Compétences : Oxydes lamellaires / Batteries au sodium / Cristallographie / Diffusion des rayons X et des neutrons
Education and scientific position
2018 : Habilitation à Diriger les Recherches (HDR) diploma from Bordeaux
University, in physical chemistry of condensed matter.
2009 – : CNRS junior scientist : Institut de Chimie de la Matière Condensée de Bordeaux (ICMCB), CNRS, France
2007 – 2009 : Postdoctoral fellow : Institut de Minéralogie et de Physique de la Matière Condensée (IMPMC), Pierre et Marie Curie University, France. Supervisor : Laurent CORMIER
2005 – 2006 : Postdoctoral fellow : Department of Chemistry, Dalhousie University, Canada. Supervisor : Josef W. ZWANZIGER
2002 – 2005 : PhD student : Institut des Sciences Chimiques de Rennes, University of Rennes, France. Supervisors : Frédéric SMEKTALA and Xianhua ZHANG
Keywords : Sodium batteries ; Sodium layered oxides ; Crystal Structure ; In situ and operando diffraction.
My scientific research interests are currently focused on the synthesis and detailed structure understanding of new layered crystalline oxides realized by electrochemical methods of alkali ions deintercalation/intercalation. The main goals are to synthesise new materials showing promising novel physical properties and to determine their structure in detail using multiple complementary to elucidate the composition-structure-property relationships.
Synthesising and exploring new layered oxide systems : Electrochemical sodium deintercalation/intercalation in a battery is a very elegant way to determine the real phase diagram of NaxMO2 systems and, moreover, to synthesize a given material by fixing its Fermi level versus the Na+/Na redox couple instead of trying to obtain a specific sodium amount chemically. As the current is controlled during the charge/discharge of the battery, the number of electrons exchanged by the system can precisely calculated, and therefore the stoichiometry, and more accurately the sodium amount, is perfectly known.
Tracking novel physical properties : All the new single phases synthesised are screened in terms of electronic conductivity, magnetic properties and thermoelectric response. The search for superconductivity can be done by measuring the magnetic moment down to 2 K and the electric resistivity down to 5 K. Other electronic or magnetic properties can also be explored at elevated temperatures at the ICMCB.
Studying structures in detail : The structures of new phases with the most promising physical properties are studied in further detail using multiple complementary probes to elucidate the composition-structure-property relationships. Whereas diffraction data (X-ray, electron or neutron) obtained at the ICMCB or at user facilities from powder samples help solve the long range structure of the newly discovered crystalline materials, local probes such as Pair Distribution Function (PDF) analysis or solid state Nuclear Magnetic Resonance (NMR) Spectroscopy are used to reveal local order in these materials in the case of complex superstructures or incommensurate structures.
B.J. Hwang (NTUST, Taiwan)
J. Sugiyama (Toyota, Japan)
N. Sharma (UNSW, Australia
Project with the Toyota company : “New layered oxides for Na-ion batteries”, 2013-2015 and 2016-2019.
Scientific production and supervision
37 articles/ 4 proceedings/ 2 patents
7 invited talks international conferences
Supervision : 3 PhD students (currently 1), 1 postdoctoral fellow (currently 1), 1 master students, 2 undergraduate students.
10 Relevant publications (total : 36)
M. Guignard, D. Carlier, C. Didier, M. R. Suchomel, E. Elkaim, P. Bordet, R. Decourt, J. Darriet, C. Delmas. “Vanadium clustering/declustering in P2-Na1/2VO2 layered oxide”. Chemistry of Materials 2014, 26, 1538-1548.
B. Mortemard, D. Carlier, M. Guignard, L. Bourgeois, C. Delmas. « P2-NaxMn1/2Fe1/2O2 Phase Used as Positive Electrode in Na Batteries : Structural Changes Induced by the Electrochemical (De)intercalation Process”. Inorganic Chemistry 2014, 53, 11197−11205.
M. Guignard, C. Didier, J. Darriet, P. Bordet, E. Elkaïm, C. Delmas. “P2-NaxVO2 system as electrodes for batteries and electron-correlated materials”. Nature Materials 2013, 12, 74-80.
B. Mortemard de Boisse, D. Carlier, M. Guignard, C. Delmas. “Structural and Electrochemical Characterizations of P2 and New O3-NaxMn1-yFeyO2 Phases Prepared by Auto-Combustion Synthesis for Na-Ion Batteries”. Journal of the Electrochemical Society 2013, 160, A569-A574.
C. Didier, M. Guignard, J. Darriet, C. Delmas. “The O’3-NaxVO2 system : a superstructure for Na1/2VO2”. Inorganic Chemistry 2012, 51, 11007-11016.
C. Didier, M. Guignard, C. Denage, O. Szajwaj, S. Ito, I. Saadoune, J. Darriet, C. Delmas. “Electrochemical Na-Deintercalation from NaVO2”. Electrochemical and Solid-State Letters 2011, 14, A75-A78.
M. Guignard, L. Cormier, V. Montouillout, N. Menguy, D. Massiot. “Structural fluctuations and role of Ti as nucleating agent in an aluminosilicate glass”. Journal of Non-Crystalline Solids 2010, 356, 1368.
M. Guignard, L. Cormier. “Environments of Mg and Al in MgO-Al2O3-SiO2 glasses : A study coupling neutron and X-ray diffraction and Reverse Monte Carlo modelling”. Chemical Geology 2008, 256, 110-117.
M. Guignard, L. Albrecht, J. W. Zwanziger. “Zero-Stress Optic Glass without Lead”. Chemistry of Materials 2007, 19, 286-290.
M. Guignard, V. Nazabal, F. Smektala, O. Bohnke, C. Duverger, A. Moréac, H. Zeghlache, A. Kudlinski, G. Martinelli, Y. Quiquempois. “Germanium disulfide based chalcogenide glasses for second harmonic generation”. Advanced Functional Materials 2007, 17, 3284-3294.