Wang Yaqing, Chen Wenjun, Zhao Qi, Jin Guizhen, Xue Zhimin, Wang Yingxiong, Mu Tiancheng
Department of Chemistry, Renmin University of China, Beijing 100872, China.
Phys Chem Chem Phys. 2020 Nov 18;22(44):25760-25768. doi: 10.1039/d0cp01431a.
Deep eutectic solvents (DESs) have attracted considerable attention due to their unique properties. Owing to similar structures and properties, DESs are also called "quasi-ionic liquids" or "ionic liquid analogous". However, for a deeper understanding and application of DESs, a comprehensive investigation on the ionicity of DESs is crucial. In this work, the effects of the structure and components of typical DESs on the ionicity were investigated. Moreover, the ionicity was discussed by using Walden plot, and the validity of applying it to DESs was verified using pulsed field gradient nuclear magnetic resonance (PFG-NMR). We found that the lack of free charged species and high viscosities make it difficult to achieve optimal conductivities for DESs, and thus most of them exhibit "poor ionic" nature. Fortunately, with an in-depth understanding of its microstructure and physicochemical properties, the properties of DESs can be finely tailored by selecting or even designing suitable parent compounds for functional applications. In particular, the ionicity of Li-based DESs was investigated for their potential application as electrolytes in Li-ion batteries.
深共熔溶剂（DESs）因其独特的性质而备受关注。由于结构和性质相似，DESs也被称为“准离子液体”或“离子液体类似物”。然而，为了更深入地理解和应用DESs，对其离子性进行全面研究至关重要。在这项工作中，研究了典型DESs的结构和组成对离子性的影响。此外，利用瓦尔登图讨论了离子性，并通过脉冲场梯度核磁共振（PFG-NMR）验证了将其应用于DESs的有效性。我们发现，缺乏自由带电物种和高粘度使得DESs难以实现最佳电导率，因此它们大多表现出“离子性较差”的性质。幸运的是，随着对其微观结构和物理化学性质的深入了解，可以通过选择甚至设计合适的母体化合物来精细调整DESs的性质以用于功能应用。特别是，研究了锂基DESs作为锂离子电池电解质的潜在应用中的离子性。
