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

doi:10.1038/nchem.2132

paper

On the Origin and Implications of Li $_{2}$ O $_{2}$ Toroid Formation in Nonaqueous Li-O $_{2}$ Batteries

arXiv:1406.3335 · doi: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.

15 pages, 6 figures and Supplementary Information

On the Origin and Implications of Li2​O2​ Toroid Formation in Nonaqueous Li-O2​ Batteries

Abstract

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On the Origin and Implications of Li $_{2}$ O $_{2}$ Toroid Formation in Nonaqueous Li-O $_{2}$ Batteries