Thermogalvanic cells demonstrate inherent physiochemical limitations in redox-active electrolytes at water-in-salt concentrations
Thermogalvanic cells demonstrate inherent physiochemical limitations in redox-active electrolytes at water-in-salt concentrations
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DOI：
10.1016/j.xcrp.2021.100510
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发表时间：
2021-08-18
影响因子：
8.9
通讯作者：
Aldous, Leigh
中科院分区：
文献类型：
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作者：
Buckingham, Mark A.;Laws, Kristine;Aldous, Leigh
人类产生的大部分可用能源作为废热损失，但热电系统(或热电池)可以通过使用氧化还原化学将低品位废热直接转化为电能来解决这一问题。氧化还原对的浓度是一个关键参数；几乎总是，浓度越高，功率越大。这项研究利用Na+和K+反离子之间的简单协同作用，实现了-据我们所知-到目前为止最集中的稳定的铁氰化物/亚铁氰化物水溶液热电池，在1.6m[Fe(CN)(6)](3-/4-)。尽管与标准K-3/K-4[Fe(CN)(6)]电解液(0.4m)相比，浓度提高了400%，但发电量仅增加了166%。将系统从传统的水包盐电解液推入准稳定的盐包水区(长达2.4米)，导致功率下降。详细的描述突出了这些极其浓缩的电解液造成的各种物理化学障碍；所确定的问题与也寻求使用尽可能高浓度的其他能源系统有直接关系。
The majority of usable energy generated by humanity is lost as waste heat, but thermogalvanic systems (or thermocells) can address this problem by converting low-grade waste heat directly into electricity using redox chemistry. The concentration of the redox couple is a critical parameter; almost invariably, higher concentrations result in more power. This study exploits the simple synergy between Na+ and K+ counter ions to achieve-to the best of our knowledge-the most concentrated stable aqueous ferricyanide/ferrocyanide thermocell to date, at 1.6 m [Fe(CN)(6)](3-/4-). Despite increasing the concentration by 400% relative to the standard K-3/K-4[Fe(CN)(6)] electrolyte (0.4 m), electrical power production increased only 166%. Pushing the system from conventional salt-in-water electrolytes into the quasi-stable water-in-salt region (up to 2.4 m) resulted in a decrease in power. Detailed characterization highlighted the various physicochemical hurdles introduced by these extremely concentrated electrolytes; the identified issues have direct relevance to other energy systems also seeking to use the highest possible concentration.