The utilization of the strategy to replace Li + ions with ions carrying greater positive charges, thereby creating vacancies through which lithium ions can migrate, has been proven effective for materials exhibiting crystal structures akin to the mineral garnet. with the M ion potentially being Nb or Ta. These materials were reported to possess lithium ion conductivities of approximately 10 -6 S cm -1 at room temperature, which is roughly three orders of magnitude lower than the data reported for the previously mentioned (La,Li)TiO 3