预测钠电解质中的离子缔合：用于研究甘氨酸的可转移模型,The Journal of Physical Chemistry C

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预测钠电解质中的离子缔合：用于研究甘氨酸的可转移模型
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2017-11-22 00:00:00 , DOI: 10.1021/acs.jpcc.7b09995
Ke Li ₁ , Susith R Galle Kankanamge ₁ , Thomas K Weldeghiorghis ₁ , Ryan Jorn ₂ , Daniel G. Kuroda ₁ , Revati Kumar ₁

Affiliation

鉴于先前在开发用于类似目的的锂电池方面取得的成功，已经研究了许多相同类型的溶剂分子和盐对作为钠离子和钠氧系统中的电解质。在这些候选物中，由于它们的电化学稳定性和可用于调节相关电化学的结果，含醚电解质已成为一种有前途的材料。醚螯合金属离子的能力为离子溶剂化结构提供了独特的功能。然而，其在改变溶液中离子缔合方面的作用尚未得到充分探讨。通过使用经FTIR和NMR光谱验证的计算模拟，研究了一系列醚（一元单体到四元单体）由于螯合和浓度而导致的溶剂化结构变化的详细描述。从这些模拟中可以清楚地看到，随着螯合度的增加，离子缔合以非线性方式降低。对于一甘醇二甲醚溶剂，即使在低浓度下，钠也完全由溶液中的三氟甲磺酸盐配位。相反，即使在高浓度下，四甘醇二甲酸酯仍保留钠阳离子与三氟甲磺酸酯阴离子的显着溶剂分离。前者暗示一糖精和二甘醇二甲醚溶剂特别适用于钠空气电池，可能与它们偏爱的离子缔合有关，而四甘醇二甲醚的不良性能是由于其与钠的过度结合所致。最后，由于钠配位和空间相互作用之间不匹配，三甘醇二甲醚会产生异常行为。离子缔合以非线性方式减少。对于一甘醇二甲醚溶剂，即使在低浓度下，钠也完全由溶液中的三氟甲磺酸盐配位。相反，即使在高浓度下，四甘醇二甲酸酯仍保留钠阳离子与三氟甲磺酸酯阴离子的显着溶剂分离。前者暗示一糖精和二甘醇二甲醚溶剂特别适用于钠空气电池，可能与它们偏爱的离子缔合有关，而四甘醇二甲醚的不良性能是由于其与钠的过度结合所致。最后，由于钠配位和空间相互作用之间的不匹配，三甘醇二甲醚会产生异常行为。离子缔合以非线性方式减少。对于一甘醇二甲醚溶剂，即使在低浓度下，钠也完全由溶液中的三氟甲磺酸盐配位。相反，即使在高浓度下，四甘醇二甲酸酯仍保留钠阳离子与三氟甲磺酸酯阴离子的显着溶剂分离。前者暗示单糖和二甘醇二甲醚溶剂在钠-空气电池中的实用性很可能与它们有利的离子缔合有关，而四甘醇二酯的不良性能是由于其与钠的过度结合所致。最后，由于钠配位和空间相互作用之间的不匹配，三甘醇二甲醚会产生异常行为。甚至在高浓度下，四甘醇二甲醚仍保留钠离子与三氟甲磺酸根阴离子的显着溶剂分离。前者暗示一糖精和二甘醇二甲醚溶剂特别适用于钠空气电池，可能与它们偏爱的离子缔合有关，而四甘醇二甲醚的不良性能是由于其与钠的过度结合所致。最后，由于钠配位和空间相互作用之间的不匹配，三甘醇二甲醚会产生异常行为。甚至在高浓度下，四甘醇二甲醚仍可将钠阳离子与三氟甲磺酸根阴离子的溶剂明显分离。前者暗示一糖精和二甘醇二甲醚溶剂特别适用于钠空气电池，可能与它们偏爱的离子缔合有关，而四甘醇二甲醚的不良性能是由于其与钠的过度结合所致。最后，由于钠配位和空间相互作用之间的不匹配，三甘醇二甲醚会产生异常行为。

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Predicting Ion Association in Sodium Electrolytes: A Transferrable Model for Investigating Glymes

Given the prior success in developing lithium batteries for similar purposes, many of the same types of solvent molecules and salt pairings have been investigated as electrolytes in sodium-ion and sodium–oxygen systems. Of these candidates, ether-containing electrolytes have emerged as a promising material as a result of their electrochemical stability and utility in tuning the pertinent electrochemistry. The ability for ethers to chelate metal ions provides a unique feature to ion solvation structure; however its role in changing the association of ions in solution has not been fully explored. By using computational simulations validated by FTIR and NMR spectroscopy, detailed descriptions of the changes to solvation structure as a result of chelation and concentration were investigated for a series of ethers (monoglyme to tetraglyme). From these simulations it can clearly be seen that with increasing chelation, ion association is diminished in a nonlinear fashion. For a monoglyme solvent, sodiums are entirely coordinated by triflates in solution, even at low concentrations. In contrast, tetraglymes retain a significant solvent separation of sodium cations from triflate anions even at high concentrations. The former implies that the utility of monoglyme and diglyme solvents for sodium–air batteries in specific is likely linked to their favoring ion association, while the poor performance of tetraglyme is a result of its excessive binding to sodium. Finally, triglyme was shown to produce anomalous behavior as a result of a mismatch between sodium coordination and steric interactions.

更新日期：2017-11-22

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