Classification\nand Analysis of Halide Mixtures in\nLi<sub>10</sub>P<sub>3</sub>S<sub>12</sub>M (M = Cl, Br, I) Solid\nElectrolytes for Superionic Conductors

The\nlithium thiophosphate group of solid electrolytes (SEs) is\nconsidered one of the best lithium-ion conductors that could be compatible\nwith liquid electrolytes. However, the interface stability of lithium\nthiophosphate SEs against the lithium anode and oxide cathode could\nbe a challenge due to severe degradation over charge–discharge\ncycles. In this study, we aim to analyze and introduce the addition\nof halides into lithium thiophosphate SEs with a molar ratio of 3Li<sub>3</sub>PS<sub>4</sub> to 1LiM (M = Cl, Br, I) in order not only to\nimprove ion conductivity but also to increase the interface stability\nof the SEs. Li<sub>10</sub>P<sub>3</sub>S<sub>12</sub>Br (LPSBr) and\nLi<sub>10</sub>P<sub>3</sub>S<sub>12</sub>I (LPSI) results in high\nionic conductivity at 1.7 and 2.9 mS cm<sup>–1</sup>, respectively,\nat room temperature. Although LPSBr has lower ion conductivity, it\nshows better electrochemical stability compared to LPSI. By combining\nthe advantages of both LiI and LiBr to form Li<sub>10</sub>P<sub>3</sub>S<sub>12</sub>Br<sub>1–<i>x</i></sub>I<sub><i>x</i></sub>, we have observed improvements not only in high\nionic conductivity but also in the interface stability of SEs, which\nis important for extending the lifetime cycle of all-solid-state lithium\nbatteries (ASSLBs).