Figure: Theodosios Famprikis (Ph.D. graduate from Université de Picardie Jules Verne, Amiens, France since November 10, 2020) in the experimental hutch of the MSPD beamline at the ALBA Synchrotron.
Cerdanyola del Vallès, 16 November 2020. In the key area of sustainable energy storage, solid-state batteries have attracted considerable attention due to their potential safety, energy-density and cycle-life benefits. These batteries are based on solid electrodes and electrolytes, as opposed to the liquid or polymer gel electrolytes found in lithium-ion and lithium-polymer commercially available batteries.
A large international research team coordinated by the Laboratoire de Réactivité et Chimie des Solides -LRCS (France), in collaboration with the University of Bath (United Kingdom), the Newcastle University (United Kingdom), the National University of Singapore, the ALBA Synchrotron, the Institut Laue-Langevine (France), the Physico-Chimie des Electrolytes et Nano-systèmes Interfaciaux -PHENIX (France), the Advanced Photon Source of the Argonne National Laboratory (United States), the Laboratoire de Physique de la Matière Condensée - LPMC (France), the University of Cambridge (United Kingdom), Institute of Inorganic and Analytical Chemistry, (University of Muenster, Germany); and supported by the Réseau sur le Stockage Électrochimique de l’Énergie (RS2E) and the ALISTORE ERI networks, has described the effects of pressure on the structure and ionic conductivity of Na3PS4, a thiophosphate solid electrolyte.
The study separates extrinsic effects linked to densification and intrinsic effects linked to the activation volume of conduction. These mechanisms can be correlated to the microstrain and particle size measurements determined by high angular resolution Bragg diffractograms at the MSPD beamline in ALBA. Researchers used several techniques and carried out unique variable-pressure impedance spectroscopy experiments to investigate the response of ionic conduction to applied pressure.
"Pressure and mechanochemical effects provide important parameters to optimize solid electrolytes and by extension improve next-generation batteries. Synchrotron-based techniques have a key role to play in characterizing such subtle features that can have a great impact on the performance of materials and devices." says lead author Theo Famprikis.
The results of this study are of high interest in the field of solid-state batteries as a next‑generation technology for large-scale electrochemical energy to enable electric vehicles and renewable electricity production.
Figure: Synchrotron diffraction experiments highlighting the differences between the average and local structure of mechanochemically synthesized Na3PS4. Bragg diffraction measured at the MSPD beamline of the ALBA Synchrotron. Pair Distribution Function measured at 11-ID-B beamline of the Advanced Photon Source at Argonne National Laboratory (USA). The structure can be described in an average cubic motif, featuring localized tetragonal distortions.
A multi-technique approach
Samples of Na3PS4 were prepared through classical solid‑state synthesis and mechanochemistry, respectively, to investigate the previously observed beneficial effects of mechanochemistry on the ionic conductivity. Next, these samples were investigated through X-ray and neutron Bragg diffraction, X-ray Total‑scattering, Raman spectroscopy, Nuclear Magnetic Resonance Spectroscopy, Inelastic Neutron Spectroscopy and Impedance Spectroscopy.
Researchers reported for the first time the activation volume – the volume change needed - for Na+ migration in Na3PS4. To this aim, unique experiments were performed by measuring impedance spectra while applying pressure in‑situ in a uniaxial hydraulic press to directly probe the effects of pressure on the ion transport.
The diffraction experiments were performed at synchrotron sources: the Bragg diffraction experiments took place at the MSPD beamline in the ALBA Synchrotron and the Total Scattering ones at the Advanced Photon Source of the Argonne National Laboratory. The combination of these experiments allowed an accurate characterization of the structure over multiple scales, from the angstrom (Å) scale local structure to the tenths of nanometers (nm) scale average structure, and the micron-(μm) scale microstructure. This is especially interesting in the investigated ball-milled Na3PS4 samples where the local- and average- structures cannot be described by the same motif.
A proposal for complementary Bragg diffraction experiments at High Pressure has been accepted at ALBA to complement these results.
Reference: Theodosios Famprikis, Ö. Ulaş Kudu, James A. Dawson, Pieremanuele Canepa, François Fauth, Emmanuelle Suard, Mohamed Zbiri, Damien Dambournet, Olaf J. Borkiewicz, Houssny Bouyanfif, Steffen P. Emge, Sorina Cretu, Jean-Noël Chotard, Clare P. Grey, Wolfgang G. Zeier, M. Saiful Islam, and Christian Masquelier. Under Pressure: Mechanochemical Effects on Structure and Ion Conduction in the Sodium-Ion Solid Electrolyte Na3PS4. Journal of the American Chemical Society, 2020. DOI: 10.1021/jacs.0c06668
