The SoLiK project examines the interrelations between the chemical composition, morphology and electrical conductivity (focus on lithium-ion conductivity) in lithium oxide garnets (LLZO) through the use of very innovative electrochemical measuring methods. Using microelectrodes, local conductivity investigations are carried out on grains and grain boundaries and these are correlated with precise local quantitative chemical analyzes of the measured samples. The structure-property relationships are studied in detail in LLZO bulk samples and LLZO thin films, with two important methods for the preparation of thin films being directly compared. In the final phase of the project, the preparability of sandwich-design type thin-film all-solid-state batteries is investigated with LLZO electrolyte and the cells are characterised electrochemically.