Dr. Xiaolin Li, Senior Scientist and Team Lead for Battery Development and Reliability Group, Pacific Northwest National Laboratory
As electrification becomes the megatrend of the world’s energy economy, better batteries are greatly needed to make electrical grid more reliable, to drive electric cars farther, and to power the next game-changing device more efficiently. My group at Pacific Northwest National Laboratory studies chemistries, materials, performance, and design of batteries to understand how to create batteries for something as large as the electric grid to as small as a garage opener. In this seminar, I will present several examples to show how we learn from fundamental understanding of the ion transfer and fading mechanism of Li/Na-ion batteries and use them for applied research to develop high performance batteries towards practical applications.
In one example, we investigated the correlation of Si porous structure with particle pulverization/swelling and electrochemical performance and leverage that in the design of porous Si-graphite composite anodes and hierarchical CNT @ Si microspheres that deliver high performance at nearly practical conditions. Porous Si materials with appropriate porosity, have limited particle volume expansion of ~30% at full lithiation and mitigated pulverization. The composite electrode of porous Si and graphite (~3 mAh/cm2 loading) with a specific capacity of ~650 mAh/g demonstrated ~82% capacity retention over 450 cycles. The full-cell of Li(Ni1/3Mn1/3Co1/3)O2 and the pre-lithiated anode showed ~84% capacity retention over 300 cycles. The hierarchical structured CNT @ Si @ C microspheres not only have good porous structure to accommodate the volume expansion and achieve ~40% apparent particle swell at full lithiation, but also demonstrate good mechanical integrity with the structure sustained up to ~200 MPa pressure. The anodes deliver 85% capacity retention over 200 cycles at the areal loading of ~3 mAh/cm2.
In another example, we inspired by the critical role of the electrode-electrolyte interphase in controlling the Li and Na-ion transfer and developed advanced electrolyte systems that can enable hard carbon of high initial Coulombic efficiency and good Na-ion intercalation kinetics and cathode material with high specific capacity of ~190 mAh/g and long cycling stability. The NaNi0.68Mn0.22Co0.1O2-hard carbon coin full cells with cathode loading > 2mAh/cm2 demonstrated 91% capacity retention after 200 cycles. Single layer pouch cell of >50 mAh capacity was fabricated. The capacity retention over 50 cycles is >95%.
Dr. Xiaolin Li is a senior scientist and currently team lead for Battery Development and Reliability group at Pacific Northwest National Laboratory. He received his Ph.D. in 2005 from the Department of Chemistry, Tsinghua University (Ph.D advisor, Prof. Yadong Li) and conducted his postdoctoral research in Prof. Hongjie Dai’s group at Stanford University. He has extensive experience with carbon nanotubes, graphene, and is an expert in designing nanostructured functional materials for various applications. His current research interest is on battery materials and renewable energy. Dr. Li has published many papers in top research journals including Science, Nature Nanotechnology, Nature Communications, Energy Environmental Science and the Journal of the American Chemical Society. His work has resulted in more than 28,000 citations over the years. In 2018, Dr. Xiaolin Li was selected as “the top 1% highly cited researchers”. He is organizer for Nature conference of Materials Electrochemistry: Fundamentals and Applications. He is a guest editor of Nano Research, Advanced Energy Materials, and an editorial advisory board member of ACS Energy Letters, and the journal Advanced Composites and Hybrid Materials.