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Polysulfides Capture-Copper Additive for Long Cycle Life Lithium Sulfur Batteries

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journal contribution
posted on 2016-10-18, 00:00 authored by Lei Jia, Tianpin Wu, Jun Lu, Lu Ma, Wentao Zhu, Xinping Qiu
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–1 could 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.

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