Solvating additives drive solution-mediated electrochemistry and enhance toroid growth in non-aqueous Li–O2 batteries
- 15 December 2014
- journal article
- Published by Springer Science and Business Media LLC in Nature Chemistry
- Vol. 7 (1), 50-56
- https://doi.org/10.1038/nchem.2132
Abstract
The lithium-air (Li-O$_2$) battery has received enormous attention as a possible alternative to current state-of-the-art rechargeable Li-ion batteries given their high theoretical specific energy. However, the maximum discharge capacity in nonaqueous Li-O$_2$ batteries is limited to a small fraction of its theoretical value due to the insulating nature of lithium peroxide, Li$_2$O$_2$, the battery$'$s primary discharge product. In this work, we show that the inclusion of trace amounts of electrolyte additives, such as H$_2$O, significantly improve the capacity of the Li-O$_2$ battery. These additives trigger a solution-based growth mechanism due to their solvating properties, thereby circumventing the Li$_2$O$_2$ conductivity limitation. Experimental observations and a growth model imply that this solution mechanism is responsible for Li$_2$ toroid formation. We present a general formalism describing an additive$'$s tendency to trigger the solution process, providing a rational design route for electrolytes that afford larger Li-air battery capacities.Comment: 15 pages, 6 figures and Supplementary InformatioKeywords
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