Enhancing the Li Storage Capacity and Initial Coulombic Efficiency for Porous Carbons by Sulfur Doping

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• 作者：Guoqing Ning ; Xinlong Ma ; Xiao Zhu ; Yanming Cao ; Yuzhen Sun ; Chuanlei Qi ; Zhuangjun Fan ; Yongfeng Li ; Xin Zhang ; Xingying Lan ; Jinsen Gao
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2014
• 出版时间：September 24, 2014
• 年：2014
• 卷：6
• 期：18
• 页码：15950-15958
• 全文大小：800K
• ISSN：1944-8252

文摘

Here, we report a new approach to synthesizing S-doped porous carbons and achieving both a high capacity and a high Coulombic efficiency in the first cycle for carbon nanostructures as anodes for Li ion batteries. S-doped porous carbons (S-PCs) were synthesized by carbonization of pitch using magnesium sulfate whiskers as both templates and S source, and a S doping up to 10.1 atom % (corresponding to 22.5 wt %) was obtained via a S doping reaction. Removal of functional groups or highly active C atoms during the S doping has led to formation of much thinner solid-electrolyte interface layer and hence significantly enhanced the Coulombic efficiency in the first cycle from 39.6% (for the undoped porous carbon) to 81.0%. The Li storage capacity of the S-PCs is up to 1781 mA h g^鈥? at the current density of 50 mA g^鈥?, more than doubling that of the undoped porous carbon. Due to the enhanced conductivity, the hierarchically porous structure and the excellent stability, the S-PC anodes exhibit excellent rate capability and reliable cycling stability. Our results indicate that S doping can efficiently promote the Li storage capacity and reduce the irreversible Li combination for carbon nanostructures.

Keywords:

sulfur doping; carbon nanostructure; synthesis; Coulombic efficiency; anode; Li ion battery