Significance Statement
In this work, polyoxometalates (POMs) are introduced as a new material class for Na-ion battery (NIB) anodes using the example of Na6[V10O28], which combines promising capacities with high cycling performance due to the elimination of detrimental structural processes during repeated Na+-insertion into the electrode material.
NIBs carry the potential to become an alternative to the widespread lithium-ion battery (LIB) technology due to cost advantages based on resource abundance and the option to replace the copper current collector by aluminium, but also due to kinetic advantages. However, cycling performance still remains a challenge on the route to commercial applications of NIBs. Consequently, new materials that combine high cycling performance with high capacity need to be identified and thoroughly understood to bring this technology closer to promising commercial applications. One route to decrease capacity fading is to eliminate processes that cause a decrease in capacity over the course of cycling, such as structural deterioration as a consequence of repeated Na+-insertion into a given crystal structure.
Polyoxometalates are anionic metal-oxo clusters of early transition metals in high oxidation states. They consist of isolated, discrete polyanions, such as [V10O28]6- for the material presented in this work, rather than extended crystal lattices. Thus, instead of incorporating Na+ into a crystal lattice, Na-ions can insert into the cavities between the polyanionic clusters, which reduces structural stress for the electrode material and therefore increases cycling performance.
The obtained results show that capacities above 250 mA h g-1 can be obtained with Na6[V10O28] as NIB anode while cycling performance is very promising. During cycling, Na-ions are reasoned to be inserted into and extracted from intercluster cavities between the [V10O28]6- polyanions. A successful proof of concept in a full cell set-up verified the suitability of the polyoxometalate Na6[V10O28] as NIB anode, paving the way for further exploration of this material class in NIBs.
About the author
Dr. Steffen Hartung is a Research Fellow at TUM CREATE (Singapore), which is a joint project of the Technische Universität München (TUM), Germany, and Nanyang Technological University (NTU), Singapore, under the Singapore National Research Foundation’s Campus for Research Excellence and Technological Enterprise (CREATE) programme. In 2016, he graduated from the joint Ph.D. programme of TUM and NTU in the field of sodium-ion batteries under the supervision of Prof. Maria-Elisabeth Michel-Beyerle and Prof. Madhavi Srinivasan. Prior to his doctoral studies, he interned at Siemens Management Consulting. In 2011, he graduated (equivalent to Master of Science) from Ulm University in ‘Chemistry and Management’. During his studies, he spent one year at Carleton University, Canada, and gathered work experience at BASF and Bayer, Germany, as well as at TUM CREATE, Singapore. He was awarded several scholarships, including one from the German National Academic Foundation. In 2012, he received an award from the German Chemical Society for excellent achievements in the studies of ‘Chemistry and Management’. In 2013, he was selected to participate in the Global Young Scientist Summit in Singapore. His current research is on novel materials for sodium- and lithium-ion batteries.
About the author
Dr. Nicolas Bucher is currently employed as Research Fellow at TUM CREATE Ltd. In 2016, he graduated from the joint Ph.D. Programme of the Technical University of Munich and Nanyang Technological University under the supervision of Prof. Maria-Elisabeth Michel-Beyerle and Prof. Madhavi Srinivasan. During his Ph.D. studies, he focussed on sodium-ion batteries. In 2011 he graduated (equivalent to Master of Science) with highest distinction for his studies in chemistry with a focus on organic chemistry at Ulm University and the École Polytechnique Fédérale de Lausanne (EPFL). He gathered work experience as an intern at Ratiopharm – Merckle GmbH and the Chemische Fabrik Karl Bucher GmbH and was fully employed from 2002 –2004 as a Laboratory Assistant at Boehringer Ingelheim GmbH & Co KG. He has received several awards so far including a scholarship from the German National Academic Foundation and the Dr. Barbara Mez-Starck Foundation Award for excellent accomplishments during his studies of chemistry at Ulm University. In 2013 he was a selected participant at the Global Young Scientist Summit in Singapore. His current interest is on new materials and electrolytes for sodium-ion and lithium-ion batteries.
About the author
Han-Yi Chen is currently employed as Research Associate at TUM CREATE Ltd. Since 2012 she is enrolled in the joint Ph. D. Programme of the Technical University of Munich and Nanyang Technological University under the supervision of Prof. Ulrich Stimming and Prof. Madhavi Srinivasan . She obtained her Bachelors from the Department of Chemical and Materials Engineering, National Central University, Taiwan in 2008 and Masters from the Institute of NanoEngineering and MicroSystems, National Tsing Hua University, Taiwan in 2011. Her current research involves metal oxide clusters and nanocarbon materials for energy storage applications such as supercapacitors, lithium ion batteries, and sodium ion batteries.
