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arXiv · 1406.3335

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

Nagaphani B. Aetukuri·Bryan D. McCloskey·Jeannette M. García·Leslie E. Krupp·Venkatasubramanian Viswanathan·Alan C. Luntz
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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.

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Nagaphani B. Aetukuri, Bryan D. McCloskey, Jeannette M. García, Leslie E. Krupp, Venkatasubramanian Viswanathan, Alan C. Luntz. 2014-06-12. On the Origin and Implications of Li$_2$O$_2$ Toroid Formation in Nonaqueous Li-O$_2$ Batteries. https://doi.org/10.1038/nchem.2132

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