Structural and Mechanistic Insights into Fast Lithium-Ion Conduction in Li4SiO4–Li3PO4 Solid Electrolytes
Islam, M Saiful
Journal of the American Chemical Society
American Chemical Society
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Deng, Y., Eames, C., Chotard, J., Lalère, F., Seznec, V., Emge, S., Pecher, O., et al. (2015). Structural and Mechanistic Insights into Fast Lithium-Ion Conduction in Li4SiO4–Li3PO4 Solid Electrolytes. Journal of the American Chemical Society, 137 9136-9145. https://doi.org/10.1021/jacs.5b04444
Solid electrolytes that are chemically stable and have a high ionic conductivity would dramatically enhance the safety and operating lifespan of rechargeable lithium batteries. Here, we apply a multi-technique approach to the Li-ion conducting system (1–z)Li4SiO4–(z)Li3PO4 with the aim of developing a solid electrolyte with enhanced ionic conductivity. Previously unidentified superstructure and immiscibility features in high-purity samples are characterized by X-ray and neutron diffraction across a range of compositions (z = 0.0–1.0). Ionic conductivities from AC impedance measurements and large-scale molecular dynamics (MD) simulations are in good agreement, showing very low values in the parent phases (Li4SiO4 and Li3PO4) but orders of magnitude higher conductivities (10–3 S/cm at 573 K) in the mixed compositions. The MD simulations reveal new mechanistic insights into the mixed Si/P compositions in which Li-ion conduction occurs through 3D pathways and a cooperative interstitial mechanism; such correlated motion is a key factor in promoting high ionic conductivity. Solid-state 6Li, 7Li, and 31P NMR experiments reveal enhanced local Li-ion dynamics and atomic disorder in the solid solutions, which are correlated to the ionic diffusivity. These unique insights will be valuable in developing strategies to optimize the ionic conductivity in this system and to identify next-generation solid electrolytes.
The ALISTORE ERI and CNRS are acknowledged for supporting Y.D. through a joint Ph.D. scholarship between Picardie (France) and Bath (UK). The authors thank D. Sheptyakov (PSI, Switzerland) and M. Bianchini (ILL-Grenoble, France) for assistance with neutron diffraction experiments, and M. T. Dunstan (Cambridge, UK) for assistance with NMR experiments. Financial support from the EPSRC Energy Materials Programme (Grant EP/K016288) is gratefully acknowledged. The HPC Materials Chemistry Consortium (EP/L000202) allowed use of the ARCHER facilities. O.P. and S.E. acknowledge support from a Marie Skłodowska-Curie Fellowship (H2020-MSCA-IF-2014-EF, no. 655444) and an ERASMUS+ scholarship, respectively.
European Commission (655444)
External DOI: https://doi.org/10.1021/jacs.5b04444
This record's URL: https://www.repository.cam.ac.uk/handle/1810/253962