title: Polysulfides Capture-Copper Additive for Long Cycle Life Lithium Sulfur Batteries.
abstract: Copper powder was introduced into the lithium sulfur battery system to capture intermediate polysulfides and CuxS (x = 1 or 2) species was generated depending on the chain length of polysulfides. This phenomenon was verified by X-ray absorption near edge structure technique. The results indicated that copper can be oxidized to CuS by Li2Sx(x ≥ 6), and a mixture of Cu2S and CuS was obtained when x ranges from 3 to 6. While Cu2S is eventually formed in the presence of Li2S3. After several cycles activation, the polysulfide-shuttle effect and self-discharge phenomenon which hinder the application of lithium sulfur batteries are found nearly eliminated Further experiments demonstrated that in the case of Cu2S generation, a high specific sulfur capacity of 1300 mAh g-1could be delivered, corresponding to 77.6% sulfur utilization, while the Coulombic efficiency approximates around 100%. Self-discharge experiment further demonstrated that polysulfides almost disappear in the electrolyte, which verified the polysulfide-capture capability of copper.
authors.affiliation: Key Laboratory of Organic Optoelectronics and Molecular Engineering, Department of Chemistry, Tsinghua University , Beijing 100084, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Jia
authors.forename: Tianpin
authors.initials: T
authors.lastname: Wu
authors.forename: Jun
authors.initials: J
authors.lastname: Lu
authors.forename: Lu
authors.initials: L
authors.lastname: Ma
authors.affiliation: Key Laboratory of Organic Optoelectronics and Molecular Engineering, Department of Chemistry, Tsinghua University , Beijing 100084, China.
authors.forename: Wentao
authors.initials: W
authors.lastname: Zhu
authors.affiliation: Key Laboratory of Organic Optoelectronics and Molecular Engineering, Department of Chemistry, Tsinghua University , Beijing 100084, China.
authors.forename: Xinping
authors.initials: X
authors.lastname: Qiu
keywords: Coulombic efficiency; in situ generation; lithium sulfur battery; polysulfides capture; shuttle effect free; sulfur utilization