved by improving mass transport, highlighting the critical role of the SEI on fast-charge performance. [1] Y. Chen, K.-H. Chen, A. J. Sanchez, E. Kazyak, V. Goel, Y. Gorlin, J. Christensen, K. Thornton, N. P. Dasgupta, J. Mater Chem. A 9 , 23522 (2021). [2] K.-H. Chen, M. Namkoong, V. Goel, C. Yang, S. Kazemiabnavi, S. M. Mortuza, E. Kazyak, J. Mazumder, K. Thornton, J. Sakamoto, N. P. Dasgupta, J. Power Sources 471 , 228475 (2020). [3] K.-H. Chen, V. Goel, M. J. Namkoong, M. Wied, S. Müller, V. Wood, J. Sakamoto, K. Thornton, N. P. Dasgupta, Adv. Energy Mater. 11 , 2003336 (2020). [4] E. Kazyak, K.-H. Chen, Y. Chen, T. H. Cho, N. P. Dasgupta, Adv. Energy Mater, In Press (2021).