The Aprotic Li-O2 Battery: O2 Reduction Mechanism and Its Implications

Li-ion and related battery technologies will be important for years to come. However, society needs energy storage that exceeds the capacity of Li-ion batteries. We must explore alternatives to Li-ion if we are to have any hope of meeting the long-term needs for energy storage. One such alternative is the Li-air (O₂) battery; its theoretical specific energy exceeds that of Li-ion, but many hurdles face its realization.^1-5

One spin-off of the recent interest in rechargeable Li-O₂ batteries, based on aprotic electrolytes is that it has highlighted the importance of understanding the fundamental electrochemistry at the positive electrode within the battery.^6-15

The challenges of obtaining efficient, reversible charge and discharge are well documented in the field.  Here, we describe how our recent studies into the electrochemical mechanism of O₂ reduction to form Li₂O₂ at the positive electrode might allow us to design new strategies to overcome these limitations.¹⁶ For example, exploiting the effect of solvent donor number, Fig. 1. We will describe our resent results using redox mediators¹⁷ to facilitate the electrochemistry along with the implications of the results for the future of rechargeable Li-O₂ batteries.

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