S3E5
Episode 5 (February 7, 2021)
Diego Mateo
King Abdullah University of Science and Technology (KAUST)
Rong Xu
Stanford Univeristy
Regina Garcia-Mendez
Cornell University
Photo-thermal catalysis: Fundamentals and Applications
Abstract of Talk 1
Photo-thermal catalysis has recently emerged as an alternative route to drive chemical reactions using light as energy source. Through the synergistic combination of photo- and thermochemical contributions of sunlight, photo-thermal catalysis has the potential to enhance reaction rates and to change selectivity patterns, even at moderate operation conditions.
Biosketch of Speaker 1
Dr. Diego Mateo is a postdoctoral fellow in the Physical Science and Engineering Division at King Abdullah University of Science and Technology (KAUST). He received his bachelor's degree in Chemistry in 2009 and his bachelor's degree in Food Technology in 2011, both from the University of Valencia. After working for two years as a research technician at Complutense University of Madrid, in 2015 he started his PhD in the development of new graphene-based photocatalysts for the production of solar fuels in the group of Prof. Hermenegildo Garcia at the Institute of Chemical Technology (UPV-CSIC). After obtaining his PhD in 2019, he moved to the group of Prof. Jorge Gascon at King Abdullah University of Science and Technology (KAUST). His current research is focused on novel photo- and electro-catalytic routes for the production of fuels and chemicals. In 2020, he was given an Extraordinary Doctoral Award at Polytechnic University of Valencia. In the same year, the Foundation for the Development of New Hydrogen Technologies awarded him with the prize for the Best Doctoral Thesis.
Mechanical stability of LiNixMnyCozO2 (NMC) cathode
investigated by an integrated experimental-modeling approach
Abstract of Talk 2
LiNixMnyCozO2 (NMC) is the current choice of cathode for high-performance Li-ion batteries. The mechanical stability of NMC plays a vital role in determining the electrochemical performance of batteries. However, the dynamic mechanical response of NMC during Li reactions are widely unknown because of the microscopic heterogeneity of composite electrodes as well as the challenge of mechanical measurement for air-sensitive battery materials. We employ nanoindentation in an inert environment to measure the elastic modulus, hardness, and fracture strength of NMC of a hierarchical meatball structure as a function of the state of charge and cycle number. The mechanical properties significantly depend on the lithiation state and degrade as the electrochemical cycles proceed. We further perform finite element modeling to understand the damage accumulation in NMC cathode over cycles. The evolving interfacial strength at different states of charge and different cycle numbers measured by nanoindentation is implemented in the simulation.
Biosketch of Speaker 2
Dr. Rong Xu is a postdoctoral associate in the Department of Materials Science and Engineering at Stanford University. He obtained his B.S and M.S from Xi’an Jiaotong University in 2011 and 2014, respectively. He received his Ph.D in School of Mechanical Engineering in 2019 from Purdue University. During his PhD, he obtained several awards including Outstanding Research Award from the College of Engineering at Purdue University, Ward A. Lambert Graduate Teaching Fellowship and Drs. Helen and Marvin Adelberg Fellowship. His research focuses on the electrochemistry and mechanics of battery materials using integrated experimental and modeling approaches.
Correlating structural effects of ceramic solid electrolytes with cycling stability of Li metal for Solid-State batteries
Abstract of Talk 3
The need for advanced batteries than can deliver the energy required to power high-energy applications with improved safety has accelerated the development of lithium metal solid state batteries. Despite the substantial progress made in the discovery of a variety of solid-state electrolytes (SSEs), stable cycling of Li metal remains a challenge and not thoroughly understood.
In this seminar, I will discuss the interplay between microstructure-processing and electrochemical behavior of sulfide-based 75Li2S-25P2S5 mol% (LPS) SSE when paired with a Li metal electrode. More specifically, the effect of pressure and temperature on structural changes during densification, and their effect in electrochemical performance. It was demonstrated that the maximum charging rate of LPS can be increased by controlling the crystalline structure that precipitates from the mother glass. In addition, a dense microstructure with low porosity is desirable for higher rate capabilities, motivating the subsequent work I will be presenting in this seminar. To this effect, the role that pressure has on densification at the glass transition temperature was investigated. Correlations between macro and atomic structure with elastic properties and ionic transport allowed a five-fold increase in ionic conductivity and a two-fold increase in elastic constants compared to conventional room temperature molding conditions. The changes observed in elastic properties and ionic conduction were attributed to favorable coordination environments for Li ion transport and molecular rearrangements. Lastly, the DC electrochemical stability of the optimized microstructure was characterized achieving an increase in maximum charging rate compared to the conventional molding conditions, but highlighting the importance of external variables as practical challenges that sulfide-based and other SSEs must overcome to improve cycling of Li metal.
The findings in this work provide mechanistic insight into processing-structure-property relationships that can be used as a guide for future microstructure/property design, which can translate into extending the stable Li electrodeposition regimes for further battery development.
Biosketch of Speaker 3
Regina Garcia-Mendez is a postdoctoral fellow at Cornell University under the supervision of Professors Andrej Singer and Lynden Archer. Her research focus is divided in two thrusts: Materials and Interphase design for rechargeable Al-ion batteries and in-situ generated cathode electrode interfaces for high-voltage stabilization of ceramic electrolytes. Previously, she earned her Ph.D. in Materials Science and Engineering at the University of Michigan in 2020 under the supervision of Professor Jeff Sakamoto. Her graduate work focused on correlating structural and interfacial effects of ceramic solid electrolytes with cycling stability of Li metal in solid-state batteries. Prior to that, she received her B.S in Chemical Engineering, summa cum laude, from UVG, Guatemala, followed by a M.S. in Materials Science and Engineering at Michigan State University under a Fulbright fellowship. She is interested in ceramic materials chemistry and physics, solid-state electrochemistry and materials development for energy applications.
Guest Host: Eric Kazyak
Eric Kazyak is currently a Postdoctoral Fellow at the University of Michigan where he completed his Ph.D. in Mechanical Engineering in 2019, under the guidance of Prof. Neil Dasgupta. Eric has published more than 22 peer-reviewed journal articles in the areas of Lithium-ion and Li metal batteries, solid-state electrolytes, atomic layer deposition, operando video microscopy, and hierarchical nanostructure synthesis.