title: Enhancing the Li storage capacity and initial coulombic efficiency for porous carbons by sulfur doping.
abstract: 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.
authors.affiliation: State Key Laboratory of Heavy Oil Processing, China University of Petroleum , Beijing 102249, China.
authors.forename: Guoqing
authors.initials: G
authors.lastname: Ning
authors.forename: Xinlong
authors.initials: X
authors.lastname: Ma
authors.forename: Xiao
authors.initials: X
authors.lastname: Zhu
authors.forename: Yanming
authors.initials: Y
authors.lastname: Cao
authors.forename: Yuzhen
authors.initials: Y
authors.lastname: Sun
authors.forename: Chuanlei
authors.initials: C
authors.lastname: Qi
authors.forename: Zhuangjun
authors.initials: Z
authors.lastname: Fan
authors.forename: Yongfeng
authors.initials: Y
authors.lastname: Li
authors.forename: Xin
authors.initials: X
authors.lastname: Zhang
authors.forename: Xingying
authors.initials: X
authors.lastname: Lan
authors.forename: Jinsen
authors.initials: J
authors.lastname: Gao
keywords: Coulombic efficiency; Li ion battery; anode; carbon nanostructure; sulfur doping; synthesis