锂离子二次电池高比容电极材料非水界面过程的谱学研究

锂离子二次电池的电化学性能和安全性不仅与电极材料，也与其电极/电解液的非水界面过程相关。高比容、高功率电极材料导致其界面过程在热力学和动力学层面上的复杂化。目前对各种新型高比容电极材料的界面过程研究的报道还非常少。因此本项目继续发展通过FTIRS（原位/非原位），EQCM（原位），XPS、ToF-SIMS（非原位，与手套箱相联）等技术研究锂离子二次电池界面过程的方法。从分子水平、微观层次认识硅基负极材料和三元富锂正极材料的非水界面过程，这些过程主要包括：电解液在硅负极上的还原和高电位时在三元富锂正极分解过程，不同电解液中SEI生成变化和化学组分，锂离子在固相材料中的分布和扩散，以及两种电极材料容量衰竭的界面因素。分析界面反应的机理和对电池性能的影响。研究结果有助于发展认识锂离子二次电池界面过程的研究方法和非水电解质理论，并为进一步提高锂离子二次电池电化学性能和安全性能提供理论依据。

The electrochemical and safety performance of lithium ion battery are strongly depended on not only the electrode material, but also the non- aqueous electrode/electrolyte interfacial processes. The electrode of high energy density make the interface processes more complicated at thermodynamic and kinetic aspect. Up to now, however, the research about interfacial processes of electrode material with high energy density is rarely reported. .The scope of this project is development of the spectroscopic investigation of interfacial processes by Fourier transform infrared reflection spectroscopy (FTIRS, in situ/ex situ), electrochemical quartz crystal microbalance (EQCM, in situ), X-ray photoelectron spectroscopy (XPS, connected with glove, ex situ), and time of flight secondary ion mass spectrometry (ToF-SIMS, connected with glove, ex situ ). By the advantages of these spectroscopic techniques, we try to understand their interfacial reactions on Si-based and Li [Li-Ni-Mn-Co]O2 at molecular level. The interfacial processes mainly include: the reduction of electrolyte on Si-based anodes, the oxidation decomposition on Li [Li-Ni-Mn-Co]O2 at high electrode potential, the formation and chemical composition of SEI layer in different electrolyte, the diffusion and distribution of lithium ion in the electrode material, and the decay of the charge/discharge capacity induced by the interfacial processes. .In this project, we will discuss the rule of interfacial reaction, especiaaly the decomposition of electrolyte and formation of SEI layer. The influence of interfacial processes on electrochemical and safety performance of Si-based anode and [Li-Ni-Mn-Co]O2 cathode will also be discussed in detail. This project is devoted to: (1) new methods to investigate the interfacial processes, (2) new approaches to improve the electrochemical and safety performance lithium ion battery and (3) new theory for the non-aqueous interfaces.