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The University of Southampton

What is 'Battery Science'? (Interplay of Bulk and Surface)  Seminar

6 March 2015
Building 27, Room 2003 Chemistry University of Southampton Southampton SO17 1BJ

For more information regarding this seminar, please email Nuria Garcia-Araez at .

Event details

Prof Petr Novak presents a seminar as part of the Electrochemistry seminar series.


The next generation of high-end rechargeable batteries will still rely on lithium-ion host materials. Later, post-lithium-ion systems, such as Li/S and eventually Li/air, are claimed to enter the market. Independently of the technology, understanding the fundamental properties of battery materials and the interactions of these materials with their environment will be the key to further im¬provements in energy density, safety, and life time of batteries. Our approach to answer the related scientific questions starts with the development of various in situ methods for use mainly in the field of nonaqueous solid-state electrochemistry. Then, the physi¬cal and electro¬chemical proper¬ties of host materials and electrochemical interfaces are investigated in situ. Wherever possible, the combina¬tion of two in situ methods in a single electrochemical cell is a highly promising approach. In the talk, an overview of the most promising methods will be given.

(i) Differential Electrochemical Mass Spectrometry (DEMS) can detect qualitatively and quantitatively volatile reaction products that are evolved during cycling of an electrochemical cell. The evolution of CO2 due to the decomposition of carbonate electrolyte solvents was investigated for anodes as well as for cathodes. For cathodes we demonstrated, e.g., that the extra charge observed in the first oxidation of the overlithiated NCM material is due to the release of oxygen from the bulk structure. Furthermore, using the DEMS technique we follow the reversibility of the oxygen electrode in lithium/air test cells.

(ii) Spectroscopic techniques are established for investigations of surface related electrochemical processes, with the comprehensive understanding of the SEI film formation as a center of attention. In situ Raman spectroscopy allows following the intercalation and deintercalation of lithium and other ions into/from graphite, and the lithiation /delithiation as well as other structural changes of layered materials, such as NCM. It is possible to measure on multiple spots on the surface in order to get statistics about the homogeneity of the electrochemical processes at the electrode. Special electrochemical cells have been developed also for in situ FTIR microscopy, and finally for the combined Raman / FTIR microscopic techniques to collect spectral information in situ from the same spot at an electrode under current flow.

(iii) In contrast to XRD, neutrons are sensitive to lithium. Therefore, the combination of results from synchrotron based in situ X-ray diffraction methods and in situ neutron diffraction is essential for understanding the reactions of battery materials. In situ XRD is used to monitor structural changes of battery materials with high resolution in a short time scale. Structural changes of alloys, graphite, and oxide materials (e.g., overlithiated transition metal oxides) were followed and the corresponding reaction mechanisms evaluated. For in situ neutron diffraction experiments a sophisticated electrochemical cell was constructed allowing quantitative analysis using the Rietveld method. Investigations of various materials, especially overlithiated NCM, were successfully performed and changes of the cell parameters as well as oxygen release were determined during cycling.



Speaker information

Prof Petr Novak, Paul Scherrer Institute, Electrochemistry Laboratory, Switzerland. Professor Petr Novák is head of the Section “Electrochemical Energy Storage” of the Paul Scherrer Institute in Villigen, Switzerland. A graduate of the Institute of Chemical Technology in Prague, he obtained his PhD in electrochemical engineering in 1984 and his “habilitation” in 1994. He has been working in the field of electrochemical energy storage (focusing on batteries, mainly lithium-based) since 1983, first at the J. Heyrovský Institute, Prague, later as Alexander von Humboldt-Fellow at the University of Bonn, and since 1991 at the Paul Scherrer Institute. He was awarded the Tajima Prize of the International Society of Electrochemistry and the Technology Award of the Battery Division of The Electrochemical Society, Inc. He was appointed as a full (W3) professor at the University of Karlsruhe in 2008 (rejected). Petr Novák was awarded the title of Professor of ETH Zurich in 2009.

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