Effect of Fluorine Substitution in Li₃YCl₆ Chloride Solid Electrolytes for All-solid-state Battery

Abstract

All-solid-state batteries experience irreversible capacity loss particularly in the initial potential cycle, owing to electrolyte decomposition at the electrode/electrolyte interface. A strategy for expanding the oxidation stability of electrolytes is replace the anion in solid electrolytes with fluorine. However, fluorine substitution has a negative influence on ionic conductivity. In this study, we introduced trace amounts of fluorine replacement in Li3YCl6 solid electrolytes which exhibit high ionic conductivities and wide potential windows. The effect of replacement on ionic conductivity, oxidation stability, and charge-discharge characteristics we studied. The trace amounts of fluorine in Li3YCl6 did not reduce the conductivity, but improved the apparent oxidation stability. The decomposed product of LiF from the fluorine-substituted electrolyte disturbed the formation of a high-resistance layer at the electrode/electrolyte interface. The initial charge-discharge efficiency of the uncoated LiCoO2 cathode was improved by the trace amount of fluorine replacement in the Li3YCl6 solid electrolyte.

Potential electrolytes for solid state batteries and its electrochemical analysis—A review

“…In air batteries, the halide solid‐state electrolytes are renowned for their high potential stability, cost‐effectiveness, high ionic behavior, and scalable synthesis routes 276 . Moreover, the hygroscopic properties of these materials could be significantly decreased by depositing a protective thin layer of AlO 2 , 275 doping fluorine improves the oxidative stability of material, 10 adding additives, and composite polymer hybrid composites 115,277 . Shuting Luo tried to investigate order and disorder phase transition in Li 2 S, which would help to reduce dendrite formation.…”

“…276 Moreover, the hygroscopic properties of these materials could be significantly decreased by depositing a protective thin layer of AlO 2 , 275 doping fluorine improves the oxidative stability of material, 10 adding additives, and composite polymer hybrid composites. 115,277 Shuting Luo tried to investigate order and disorder phase transition in Li 2 S, which would help to reduce dendrite formation. Furthermore, it could be beneficial to design sulfide-based solid electrolytes in the future.…”

Fluorine-Substituted Lithium Chloride Solid Electrolytes for High-Voltage All-Solid-State Lithium-Ion Batteries

“…The F-containing passivating interphases enhanced the oxidation stability of Li 3 InCl 4.8 F 1.2 to over 6 V and stabilized the cathode surfaces at high cutoff voltages while maintaining a reasonable ionic conductivity above 10 –4 S/cm . Similarly, Yamagishi et al reported that a small amount of F substitution in Li 3 YCl 6 (Li 3 YCl 5.97 F 0.03 ) improved oxidation stability without impacting ionic conductivity . In addition, Kwak et al reported fluorinated halide nanocomposite solid electrolytes ZrO 2 -2Li 2 ZrCl 5 F with high ionic conductivity and improved high-voltage stability …”

“…Despite the promise of fluorine substitution for enhancing oxidation stability of Li 3 MCl 6 , only a few investigations on Li 3 InCl 4.8 F 1.2 , Li 3 InCl 5.6 F 0.4 , and Li 3 YCl 5.97 F 0.03 have been reported in the literature. − Therefore, a thorough examination of F substitution in Li 3 MCl 6 with a diverse range of M elements and varying mixing ratios would serve as a fundamental guideline for the development of novel SE compositions. To this end, this study outlines a computationally motivated material design strategy through theoretical analyses of the phase stability, structural preference, ionic conductivity, and oxidation stability of F-substituted Li 3 MCl 6 with 18 different M 3+ elements.…”