Solvent-Dependent Oxidizing Power of LiI Redox Couples for Li-O2 Batteries
Name
Solvent-Dependent Oxidizing Power of LiI Redox Couples for Li-O2 Batteries.pdf
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3.1 MB
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Adobe PDF
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Author(s)
Leverick, Graham M.
Tułodziecki, Michał
Tatara, Ryoichi
Bardé, Fanny
Shao-Horn, Yang
Date Issued
April 2019
Journal
Joule
Publisher
Elsevier BV
Citation
Leverick, Graham M. et al. "Solvent-Dependent Oxidizing Power of LiI Redox Couples for Li-O2 Batteries." Joule 3, 4 (April 2019): 1106-1126. © 2018 Elsevier Inc.
Version
Author's final manuscript
Abstract
Li-O₂ batteries offer higher gravimetric energy density than commercial Li-ion batteries. Despite this promise, catalyzing oxidation of discharge products, Li₂O₂ and LiOH, during charging remains an obstacle to improved cycle life and round-trip efficiency. In this work, reactions between LiI, a soluble redox mediator added to catalyze the charging process, and Li₂O₂ and LiOH are systematically investigated. We show that stronger solvation of Li⁺ and I⁻ ions led to an increase in the oxidizing power of I₃⁻, which allowed I₃⁻ to oxidize Li₂O₂ and LiOH in DMA, DMSO, and Me-Im, whereas in weaker solvents (G4, DME), the more oxidizing I₂ was needed before a reaction could occur. We observed that Li₂O₂ was oxidized to O₂, whereas LiOH reacts to form IO⁻, which could either disproportionate to LiIO₃ or attack solvent molecules. This work clarifies significant misconceptions in these reactions and provides a thermodynamic and selectivity framework for understanding the role of LiI in Li-O₂ batteries.
MIT Department
Massachusetts Institute of Technology. Department of Mechanical Engineering
Massachusetts Institute of Technology. Research Laboratory of Electronics
Massachusetts Institute of Technology. Department of Materials Science and Engineering
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Creative Commons Attribution-NonCommercial-NoDerivs License
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DOI of Published Version
https://doi.org/10.1016/j.joule.2018.12.014
