An Iodine Quantum Dots Based Rechargeable Sodium-Iodine Battery

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• 作者：Decai Gong ; Bin Wang ; Jingyi Zhu ; Ramakrishna Podila ; Apparao M. Rao ; Xinzhi Yu ; Zhi Xu and Bingan Lu
• 刊名：Advanced Energy Materials
• 出版年：2017
• 出版时间：February 8, 2017
• 年：2017
• 卷：7
• 期：3
• 全文大小：4788K
• ISSN：1614-6840

文摘

Rechargeable sodium–iodine batteries represent a promising scalable electrochemical energy storage alternative as sodium and iodine are both low cost and widely abundant elements. Here, the authors demonstrate a rechargeable sodium–iodine battery that employs free-standing iodine quantum dots (IQDs) decorated reduced graphene oxide (IQDs@RGO) as the cathode. Consistent with the density functional theory the authors find the Na⁺ ions to intercalate into the I unit cell forming stable NaI, and the battery exhibits high capacity, outstanding cycle stability (with a reversible specific capacity of 141 mA h g⁻¹ after 500 cycles at current density of 100 mA g⁻¹), and high rate performance (170, 146, 127, 112, and 95 mA h g⁻¹ at current densities of 100, 200, 400, 600, and 1000 mA g⁻¹, respectively). The reversible reactions, I₂/I₃ ⁻ and I₃ ⁻/I⁻ redox couples on insertion of Na⁺ ions, are confirmed via in situ Raman spectroscopy. Notably, even after 500 cycles the morphology and structure of the IQDs exhibit no noticeable change implying their use as a stable cathode material for sodium–iodine batteries. Moreover, the IQDs based flexible full-cells also exhibit high capacity and long cycle life (the capacity with 123 mA h g⁻¹ at current density of 100 mA g⁻¹ after 100 cycles).