Nanofibers Comprising Yolk-Shell Sn@void@SnO/SnO2 and Hollow SnO/SnO2 and SnO2 Nanospheres via the Kirkendall Diffusion Effect and Their Electrochemical Properties
Nanofibers Comprising Yolk-Shell Sn@void@SnO/SnO2 and Hollow SnO/SnO2 and SnO2 Nanospheres via the Kirkendall Diffusion Effect and Their Electrochemical Properties
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DOI：
10.1002/smll.201500940
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发表时间：
2015-09-23
期刊：
影响因子：
13.3
通讯作者：
Kang, Yun Chan
中科院分区：
文献类型：
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作者：
Cho, Jung Sang;Kang, Yun Chan
通过在常规静电纺丝过程中应用纳米级柯肯德尔扩散过程，制备了具有独特结构的纳米纤维，其包含Sn@void@SnO/SnO₂蛋黄 - 壳纳米球以及中空的SnO/SnO₂和SnO₂纳米球。在还原气氛下，对2 - 乙基己酸锡 - 聚乙烯吡咯烷酮静电纺丝纳米纤维进行后处理，可得到嵌入球形Sn纳米粉末的碳纳米纤维。Sn纳米粉末沿碳纳米纤维轴线性排列，纳米粉末无团聚现象。在空气气氛下，Sn - C复合纳米纤维的氧化会产生包含Sn@void@SnO/SnO₂蛋黄 - 壳纳米球以及中空的SnO/SnO₂和SnO₂纳米球的纳米纤维，这取决于后处理温度。在500℃和600℃后处理的嵌入氧化锡纳米纤维内的中空纳米球的平均尺寸分别为146纳米和117纳米。在第250次循环时，在400℃、500℃和600℃下经过纳米级柯肯德尔扩散过程后处理的纳米纤维在2 A g⁻¹的高电流密度下的放电容量分别为663、630和567 mA h g⁻¹。从第二次循环计算，相应的容量保持率分别为77%、84%和78%。与通过常规后处理过程制备的多孔结构SnO₂纳米纤维相比，应用纳米级柯肯德尔扩散过程制备的纳米纤维表现出更优异的电化学性能。
Nanofibers with a unique structure comprising Sn@void@SnO/SnO2 yolk-shell nanospheres and hollow SnO/SnO2 and SnO2 nanospheres are prepared by applying the nanoscale Kirkendall diffusion process in conventional electrospinning process. Under a reducing atmosphere, post-treatment of tin 2-ethylhexanoate-polyvinylpyrrolidone electrospun nanofibers produce carbon nanofibers with embedded spherical Sn nanopowders. The Sn nanopowders are linearly aligned along the carbon nanofiber axis without aggregation of the nanopowders. Under an air atmosphere, oxidation of the Sn-C composite nanofibers produce nanofibers comprising Sn@void@SnO/SnO2 yolk-shell nanospheres and hollow SnO/SnO2 and SnO2 nanospheres, depending on the post-treatment temperature. The mean sizes of the hollow nanospheres embedded within tin oxide nanofibers post-treated at 500 degrees C and 600 degrees C are 146 and 117 nm, respectively. For the 250th cycle, the discharge capacities of the nanofibers prepared by the nanoscale Kirkendall diffusion process post-treated at 400 degrees C, 500 degrees C, and 600 degrees C at a high current density of 2 A g(-1) are 663, 630, and 567 mA h g(-1), respectively. The corresponding capacity retentions are 77%, 84%, and 78%, as calculated from the second cycle. The nanofi bers prepared by applying the nanoscale Kirkendall diffusion process exhibit superior electrochemical properties compared with those of the porous-structured SnO2 nanofibers prepared by the conventional post-treatment process.