Ab lnitio Characterization of the Electrochemical Stability and Solvation Properties of Condensed-Phase Ethylene Carbonate and Dimethyl Carbonate Mixtures
Ab lnitio Characterization of the Electrochemical Stability and Solvation Properties of Condensed-Phase Ethylene Carbonate and Dimethyl Carbonate Mixtures
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DOI：
10.1021/jp510882g
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发表时间：
2015-02-26
影响因子：
3.7
通讯作者：
Miller, Thomas F., III
中科院分区：
文献类型：
--
作者：
Barnes, Taylor A.;Kaminski, Jakub W.;Miller, Thomas F., III
改进锂离子电池的一个核心挑战是控制阴极诱导的电解液溶剂的氧化分解，如碳酸乙烯(EC)和碳酸二甲酯(DMC)。我们用新发展的基于投影的嵌入方法研究了纯EC、纯DMC以及EC和DMC的1：1混合物的氧化电势，证明该方法能够修正由传统Kohn-Sham密度泛函理论(DFT)得到的电子密度和电离能的定性误差。我们的DFT波函数嵌入方法能够在CCSD(T)理论水平上准确计算单个分子的垂直电离能(IE)，同时使用DFT和分子力学相互作用的组合显式地考虑溶剂。我们发现，垂直离子交换系数的系综平均分布与溶剂组态统计的线性响应解释一致，从而能够确定溶剂的本征氧化势和相应的溶剂重组能。有趣的是，我们发现DMC的溶剂化性质的很大贡献来自于四极相互作用，导致了比用简单的介电连续模型预测的更大的溶剂重组能。证明了EC和DMC的溶剂化性质是由根本不同的分子间相互作用决定的，这有助于深入了解锂离子电池的关键方面，与电解液分解过程、固体电解液界面形成和锂离子的局部溶剂化环境有关。
A central challenge in the refinement of lithium-ion batteries is to control cathode-induced oxidative decomposition of electrolyte solvents, such as ethylene carbonate (EC) and dimethyl carbonate (DMC). We study the oxidation potentials of neat EC, neat DMC, and 1:1 mixtures of EC and DMC using the newly developed projection-based embedding method, which we demonstrate to be capable of correcting qualitative inaccuracies in the electronic densities and ionization energies obtained from conventional Kohn-Sham density functional theory (DFT) methods. Our wave function-in-DFT embedding approach enables accurate calculation of the vertical ionization energy (IE) of individual molecules at the CCSD(T) level of theory while explicitly accounting for the solvent using a combination of DFT and molecular mechanics interactions. We find that the ensemble-averaged distributions of vertical IEs are consistent with a linear response interpretation of the statistics of the solvent configurations, enabling determination of both the intrinsic oxidation potential of the solvents and the corresponding solvent reorganization energies. Interestingly, we reveal that large contributions to the solvation properties of DMC originate from quadrupolar interactions, resulting in a much larger solvent reorganization energy than that predicted using simple dielectric continuum models. Demonstration that the solvation properties of EC and DMC are governed by fundamentally different intermolecular interactions provides insight into key aspects of lithium-ion batteries, with relevance to electrolyte decomposition processes, solidelectrolyte interphase formation, and the local solvation environment of lithium cations.