title: Structural and Mechanistic Insights into Fast Lithium-Ion Conduction in Li4SiO4-Li3PO4 Solid Electrolytes.
abstract: 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 (6)Li, (7)Li, and (31)P 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.
authors.affiliation: †Laboratoire de Réactivité et Chimie des Solides (UMR CNRS 7314), Université de Picardie Jules Verne, 33 rue Saint Leu, 80039 Amiens Cedex, France.|‡Department of Chemistry, University of Bath, Bath BA2 7AY, U.K.
authors.forename: Yue
authors.initials: Y
authors.lastname: Deng
authors.affiliation: ‡Department of Chemistry, University of Bath, Bath BA2 7AY, U.K.
authors.forename: Christopher
authors.initials: C
authors.lastname: Eames
authors.affiliation: †Laboratoire de Réactivité et Chimie des Solides (UMR CNRS 7314), Université de Picardie Jules Verne, 33 rue Saint Leu, 80039 Amiens Cedex, France.
authors.forename: Jean-Noël
authors.initials: JN
authors.lastname: Chotard
authors.affiliation: †Laboratoire de Réactivité et Chimie des Solides (UMR CNRS 7314), Université de Picardie Jules Verne, 33 rue Saint Leu, 80039 Amiens Cedex, France.
authors.forename: Fabien
authors.initials: F
authors.lastname: Lalère
authors.affiliation: †Laboratoire de Réactivité et Chimie des Solides (UMR CNRS 7314), Université de Picardie Jules Verne, 33 rue Saint Leu, 80039 Amiens Cedex, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Seznec
authors.affiliation: §Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, U.K.
authors.forename: Steffen
authors.initials: S
authors.lastname: Emge
authors.affiliation: §Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, U.K.
authors.forename: Oliver
authors.initials: O
authors.lastname: Pecher
authors.affiliation: §Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, U.K.
authors.forename: Clare P
authors.initials: CP
authors.lastname: Grey
authors.affiliation: †Laboratoire de Réactivité et Chimie des Solides (UMR CNRS 7314), Université de Picardie Jules Verne, 33 rue Saint Leu, 80039 Amiens Cedex, France.
authors.forename: Christian
authors.initials: C
authors.lastname: Masquelier
authors.affiliation: ‡Department of Chemistry, University of Bath, Bath BA2 7AY, U.K.
authors.forename: M Saiful
authors.initials: MS
authors.lastname: Islam