In an example of stability from instability, a Li7P2S8I solid-state Li-ion conductor derived from beta-Li3PS4 and LiI demonstrates electrochemical stability up to 10 V vs Li/Li+. The oxidation instability of I is subverted via its incorporation into the coordinated structure. The inclusion of I also creates stability with the metallic Li anode while simultaneously enhancing the interfacial kinetics and ionic conductivity. Low-temperature membrane processability enables facile fabrication of dense membranes, making this conductor suitable for industrial adoption.