Feifei Fan’s research through the Department of Mechanical Engineering is set against the backdrop of the growing and critical importance of rechargeable batteries. Her CAREER proposal, supported by a $500,000 grant, focuses on the complex electrochemical cycling of batteries and, through study of the mechanics and other physical and chemical processes in electrodes, seeks to improve energy density, power density and capacity retention.
Recently, Fan was kind enough to answer a few questions about her research and its implications for society. An alumna of the University, she also shared how she hopes the CAREER award will help support the development of a diverse and thriving scientific workforce on campus and in our community.
What is the goal of the CAREER project?
The overarching goal of this CAREER project is to develop an integrated and sustainable research and education program on the electro-chemo-mechanics of high-capacity electrodes and their interfaces in lithium (Li)-ion rechargeable batteries. To develop high-energy-density Li-ion batteries requires a thorough understanding of electro-chemo-mechanics (i.e., the mechanics and its coupling with other physical and chemical processes during electrochemical cycling) in electrodes and their interfaces. The overall research objective is to fundamentally understand the electro-chemo-mechanics of electrodes and interfaces for mitigating degradation and improving the kinetics of diffusion and reaction. The central hypothesis is that multiphysics modeling and simulations via coupling reaction, diffusion, phase transformation, and mechanics on relevant scales can provide mechanisms for the degradation and failures of high-capacity electrodes and their interfaces. The proposed research will complete three specific objectives: 1) to identify and characterize the role of heterogeneities in stress-mediated (de)lithiation kinetics with the effect of charge by combining atomistic reaction pathway modeling and molecular dynamics simulations with a reactive force field, 2) to identify how defects and mechanical stress affect (de)lithiation kinetics and pore formation/annihilation by accounting for deformation kinematics in amorphous and open material systems and by coupling phase field and finite strain elastoplastic analysis, and 3) to evaluate the coupling between chemo-mechanics in electrodes and electrochemical performance at the cell level via proposing a Butler-Volmer type approach that integrates reaction kinetics, ion transport, and the influence of mechanics.
What impact will the project have on science and engineering?
The research will advance an understanding of degradation and failure mechanisms in high-capacity alloy-type Li-ion anodes and associated interfaces during electrochemical cycling. The research will answer many fundamental questions such as: What are the cooperative and competitive interactions among material heterogeneities, kinetics of (de)lithiation, and mechanical stress? How does mechanical stress influence pore formation/annihilation in open and amorphous systems during electrochemical (de)lithiation? How does electrochemical reaction kinetics at electrode-electrolyte interfaces interact with the chemo-mechanics of electrodes? Under what electrochemical conditions can mechanical constraints suppress pore formation or fracture in electrodes? The pursuit of the underlying mechanisms, by proposing the mechanistic-based multiscale and multiphysics modeling studies, will bridge missing links between nanoscale chemo-mechanical phenomena in individual electrodes to electrochemical performance at the battery cell level.
What impact will the project have on society?
Li-ion batteries are efficient energy storage devices that have transformed personal electronics and enabled the market introduction of electric vehicles. However, the ever-growing energy storage industry imposes dramatically increased demands that current Li-ion batteries are unable to meet. The proposed work will link chemo-mechanical concerns raised by the mechanics community to cell-level electrochemical performance focused by the electrochemistry community. The proposed modeling studies will lay the groundwork for a knowledge of electro-chemo-mechanics of high-capacity electrodes in Li-ion batteries and beyond (e.g., solid-state Li metal batteries and Li-air batteries). The gained knowledge will lead to the discovery of electrochemically induced mechanical failure mechanisms in electrodes and ultimately guide the electrode design.
A key element of your project is its educational component. Can you describe how the research you’re doing will relate to the educational outcomes of Nevada students starting in K-12?
The overall education objective of this project is to improve the engagement of young generation and diversity groups in mechanics of materials for developing future scientific workforce. The education and outreach activities consist of four parallel and interrelated components: 1) curriculum development for a minor program, Batteries and Energy Storage Technologies, and a new computational mechanics course using ANSYS Workbench, 2) design of Senior Capstone projects to appreciate the mechanical benefits of porous structures, 3) interactions with K-12 by introducing role of heterogeneities in buckling of soda cans, and 4) recruiting and promoting females and minorities in undergraduate research via WiSE events.
Anything else you'd like us to know?
I am a UNR alumna. I really appreciate the opportunities, freedom and encouragement that UNR provided me when I was a student and now that I am a faculty member. These allow me to explore what I am truly interested in.
