History effects in lithium-oxygen batteries: How initial seeding influences the discharge capacity

In laboratory experiments, Li-O₂ systems show "sudden death" at capacities far below the theoretical value. Identifying how discharge products limit the total capacity is crucial in Li-O₂ system. We investigated the effect of Li₂O₂ seed layer deposited on carbon cathode under potentiostatic conditions at increasing overpotentials to the subsequent slow discharge at galvanostatic condition. The discharge capacity attainable in the second step is found to vary by more than a factor of 3 depending on the history, i.e., the seed layer. These results provide evidence that the battery history is decisive for the total discharge capacities. History lesson: The discharge product will at some point form the surface of the ongoing electrochemical reaction in Li-O₂ battery. The nature of Li₂O₂ deposits are crucial for a battery's capacity performance. The discharge profiles of carbon cathodes that are precovered by Li₂O₂ seed layers are compared. The layers are Coulometrically equal but are deposited at varying deposition rates, and demonstrate how faster initial seeding leads to lower total discharge capacities. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.