Thermoelectrochemical cells, also known as thermocells, are electrochemical devices for the conversion of thermal energy directly into electricity. They are a promising method for harvesting low‐grade waste heat from a variety of different natural and manmade sources. The development of solid‐ or quasi‐solid‐state electrolytes for thermocells could address the possible leakage problems of liquid electrolytes and make this technology more applicable for wearable devices. Here, we report the gelation of an organic‐solvent‐based electrolyte system containing a redox couple for application in thermocell technologies. The effect of gelation of the liquid electrolyte, comprising a cobalt bipyridyl redox couple dissolved in 3‐methoxypropionitrile (MPN), on the performance of thermocells was investigated. Polyvinylidene difluoride (PVDF) and poly(vinylidene fluoride‐co‐hexafluoropropene) (PVDF‐HFP) were used for gelation of the electrolyte, and the influence of the different polymers on the mechanical properties was studied. The Seebeck coefficient and diffusivity of the cobalt redox couple were measured in both liquid and gelled electrolytes, and the effect of gelation on the thermocell performance is reported. Finally, the cell performance was further improved by optimizing the concentration of the redox couple and the separation between the hot and cold electrodes, and the stability of the device over 25 h of operation is demonstrated.

中文翻译：

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使用钴氧化还原对的低固态热能收集准固态电解质

热电化学电池，也称为热电池，是用于将热能直接转化为电能的电化学装置。它们是从各种不同的自然和人为来源收集低品位废热的有前途的方法。用于热电池的固态或准固态电解质的开发可以解决液态电解质可能发生的泄漏问题，并使该技术更适用于可穿戴设备。在这里，我们报告了一种包含氧化还原对的有机溶剂型电解质体系的胶凝作用，可用于热电池技术。研究了溶解在3-甲氧基丙腈（MPN）中的联吡啶钴氧化还原对钴液体电解质的凝胶化对热电池性能的影响。聚偏二氟乙烯（PVDF）和聚偏二氟乙烯-共-六氟丙烯（PVDF-HFP）用于电解质的凝胶化，研究了不同聚合物对机械性能的影响。在液体和凝胶电解质中都测量了钴氧化还原对的塞贝克系数和扩散系数，并报道了凝胶化对热电池性能的影响。最后，通过优化氧化还原对的浓度以及热电极和冷电极之间的间距，进一步提高了电池性能，并证明了该器件在运行25小时后的稳定性。在液体和凝胶电解质中都测量了钴氧化还原对的塞贝克系数和扩散系数，并报道了凝胶化对热电池性能的影响。最后，通过优化氧化还原对的浓度以及热电极和冷电极之间的间距，进一步提高了电池性能，并证明了该器件在运行25小时后的稳定性。在液体和凝胶电解质中都测量了钴氧化还原对的塞贝克系数和扩散系数，并报道了凝胶化对热电池性能的影响。最后，通过优化氧化还原对的浓度以及热电极和冷电极之间的间距，进一步提高了电池性能，并证明了该器件在运行25小时后的稳定性。