Zhijie Gong,Qixing Wu,Fang Wang,Xu Li,Xianping Fan,Hui Yang,Zhongkuan Luo
Increasing the sulfur loading in the cathode of a lithium–sulfur battery is an important way to improve its capacity for practical applications. To achieve this, the present work proposes using PEDOT-PSS to encapsulate sulfur/carbon black (S/BP) by a facile solution mixing method and the formed composite is then coated on a porous carbon paper. It is believed that the formation of a core/shell structure in the PEDOT@S/BP composite can promote the electron transport and effectively impede the diffusion of polysulfides, and the porous carbon paper is able to retain the electrolyte containing the dissolved polysulfides in the cathode and alleviate the adverse effect of sulfur volumetric expansion. Due to such advantages, the proposed cathode, with a high sulfur loading of 3 mg cm−2, can yield a high reversible capacity of 1041 mA h g−1 and an excellent cycle stability with a capacity retention of 868 mA h g−1 after 100 cycles and an average coulombic efficiency of 99.4%.
Zhenhua Wang,Jing Zhang,Yuxiang Yang,Xinyang Yue,Xiaoming Hao,Wang Sun,David Rooney,Kening Sun
Traditionally polyvinylidene fluoride membranes have been used in applications such as membrane distillation , wastewater treatment , desalination and separator fabrication. Within this work we demonstrate that a novel carbon nanofiber/polyvinylidene fluoride (CNF/PVDF) composite membrane can be used as an interlayer for Lithium Sulfur (Li S) batteries yielding both high capacity and long cycling life. This PVDF membrane is shown to effectively separate dissolved lithium polysulfide with the high electronic conductivity CNF not only reducing the internal resistance in the sulfur cathode but also helping immobilize the polysulfide through its abundant nanospaces. The resulting Li S battery assembled with the CNF/PVDF composite membrane effectively solves the polysulfide permeation problem and exhibits excellent electrochemical performance. It is further shown that the CNF/PVDF electrode has an excellent cycling stability and retains a capacity of 768.6 mAh g −1 with a coulombic efficiency above 99% over 200 cycles at 0.5C, which is more than twice that of a cell without CNF/PVDF (374 mAh g −1 ). In addition, the low-cost raw materials and the simple preparation process of CNF/PVDF composite membrane is also amenable for industrial production.
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