锂离子电池新型纳米硅基复合多孔负极构效关系及界面特性研究

Silicon is most likely to replace the existing carbon anode material of lithium ion batteries. However, the huge volume expansion of silicon has a fatal influence on cyclic properties during the lithiation and delithiation. Based on the previous research, we intend to put forward building the porous silicon-based nanocomposite anode by cold spraying method to solve the problem of volume expansion in this project. By studying the formation mechanism of the porous structure and analyzing the collaborative between the gradient change of porosity and the electrode performance. It is expected to realize the controllable preparation and establish the structure-performance relationship of the porous silicon-based nanocomposite anode; On the other hand, at the atomic scale, we analyze the impact mechanism of the interface characteristics on the microscopic behavior of ions, then study the impact of the interface characteristics on the volume change and the performance of the silicon-based anode by combining the experiment. The aim of the project is not only to lay the experiment or theoretical foundation for the preparation of porous silicon-based nanocomposite anode by cold spraying method but also to provide the theoretical guidance for the structure design and performance improvement of the silicon-based anode. The project has the important engineering and theoretical significances.

硅是最有可能取代现有锂离子电池碳负极的一类活性材料，然而巨大的体积效应对电极的循环性能有着致命的影响，基于前期研究，本项目提出采用冷喷涂制备纳米硅基复合多孔电极以解决体积效应问题的新方法。深入研究复合电极多孔结构的形成机制，揭示电极涂层孔隙率梯度变化与电极性能的协同机制，实现纳米硅基复合多孔电极的可控制备，建立其构效关系；另一方面，从原子尺度研究电极界面特性对锂离子微观行为的作用机制，结合实验研究进一步阐明界面特性对硅基电极体积变化及性能的影响机理。本项目的研究，不仅为冷喷涂方法制备纳米硅基复合多孔电极奠定实验和理论基础，也为锂离子电池硅基电极的结构设计和性能提升提供理论指导，具有重要的工程和理论意义。

硅基负极作为一类极具潜力的商业化负极材料，其脱嵌锂过程中巨大的体积效应严重限制了其商业化应用。本项目采用冷喷涂结合球磨法制备铜硅复合电极，提供了一种高效、低成本的解决方案。主要研究了包覆型铜硅复合粉末的可控制备，冷喷涂结合特性对电极性能的影响机制，冷喷涂制备铜硅复合电极构效关系，铜硅合金对电极性能的影响的原子尺度模拟，新型硅基二维薄膜材料的设计。结果表明，铜的加入有利于电极结构的稳定性，冷喷涂较高的结合强度改善了电极的循环稳定性，冷喷涂方法制备的铜硅合金负极在加入导电炭黑可显著提高其循环性能和容量性能，循环200次后，比容量高达600mAh/g。球磨过程中形成的Cu3Si合金有利于缓解体积膨胀，促进锂离子的嵌入。理论设计的SiGe/D-Gra二维材料不仅具有良好的导电性，且三种异质结分别具有340.90mAh/g、343.66mAh/g和338.18mAh/g的理论比容量。本项目的研究不仅为冷喷涂方法制备硅-金属复合电极提供了理论和实验基础，也为新型硅基薄膜材料的设计提供了理论指导，对促进硅基负极的发展具有重要的理论和工程意义。