July 25, 2025; MSE Conference Room

Cook Hall - Room #2058; 9:30 - 11:30 AM (CT)

Coffee will be provided!

Registration is not required for this event.

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Seminar Speakers

Prof. Jinsong Wu

"Entropy-increased LiMn2O4 cathodes for fast-charging lithium-ion batteries"

Abstract:

Extremely fast-charging lithium-ion batteries are desired to reduce the charging time (<15 min) for electronics and electric vehicles. The low-cost and environmentally-friendly LiMn2O4 is one of the cathodes with the best ionic diffusivity due to the three-dimensional Li-ion diffusion channels. However, LiMn2O4 usually exhibits low rate-capacity and rapid structural degradation at high charging rates. Here, by introducing multiple additional cations to increase entropy of LiMn2O4, we have significantly improved its rate performance and stability. As a result, the entropy-increased LiMn2O4 can now operate at 10C over 1000 cycles, reducing the charging time to just 6 minutes.

Biography

Jinsong Wu, professor of the State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, is the executive director of Nanostructures Research Center at Wuhan University of Technology. He had worked at world-renowned electron microscopy centers in France, Germany, and the United States, in electron microscopy research for over 20 years. He is currently a council member of the Chinese Society of Electron Microscopy. He has primarily focused on advancing in-situ high-resolution electron microscopy, applying it to study the lithiation mechanisms of battery electrode materials and the resistive switching mechanisms of semiconductor memristors. He has published more than 300 scientific papers.

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Dr. See Wee Chee

"Combining Microscopes: Correlative Operando Spectro-Microscopy as a Bridge between Microscopy and Spectroscopy of Working Electrocatalysts"

Abstract:

Electrocatalysts exist within a complex reaction environment and experience (electro)chemical driving forces that can change their structure and composition from their as-synthesized state and during sustained operation. It is, therefore, crucial that we understand how the working state of the catalyst evolves under operating conditions if we are to relate catalyst morphologies with their associated catalytic performance. The need to provide insights under working conditions and inform the design of catalysts for various green energy applications has driven the widespread development and adoption of operando techniques, but there is still a crucial gap in our current methods because they largely fall under two categories, broad beam spectroscopy techniques sensitive to the ensemble chemical signatures of the catalytic system or microscopic techniques capable of high spatial resolution imaging but provide limited information about the catalyst's chemical state. In this presentation, I will first discuss my group's work using electrochemical liquid cell transmission electron microscopy (EC-TEM) to follow the restructuring of electrocatalysts in a spatially and temporally resolved manner. Then, I will discuss our work using these cells employed for EC-TEM studies inside transmission X-ray microscopes to obtain spectro-microscopic data that reveal the local chemical state of individual electrocatalyst particles under conditions identical to the EC-TEM studies. The ability to complement nanoscale microscopy and ensemble spectroscopy with the structure and chemical composition of electrocatalysts under reaction conditions allows us to connect different operando methods and provide new insight into the transient or minority catalyst motifs that exist during reaction.

Biography

See Wee Chee is the group leader for liquid phase electron microscopy in the Department of Interface Science at the Fritz Haber Institute (FHI) of the Max Planck Society. He graduated with a B.Appl.Sc. from the Materials Science department in the National University of Singapore and then, with a PhD in Materials Science and Engineering from the University of Illinois at Urbana-Champaign. His research group in Berlin, Germany focuses on studying the transformations that take place in electrocatalysts under applied potential and in the electrolyte with liquid phase electron microscopy. Recently, they have also started to conduct operando microscopy experiments at the X-ray synchrotron beamlines.