About the author
Dr. Rami Al-Oweini is an Assistant Professor of Inorganic Chemistry at Beirut Arab University (Beirut, Lebanon) since 2014. He graduated with a B.Sc. in Chemistry and Biology Minor in 2007, and with a M.Sc. in 2009 under the supervision of Prof. H. El-Rassy at the American University of Beirut, Lebanon. He earned his Ph.D. in 2013, supported by a DAAD scholarship, under the supervision of Prof. U. Kortz at Jacobs University (Bremen, Germany). Then he was awarded an ITM-CNR Postdoctoral Fellowship to conduct his postdoctoral studies under the supervision of Prof. M. Bonchio at the University of Padova, Italy. His research interests are mainly focused on the synthesis and structural characterization of novel inorganic nano-materials and their use in water treatment, corrosion control, protein crystallization, biological and medicinal applications, as well as homogeneous and heterogeneous catalysis.
About the author
Sivaramapanicker Sreejith received his Ph.D. in 2010 from the CSIR-National Institute for Interdisciplinary Science and Technology (CSIR-NIIST), India under the supervision of Prof. Dr. Ayyappanpillai Ajayaghosh. Subsequently he became an Alexander von Humboldt Fellow (2010-2011) at Humboldt University, Berlin, Germany. Later, he joined as a Research Fellow (2011-2015) in the research group of Prof. Yanli Zhao at Division of Chemistry and Biological Chemistry, Nanyang Technological University, Singapore. Currently, he is a senior fellow (2015-till date) in the group of Prof. Mihaiela Stuparu at CBC, NTU-Singapore. His research interest includes the chemistry of functional organic/nano materials and their hybrids with a focus on biological, catalytic and energy applications.
About the author
Dr Parijat Borah completed his Ph.D. in Chemistry (2014) from Nanyang Technological University under the supervision of Prof. Yanli Zhao. Currently he is working as JSPS postdoctoral fellow at the University of Tokyo, Japan. His primary research interest is to design and synthesis of various organic-inorganic hybrid materials for range of applications such as catalysis, energy storage, bio-imaging etc.
About the author
Yanli Zhao is currently an Associate Professor at Nanyang Technological University, Singapore. He received his B.Sc. degree in Chemistry from Nankai University in 2000 and his Ph.D. degree in Physical Chemistry there in 2005 under the supervision of Professor Yu Liu. He was a postdoctoral scholar with Professor Sir Fraser Stoddart at University of California Los Angeles (October 2005 to November 2008) and subsequently at Northwestern University (January 2010 to August 2010). In between (December 2008 to December 2009), he was a postdoctoral scholar with Professor Jeffrey Zink at University of California Los Angeles. He has published over 200 scientific papers, and received several awards including the TR35@Singapore Award in 2012 and the Singapore National Research Foundation Fellowship in 2010. His current research focuses on the development of integrated systems for diagnostics and therapeutics, as well as porous materials for gas storage and catalysis.
About the author
Ulrich Kortz studied Chemistry and Chemical Engineering in Giessen and Darmstadt (1982–1989), before he moved to Georgetown University in Washington, DC for his Ph.D. under the supervision of Michael T. Pope (1995). After postdoctoral studies with Dante Gatteschi (Florence, Italy) and André Tézé and Gilbert Hervé (Versailles, France) he started his independent academic career at the American University of Beirut in Lebanon in 1997. In 2002 he joined the newly established International University Bremen (now Jacobs University) as an Associate Professor, and in 2007 became a Full Professor. His research interests include synthetic inorganic and organometallic chemistry, structural inorganic chemistry, polyoxometalates, catalysis, magnetism, and electrochemistry. He was awarded the President’s International Visiting Scientist Fellowship in 2015 and 2016 (Chinese Academy of Sciences, Beijing, China) and a Guest Professorship of Henan Province (since December 2013).
About the author
Ulrich Stimming is currently Professor of Chemistry and Head of School of Chemistry at Newcastle University. He was a Chair of Technical Physics University of Munich (TUM). He was Scientific Advisor and Principal Investigator of TUM Create. He is the founder and Editor-in-chief of the scientific journal “Fuel Cells-From Fundamentals to Systems”, VCH-Wiley. He is member of various national and international academic advisory committees and served on evaluation panels of the European Research Council (ERC). He also coordinated for the Association of Leading Technical Universities in Germany (TU9) a research network of a total of 8 universities in electromobility between Germany and China, and was co-director of the Joint “Institute for Advanced Power Sources” of TUM and Tsinghua University from 2010-2014.
