中文摘要
利用基于平面波展开的第一原理赝势方法，研究Si以及Si基合金材料在锂离子嵌入过程中的结构相变以及体积变化等性质，结合合金材料的电导率以及膨胀系数等物性参数，对材料的嵌脱机理以及循环稳定性能做出合理的解释和预测；利用计算结果选取较优合金组分，采用机械球磨等方法结合SPS技术得到Si基合金材料，研究SPS制备参数对材料的结构与电极性能的影响，分析合金材料的嵌脱锂机理；研究锂离子嵌入过程形成的SEI膜的组成、结构及反应历程，分析其与碳负极表面SEI膜的异同，探索SEI膜致密性、稳定性的影响因素，确定锂离子在穿过SEI膜并进行固相扩散过程的控制步骤，揭示材料循环性能下降的深层次原因，探索材料体积膨胀/收缩的粉化机理以及抑制方法。本研究对于发展量子化学计算方法，揭示硅负极材料的嵌脱机理和失效机制，丰富电极过程动力学理论，以及获得高性能锂离子电池硅基负极材料有重要意义。
英文摘要
Based on the plane-wave method and first-principles pseudopotentials, the phase transition, volume change and other properties of Si and Si-based alloy materials will be researched in this project. Moreover, the lithium insertion/extraction and capacity loss mechanism for active materials will be proposed reasonable explanation and prediction by combining with conductivity, expansion coefficient and other physical properties. The optimal composition of Si-based alloys will be determinated according to theoretical calculation results, and the alloy material will be prepared by mechanical ball milling combining with SPS technology. The effect of the operation parameters using SPS equipment on the structure and electrochemical performance will be optimized further. The formation process and composition of SEI film for Si-based from traditional carbonous materials will be studied, which will reveal the nature of irreversible capacity loss and decide the determining step during the migration through the SEI film and diffusion process of lithium ions, and the pulverization mechanism and restrain method of capacity loss will be proposed. Accomplishment of this project is to advance the development of quantum chemistry and reveal the insertion/extraction mechanism of lithium ions into/from alloy negative materials, and it can also give more knowledge on electrode process and electrochemistry dynamics theoretics.
结题摘要
利用基于平面波展开的第一原理赝势方法，研究Si以及Si基合金材料在锂离子嵌入过程中的结构相变以及体积变化等性质，结合合金材料的电导率以及膨胀系数等物性参数，对材料的嵌脱机理以及循环稳定性能做出合理的解释和预测；利用计算结果选取较优合金组分，采用机械球磨等方法结合SPS技术得到Si基合金材料，研究SPS制备参数对材料的结构与电极性能的影响，分析合金材料的嵌脱锂机理；研究锂离子嵌入过程形成的SEI膜的组成、结构及反应历程，分析其与碳负极表面SEI膜的异同，探索SEI膜致密性、稳定性的影响因素，确定锂离子在穿过SEI膜并进行固相扩散过程的控制步骤，揭示材料循环性能下降的深层次原因，探索材料体积膨胀/收缩的粉化机理以及抑制方法。本研究对于发展量子化学计算方法，揭示硅负极材料的嵌脱机理和失效机制，丰富电极过程动力学理论，以及获得高性能锂离子电池硅基负极材料有重要意义。