Cobalt(II) complexes with azole-pyridine type ligands for non-aqueous redox-flow batteries: Tunable electrochemistry via structural modification
Cobalt(II) complexes with azole-pyridine type ligands for non-aqueous redox-flow batteries: Tunable electrochemistry via structural modification
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DOI：
10.1016/j.jpowsour.2017.03.034
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发表时间：
2017-05-01
影响因子：
9.2
通讯作者：
Toghill, Kathryn E.
中科院分区：
文献类型：
--
作者：
Armstrong, Craig G.;Toghill, Kathryn E.
报道了一种新型的三齿吡咯-吡啶配体钴配合物的单物种氧化还原液流电池。四种结构的合成和它们的电化学，物理和电池特性进行了研究，作为一个功能的配体末端吡啶基供体的连续取代。Co（II/I）和Co（III/II）对在金和玻碳电极上是稳定的和准可逆的，然而氧化还原电位是可调的，允许钴电位差通过用较弱的σ-供给/π-接受3，5-二甲基吡唑基团的吡啶取代从1.07优先增加到1.91 V。使用H型玻璃电池和石墨棒电极评价了系统的充放电性能。配合物提供89.7-99.8%的高库仑效率和70.3- 81.0%的非常好的伏打效率。因此，能源效率高达63.1- 80.8%，标志着对其他类似非水系统的改进。通过用3，5-二甲基吡唑取代吡啶基，配体的改性也将溶解度从0.18 M提高到0.50 M，尽管络合物的低溶解度将总能量限制在2.58和12.80 W h L-1之间。初步的流动池研究在一个原型流动池也证明。皇冠版权所有（C）2017由Elsevier B. V.发布。保留所有权利。
A single species redox flow battery employing a new class of cobalt(II) complexes with 'tunable' tridentate azole-pyridine type ligands is reported. Four structures were synthesised and their electrochemical, physical and battery characteristics were investigated as a function of successive substitution of the ligand terminal pyridyl donors. The Co(II/I) and Co(III/II) couples are stable and quasi-reversible on gold and glassy carbon electrodes, however redox potentials are tunable allowing the cobalt potential difference to be preferentially increased from 1.07 to 1.91 V via pyridine substitution with weaker sigma-donating/pi-accepting 3,5-dimethylpyrazole groups. The charge-discharge properties of the system were evaluated using an H-type glass cell and graphite rod electrodes. The complexes delivered high Coulombic efficiencies of 89.7-99.8% and very good voltaic efficiencies of 70.3-81.0%. Consequently, energy efficiencies are high at 63.1-80.8%, marking an improvement on other similar non-aqueous systems. Modification of the ligands also improved solubility from 0.18 M to 0.50 M via pyridyl substitution with 3,5-dimethylpyrazole, though the low solubility of the complexes limits the overall energy capacity to between 2.58 and 12.80 W h L-1. Preliminary flow cell studies in a prototype flow cell are also demonstrated. Crown Copyright (C) 2017 Published by Elsevier B.V. All rights reserved.