Metallic Lithium formation during Solid State Electrolyte Failure

POLARIS beamtime will be used to determine the origin of the atoms that form metallic lithium during solid state electrolyte failure. Fast Li+ conducting garnets will be cycled offline at varying critical current densities to induce formation of metallic lithium and a short circuit. By performing this experiment with 6Li electrodes and 7Li garnet electrolyte we will be able to determine if the metallic lithium is formed (a) from 7Li already present in the electrolyte or (b) from 6Li which requires mass transport from the electrode/electrolyte interface. Resolving between these two cases will give unique insight into the garnet failure mechanisms for solid state batteries. Two days of beamtime will be used to examine three garnet compositions in pristine form and post-mortem and determine the role of different dopants in inhibiting/facilitating different failure modes.