Paolone Annalisa, Di Muzio Simone, Palumbo Oriele, Brutti Sergio
Consiglio Nazionale delle Ricerche, Istituto dei Sistemi Complessi, Piazzale Aldo Moro 5, 00185 Rome, Italy.
Department of Physical and Chemical Sciences, University of L'Aquila, Via Vetoio, 67100 L'Aquila, Italy.
Entropy (Basel). 2023 May 12;25(5):793. doi: 10.3390/e25050793.
Ionic liquids are good candidates as the main component of safe electrolytes for high-energy lithium-ion batteries. The identification of a reliable algorithm to estimate the electrochemical stability of ionic liquids can greatly speed up the discovery of suitable anions able to sustain high potentials. In this work, we critically assess the linear dependence of the anodic limit from the HOMO level of 27 anions, whose performances have been experimentally investigated in the previous literature. A limited Pearson's value of ≈0.7 is found even with the most computationally demanding DFT functionals. A different model considering vertical transitions in a vacuum between the charged state and the neutral molecule is also exploited. In this case, the best-performing functional (M08-HX) provides a Mean Squared Error (MSE) of 1.61 V on the 27 anions here considered. The ions which give the largest deviations are those with a large value of the solvation energy, and therefore, an empirical model that linearly combines the anodic limit calculated by vertical transitions in a vacuum and in a medium with a weight dependent on the solvation energy is proposed for the first time. This empirical method can decrease the MSE to 1.29 V but still provides an Pearson's value of ≈0.72.
离子液体是高能锂离子电池安全电解质主要成分的理想选择。确定一种可靠的算法来估算离子液体的电化学稳定性，能够极大地加速发现能够承受高电位的合适阴离子。在这项工作中，我们严格评估了27种阴离子的阳极极限与最高占据分子轨道（HOMO）能级的线性相关性，这些阴离子的性能已在先前的文献中进行了实验研究。即使使用计算量最大的密度泛函理论（DFT）泛函，得到的皮尔逊值也仅约为0.7。我们还采用了另一种考虑在真空中带电状态与中性分子之间垂直跃迁的模型。在这种情况下，表现最佳的泛函（M08-HX）在所考虑的27种阴离子上的均方误差（MSE）为1.61伏。偏差最大的离子是那些溶剂化能值较大的离子，因此，首次提出了一种经验模型，该模型将在真空中和介质中通过垂直跃迁计算出的阳极极限与一个依赖于溶剂化能的权重进行线性组合。这种经验方法可将均方误差降低至1.29伏，但皮尔逊值仍约为0.72。
