纳米硅可控制备、储锂性能调控及其在硅碳复合负极材料中的应用基础研究

Silicon/carbon (Si/C) composites based on nano-sized Si have been recognized as critical anode materials for next-generation high-energy lithium-ion batteries (LIBs). Currently, the large scale production of Si nanostructures with low cost, optimal internal composition and superior Li storage property has become the main technical bottleneck limiting the practical application of the Si/C composite anodes. In this project, we propose a “top-down” and high-efficient route to produce Si nanostructures with controllable intrinsic Li storage properties and apply the optimized nano-Si into high-performance Si/C composites. Specifically, first of all, the micro-, submicro-Si intermediate products are efficiently fabricated from crystalline Si bulk materials with various doping characteristics by means of mechanical grinding or spark discharge method. Subsequently, the particle size can be further reduced to dozens of nanometers using high-energy ball milling and purification technique, resulting in nano-Si with a variety of morphology, dimensions and doping characteristic. On the basis of these combination processes, a novel processing technical system can be established with more scalable and cost-effective target. The intrinsic Li storage properties of different Si nanostructures are systematically evaluated by an integrated method with the combination of　‘porous electrode’ and ‘single-particle microelectrode’ measurements. The correlationship between characteristics of doping (e.g., type, element and concentration) and reaction kinetic parameters will be mathematically analyzed, revealing the regulating effect of doping characteristics on the lithiation/delithiation processes of nano-Si. A quantitative analysis evaluation system for the Li storage property of electrode active materials will be established in accordance with such investigation results. Finally, the nano-Si with optimized internal composition and best intrinsic Li storage property will be used for the preparation of Si/C composite materials. By optimizing the compatibility and the electrochemical interface characteristics of Si/C composites, the research of this new sort of anode materials will mainly focus on superior cycling stability and rate capability to make an important breakthrough in the key generic technologies of high-energy LIBs.

基于纳米硅的硅碳复合材料是高比能锂离子电池负极亟待突破的重要体系。本项目针对高性能纳米硅的低成本制备技术瓶颈，提出一种高质高效、自顶而下的纳米硅制备方法，通过硅本征储锂性能调控，开展硅碳复合材料应用基础研究。从半导体复合加工方法入手，以不同掺杂特性晶体硅为原料，采用机械磨削或火花放电法高效预制备微米/亚微米级硅材料，进而通过高能球磨法将尺寸缩减至数十纳米，获得不同形貌、尺寸和掺杂特性纳米硅，建立全新的高效低成本规模化制备技术体系；采用多孔电极和“微电极”组合方法对纳米硅本征储锂性能进行系统表征，建立掺杂类型、元素和浓度与反应动力学参数间的关联规律，揭示不同掺杂特性对纳米硅储锂过程的调控机制，探索电极材料储锂性能定量分析和评价方法；基于纳米硅技术制备硅碳复合材料，优化硅碳材料间相容性和电化学界面特性，开展储锂性能优异的硅碳复合材料关键技术研究，实现高比能锂离子电池产业共性关键技术的重要突破。

基于纳米硅的硅碳复合材料是高比能锂离子电池负极亟待突破的重要体系。本项目针对高性能纳米硅的低成本制备技术瓶颈，提出一种高质高效、自顶而下的纳米硅制备方法，通过硅本征储锂性能调控，开展硅碳复合材料应用基础研究。从半导体复合加工方法入手，以不同掺杂特性晶体硅为原料，采用机械磨削或火花放电法高效预制备微米/亚微米级硅材料，进而通过高能球磨法将尺寸缩减至数十纳米，获得不同形貌、尺寸和掺杂特性纳米硅，建立全新的高效低成本规模化制备技术体系；采用多孔电极和“微电极”组合方法对纳米硅本征储锂性能进行系统表征，建立掺杂类型、元素和浓度与反应动力学参数间的关联规律，揭示不同掺杂特性对纳米硅储锂过程的调控机制，探索电极材料储锂性能定量分析和评价方法；基于纳米硅技术制备硅碳复合材料，优化硅碳材料间相容性和电化学界面特性，开展储锂性能优异的硅碳复合材料关键技术研究，实现高比能锂离子电池产业共性关键技术的重要突破。