title: Ambipolar zinc-polyiodide electrolyte for a high-energy density aqueous redox flow battery.
abstract: Redox flow batteries are receiving wide attention for electrochemical energy storage due to their unique architecture and advantages, but progress has so far been limited by their low energy density (~25 Wh l(-1)). Here we report a high-energy density aqueous zinc-polyiodide flow battery. Using the highly soluble iodide/triiodide redox couple, a discharge energy density of 167 Wh l(-1) is demonstrated with a near-neutral 5.0 M ZnI2 electrolyte. Nuclear magnetic resonance study and density functional theory-based simulation along with flow test data indicate that the addition of an alcohol (ethanol) induces ligand formation between oxygen on the hydroxyl group and the zinc ions, which expands the stable electrolyte temperature window to from -20 to 50 °C, while ameliorating the zinc dendrite. With the high-energy density and its benign nature free from strong acids and corrosive components, zinc-polyiodide flow battery is a promising candidate for various energy storage applications.
authors.affiliation: Energy and Environment Directorate, Pacific Northwest National Laboratory, PO Box 999, Richland, Washington 99352, USA.
authors.forename: Bin
authors.initials: B
authors.lastname: Li
authors.affiliation: Energy and Environment Directorate, Pacific Northwest National Laboratory, PO Box 999, Richland, Washington 99352, USA.
authors.forename: Zimin
authors.initials: Z
authors.lastname: Nie
authors.affiliation: Energy and Environment Directorate, Pacific Northwest National Laboratory, PO Box 999, Richland, Washington 99352, USA.
authors.forename: M
authors.initials: M
authors.lastname: Vijayakumar
authors.affiliation: Energy and Environment Directorate, Pacific Northwest National Laboratory, PO Box 999, Richland, Washington 99352, USA.
authors.forename: Guosheng
authors.initials: G
authors.lastname: Li
authors.affiliation: Energy and Environment Directorate, Pacific Northwest National Laboratory, PO Box 999, Richland, Washington 99352, USA.
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.affiliation: Energy and Environment Directorate, Pacific Northwest National Laboratory, PO Box 999, Richland, Washington 99352, USA.
authors.forename: Vincent
authors.initials: V
authors.lastname: Sprenkle
authors.affiliation: Energy and Environment Directorate, Pacific Northwest National Laboratory, PO Box 999, Richland, Washington 99352, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang