Figure shows the discharge of the cell at 20 mA, with periodic rests to measure the open circuit voltage. From this result, it is clear that the open circuit voltage stays constant over a wide compositional change in the system. The constant open circuit voltage supports that the reaction being performed upon discharge is indeed the lithium-oxygen reaction shown in Table . However, more direct evidence is needed to confirm the true discharge reaction. We observe that the cell was able to discharge a total of ~43 mAh of capacity before the open circuit voltage deviates significantly from the Li2O reaction. This is somewhat surprising because the capacity of lithium added to the cell is only ~38 mAh. It is unclear if this is a simple mass measurement error, or if the added capacity is due to additional reactions occurring in the cell. In addition, upon attempting to reverse the reaction, the OCV never returns to lithium metal potentials, indicating that lithium metal is not able to be re-deposited once discharged. We suspect that this lack of reversibility is due to the parasitic reduction of the LLZO tube preventing the deposition of lithium metal.