Modeling the effects of salt concentration on aqueous and organic electrolytes

Stephanie C. C. van der Lubbe & Pieremanuele Canepa 

npj Com:putational Materials  9: 175 (2023).

编辑概述：电解质溶液热力参数的计算模拟

盐浓度与电解质溶液热力学性质之间的相互作用对于许多生理和技术应用都是至关重要的，如生物化学、催化、能量储存和材料科学。电解质的性质是由所使用的溶剂、盐和添加剂类型之间复杂的相互作用决定的，而且还强烈地依赖于环境的浓度和操作温度。理解任何给定溶剂/盐组合下电解质热力学性质的浓度和温度依赖性，对于选择合适的电解质和进一步优化其性质都至关重要。平均活度系数γ_±与电解质溶液偏离其理想行为有关，可以通过结合Debye-Huckel（DH）和Born (B)方程得到。然而，DH+B所需的参数，例如与溶液浓度和温度有关的静态介电常数ε_r(c, T)和溶液离子大小r_i，往往缺乏实验数据的支撑。因此，需要在方法上实现创新，使DH+B模型获得更广阔的实用性。在这一点上，计算模拟成为获取所需参数的重要来源。在本工作中，来自新加坡国立大学材料科学与工程系的Pieremanuele Canepa教授等人，扩展了DH+B方法，将其应用于一系列水溶液和有机电解质。首先，作者通过分子动力学和密度泛函理论计算，预测了水溶液电解质的γ_±，并利用ε_r和玻恩溶剂化半径R^B的计算值来探测DH+B模型的性能。然后，作者将DH+B框架应用于非水相有机电解质。结果表明，计算获得参数的DH+B模型对水相电解质的性能大多令人满意，而对于具有低静态介电导数的非水相电解质则准确性有所欠缺。本工作使用的计算方法有助于理解和预测水溶液和有机电解质的性质，对推动科学和技术进步有重要意义。

Editorial Summary: Simulations on the thermodynamic parameters of electrolyte solutions

The interplay between salt concentration and thermodynamic properties of electrolyte solutions is of vital importance for many physiological and technological applications, e.g. biochemistry, catalysis, energy storage, and materials science. Electrolyte properties are determined by a complex interplay between the types of solvents, salts, and additives used, and are furthermore strongly dependent on the concentration and operating temperature of the environment. Understanding the concentration and temperature dependence of the thermodynamic properties of an electrolyte for any given solvent/salt combination is essential for selecting the proper electrolyte and further optimization of its properties. The mean activity coefficient γ_± is associated with the deviation of an electrolyte solution from its ideal behavior and may be obtained by combining the Debye-Hückel (DH) and Born (B) equations. However, parameters DH + B required, such as the concentration and temperature-dependent static permittivity of the solution ε_r(c, T) and the size of the solvated ions r_i, often lack support of experimental data. Therefore, it is necessary to make innovations in method to achieve broader practicality for DH+B model. In this regard, theoretical simulation becomes an important source of required constants. In this work, Prof. Pieremanuele Canepa et al. from the Department of Materials Science and Engineering, National University of Singapore, extended Debye-Hückel (DH) and Born (B) model, and applied the model on a series of aqueous and organic electrolytes. Firstly, by molecular dynamics (MD) and density functional theory (DFT) calculations, the authors predicted γ_± for aqueous electrolytes and probed the performance of the DH+B model with computed values for ε_r and the Born solvation radius R^B. Then, the DH+B framework was applied to nonaqueous organic electrolytes. The results demonstrate that the DH+B model with computationally obtained parameters performs mostly satisfactorily for aqueous electrolytes and becomes increasingly inaccurate for nonaqueous electrolytes bearing low static permittivities. The approach proposed in this work may aid in understanding and predicting the properties of relevant aqueous and organic electrolytes, which remains important value in paving both scientific and technological progress.