Welcome!
Welcome to Wenxiang’s website! I am a postdoctoral research associate working with Prof. Qian Chen in Materials Science and Engineering at the University of Illinois Urbana-Champaign (UIUC). I work at the intersection of electron microscopy and redox-active materials. Before joining UIUC, I obtained my Ph.D. degree in Electrical and Systems Engineering at the University of Pennsylvania. I worked on optical metamaterials based on colloidal nanocrystals, advised by Prof. Cherie Kagan.
Research:
Redox-active materials are crucial for achieving carbon-neutral energy cycles. Understanding phase transformations in redox-active materials, such as inorganic insertion compounds and organic electrode materials, is key to the design and optimization of technologies such as batteries, electrocatalysis, separation, desalination, and electrochromics. Electrochemical phase transformation in redox-active materials is accompanied by compositional and structural changes, including microstructural development. Previous studies on electrochemical phase transformation have largely focused on nanoscale electrochemical inhomogeneity in composition associated with diffusion- or reaction-limited mechanisms. In comparison, crystallographic changes such as transformation-induced microstructure, oriented phase domains, and local defects remain challenging to image and comprehend, despite their significant role in regulating the materials’ electrochemical properties and performance.
As a postdoc at UIUC, I have developed an imaging platform based on data mining and correlative 4D-STEM and EELS to provide crystallographic information and chemical composition information. I have applied this approach to study phase transformations in battery cathode materials at the nanometer resolution. A major breakthrough is reported in my first-authored Nature Materials paper, which elucidates, for the first time, the existence and evolution of nanosized “oriented phase domains” in cathodes during electrochemical ion insertion. The nanodomains redistribute strain and impact ion diffusivity by more than ten times. For this work and my other three first-authored publications during my postdoc, including one to demonstrate the “nanosizing” effect in cathodes (Nano Lett. 2019), I was selected as an invited speaker for the “North American Materials Colloquium Series”.
My experience is also broad. During my Ph.D. study in Electrical and Systems Engineering at the University of Pennsylvania, I was the first to design and construct plasmonic metasurfaces based on colloidal nanoparticles, and I made a range of devices including broad-bandwidth optical waveplates and reconfigurable plasmonic lattice arrays. My research resulted in four first-authored papers in journals including Nano Letters, ACS Nano, and ACS Applied Nano Materials and I won the prestigious S. J. Stein Prize at the University of Pennsylvania for outstanding Ph.D. thesis.
Based on my background in electron microscopy, redox-active materials, and optical metamaterials, I am interested in studying phase transformations and microstructural developments in redox-active materials at the atomic to the nanoscopic length scales. Questions of interest could range from the structure, phase, composition, morphology, and function change of the materials to the strain, defects, symmetry, and bonding in the lattice structure at the atomic level. The applications vary from energy storage devices to plasmonics. I have a unique combination of knowledge and expertise to address the challenges. My approaches are based on correlative imaging, represented by 4D-STEM, EELS, and data mining methods, as well as material synthesis, structural engineering, surface treatment, and electrolyte engineering.
Keywords:
Electron microscopy, 4D-STEM, analytical STEM, correlative imaging, data mining, phase transformation, microstructure, energy storage, ion insertion, chemomechanical coupling, electrochromics, metasurfaces, plasmonics
Contact:
Wenxiang Chen
Address: 104 South Goodwin Avenue, Urbana, IL 61801
Email: wxchen at illinois dot edu