碳纳米管限域锡基氧化物复合材料的可控合成与电化学性能研究

Tin oxides have high theoretical capacity is 2~3 times as of graphite. The practical use of SnOx as a negative electrode in Li-ion batteries is still hindered by the severe volume changes and agglomeration during the process of charge and discharge. In the project CNTs which was truncated in advance is used as a container, marked as OCNTs. The solution containing Sn2+ is filled into the OCNTs successfully due to the capillary forces and electrostatic interaction. After in-situ REDOX reaction the CNTs confined SnOx composites are prepared. The severe volume change and agglomeration of SnOx during the electrochemistry reaction process is reduced by the restraint and separate effect of OCNTs and the electrochemical performance of SnOx is greatly enhanced. In the meantime, OCNTs have high electrical conductivity which can play a role of a bridge between electrode materials to form a highway of conductive network. This highway is useful to the electronic transmission and dispersion, and improve the electrochemical performance of electrode effectively, especially the ratio performance.

金属锡及其氧化物做为锂离子电池负极活性材料的放电容量是目前碳基材料的2~3倍，但由于锡基材料在充放电过程中剧烈的体积变化及锡纳米颗粒团聚现象使其应用受到了极大的阻碍。本申请以预先处理被截短且原本封闭的端口已打开的碳纳米管为容器，通过调控表面张力，利用毛细管作用将含有锡离子的溶液引入碳纳米管的空腔内，然后以原位氧化还原反应生成SnOx，合成一系列碳纳米管限域锡基氧化物复合材料SnOx@OCNTs。在碳纳米管壁的限域和分隔作用下，SnOx充放电过程中剧烈的体积变化得以缓解且在电化学反应过程中生成的锡纳米颗粒也无法团聚在一起，极大地改善了SnOx活性材料的电化学性能。另外碳纳米管本身具有高导电性，能在活性材料之间起到桥梁作用形成高导电网络，利于电子的传输与分散，有效加强材料的电化学性能，特别是高倍率时的性能。

锡基氧化物做为锂离子电池负极活性材料的放电容量是目前碳基材料的2~3倍，应用前景好。但由于锡基氧化物在充放电过程中剧烈的体积变化及锡纳米颗粒团聚现象使其应用受到了极大的阻碍。本项目以预先处理被截短且原本封闭的端口已打开的碳纳米管为容器，通过调控表面张力，利用毛细管作用将含有锡离子的溶液引入碳纳米管的空腔内，然后以原位氧化还原反应生成SnOx，合成一系列碳纳米管限域锡基氧化物复合材料SnOx@OCNTs。在碳纳米管壁的限域和分隔作用下，SnOx充放电过程中剧烈的体积变化得以缓解且在电化学反应过程中生成的锡纳米颗粒也无法团聚在一起，极大地提升了SnOx活性材料的使用寿命。另外碳纳米管本身具有高导电性，能在活性材料之间起到桥梁作用形成高导电网络，利于电子的传输与分散，显著增强了复合材料的倍率性能。研究结果对于电化学储能领域中应用的金属氧化物具有较为积极的意义，为提高此类材料的电化学性能提供了一个行之有效的解决方法。