Extending the Redox Potentials of Metal-Free Anolytes: Towards High Energy Density Redox Flow Batteries
Extending the Redox Potentials of Metal-Free Anolytes: Towards High Energy Density Redox Flow Batteries
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DOI：
10.1149/1945-7111/ab9e84
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发表时间：
2020-06
影响因子：
3.9
通讯作者：
J. Chai;A. Lashgari;Xiao Wang;J. Jiang
中科院分区：
文献类型：
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作者：
J. Chai;A. Lashgari;Xiao Wang;J. Jiang
非水有机氧化还原液流电池（NORFBs）已成为一种有前途的可再生能源存储和转换技术。由于有机阳极电解液和阴极电解液在有机介质中的高溶解度和高工作电压，可以实现高容量和功率密度。然而，缺乏具有高氧化还原电位的阳极电解质材料及其差的电化学稳定性阻碍了NORFB的广泛应用。在这里，我们研究了一组联吡啶及其类似物作为阳极电解液的进化设计，并研究了它们在全液流电池中的性能。使用重复伏安法，较低的扫描速率循环伏安法，质子核磁共振和密度泛函理论计算的组合技术，我们可以快速评估这些氧化还原候选人的氧化还原电位，稳定性和可逆性。将有希望的候选物4-吡啶基吡啶鎓双（三氟甲磺酰基）酰亚胺（monoMebiPy）和4，4 '-联吡啶（4，4'-biPy）进行电池循环。对后循环电解质进行了扩展研究，以分析容量衰减的途径，并揭示了monoMebiPy的还原促进甲基转移机制。发现了一系列易于获得的具有高氧化还原稳定性和氧化还原电位的阳极电解液分子，其可应用于NORFB中。
Non-aqueous organic redox flow batteries (NORFBs) have emerged as a promising technology for renewable energy storage and conversion. High capacity and power density can be achieved by virtue of high solubility and high operating voltage of the organic anolytes and catholytes in organic media. However, the lack of anolyte materials with high redox potentials and their poor electrochemical stability retard the wider application of NORFBs. Here, we investigated an evolutionary design of a set of bipyridines and their analogues as anolytes and examined their performance in full flow batteries. Using combined techniques of repeated voltammetry, lower scan rate cyclic voltammetry, proton nuclear magnetic resonance, and density functional theory calculations, we could rapidly evaluate the redox potential, stability, and reversibility of these redox candidates. The promising candidates, 4-pyridylpyridinium bis (trifluoromethanesulfonyl) imide (monoMebiPy) and 4, 4'-bipyridine (4, 4'-biPy), were subjected to battery cycling. Extended studies of the post-cycling electrolytes were conducted to analyze the pathway of capacity fading and revealed a reduction-promoted methyl group shift mechanism for monoMebiPy. A family of easily accessible anolyte molecules with high redox stability and redox potentials was discovered that can be applied in NORFBs.