Bi Songshan, Wang Huimin, Zhang Yanyu, Yang Min, Li Qingjie, Tian Jinlei, Niu Zhiqiang
Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Renewable Energy Conversion and Storage Center, Haihe Laboratory of Sustainable Chemical Transformations, College of Chemistry, Nankai University, Tianjin, 300071, P. R. China.
Angew Chem Int Ed Engl. 2023 Dec 4;62(49):e202312982. doi: 10.1002/anie.202312982. Epub 2023 Nov 3.
Iodine (I ) shows great promising as the active material in aqueous batteries due to its distinctive merits of high abundance in ocean and low cost. However, in conventional aqueous I -based batteries, the energy storage mechanism of I /I conversion is only two-electron redox reaction, limiting their energy density. Herein, six-electron redox chemistry of I electrodes is achieved via the synergistic effect of redox-ion charge-carriers and halide ions in electrolytes. The redox-active Cu ions in electrolytes induce the conversion between Cu ions and I to CuI at low potential. Simultaneously, the Cl ions in electrolytes activate the I /ICl redox couple at high potential. As a result, in our case, I -based battery system with six-electron redox is developed. Such energy storage mechanism with six-electron redox leads to high discharge potential and capacity, excellent rate capability, as well as stable cycling behavior of I electrodes. Impressively, six-electron-redox I cathodes can match various aqueous metal (e.g. Zn, Mn and Fe) anodes to construct metal||I hybrid batteries. These hybrid batteries not only deliver enhanced capacities, but also exhibit higher operate voltages, which contributes to superior energy densities. Therefore, this work broadens the horizon for the design of high-energy aqueous I -based batteries.
碘（I）因其在海洋中储量丰富且成本低的独特优点，在水系电池中作为活性材料展现出巨大潜力。然而，在传统的水系碘基电池中，I⁻/I的储能机制仅是两电子氧化还原反应，限制了它们的能量密度。在此，通过氧化还原离子电荷载体与电解质中卤离子的协同效应，实现了I电极的六电子氧化还原化学。电解质中的氧化还原活性Cu离子在低电位下诱导Cu离子与I⁻转化为CuI。同时，电解质中的Cl离子在高电位下激活I⁻/ICl氧化还原对。结果，在我们的研究中，开发出了具有六电子氧化还原的碘基电池系统。这种具有六电子氧化还原的储能机制导致I电极具有高放电电位和容量、优异的倍率性能以及稳定的循环行为。令人印象深刻的是，六电子氧化还原的I阴极可以与各种水系金属（如Zn、Mn和Fe）阳极相匹配，构建金属||I混合电池。这些混合电池不仅具有更高的容量，还表现出更高的工作电压，这有助于实现更高的能量密度。因此，这项工作拓宽了高能水系碘基电池设计的视野。
