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Enhancing the Li Storage Capacity and Initial Coulombic Efficiency for Porous Carbons by Sulfur Doping
- Ning, Guoqing, Ma, Xinlong, Zhu, Xiao, Cao, Yanming, Sun, Yuzhen, Qi, Chuanlei, Fan, Zhuangjun, Li, Yongfeng, Zhang, Xin, Lan, Xingying, Gao, Jinsen
- ACS Applied Materials & Interfaces 2014 v.6 no.18 pp. 15950-15958
- anodes, batteries, carbon, carbonization, magnesium sulfate, nanomaterials, sulfur
- 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–¹ at the current density of 50 mA g–¹, 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.