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Issue 3, 2017
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Unlocking the capacity of iodide for high-energy-density zinc/polyiodide and lithium/polyiodide redox flow batteries

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Abstract

Highly soluble iodide/triiodide (I/I3) couples are one of the most promising redox-active species for high-energy-density electrochemical energy storage applications. However, to ensure high reversibility, only two-thirds of the iodide capacity is accessed and one-third of the iodide ions act as a complexing agent to stabilize the iodine (I2), forming I3 (I2I). Here, we exploit bromide ions (Br) as a complexing agent to stabilize the iodine, forming iodine–bromide ions (I2Br), which frees up iodide ions and increases the capacity. Applying this strategy, we demonstrate a novel zinc/iodine–bromide battery to achieve an energy density of 101 W h Lposolyte+negolyte−1 (or 202 W h Lposolyte−1), which is the highest energy density achieved for aqueous flow batteries to date. This strategy can be further generalized to nonaqueous iodide-based batteries (i.e. lithium/polyiodide battery), offering new opportunities to improve high-energy iodide-based energy storage technologies.

Graphical abstract: Unlocking the capacity of iodide for high-energy-density zinc/polyiodide and lithium/polyiodide redox flow batteries

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Publication details

The article was received on 07 Dec 2016, accepted on 16 Feb 2017 and first published on 16 Feb 2017


Article type: Communication
DOI: 10.1039/C6EE03554J
Citation: Energy Environ. Sci., 2017,10, 735-741
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    Unlocking the capacity of iodide for high-energy-density zinc/polyiodide and lithium/polyiodide redox flow batteries

    G. Weng, Z. Li, G. Cong, Y. Zhou and Y. Lu, Energy Environ. Sci., 2017, 10, 735
    DOI: 10.1039/C6EE03554J

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