Seminar on Li-ion Battery Materials

In conjunction to Jackie Yik defence, on March 19th, a seminar will be held with Professor Corsin Battaglia, EMPA and Professor Dorthe Bomholdt Ravnsbæk, Aarhus University.

Understanding and controlling solid electrolyte interphase formation in lithium-ion batteries

by Professor Corsin Battaglia

To achieve lithium-ion batteries with high energy density, electrodes are typically operated outside the electrochemical stability window of the electrolyte requiring the formation of a passivating solid electrolyte interphase to guarantee long cycle life. Fluorine-induced transition metal dissolution from the positive electrode is particularly detrimental because the dissolved metal ions migrate through the electrolyte and deposit on the negative electrode, where they trigger additional solid electrolyte interphase growth increasing cell resistance and consuming electrochemically active lithium. In my presentation, I will present a new strategy to prevent transition metal dissolution without the need for sacrificial electrolyte additives. I will also demonstrate how operando transmission electron microscopy and automated experimental workflows provide new insights into solid electrolyte interphase formation. I will conclude with a comparison of solid electrolyte interphase growth in next-generation all-solid-state batteries based on argyrodite and hydroborate solid electrolytes.

Out of order – Unravelling structural disorder in battery electrodes

by Dorthe Ravnsbaek

Abstract: The functionality of electrode materials for rechargeable ion batteries is governed by their ability to store and transport electrons and ions, such as Li-ions in Li-ion batteries. The efficiency and reversibility of these processes depend on the electrode structure and the nature of the phase evolution during charge and discharge.
In the quest to understand the phase evolution in battery electrodes, the focus has mainly been on elucidating crystalline structures of the electrode materials, e.g. by diffraction methods. However, as evidenced in a growing number of studies,[1] ion-intercalation can induce structural disorder ranging from defect formation to complete amorphization. Furthermore, recent attention to the phenomena has revealed that the order-disorder transition can occur in both reversible and irreversible manners. Interestingly, this is not necessarily linked to the reversibility of the ion-storage process.
This talk will demonstrate how we combine operando synchrotron X-ray diffraction, total scattering, absorption spectroscopy and electrochemistry to elucidate the structural evolution in a series of battery electrode materials that undergo varying degrees of disordering during charge or discharge. The talk will demonstrate the approaches through new findings on a series of layered NaxMO2 (M = transition metal) Na-ion battery electrodes, revealing correlations between redox behavior and structural disorder (i.e. transition metal migration and stacking fault formation) and how these affect the phase evolution with prolonged cycling.

Short bio:

Corsin Battaglia is directing the laboratory Materials for Energy Conversion at Empa, the Swiss Federal Laboratories of Materials Science and Technology, and is Adjunct Professor of Electrical Engineering at ETH Zurich, Department of Information Technology and Electrical Engineering and Adjunct Professor of Materials Science at EPFL, School of Engineering, Institute of Materials.

After receiving his PhD in Physics from the Université de Neuchâtel in 2008, he was a postdoctoral researcher at EPFL until 2012 and at the University of California Berkeley and Lawrence Berkeley National Laboratories until 2014, before joining Empa. His current research focuses on sustainable next-generation lithium-ion and sodium-ion batteries, post-lithium-ion batteries, and the electrochemical conversion of CO2 to synthetic fuels.

Short bio:

Dorthe Bomholdt Ravnsbæk is a Professor of Materials Chemistry and the Director of the Center for Sustainable Energy Materials (CENSEMAT) at the Department of Chemistry, Aarhus University, Denmark.

She obtained her Ph.D. in Nanotechnology from Aarhus University in 2011 and subsequently held a postdoctoral position Massachusetts Institute of Technology (MIT, USA) until 2014. Before returning to Aarhus University as Professor in 2021, she was Assistant and later Associate Professor at the University of Southern Denmark.

Her research revolves around developing sustainable energy materials, and for more than 13 years, she has worked in the field of rechargeable batteries, particularly on developing and understanding electrode materials through advanced atomic and nano-scale characterization using operando and synchrotron-based methods for studying structural changes during electrochemical processes in real time.