和频谱研究锂离子电池电极表面固态界面膜的结构与性能

An ideal electrolyte solution for Lithium ion battery should have high dielectric constant, low viscosity, high stability and safety. Whether we want to select suitable electrolyte solution, which significantly depends on our comprehensive understanding not only of the bulk properties of electrode and electrolyte solutions, but also of their structures at the electrode/electrolyte interface of Li-ion batteries at a molecular level. In this project, the sum frequency generation which has high surface selectivity and sensitivity has been employed to investigate the adsorption structure of electrolyte solution on different cathode electrode surface in lithium ion battery in the different electrolyte solution such as ethylene carbonate (EC),diethyl carbonate (DEC), dimethyl carbonate (DMC) lithium salts or their binary and ternary mixtures. Quantitative information for arrangement and orientation of electrolyte solution can be abtained by the fit of theoretical calculation to experimental data at electrode/electrolyte interface in lithium ion battery. We will investigate the molecular structures of solid electrolyte interphase (SEI) on the cathode electrode surface during the charge and discharge process, comparing the corresponding adsorption structures on the electrode before the charge and discharge, we can deduce the formation mechanism of SEI films and elucidate the structure-property relation between the molecular structure of SEI film and cycle performance. We will study the adsorption structures and the structures of SEI film before and after the charge and discharge when the additive was added into the electrolyte solution, Exploring the effects of additives on the structure of SEI film and cycle performance, so as to provide the theoretical basis for design and synthesis of effective additive materials for the purpose of improving the performance of Li-ion batteries.

锂离子电池的理想电解质溶液应具有高的介电常数、低的粘性、高的稳定性和安全性。想要获得合适的电解质溶液，不仅需要了解电极和电解质溶液性质，而且更要从分子水平上全面理解电极/电解质溶液界面分子结构。本课题拟以碳酸乙烯酯(EC)、碳酸二乙酯（DEC）、碳酸二甲酯（DMC）锂盐溶液或其混合物为电解质溶液，真空蒸度法制备阴极薄膜电极材料,利用具有独特界面选择性和敏感性的和频振动光谱，研究锂离子电池不同电解质溶液或其混合液在不同阴极电极材料表面的吸附结构，理论计算电极表面的取向信息；研究充放电过程中阴极电极表面在不同电解质溶液中的SEI膜分子结构，比较充放电前相应的表面吸附结构，揭示SEI膜形成机理，阐明SEI膜分子结构与循环性能间的构效关系；研究在电解质溶液中加入添加剂时电极表面吸附结构和充放电过程中SEI膜的结构，探索添加剂对SEI膜结构和循环性能的影响，为设计、合成高效的添加剂材料提供理论依据。

锂离子电池以其比能量高、循环寿命长、安全性能好、无记忆效应、对环境友好等优势引起了人们的广泛关注,现已广泛应用于移动电话、电脑、混合动力电动汽车等。因此，锂离子电池是最具发展和应用前景的电源。.（1）釆用真空蒸度法在600 ºC氧气压力为0.2 mpa时沉积LiCoO2、LiNiO2和 LiMnO2膜，循环伏安法显示出LiCoO2、LiNiO2和 LiMnO2膜具有良好的循环性能。（2）利用和频振动光谱研究充放电前锂离子电池LiCoO2电极在电解质溶液（EC，DEC，DMC或其混合物）吸附构造。通过理论计算各种电解质溶液在不同电极表面的排列和取向性息。（3）利用和频振动光谱研究充放电前锂离子电池石墨电极在电解质溶液（EC，DEC，DMC或其混合物）吸附构造。通过理论计算各种电解质溶液在不同电极表面的排列和取向性息。（4）设计合成系列的二胺衍生物（SAD-4, SAD-6, SAD-8, SAD-10），并将其与单头脂肪胺（R-NH2）按1:2的摩尔比复合得到系列新型的双组份热致凝胶，利用FT-IR、XRD、SEM、DSC等现代检测技术研究其在各种有机溶剂中的微观结构和形成机制。（5）)设计合成对十二烷氧基偶氮苯甲酸，其不能使任何溶剂胶凝化，但与等摩尔的脂 肪胺混合后，其能使很多极性溶剂胶凝化。利用SEM，FTIR，小角X-射线衍射，H NMR，U V-vis等现代检测技术研究凝胶的微观构造及其形成机制。