Zou Guoqiang, Wang Chao, Hou Hongshuai, Wang Chiwei, Qiu Xiaoqing, Ji Xiaobo
College of Chemistry and Chemical Engineering, Central South University, Changsha, 410083, China.
University of Electronic Science and Technology of China, Chengdu, 611731, China.
Small. 2017 Aug;13(31). doi: 10.1002/smll.201700762. Epub 2017 Jun 26.
The electrochemical behaviors of current graphitic carbons are seriously restricted by its low surface area and insufficient interlayer spacing for sodium-ion batteries. Here, sulfur-doped graphitic carbon nanosheets are reported by utilizing sodium dodecyl sulfate as sulfur resource and graphitization additive, showing a controllable interlayer spacing range from 0.38 to 0.41 nm and a high specific surface area up to 898.8 m g . The obtained carbon exhibits an extraordinary electrochemical activity for sodium-ion storage with a large reversible capacity of 321.8 mAh g at 100 mA g , which can be mainly attributed to the expanded interlayer spacing of the carbon materials resulted from the S-doping. Impressively, superior rate capability of 161.8 mAh g is reserved at a high current density of 5 A g within 5000 cycles, which should be ascribed to the fast surface-induced capacitive behavior derived from its high surface area. Furthermore, the storage processes are also quantitatively evaluated, confirming a mixed storage mechanism of diffusion-controlled intercalation behavior and surface-induced capacitive behavior. This study provides a novel route for rationally designing various carbon-based anodes with enhanced rate capability.
当前石墨碳的电化学行为因其低表面积和钠离子电池层间距不足而受到严重限制。在此，通过利用十二烷基硫酸钠作为硫源和石墨化添加剂制备了硫掺杂石墨碳纳米片，其层间距可控范围为0.38至0.41nm，比表面积高达898.8m²/g。所制备的碳材料对钠离子存储表现出非凡的电化学活性，在100mA/g电流密度下具有321.8mAh/g的大可逆容量，这主要归因于硫掺杂导致碳材料层间距扩大。令人印象深刻的是，在5A/g的高电流密度下经过5000次循环后仍保留161.8mAh/g的优异倍率性能，这应归因于其高比表面积所产生的快速表面诱导电容行为。此外，还对存储过程进行了定量评估，证实了扩散控制插层行为和表面诱导电容行为的混合存储机制。本研究为合理设计具有增强倍率性能的各种碳基负极提供了一条新途径。