About the author
Harry Hoster is Professor of Physical Chemistry and Director of the research centre “Energy Lancaster” at Lancaster University. Harry Hoster explores the physical and chemical properties of surfaces and solids. His goal is rational design: improving electrode materials for fuel cells and batteries. His special interest: boiling it all down to single atoms and molecules, i.e., understanding the microscopic fundamentals behind the macroscopic performance of electrochemical cells. After receiving a degree in physics from Bonn University in 1996, Professor Hoster was awarded a fellowship by the German “Fonds der Chemischen Industrie” for full-time doctoral study on anode materials for methanol fuel cells. Having acquired his postdoctoral teaching qualification (venia legendi/habilitation) in physical chemistry in 2010, he assumed the position of Associate Professor at the Institute of Technical Electrochemistry at TUM (Munich). In 2011 he became Scientific Director of TUM CREATE in Singapore. TUM CREATE is a collaborative and interdisciplinary research programme on electric vehicle technology. Within TUM CREATE, he also became Principal Investigator of the research project “Electrochemistry and New Materials”. In 2013, he was awarded a position as Visiting Professor at the Nanyang Technological University in Singapore. In 2015, he became a Fellow of the Royal Society of Chemistry.
About the author
Madhavi Srinivasan is currently an Associate Professor at the School of Materials Science and Engineering, Nanyang Technological University (NTU), Singapore. Her research interest is to enhance the performance of energy storage devices such as lithium ion batteries, supercapacitors, and advanced batteries with the help of multifunctional nanoscale materials to power printed electronics, to store energy from renewable sources, and for powering electricvehicles. Her focus is on the fabrication and investigation of nanoscale materials/architectures for next generation electrochemical energy storage devices. She has been awarded the prestigious L’Oreal-UNESCO for women in Science National Fellowships and was also one of the three “Great Women of Our Time” in the Science and Technology Category awarded by “Singapore Women’s Weekly” Magazine. She is one of the 10 young scientist worldwide (future leaders forum) awarded at the Science and Technology forum, Kyoto (Japan). She has won both the “Nanyang Excellence in Teaching” award in 2012 and “Nanyang Excellence in Research” award in 2014.
Journal Reference
Journal of Power Sources, Volume 288, 15 August 2015, Pages 270-277.
Steffen Hartung1,2, icolas Bucher1,2, Han-Yi Chen1,2, Rami Al-Oweini4,7, Sivaramapanicker Sreejith6, Parijat Borah6, Zhao Yanli6, Ulrich Kortz4, Ulrich Stimming1, Harry E. Hoster1,2,5, Madhavi Srinivasan1,3,5
[expand title=”Show Affiliations”]
- TUM CREATE, 1 CREATE Way, #10-02 CREATE Tower, Singapore 138602, Singapore
- Technische Universität München, 85748 Garching, Germany
- School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore
- School of Engineering and Science, Jacobs University, P.O. Box 750561, 28725 Bremen, Germany
- Energy Research Institute @ NTU (ERI@N), Research Techno Plaza, 50 Nanyang Drive, Singapore 637553, Singapore
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
- Department of Chemistry, Faculty of Science, Beirut Arab University, P.O. Box 11 50 20, Riad El Solh 1107 2809, Beirut, Lebanon [/expand]
Abstract
Affordable energy storage is crucial for a variety of technologies. One option is sodium-ion batteries (NIBs) for which, however, suitable anode materials are still a problem. We report on the application of a promising new class of materials, polyoxometalates (POMs), as an anode in NIBs. Specifically, Na6[V10O28]·16H2O is being synthesized and characterized. Galvanostatic tests reveal a reversible capacity of approximately 276 mA h g−1 with an average discharge potential of 0.4 V vs. Na/Na+, as well as a high cycling stability. The underlying mechanism is rationalized to be an insertion of Na+ in between the [V10O28]6− anions rather than an intercalation into a crystal structure; the accompanying reduction of V+V to V+IV is confirmed by X-ray Photoelectron Spectroscopy. Finally, a working full-cell set-up is presented with the polyoxometalates as the anode, substantiating the claim that Na6[V10O28]·16H2O is a promising option for future high-performing sodium-ion batteries.
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