共轴结构MnO/Ag@介孔碳锂离子电池负极材料的制备及性能

Synthesis and electrochemical performances of coaxial MnO/Ag@ mesoporous carbon nanowires as anode materials for lithium-ion batteries

基于多巴胺易于成膜且其聚合物具有丰富官能基团的特性,通过在介孔碳中嵌入高分散性的Ag纳米晶,设计制备了嵌有Ag纳米晶的介孔碳/Mn O(Mn O/Ag@MC)共轴纳米复合材料并作为锂离子电池负极材料.所制备的Mn O/Ag@MC核壳纳米线平均直径约80nm,碳层厚度约20 nm,Ag纳米晶(<10 nm)均匀地嵌在碳层内部.Ag纳米晶嵌入的介孔碳层包覆可以增强氧化锰的电化学活性,循环充放电能力以及快速的电子传递和离子传输速率.与无Ag纳米晶的Mn O/MC核壳纳米线、纯Mn O纳米线相比,当前所制备的Mn O/Ag@MC核壳结构纳米线的电化学性能得到了显著提升.当电流密度为100 m A g-1时,放电比容量可以达到673 m A h g-1,即使在电流密度高达3000 m A g-1时,比容量仍保持291.2 m A h g-1.此外,在500 m A g-1电流密度时经过200次连续充放电测试后,其比电容量仍保持478.2 m A h g-1.所制备Mn O/Ag@MC复合纳米线有希望成为锂离子电池负极材料.

Based on the easy film-forming characteristic of dopamine and rich functional groups of polydopamine, Ag nanocrystals embedded mesoporous carbon/MnO （labelled as MnO/Ag@MC） coaxial nanocomposites have been successfully designed and prepared. In this nanostructure, Ag nanocrystals were well-dispersed and incorporated into mesoporous carbon layer with diameters of 〈10 nm. The coaxial MnO/Ag@MC nanowires have an average diameter of -80 nm with a carbon layer thickness of about 20 nm. The coating of Ag nanocrystals embedded mesoporous carbon can not only enhance the electrical conductivity, but also can avoid the direct contact between active materials and electrolyte, and meanwhile alleviate the volume change of MnO during charge/discharge process. These advantages will lead to intriguing electrochemical performances. As a result, the as-prepared MnO/Ag@MC nanowires demonstrate a specific capacity of 673 mA h g^-1 with excellent rate capability （291.2 mA h g^-1 at 3000 mA g^-1）, which is much higher than the MnO@MC nanowires （185.8 mA h g^-1 at 3000 mA g^-1） and MnO nanowires （6.9 mA h g^-1 at 3000 mA g^-1）. In addition, the specific capacity can still maintains 478.2 mA h g^-1 after 200 cycles at 500 mA g^-1. It is reckoned that the as-prepared MnO/Ag@MC nanowires will be a promising anode material for LIBs.