Materials for stretchable electronics

“Designing polymer materials for flexible and stretchable batteries”
David Mackanic, Ph.D. Candidate, Chemical Engineering, Stanford University

“Self-healable elastomers for skin electronics: from molecular structure to mechanical properties”
Yikai Yin, Ph.D. Candidate, Materials Science and Engineering, Stanford University

Date: Wednesday, July 29th, 2020 from 4:00 – 5:00 pm PDT

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“Designing polymer materials for flexible and stretchable batteries”

David Mackanic, Ph.D. Candidate, Chemical Engineering, Stanford University

Abstract:  The emergence of wearable electronics puts batteries closer to the human skin, exacerbating the need for batteries that are safe, conformal, and high-performance. Conventionally, flexible/stretchable batteries are created via strain-engineering approaches that are complicated and expensive. In this work, we demonstrate how functional polymer materials can be used to directly create highly deformable batteries via conventional fabrication processes. The design and synthesis of the polymeric supramolecular lithium ion conductor (SLIC) yields an unprecedented combination of mechanical properties and ionic conductivity; enabling stretchable electrolytes, binders, and current collectors.

Bio: David Mackanic is a Ph.D. Candidate in the Department of Chemical Engineering at Stanford University. Advised by Professor Zhenan Bao, his research focuses on the development of novel polymeric systems to improve the safety, longevity, and energy density of lithium-ion batteries. He is also interested in developing materials for stretchable and flexible batteries. David received the National Science Foundation Graduate Research Fellowship, the Stanford Graduate Fellowship, and the MRS Graduate Student Gold Award during his Ph.D. David is currently working to commercialize flexible battery technology as the founder of Anthro Energy. Prior to Stanford, David received his B.S. in Mechanical Engineering and B.A. in Chemistry from Virginia Polytechnic Institute and State University.

“Self-healable elastomers for skin electronics: from molecular structure to mechanical properties”

Yikai Yin, Ph.D. Candidate, Materials Science and Engineering, Stanford University

Abstract: Highly stretchable and self-healable supramolecular elastomers are potential requisites for skin electronics. Their desirable capabilities are due to dynamic cross-linking bonds that can be easily broken and re-formed. However, the underlying self-healing mechanisms of these elastomers as a result of their molecular structure remain elusive. Using coarse-grained molecular dynamics, we predicted the strain-induced damage of elastomers by bond-breaking and the self-healing of elastomers by bond-reforming. By performing network analysis on the microstructure of elastomers, we found that the damage and self-healing of elastomer are controlled by a key topological feature, i.e., the shortest paths between distant dynamic bonds. The straightness of shortest paths evolves with both strain and bond dynamics; it leads to a simple analytic model with an explicit microstructure-property relationship. This relationship serves as a basis for understanding the existing self-healable elastomers and a guide for the design of new ones. Abstract is attached.

Bio: Yikai Yin is a Ph.D. candidate in Materials Science and Engineering at Stanford University, and he recently completed a successful doctoral dissertation defense.  Yikai’s research focuses on elastomers for stretchable electronics, advised by Prof. Wei Cai.  Yikai received his M.S. in Materials Science and Engineering from Stanford University during which he investigated the fracture behavior of adhesively bonded composites under various environmental conditions in the research group of Prof. Reinhold Dauskardt.  Prior to Stanford, Yikai earned his M.S. in Mechanical Engineering from the University of Michigan and his B.E. in Mechanical Engineering from Xi’an Jiaotong University.