Li+ interstitials as the charge carriers in superionic lithium-rich anti-perovskites

Here, we report that in lithium-rich anti-perovskites (LiRAPs) with lithium halide deficiency, Li+ interstitials outnumber vacancies by 2-3 orders of magnitude, so that interstitials might be the actual charge carriers responsible for superionic conduction, as opposed to what has been assumed so far. This finding has important implications and may be crucial to an efficient tailoring of LiRAPs, aiming their commercial use as safe electrolytes in all-solid-state lithium-ion batteries.