K+ Single Cation Ionic Liquids Electrolytes with Low Melting Asymmetric Salt
K+ Single Cation Ionic Liquids Electrolytes with Low Melting Asymmetric Salt
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具有低熔点不对称盐的 K 单阳离子离子液体电解质
DOI：
10.1021/acs.jpcc.2c03030
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发表时间：
2022
期刊：
影响因子：
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通讯作者：
Yiying Wu
中科院分区：
文献类型：
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作者：
Luke Schkeryantz;Phu Nguyen;W. McCulloch;C. Moore;K. Lau;Yiying Wu
K+单阳离子离子液体(K-SCIL)仅含有K+阳离子。作为钾电池电解质时，它不仅具有常规离子液体的不燃性、蒸气压可忽略不计、电化学稳定性好等特性，而且提高了K+传输数，减少了电解质的浓差极化，提高了电池的功率性能。在这项研究中，我们报道了基于(3-甲氧基丙基)((三氟甲基)磺酰基)酰胺(MPSA–)的低熔点(Tm∼50°C)钾盐的K-SCIL。与双(氟磺酰基)亚胺钾 (KFSI) 结合，两种盐的混合物在低至 -13 °C 时以液体形式存在，首次产生室温 K-SCIL。建立相图，并测量各种组合物的离子电导率。尽管室温离子电导率较低，但温和加热至 55 °C 可将电导率提高至 >1 mS/cm。在该 K-SCIL 中还发现了对 K+ 浓度梯度具有强烈抵抗力以及接近统一的 K 传输数的证据。该报告希望为发现熔点更低的钾盐提供灵感，以实现低温 K-SCIL 电解质，并探索 SCIL 在实际电池中的优势。
A K+single cation ionic liquid (K-SCIL) contains only K+cations. When used as an electrolyte in potassium batteries, it not only possesses the properties of conventional ionic liquids such as nonflammability, negligible vapor pressure, and good electrochemical stability but also increases the K+transport number, which reduces concentration polarization of the electrolyte and improves the battery power performance. In this study, we report K-SCILs based on the low melting (Tm∼ 50 °C) potassium salt of (3-methoxypropyl)((trifluoromethyl)sulfonyl) amide (MPSA–). Combined with potassium bis(fluorosulfonyl)imide (KFSI), the mixture of the two salts exists as a liquid at as low as −13 °C, generating for the first time a room-temperature K-SCIL. The phase diagram is established, and the ionic conductivities of various compositions are measured. Although the room-temperature ionic conductivity is low, mild heating to 55 °C enhances the conductivity to >1 mS/cm. Evidence for a strong resistance to K+concentration gradients as well as a near unity K transport number were also found in this K-SCIL. This report hopes to serve as inspiration for the discovery of even lower melting K salts to enable low temperature K-SCIL electrolytes and to explore the benefits of SCILs in practical cells.