On the Origin and Implications of Li${}_2$O${}_2$ Toroid Formation in Nonaqueous Li-O${}_2$ Batteries

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${}^{\prime }$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${}^{\prime }$s tendency to trigger the solution process, providing a rational design route for electrolytes that afford larger Li-air battery capacities.

arXiv comment15 pages, 6 figures and Supplementary Information

References in corpus (2)

• Charge transport in lithium peroxide: Relevance for rechargeable metal-air batteries
• Rate-dependent morphology of Li2O2 growth in Li-O2 batteries

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• Ion-Pairing Limits Crystal Growth in Metal-Oxygen Batteries
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• The role of disorder in NaO${}_2$ and its implications for Na-O${}_2$ batteries