Unveiling Lithium-ion Migration Mechanisms in Anti-perovskite Solid Electrolytes: A Combined EIS and EDS Study of Defect Dynamics

Understanding the defect-mediated migration mechanisms in solid electrolytes is critical for optimizing lithium-ion conductivity. This study investigates Li⁺ transport in lithium halide hydroxide anti-perovskite materials by systematically correlating defect structures with electrochemical performance. Samples with controlled compositions of 〖"Li" 〗_۲ ("OH" )_(۱-x) "F" _x "Cl (x=۰.۰۰۵)" were synthesized to stabilize orthorhombic, cubic, and Ruddlesden–Popper (RP) structural phases. To investigate ion transport mechanisms and elemental shifts during thermal cycling, EIS and EDS techniques were employed. EIS analysis revealed distinct activation energies associated with specific migration mechanisms: low-temperature transport in the RP and cubic phases was governed by Li⁺ vacancy or interstitial dumbbell migration, whereas high-temperature regimes were dominated by Schottky defect formation in LiCl or Li₂O. Complementary EDS findings indicated an increase in oxygen vacancies post-cycling, thereby corroborating the hypothesis regarding Schottky pair generation. Furthermore, high grain boundary resistance was attributed to excessive barriers arising from hydrogen-related defects. These findings provide a mechanistic framework for designing low-resistance solid-state electrolytes through the control of defect chemistry.

کلیدواژه ها:

Solid-state batteries ، Lithium-ion conductivity ، Defect chemistry ، Ruddlesden-Popper Phases ، electrochemical impedance spectroscopy