Li Yao, Xiao Ying, Wang Xia, Cao Minhua
Key Laboratory of Cluster Science, Ministry of Education of China, Beijing Key Laboratory of Photoelectronic/Electrophotonic, Conversion Materials, Department of Chemistry, Beijing Institute of Technology, Beijing 100081 (P.R. China), Fax: (+86) 10-68918572.
Chem Asian J. 2014 Jul;9(7):1957-63. doi: 10.1002/asia.201400087. Epub 2014 May 21.
High-surface-area, nitrogen-doped carbon microflowers (A-NCFs-4) assembled from porous nanosheets are prepared in a three-step process: soft-templating self-assembly, thermal decomposition, and KOH activation. The hydrazine hydrate used in our experiment serves not only as a structure-directing agent, but also as a nitrogen source. The resultant A-NCFs-4 has a hierarchical porous structure and its specific surface area is as high as 2309 m(2) g(-1). When used as anode, it exhibits a reversible capacity as high as 807 mAh g(-1) at 300 mA g(-1) after 100 cycles, and an excellent rate capability of 200 mAh g(-1) at a high current density of 8 A g(-1). Compared with unactivated counterpart, A-NCFs-4 exhibits a significantly improved lithium storage capacity and rate capability; this can be attributed to its unique structural characteristics and high surface area. The hierarchical micro-/mesopore structure, high surface area, and nitrogen doping of A-NCFs-4 could guarantee fast mass transport for lithium species, enhance the A-NCFs-4/electrolyte contact area, shorten the lithium-ion diffusion length, and accommodate strain induced by volume changes during the electrochemical reaction. The results indicate that the as-prepared A-NCFs-4 could be a promising candidate as a high-performance anode for lithium-ion batteries.
由多孔纳米片组装而成的高比表面积氮掺杂碳微花（A-NCFs-4）通过三步法制备：软模板自组装、热分解和KOH活化。我们实验中使用的水合肼不仅作为结构导向剂，还作为氮源。所得的A-NCFs-4具有分级多孔结构，其比表面积高达2309 m² g⁻¹。当用作阳极时，在100次循环后，在300 mA g⁻¹下它表现出高达807 mAh g⁻¹的可逆容量，并且在8 A g⁻¹的高电流密度下具有200 mAh g⁻¹的优异倍率性能。与未活化的对应物相比，A-NCFs-4表现出显著提高的锂存储容量和倍率性能；这可归因于其独特的结构特征和高比表面积。A-NCFs-4的分级微/中孔结构、高比表面积和氮掺杂可以保证锂物种的快速质量传输，增加A-NCFs-4/电解质的接触面积，缩短锂离子扩散长度，并适应电化学反应过程中体积变化引起的应变。结果表明，所制备的A-NCFs-4有望成为锂离子电池高性能阳极的候选材料。
