All-solid-state batteries (ASSBs) are widely viewed as a safer and more powerful alternative to conventional lithium-ion batteries, but their promise is often limited by unstable interfaces inside the cell. A new study shows that carefully introducing oxygen into a sulfide-based solid electrolyte (SE) can stabilize this vulnerable interface while keeping lithium ions moving rapidly. Using lithium sulfate (Li₂SO₄) as an oxygen source, the researchers reshaped the internal lithium pathways of an a