【作者】 张燕珂；

【导师】 莫育俊；

【作者基本信息】 河南大学 ， 光学工程， 2006， 硕士

【摘要】 作为一种新型的二次电池,锂离子电池是目前综合性能最好的可充电化学电池。随着社会的发展,人们对锂离子电池电化学容量和可逆循环性能的要求越来越高。在锂离子电池的充放电过程中,电极和电解质界面区由于电解质与电极材料之间的相互作用而在电极表面形成一层厚度在几个纳米范围的表面层,这个表面层被称为固体电解质中间相(Solid Electrolyte Interface Film,简称SEI膜)。它对锂离子电池的电化学容量、安全性、循环性、自放电等性能有十分重要的影响,并逐渐成为锂离子电池研究的重要方向。由于SEI膜很薄,对其研究需采用一些灵敏度较高的表面分析方法,比如FT-IR、HRTEM、AFM、XPS等。但是以上方法中成分分析的红外光谱和能谱不足以区分所有物种,结构分析又不能提供吸附态的信息。而拉曼光谱不但具有很高的检测灵敏度,而且可以提供有关SEI膜的组分、结构、表面吸附态的信息,是一种理想的检测方法。目前对SEI膜的研究主要集中在负极材料方面,对正极材料表面的SEI膜研究则较少。因为相对负极来说,正极SEI膜厚度较薄,电化学性能表现得不明显,直接观察有困难。我们小组前期的工作已利用活性银衬底对负极材料表面SEI膜的表面增强拉曼光谱(Surface-enhanced Raman Scattering,简称SERS)光谱进行了研究。但银衬底却不能应用于正极材料表面SEI膜的研究当中,因为锂离子电池中正极的工作电位可达4.0V以上,而银在3.6V(vs Li/Li+)附近就开始发生氧化反应,在第一次充电过程中,正极材料表面包覆的银颗粒就会因电化学反应溶入电解液中,不再具有表面增强的效果。但是金可以承受高的氧化电压,直到5.02V(vs Li/Li+)才开始氧化,而且金纳米颗粒也是良好的SERS活性衬底。于是我们制备了SERS活性金衬底,利用检测灵敏度极高的SERS光谱来研究更多还原

【Abstract】 As a new kind of secondary battery, the rechargable lithium-ion battery has the best overall performance at present. Further requirements such as higher electrochemical capacity and better reversibility are advanced to lithium ion battery with the development of our society. In the first cycle of lithium ion battery, solvent decomposition reaction on the surface of electrode will lead to the formation of a passivating layer, commonly named solid electrolyte interface film (SEI film). It is only several nanometers thick but has great impact on the electrochemical capacity, security, self-discharge and has become a focus in the study of lithium ion battery.The SEI film has been extensively investigated by FT-IR, HRTEM, SEM, XPS and AFM, which are the methods of surface analysis with very high sensitivity. However,those methods cannot differentiate all species in the SEI film. But Raman spectrum is a ideal test method to study the SEI film,which can provide the informations of the component and variety of the film.At present the mainly research of the SEI film has been concentrated on the cathode material and the investigation of the SEI film on the positive electrodes has been a rarity. For the SEI film on the positive electrode is very thin and it’s electrochemistry performance is too feeble to be observed. During the last several years our group has been concentrated on the cathode material for Lithium Ion Batteries. But the active silver substrate of SERS used in the study of the cathode material cannot be used in positive electrodes. In the lithium ion battery the working voltage of positive electrode may reach and exceed 4.0V, however the silver will be oxidated at 3.6V (vs Li/Li+), and in the first charge process, the nanometer silver can be dissolved into the electrolyte and no longer has SERS active. But the gold may withstand the high oxidized voltage as high as 5.02V (vs Li/Li+) and the nanometer gold also is a good SERS substrate.更多还原