Chem. Sci., 2026, Accepted Manuscript DOI: 10.1039/D5SC09834C, Edge Article Guopeng Han, Christopher M. Collins, Manel Sonni, Luke M. Daniels, Andrij Vasylenko, Ruiyong Chen, Craig Robertson, Matthew Stephen Dyer, John B Claridge, Matthew J. Rosseinsky We report the experimental discovery of Li7Si2S7I0.89Cl0.11, a triclinic (P-1) analogue of the recently discovered monoclinic (P21/n) Li7Si2S7I (LSSI), which retains the high computationally predicted Li+ ion conductivity of LSSI....