All AIMD calculations were carried for at least 100 ps (with the exception of Li 2 OHCl, which used a smaller time step and ran for at least 80 ps) using the NVT ensemble with a Nosé-Hoover thermostat. Simulations were ran at temperatures of 600 K, 800 K, and 1000 K for Li 2 OHCl, Li 3 PS 4 and Li 3 InCl 6 , and at elevated temperatures of 600 K, 800 K, 1000 K, and 1200 K for Li 3 OCl due to the low levels of diffusion observed at the GBs in this material.