新型硅-掺杂碳纳米复合材料制备及电化学性能研究

Silicon has attracted great attention as an anode material in rechargeable lithium-ion batteries because of its high theoretical specific capacity (ca. 4200 mAh/g) in comparison with that of the commercialized graphite (ca.372 mAh/g). The major obstacles for Si anode to be used practically in lithium-ion batteries reside in its low intrinsic electric conductivity, and the severe volume changes during Li insertion/extraction process which consequently leads to permanent capacity fading. Nano-Si/carbon composites provide a promising approach to improve the electrochemical performance for practical applications using carbon as an active coating matrix due to its low mass, good conductivity, small volume change, and reasonable Li-insertion capacity. The composition and organic precursor of carbon have significant impact on the electrochemical performance of Si/C composites in terms of initial Columbic efficiency, cycling properties and rate capability. .The focus of this proposed program is on the design and preparation of nano-Si/carbon composites with the heteroatom doped in carbon matrix based on our recent progress on nano-Si/C composites doped with sulfur element showing superior Columbic efficiency and cycling performance. Si/C composites with precise heteroatom content in the carbon matrix will be developed by carefully choosing various organic precursors containing heteroatom element as carbon sources. Electrochemical performances will be quantified and interpreted based on heteroatom content and chemical bonding data, as well as structural data of the composites. The capacity contribution from different components of the composite will be specifically identified to clarify the role of heteroatom doped in the carbon matrix on the electrochemical performance. .The principal objective of this proposal is to integrate high capacity nano-Si material with carbon material doped with heteroatom to produce novel Si/C composite electrodes having high initial Columbic efficiency, excellent cycling and rate performance for lithium-ion batteries. The successful completion of this program aims will enable us to: 1) create a new way of engineering nano-Si/C composite with superior electrochemical performances for use in lithium-ion batteries; 2) establish a new method of preparing nanostructured composites to expand the versatilty of nano science and composite materials.

硅-碳复合材料是高容量硅基负极材料应用于锂离子电池最现实和经济的技术方案之一，但其商业化进程受制于首次库伦效率、循环稳定性和倍率性能的不足。采用不同碳源和包覆方式对材料的电化学性能有巨大影响，本项目拟在我们研发的具有高首次库伦效率和循环稳定性的硫掺杂碳包覆纳米硅复合材料的前期工作基础上，以杂环导电聚合物为含杂元素碳源，通过对有机杂环单体化学结构设计和聚合方式选择，精确调控纳米硅包覆碳中的掺杂杂元素种类和含量，系统研究材料化学结构、掺杂杂元素及键价状态与电化学性能的关系，阐明杂元素掺杂碳包覆对提高其与纳米硅复合负极材料的库伦效率和循环等性能的机制。本项目的完成将为解决硅基负极材料由于电导率低和充放电过程中的大体积变化等本征缺陷造成的商业化技术瓶颈，为研究开发具有实用化价值的具有高库伦效率、循环稳定性和倍率性能的新型高容量纳米硅复合电极材料探索新途径，丰富纳米材料和复合材料的科学理论。

硅-碳复合材料是高容量硅基负极材料应用于锂离子电池最现实和经济的技术方案之一，但其商业化进程受制于首次库伦效率、循环稳定性和倍率性能的不足。采用不同碳源和包覆方式对材料的电化学性能有巨大影响，本项目拟在我们研发的具有高首次库伦效率和循环稳定性的硫掺杂碳包覆纳米硅复合材料的前期工作基础上，以杂环导电聚合物为含杂元素碳源，通过对有机杂环单体化学结构设计和聚合方式选择，精确调控纳米硅包覆碳中的掺杂杂元素种类和含量，系统研究材料化学结构、掺杂杂元素及键价状态与电化学性能的关系，阐明杂元素掺杂碳包覆对提高其与纳米硅复合负极材料的库伦效率和循环等性能的机制。本项目的完成将为解决硅基负极材料由于电导率低和充放电过程中的大体积变化等本征缺陷造成的商业化技术瓶颈，为研究开发具有实用化价值的具有高库伦效率、循环稳定性和倍率性能的新型高容量纳米硅复合电极材料探索新途径，丰富纳米材料和复合材料的科学理论。