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Nat Chem. 2015 Jan;7(1):50-6. doi: 10.1038/nchem.2132. Epub 2014 Dec 15.

Solvating additives drive solution-mediated electrochemistry and enhance toroid growth in non-aqueous Li-O₂ batteries.

Author information

1
IBM Almaden Research Center, San Jose, California 95120, USA.
2
1] IBM Almaden Research Center, San Jose, California 95120, USA [2] Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, USA [3] Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720.
3
Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA.
4
1] IBM Almaden Research Center, San Jose, California 95120, USA [2] SUNCAT, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.

Abstract

Given their high theoretical specific energy, lithium-oxygen batteries have received enormous attention as possible alternatives to current state-of-the-art rechargeable Li-ion batteries. However, the maximum discharge capacity in non-aqueous lithium-oxygen batteries is limited to a small fraction of its theoretical value due to the build-up of insulating lithium peroxide (Li₂O₂), the battery's primary discharge product. The discharge capacity can be increased if Li₂O₂ forms as large toroidal particles rather than as a thin conformal layer. Here, we show that trace amounts of electrolyte additives, such as H₂O, enhance the formation of Li₂O₂ toroids and result in significant improvements in capacity. Our experimental observations and a growth model show that the solvating properties of the additives prompt a solution-based mechanism that is responsible for the growth of Li₂O₂ toroids. 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 lithium-oxygen battery capacities.

PMID:
25515890
DOI:
10.1038/nchem.2132

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