A High‐Voltage Solid State Electrolyte Based on Spinel‐Like Chloride Made of Low‐Cost and Abundant Resources

Abstract

Recently, halide solid state electrolytes (SSEs) have received great attention owing to their fast ionic conductivity, high oxidation potential, and good chemical and electrochemical compatibility with high voltage cathode materials. However, most of reported halide SSEs contain rather rare and expensive elements, which hinders their sustainable utilizations in practical batteries. Here in this work, under the guidance of systematic modelling based on the density functional theory (DFT), a low‐cost alternative is developed through optimizing the lattice chemistry in a recently identified spinel‐like chloride Li2CrCl4 into Li5/3Cr1/3Zr1/3Cl4 for remarkably enhanced ionic conductivity and stable electrochemical window with respect to the Li‐anode. This new phase has then been synthesized successfully, delivering an ionic conductivity over 1200 times of that of the pristine phase Li2CrCl4, in addition to a high oxidation potential (up to 4.1 V vs Li/Li+) to enable outstanding interfacial compatibility with high voltage cathodes. Such a high‐voltage and fast Li‐ion conducting solid‐state electrolyte is expected to provide a highly desirable basis toward developing high energy‐density all solid‐state batteries (ASSBs) using economical and Earth‐rich elements.

Expanding the Phase Space for Halide-Based Solid Electrolytes: Li–Mg–Zr–Cl Spinels

“…EIS measurements show that Li 2 MgCl 4 exhibits ionic conductivity near σ i,30 °C = 4.0 × 10 –4 mS/cm, but increasing Zr-substitution into Li 2– z Mg 1–3 z /2 Zr z Cl 4 increases the ionic conductivity up to 0.23 mS/cm for the spinel structure (at z = 0.4). These values are similar to those recently reported for Li 1.67 Cr 0.33 Zr 0.33 Cl 4 in the spinel structure (0.313 mS/cm at 30 °C), but still lower than the Li 2 Sc 2/3 Cl 4 that inspired this work (1.6 mS/cm at 30 °C) . The maximum conductivity is observed in the two-phase region with 0.43 mS/cm at z = 0.57.…”

Unraveling the interfacial compatibility of ultrahigh nickel cathodes and chloride solid electrolyte for stable all-solid-state lithium batteries

“…Chloride SEs, such as Li 3 YCl 6 , 14 Li 2 ZrCl 6 , 15 Li 3 ScCl 6 , 16 Li 2 In x Sc 0.666− x Cl 4 , 17 Li 3− x M 1− x Zr x Cl 6 (M = In, Yb), 18,19 LiTaCl 4 O, 20 ZrO 2 –LiCl–Li 2 ZrCl 6 , 21 amorphous Li–Ta–Cl, 22 Li 2.75 (YErYb) 0.16 In 0.25 Zr 0.25 Cl 6 , 23 and Li 5/3 (CrZr) 1/3 Cl 4 24 have recently emerged as the most promising SEs because of their superionic conductivity (ranging from 1 to 12 mS cm −1 , comparable to that of liquid electrolytes), impressive anti-oxidation potential (4.3 V versus Li + /Li), and superior mechanical ductility. These outstanding achievements represent an optimal trade-off between conductivity and electrochemical stability, a balance that has yet to be accomplished in oxide and sulfide SEs.…”