A High Potential, Low Capacity Fade Rate Iron Complex Posolyte for Aqueous Organic Flow Batteries
A High Potential, Low Capacity Fade Rate Iron Complex Posolyte for Aqueous Organic Flow Batteries
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DOI：
10.1002/aenm.202202444
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发表时间：
2022-10
影响因子：
27.8
通讯作者：
Jinxu Gao;Kiana Amini;T. George;Y. Jing;Tatsuhiro Tsukamoto;Dawei Xi;R. Gordon;M. Aziz
中科院分区：
文献类型：
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作者：
Jinxu Gao;Kiana Amini;T. George;Y. Jing;Tatsuhiro Tsukamoto;Dawei Xi;R. Gordon;M. Aziz
报道了一种铁络合物，三（4，4 ′-双（羟甲基）-2，2 ′-联吡啶）二氯化铁，其在近中性pH下工作，氧化还原电位为0.985 V（相对于SHE）。这种高电位化合物用于水液流电池的正极电解液中，与双（3-三甲基铵基）丙基紫精四氯化物在正极电解液中配对，在近中性pH下显示出1.3 V的开路电压。它表现出优异的循环性能，在35天的循环中，每天的时间容量衰减率为0.07%。延长的循环寿命是新开发的铁络合物与三（联吡啶）铁络合物相比的低渗透性和改善的结构稳定性的结果。高氧化还原电位和低容量衰减速率的组合与所有先前证明的有机和有机金属水性正极液的组合相比是有利的。对可能的降解机制的广泛研究，包括死后化学和电化学分析，表明铁络合物的逐步配体解离是电池循环期间报告的容量损失的原因。这项研究提供了前所未有的洞察力，以指导进一步改进这种金属有机化合物的能量储存和转换应用。
An iron complex, tris(4,4′‐bis(hydroxymethyl)‐2,2′‐bipyridine) iron dichloride is reported, which operates at near‐neutral pH with a redox potential of 0.985 V versus SHE. This high potential compound is employed in the posolyte of an aqueous flow battery, paired with bis(3‐trimethylammonio)propyl viologen tetrachloride in the negolyte, exhibiting an open‐circuit voltage of 1.3 V at near‐neutral pH. It demonstrates excellent cycling performance with a low temporal capacity fade rate of 0.07% per day over 35 days of cycling. The extended cycling lifetime is the result of low permeability and improved structural stability of the newly developed iron complex compared to that of the iron tris(bipyridine) complex. The combination of high redox potential and low capacity fade rate compares favorably with those of all previously demonstrated organic and organometallic aqueous posolytes. Extensive investigation into the possible degradation mechanisms, including post‐mortem chemical and electrochemical analyses, indicates that stepwise ligand dissociations of the iron complex are responsible for the reported capacity loss during cell cycling. This investigation provides unprecedented insight to guide further improvements of such metalorganic compounds for energy storage and conversion applications.