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锂离子电池电解液中溶剂化锂离子的还原反应对研究碳负极与电解液相界面相互作用、预测SEI膜形成机理至关重要。本文通过密度泛函方法(DFT)对EC和PC基电解液溶剂化锂离子得电子前后的结构信息、AIM、轨道等进行深入分析,利用过渡态和IRC理论研究EC和PC基电解液单电子还原反应历程。计算表明,PC溶剂化的Li+体系更加稳定,容易插入碳层使其粉化,EC溶剂化的Li+则更易得到电子,发生单电子还原反应。通过探讨Li+(EC)n和Li+(PC)n(n=1~4)还原反应历程中电子结构的变化,推测EC和PC单电子还原形成阴离子自由基的新历程。该历程能够更加合理地解释有机电解液在碳负极表面结合电子形成SEI膜的过程,为电解液的设计和选取提供理论基础。
Reduction of Solvated Lithium Ions in Li-ion Battery Electrolytes The interaction of the carbon negative electrode with the electrolyte interface is of interest to predict the formation mechanism of SEI films. In this paper, the structural information, AIM, orbital of solvated lithium ion of EC and PC-based electrolyte were analyzed by density functional method (DFT). The transition state and IRC theory were used to study the electronic properties of EC and PC- Restore the reaction process. Calculations show that the solvated Li + system of PC is more stable, easily infiltrated into the carbon layer to make it pulverized, and the solvated Li + of EC solves the electron more easily and undergoes the single electron reduction reaction. By investigating the electronic structure changes during the reduction reaction of Li + (EC) n and Li + (PC) n (n = 1-4), we speculate that the new electron and electron of PC and PC form anionic free radicals. The process can more reasonably explain the process of forming the SEI film by the combination of electrons on the surface of the carbon negative electrode and provide a theoretical basis for the design and selection of the electrolyte.