Jónsson Erlendur, Berge Astrid H, Grey Clare P, Temprano Israel
Yusuf Hamied Department of Chemistry, University of Cambridge, UK.
Faraday Discuss. 2024 Jan 29;248(0):145-159. doi: 10.1039/d3fd00090g.
Iodide-based redox mediation in Li-O batteries is regarded as a promising system due to its relatively high round-trip efficiency, compared to alternative systems. Here we explore the role of electrolyte composition in the solvation of I, which has been shown to be critical for the efficient operation of this redox mediator, using a molecular dynamics approach. A combinatorial exploration of I and HO concentrations was performed, for a fixed concentration of Li, across a series of glymes, with increasing chain length (mono- to tetraglyme). The resulting radial distribution functions show that shorter glymes allow for a closer packing of the I redox mediator. Furthermore, increasing the I concentration also reduces the solvation of Li in the glymes, especially in G2. The presence of water further pulls the I and Li together. With increasing water content, its presence in the iodide's coordination shell increases markedly - an effect most pronounced for monoglyme. Competition between Li and I for the coordination of water is modulated by the different solvents as they perturb the local coordination shell of these important complexes, with longer chain lengths being less affected by increases in water concentrations.
与其他替代体系相比，锂氧电池中基于碘化物的氧化还原介导因其相对较高的往返效率而被视为一种很有前景的体系。在此，我们使用分子动力学方法探究电解质组成在碘（I）溶剂化过程中的作用，该作用已被证明对这种氧化还原介质的高效运行至关重要。在一系列链长不断增加（从单甘醇二甲醚到四甘醇二甲醚）的甘醇二甲醚中，针对固定的锂（Li）浓度，对碘（I）和水（HO）浓度进行了组合探索。所得的径向分布函数表明，较短的甘醇二甲醚能使碘氧化还原介质的堆积更紧密。此外，增加碘（I）的浓度也会降低锂（Li）在甘醇二甲醚中的溶剂化程度，尤其是在二甘醇二甲醚（G2）中。水的存在会进一步使碘（I）和锂（Li）靠近。随着含水量增加，其在碘化物配位壳中的存在显著增加——这种效应在单甘醇二甲醚中最为明显。锂（Li）和碘（I）对水配位的竞争受到不同溶剂的调节，因为它们会扰乱这些重要络合物的局部配位壳，链长较长的溶剂受水浓度增加的影响较小。
