Journal of Physical Chemistry & Biophysics
Open Access

Versatile approach combining theoretical and experimental aspects of Raman spectroscopy to investigate battery materials

5^th International Conference on Physical and Theoretical Chemistry

October 11- 13, 2018 | Edinburgh, Scotland

Mouna Ben Yahia

ICGM, France

Scientific Tracks Abstracts: J Phys Chem Biophys

Abstract :

The Li-ion batteries are the most efficient devices in term of energy storage. The spinel LiNi0.5Mn1.5O4 (LNMO) is a promising positive electrode for lithium-ion batteries (LIBs) thanks to its high energy density and high voltage. Two LNMO polymorphs whose structural stabilities strongly depend on their synthesis conditions have been reported: ordered LNMO (P4332) and disordered LNMO (Fd-3m) on Ni/Mn atomic sites. Unfortunately, conventional X-ray diffraction cannot easily differentiate them. An easy and efficient way to do that is to use Raman scattering. Nevertheless difficulties were encountered to properly assign the observed vibration modes. Disordered LNMO is a typical case for which different approaches were used in the literature and conclusions were drawn based on only assumptions. Some people postulate for a discernible, other no-discernable Ni-O and Mn-O vibration bond in the Raman spectrum with no real proof to support their approach. The relatively new feature of modeling the Raman intensity in periodic system within DFT codes, allow us to resolve the last bottleneck of understanding the vibrational properties of spinel LNMO. For a given normal mode, the rationalization of the origin of the Raman intensities was done through a pertinent choice of descriptor resulting from a fine analysis of electronic structure. With this approach we assign all the normal modes and prove for the first time that the most intense peaks are mainly correlated to the Li-O contrary to what was reported in the literature. Also we confirm the assumption of discernible Ni-O and Mn-O vibration bonds. All these results will be discussed, to demonstrate that Raman spectroscopy coupled to calculated Raman intensities is a tool of choice to investigate cathode material for Li-ion batteries and more generally to follow the reaction mechanisms and possible intermediate species during electrochemical process. Recent Publications: 1. M Kunduraci and G G Amatucci. (2006) Synthesis and characterization of nanostructured 4.7 V LiNi0.5Mn1.5O4. J. Electrochem. Soc. 153(7):A1345A1352. 2. D Liu et al. (2014) Spinel materials for high voltage cathodes in Li-ion batteries. RSC Adv. 4(1):154-167. 3. Maschio L et al. (2013) Ab initio analytical Raman intensities for periodic systems through a coupled perturbed Hartree-Fock/Kohn-Sham method in an atomic orbital basis. I. Theory J. Chem. Phys. 2013, 139(16):164101. 4. L Boulet Roblin et al. (2016) Versatile approach combining theoretical and experimental aspects of Raman spectroscopy to investigate battery materials: the case of the LiNi0.5Mn1.5O4 J. Phys. Chem. C. 120(30):16377-16382.

Biography :

Mouna Ben Yahia is an Assistant Professor at University of Montpellier, France. She is working on structural, mechanical, thermodynamic and vibrational properties of electrode materials for Li-ion batteries. She is developing a rapid and efficient characterization method based Raman spectroscopy for understanding the electrochemical mechanisms that occur in positive electrode materials within the lithium-ion batteries.

E-mail: mouna.ben-yahia@umontpellier.fr