We study the capacity fade rate of a flow battery utilizing 2,6-dihydroxyanthraquinone (DHAQ) and its dependence on hydroxide concentration, state of charge, cutoff voltages for the discharge step and for the electrochemical regeneration (oxidation of decomposition compounds back to active species) step, and period of performing the electrochemical regeneration events. Our observations confirm that the first decomposition product, 2,6-dihydroxyanthrone (DHA), is stable but after electro-oxidative dimerization, the anthrone dimer decomposes. We identify conditions for which there is little time after dimerization until the dimer is rapidly re-oxidized electrochemically to form DHAQ. Combining these approaches, we decrease the fade rate to 0.02%/day, which is 18 times lower than lowest rate reported previously of 0.38%/day, and over 200 times lower than the value under standard cycling conditions of 4.3%/day. The findings and their mechanistic interpretation are expected to extend the lifetime and enhance the effectiveness of in-situ electrochemical regeneration for other electroactive species with finite lifetimes.

中文翻译：

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液流电池运行期间 2,6-二羟基蒽醌的寿命延长 200 倍

我们研究了使用 2,6-二羟基蒽醌 (DHAQ) 的液流电池的容量衰减率及其对氢氧化物浓度、充电状态、放电步骤和电化学再生（分解化合物氧化回活性物质）的截止电压的依赖性) 执行电化学再生事件的步骤和周期。我们的观察证实，第一个分解产物 2,6-二羟基蒽酮 (DHA) 是稳定的，但在电氧化二聚化后，蒽酮二聚体分解。我们确定了二聚化后几乎没有时间直到二聚体被快速电化学再氧化形成 DHAQ 的条件。结合这些方法，我们将褪色率降低至 0.02%/天，比之前报告的最低褪色率 0.38%/天低 18 倍，比标准循环条件下的值 4.3%/天低 200 多倍。这些发现及其机理解释预计将延长其他寿命有限的电活性物质的寿命并提高原位电化学再生的有效性。