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.
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机译：氧化还原液流电池由于其独特的结构和优点而在电化学能量存储方面受到广泛关注，但迄今为止，其发展一直受到其低能量密度（〜25 Wh l -1 ）的限制。在这里，我们报告了一种高能量密度的水性聚氧化锌液流电池。使用高度可溶的碘化物/三碘化物氧化还原对，在接近中性的5.0 M ZnI2电解质中，放电能量密度为167 Wh l -1 。核磁共振研究和基于密度泛函理论的模拟以及流动测试数据表明，添加醇（乙醇）会诱导羟基上的氧与锌离子之间形成配体，从而将稳定的电解质温度范围扩大至- 20至50°C，同时改善锌枝晶。凭借高能量密度及其无强酸和腐蚀性成分的良性，聚碘化锌液流电池是各种储能应用的有前途的候选者。
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