Fluorine-Doped Antiperovskite Electrolyte for All-Solid-State Lithium-Ion Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• All-solid-state batteries require advanced solid electrolytes for improved safety and energy density.
• Existing solid electrolytes often face challenges with ionic conductivity and electrochemical stability.
• Antiperovskite materials are being explored as potential solid electrolyte candidates.

Purpose of the Study:

• To investigate the effect of fluorine doping on the properties of Li2(OH)X antiperovskite conductors.
• To evaluate the performance of fluorine-doped Li2(OH)X as a solid electrolyte in all-solid-state lithium-ion batteries.
• To determine the electrochemical stability and ionic conductivity of the modified material.

Main Methods:

• Synthesis of fluorine-doped Li2(OH)X (X=Cl, Br) antiperovskites.
• Structural characterization to confirm phase transformation.
• Electrochemical impedance spectroscopy to measure ionic conductivity.
• Cyclic voltammetry and battery cycling tests to assess electrochemical performance.

Main Results:

• Substitution of F(-) for OH(-) induced a phase transition from orthorhombic to a cubic phase in Li2OHCl.
• The cubic phase exhibited significantly higher Li-ion conductivity (two orders of magnitude) compared to the orthorhombic phase.
• The fluorine-doped electrolyte demonstrated electrochemical stability up to 9 V versus Li+/Li.
• An all-solid-state Li/LiFePO4 battery utilizing the F-doped electrolyte showed good cyclability and high coulombic efficiency over 40 cycles.

Conclusions:

• Fluorine doping is an effective strategy to enhance the ionic conductivity and electrochemical stability of Li2(OH)X solid electrolytes.
• The resulting cubic phase material is a promising candidate for solid electrolytes in next-generation all-solid-state lithium-ion batteries.
• The demonstrated performance in a functional battery cell validates the potential of this material for practical applications.