Inorganic Solid-State Electrolytes for Lithium Batteries: Mechanisms and Properties Governing Ion Conduction

Abstract

This Review is focused on ion-transport mechanisms and fundamental properties of solid-state electrolytes to be used in electrochemical energy-storage systems. Properties of the migrating species significantly affecting diffusion, including the valency and ionic radius, are discussed. The natures of the ligand and metal composing the skeleton of the host framework are analyzed and shown to have large impacts on the performance of solid-state electrolytes. A comprehensive identification of the candidate migrating species and structures is carried out. Not only the bulk properties of the conductors are explored, but the concept of tuning the conductivity through interfacial effects-specifically controlling grain boundaries and strain at the interfaces-is introduced. High-frequency dielectric constants and frequencies of low-energy optical phonons are shown as examples of properties that correlate with activation energy across many classes of ionic conductors. Experimental studies and theoretical results are discussed in parallel to give a pathway for further improvement of solid-state electrolytes. Through this discussion, the present Review aims to provide insight into the physical parameters affecting the diffusion process, to allow for more efficient and target-oriented research on improving solid-state ion conductors.

Effect of the binder content on the electrochemical performance of composite cathode using Li6PS5Cl precursor solution in an all-solid-state lithium battery

“…The incorporation of the binder produced a slight improvement on the conductivity, achieving 2.5 × 10 S cm . The lithium conductivity of the Li PS Cl crystal as synthetized obtained in this work is lower when compared with the reported literature (1 × 10 S cm ) [ 6,21 ]. The presence of Li S phase, detected by XRD, could be responsible for the low ionic conductivity of the material obtained after ball milling procedures.…”

“…1 b) show a band of around 380 cm associated to the PS group. The structure of argyrodite is formed by a network of isolated PS units making hexagonal cages, which are connected to each other by an interstitial site around the halide ions [ 6, 21,22 ]. The results confirm that the process of dissolution reprecipitation and the addition of the binder do not produce negative effects on the structure of the Li PS Cl solid electrolyte.…”

F anion dynamics in cation-mixed nanocrystalline LaF3: SrF2

“…They constitute an important part in many devices such as sensors [3] and those constructed for electrochemical energy storage [4,5]. Apart from Li and Na ion conductors, also materials with high F anion conductivity have increasingly attracted attention [6], because there is renewed interest in the realization of batteries with fluorine anions as main charge carriers [7][8][9].…”

Optimization of Al2O3 and Li3BO3 Content as Sintering Additives of Li7−x La2.95Ca0.05ZrTaO12 at Low Temperature

“…Introduction Garnet-type solid electrolytes have been studied extensively [1,2], because high ionic conductivity at room temperatures (10 -3 -10 -4 S/cm), high chemical stability against Li metal and wide potential windows with electrochemical decomposition voltage of ~6 V vs. elemental Li anode. Typical temperatures around 1200 °C are used to sinter the material and stabilize the cubic phase responsible of the high conductivity.…”

“…Although the Li content in the unit formula (6.4 -6.75) is slightly lower than that of LLZ [3], conductivity remains high in the order of 10 -3 -10 -4 S/cm. The enhanced Li-ion conductivity has been attributed to optimized lithium content in octahedral and tetrahedral sites of the garnet structure [1].…”