密度泛函理论方法研究锂离子电池电解液体系分子-离子结构

Density Functional Theory Study on the Structures of Solvent-Ion in the Electrolyte of Lithium Ion Battery

采用密度泛函理论方法,研究锂离子电池碳酸丙烯酯(PC)基电解液体系中锂盐离子与溶剂分子静电相互作用形成的可能结构.计算结果表明,电解液中溶剂分子-离子的结构取决于体系的溶剂分子数.在PC基电解液,Li+最多只能与4个PC溶剂分子相结合,锂盐阴离子与带正电的PC分子烷基基团相结合,而不以自由离子形式存在.本文的计算结果能很好地解释文献报道的实验结果.

In this work, the possible structures of solvent-ion complex, resulting from the electrostatic interaction in the propylene carbonate （PC） base electrolyte of lithium ion battery, have been investigated using the density functional theory. The calculated results show that the structure of solvent-ion complex depends on the solvent number. In the PC base electrolyte, maximum number of PC solvents that coexist in the Li^＋-solvent sheath is four. Additionally, the salt anion exists in a complex with the positively charged alkyl group of PC rather than in a free state. The calculated results give a good explanation to the reported experimental observations.