MechE Seminar Series: Neil Dasgupta

Speaker: Neil Dasgupta

Title: Enabling Fast and Low-Temperature Charging of Li-ion Batteries through Electrode Engineering

Abstract: Today’s Li-ion technology is highly optimized for performance at relatively slow charging operation. However, significant challenges still present for extreme fast charging conditions (< 15 minutes), which are further exacerbated at low temperatures ( 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. Therefore, new approaches are needed to overcome these energy/power tradeoffs in LIBs In this talk, I will introduce multiple strategies to enable fast charging LIBs, using industrially-relevant pouch cells with thick (>3 mAh/cm2) electrode loadings. In the first strategy, vertical channels are introduced into post-calendared electrodes using laser ablation patterning. This 3-D architecture 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 a complimentary approach, the surface of graphite is coated with a solid-state electrolyte material using Atomic Layer Deposition (ALD). 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 layer. As a result, 4C fast charging is enabled without Li plating, highlighting the critical role of the SEI on fast-charge performance. To demonstrate the potential to synergistically combine these approaches, I will discuss our recent efforts to enable fast charging of Li-ion batteries at sub-zero temperatures without Li plating. To achieve this challenging goal, we integrate the laser-patterning and ALD approaches described above. During fast charging a temperature of −10°C, these integrated electrodes enabled a >500% increase in accessible capacity, while maintaining safe operation. Finally, I will conclude with a perspective on manufacturing strategies to scale-up and translate these advances out of the laboratory and into a commercial production setting.

About the Speaker: Neil Dasgupta is a Professor in the Departments of Mechanical Engineering and Materials Science & Engineering at the University of Michigan. He is the Deputy Director of the U.S. Department of Energy, Energy Frontier Research Center (EFRC) MUSIC: Mechano-Chemical Understanding of Solid-Ion Conductors. He earned his Ph.D. from Stanford University in 2011. Prior to joining University of Michigan in 2014, he was a postdoctoral fellow at the University of California, Berkeley. He is a recipient of the Schmidt Science Polymath Award, NSF CAREER award, DARPA Young Faculty Award (YFA), and AFOSR Young Investigator Award (YIP). His research focuses on the intersection of materials chemistry, energy conversion, and manufacturing.