Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
J Phys Chem B. 2011 Mar 31;115(12):3085-90. doi: 10.1021/jp2003529. Epub 2011 Mar 9.
Lithium-ion batteries have the potential to revolutionize the transportation industry, as they did for wireless communication. A judicious choice of the liquid electrolytes used in these systems is required to achieve a good balance among high-energy storage, long cycle life and stability, and fast charging. Ethylene-carbonate (EC) and propylene-carbonate (PC) are popular electrolytes. However, to date, almost all molecular-dynamics simulations of these fluids rely on classical force fields, while a complete description of the functionality of Li-ion batteries will eventually require quantum mechanics. We perform accurate ab initio molecular-dynamics simulations of ethylene- and propylene-carbonate with LiPF(6) at experimental concentrations to build solvation models which explain available neutron scattering and nuclear magnetic resonance (NMR) results and to compute Li-ion solvation energies and diffusion constants. Our results suggest some similarities between the two liquids as well as some important differences. Simulations also provide useful insights into formation of solid-electrolyte interphases in the presence of electrodes in conventional Li-ion batteries.
锂离子电池有可能像在无线通信领域一样，彻底改变交通运输行业。为了在高能量存储、长循环寿命和稳定性以及快速充电之间取得良好平衡，需要明智地选择用于这些系统的液体电解质。碳酸乙烯酯（EC）和碳酸丙烯酯（PC）是常用的电解质。然而，迄今为止，这些流体的几乎所有分子动力学模拟都依赖于经典力场，而对锂离子电池功能的完整描述最终将需要量子力学。我们使用实验浓度下的 LiPF(6) 对碳酸乙烯酯和碳酸丙烯酯进行了精确的从头算分子动力学模拟，以构建能够解释可用的中子散射和核磁共振（NMR）结果的溶剂化模型，并计算锂离子的溶剂化能和扩散常数。我们的结果表明，这两种液体之间存在一些相似之处，也存在一些重要的差异。模拟还为在传统锂离子电池中存在电极的情况下形成固体电解质界面相提供了有用的见解。
