Iodine cathode in aqueous battery has drawn great attention due to its high energy density and high safety. However, iodine has extremely low conductivity of 1×10-7 S cm-1, which usually results in low specific capacity. In this work, a PVA-hydrogel layer was designed to enhance the areal capacity of zinc-iodine cell. The areal capacity of PVA-hydrogel layer modified CNT cathode showed twice as higher capacity than that of pure CNT film in a dual-plating cell, The significant enhancement of the capacity was attributed to the fast iodine transport in the PVA-hydrogel layer. Besides, the strong interaction between PVA chain and polyiodide anions prevented the shuttle effect. The PVA modified CNT cathode could stably operate for over 3000 hours with remarkably higher capacity and cycle life. We analyzed the uniquely fast transport behavior of polyiodides in PVA hydrogel by in-situ Raman spectroscopy, in-situ optical micrography, as well as DFT calculations. It was found that the strong binding force together with lower dissociation energy of iodine on PVA chain is the dominate reason for reduced shuttle effect and fast polyiodide transport. As a result, the assembled PVA-I2 pouch cells showed excellent performance in both dual-plating cells and conventional-type cells.

中文翻译：

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聚合物碘传输层实现高面容量双电镀锌碘电池


水系电池中的碘正极因其高能量密度和高安全性而受到广泛关注。然而，碘具有 1×10-7 S cm-1 的极低电导率，这通常会导致比活量低。在这项工作中，设计了 PVA-水凝胶层以增强锌碘电池的面容量。在双电镀电池中，PVA-水凝胶层改性的 CNT 阴极的面容量是纯 CNT 薄膜的两倍，容量的显着增强归因于 PVA-水凝胶层中的快速碘传输。此外，PVA 链与聚碘阴离子之间的强相互作用阻止了穿梭效应。PVA 改性的 CNT 阴极可以稳定运行超过 3000 小时，具有显着更高的容量和循环寿命。我们通过原位拉曼光谱、原位光学显微摄影以及 DFT 计算分析了聚碘化物在 PVA 水凝胶中独特的快速传输行为。研究发现，碘在 PVA 链上的强结合力和较低的解离能是穿梭效应降低和聚碘转运快的主要原因。结果，组装的 PVA-I2 软包电池在双电镀电池和传统电池中均表现出优异的性能。