(360e) A Study on the Ionic Conductivity Improvement Mechanism of Halospinel Li2Sc2/3Cl4 By Variable Li and Dopant Concentration

High performing solid-state electrolyte (SSE) with high ionic conductivity and electrochemical stability is of great interest for the next-generation lithium (Li) ion battery systems. Halide types have advantages with great ionic conductivity and relatively stable in operating voltage range compared to oxide and sulfide counterparts. Recently, one of spinel-type halide (Li2Sc2/3Cl4) has shown outstanding ionic conductivity of 2.07mS/cm. Here, we systematically investigate the aliovalent dopant (Fe²⁺) effects on the Li-ion conductivity of Li2Sc2/3Cl4 to induce higher collective motion of Li by increasing Li-ion concentration. Also, we study the effect of Li-ion conductivities of different doping concentrations of Fe and Li in Li2Sc2/3Cl4. Stable configurations are obtained by density functional theory (DFT) calculations and underlying mechanisms of Li-ion diffusion are analyzed by ab-initio molecular dynamics (AIMD) simulations. The results reveal that the Fe-Li interaction plays a critical role in lowering the barrier of Li-ion motion along the diffusion path. Our design can guide to improve the performance with aliovalent dopings.