We showed that using carbon-free cathodes such as ATO in Li-O2 cells can effectively prevent the formation of carbonates on the cathode surface (as generally observed with carbon cathodes). Instead, in addition to the common discharge product Li2O2, substantial amounts of Li2O are formed on ATO. Nonetheless, the fact that only 70% of the O2 consumed during discharge is released upon charge indicates that significant side reactions occur during discharge and charge. This effectively prevents a stable cycling behavior of the ATO cathodes investigated in this study. In contrast to carbon cathodes, where the discharge is governed by Li2O2 formation via a 2e−/O2 process at a constant potential while only a partial monolayer of Li2CO3 is formed on the carbon surface, ATO cathodes lead to the formation of comparable amounts of Li2O2 and Li2O at a sloping discharge potential. The linear pressure decrease during discharge of ATO cathodes implies that the two different processes do not take place in separate time or potential regimes but are superimposed: 4e−/O2 process (Li2O formation), 2e−/O2 process (Li2O2 formation) and partial electrolyte decomposition take place simultaneously. We hypothesize the formation of Li2O monolayer (ML) islands on the ATO surface and the subsequent buildup of Li2O2 layers on top of Li2O islands.
In contrast, the coverage of the ATO surface with Li2O keeps spreading simultaneously. Our hypothesized product deposition mechanism on ATO (lower panel) is compared to the widely accepted deposition mechanism on carbon. If you are looking for high quality, high purity, and cost-effective ATO, or if you require the latest price of ATO, please feel free to email contact mis-asia.