This talk focuses on the interplay of mechanics with chemical reactions in that electrochemistry induces deformation, stresses, damage, and performance degradation of battery materials, likewise, mechanics regulates charge transfer, mass diffusion, interfacial reactions, and capacity and voltage. I will use the customized operando nanoindentation to demonstrate the continuous measurement of the mechanical properties and stability of electrodes during the exercise of charging and discharging. The mechanics experiment further informs the thermodynamics and kinetics of Li reactions which explains the debated fictious phase transition in amorphous Si. I will introduce the use of synchrotron analysis to examine the heterogeneous chemistry and heterogeneous mechanical damage in commercial composite electrodes. Computational modeling integrating mechanics failure and electrochemical metrics is developed in our group to model the battery cells and to quantify the relationship between mechanical damage and battery performance in terms of voltage, capacity, and cyclic efficiency.
Dr. Kejie Zhao is an Associate Professor of Mechanical Engineering at Purdue University. He received his Ph.D degree in Engineering Science in 2012 from Harvard, and his bachelor and master degrees from Xi’an Jiaotong University in 2005 and 2008, respectively. He worked as a postdoctoral associate at MIT in 2012-2014. His group focuses on the chemomechanics of redox active materials using experimentation and multi-scale modeling approaches. He is a recipient of the NSF CAREER Award, Extreme Mechanics Letters Young Investigator Award, 3M Non-tenured Faculty Award, Energy Storage Materials Young Scientist Award, and James W. Dally Young Investigator Award from the Society for Experimental Mechanics for his research and multiple teaching awards at Purdue University.