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UV-Vis spectrophotometry of quinone flow battery electrolyte for in situ monitoring and improved electrochemical modeling of potential and quinhydrone formation
Physical Chemistry Chemical Physics ( IF 3.3 ) Pub Date : 2017-11-15 00:00:00 , DOI: 10.1039/c7cp05881k
Liuchuan Tong 1, 2, 3, 4 , Qing Chen 3, 4, 5 , Andrew A. Wong 3, 4, 5 , Rafael Gómez-Bombarelli 1, 2, 3, 4 , Alán Aspuru-Guzik 1, 2, 3, 4 , Roy G. Gordon 1, 2, 3, 4 , Michael J. Aziz 3, 4, 5
Affiliation  

Quinone-based aqueous flow batteries provide a potential opportunity for large-scale, low-cost energy storage due to their composition from earth abundant elements, high aqueous solubility, reversible redox kinetics and their chemical tunability such as reduction potential. In an operating flow battery utilizing 9,10-anthraquinone-2,7-disulfonic acid, the aggregation of an oxidized quinone and a reduced hydroquinone to form a quinhydrone dimer causes significant variations from ideal solution behavior and of optical absorption from the Beer–Lambert law. We utilize in situ UV-Vis spectrophotometry to establish (a), quinone, hydroquinone and quinhydrone molar attenuation profiles and (b), an equilibrium constant for formation of the quinhydrone dimer (KQHQ) ∼ 80 M−1. We use the molar optical attenuation profiles to identify the total molecular concentration and state of charge at arbitrary mixtures of quinone and hydroquinone. We report density functional theory calculations to support the quinhydrone UV-Vis measurements and to provide insight into the dimerization conformations. We instrument a quinone–bromine flow battery with a Pd–H reference electrode in order to demonstrate how complexation in both the negative (quinone) and positive (bromine) electrolytes directly impacts measured half-cell and full-cell voltages. This work shows how accounting for electrolyte complexation improves the accuracy of electrochemical modeling of flow battery electrolytes.

中文翻译:

醌液流电池电解质的紫外可见分光光度法,用于原位监测和改进的电位和醌氢醌形成电化学模型

基于醌的水性液流电池由于其富含地球的元素组成,高水溶性,可逆的氧化还原动力学及其化学可调性(如还原电位),为大规模,低成本的能量存储提供了潜在的机会。在使用9,10-蒽醌-2,7-二磺酸的液流电池中,氧化醌和还原对苯二酚的聚集形成醌氢醌二聚体会导致与理想溶液行为和Beer-Lambert的光吸收发生显着变化法律。我们利用原位紫外可见分光光度法确定(a)醌,对苯二酚和对苯二酚的摩尔衰减曲线,以及(b)形成对苯二酚二聚体(K QHQ〜80 M的平衡常数。-1。我们使用摩尔光学衰减曲线来确定醌和对苯二酚任意混合物的总分子浓度和电荷状态。我们报告密度泛函理论计算,以支持对醌紫外-可见光谱测量,并提供对二聚构象的深入了解。我们用Pd-H参比电极对醌-溴液流电池进行了测试,以证明在负极(醌)和正极(溴)电解质中的络合如何直接影响所测的半电池和全电池电压。这项工作表明解决电解质络合如何提高液流电池电解质电化学建模的准确性。
更新日期:2017-11-22
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