Exploring Aliovalent Substitutions in the Lithium Halide Superionic Conductor Li_3–xIn_1–xZr_xCl₆ (0 ≤ x ≤ 0.5)

Abstract

In recent years, ternary halides Li3MX6 (M = Y, Er, In; X = Cl, Br, I) have garnered attention as solid electrolytes due to their wide electrochemical stability window and favorable roomtemperature conductivities. In this material class, the influences of iso-or aliovalent substitutions are so far rarely studied in-depth, despite this being a common tool for correlating structure and transport properties. In this work, we investigate the impact of Zr substitution on the structure and ionic conductivity of Li3InCl6 (Li3-xIn1-xZrxCl6 with 0 ≤ x ≤ 0.5) using a combination of neutron diffraction, nuclear magnetic resonance and impedance spectroscopy.Analysis of high-resolution diffraction data shows the presence of an additional tetrahedrally coordinated lithium position together with cation site-disorder, both of which have not been reported previously for Li3InCl6. This Li + position and cation disorder lead to the formation of a three-dimensional lithium ion diffusion channel, instead of the expected two-dimensional diffusion. Upon Zr 4+ substitution, the structure exhibits non-uniform volume changes along with an increasing number of vacancies, all of which lead to an increasing ionic conductivity in this series of solid solutions.

A Series of Ternary Metal Chloride Superionic Conductors for High‐Performance All‐Solid‐State Lithium Batteries

“…Recently, due to the development of superionic conductor such as Li 3 YCl 6 [ 14 ] and Li 3 InCl 6 , [ 19,20 ] metal halide SSEs have received renewed attention. [ 21–34 ] Until now, only a few metal chloride SSEs have achieved high room‐temperature (RT) ionic conductivities over 10 −3 S cm −1 , including Li 3 InCl 6 , [ 19,20 ] Zr‐doped Li 3 MCl 6 (M = Y, Er, Yb, In), [ 21,26,27,33 ] Li 3 Y 1− x In x Cl 6 , [ 22 ] Li x ScCl 3+ x , [ 23 ] Li 2 Sc 2/3 Cl 4 , [ 24 ] etc. In the search for new metal chloride SSEs, a better understanding of the relationship between structure and ionic conductivity is highly demanded.…”

Sn Substitution in the Lithium Superionic Argyrodite Li6PCh5I (Ch = S and Se)

“…Currently, lithium-ion batteries are the most commonly used technology in electric automobiles and portable devices. , The current technologies generally utilize organic liquid electrolytes that have a high flammability risk along with limitations in terms of energy density . In contrast, the usage of solid electrolytes in all-solid-state batteries is associated with an enhancement of the energy density, device safety, and operation under a broader temperature range. , A variety of solid electrolytes with ionic conductivities approaching those necessary for commercial devices have been developed so far, including phosphates, , lithium-based halides, − oxides, , and lithium thiophosphates. − Particularly, solid electrolytes with high ionic conductivity are necessary in order to improve the performance of solid-state batteries.…”

Halide‐type Li‐ion conductors: Future options for high‐voltage all‐solid‐state batteries

“…Helm et al revealed that the structure obtained by doping Zr 4+ was Li 3− x In 1− x Zr x Cl 6 (with 0 ≤ x ≤ 0.5). [ 13 ] The neutron diffraction data in Figure 4d showed that this structure was successfully synthesized Li 3− x In 1− x Zr x Cl 6 ( x = 0.4). Ionic conductivity increased after Zr 4+ was doped into the halide SSE (Figure 4f).…”

“…[ 5 ] (b) Linear sweep voltammetry (LSV) of Li 3 InCl 6 and Li 3 InCl 4.8 F 1.2 from 2.6 to 7.0 V. [ 5 ] (c) X‐ray diffraction (XRD) patterns of Li 3 Y 1− x In x Cl 6 ( x = 0, 0.1, 0.2) [ 12 ] (d) XRD patterns of Li 2.6 In 0.6 Zr 0.4 Cl 6 . [ 13 ] (e) Schematic of the Li 3 Y 1− x In x Cl 6 SSE and the reversible reaction between the hydrated and dehydrated states. [ 12 ] (f) Nyquist plots of Li 3− x In 1− x Zr x Cl 6 ( x = 0, 0.2, 0.4) SSE at 298 K [ 13 ]…”

“…[ 13 ] (e) Schematic of the Li 3 Y 1− x In x Cl 6 SSE and the reversible reaction between the hydrated and dehydrated states. [ 12 ] (f) Nyquist plots of Li 3− x In 1− x Zr x Cl 6 ( x = 0, 0.2, 0.4) SSE at 298 K [ 13 ]…”