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[交流] PVP在制备锂硫电池电极材料里做分散剂，提高了电池性能

PVP通常会用于表面活性剂或者分散剂，有助于分散获得更小粒径的纳米材料。这篇论文采用PVP分散硫化锂和炭黑的体系，使得两者可以结合，并且相互有良好分散性。直接上摘要~~~

The lithium−sulfur (Li−S) battery is a great alternative to the state-of-the-art lithium ion batteries due to its high energy density. However, low utilization of active materials, the insulating nature of sulfur or lithium sulfide (Li2S), and polysulfide dissolution in organic liquid electrolyte lead to low initial capacity and fast performance degradation. Herein, we propose a facile and viable approach to address these issues. This new approach entails synthesis of Li2S/carbon black (Li2S/CB) cores encapsulated by a nitrogendoped carbon shell with polyvinylpyrrolidone (PVP) assistance. Combining energy-filtered transmission electron microscopy (EFTEM) elemental mappings, XPS and FTIR measurements, it is confirmed that the as-synthesized material has a structure of a Li2S/CB core with a nitrogen-doped carbon shell (denoted as Li2S/CB@
NC). The Li2S/CB@NC cathode yields an exceptionally high initial capacity of 1020 mAh/g based on Li2S mass at 0.1 C with stable Coulombic efficiency of 99.7% over 200 cycles. Also, cycling performance shows the capacity decay per cycle as small as 0.17%. Most importantly, to further understand the materials for battery applications, field emission transmission electron microscopy (FETEM) and elemental mapping tests without exposure to air for Li2S samples in cycled cells are reported. Along with the first ever FETEM and field emission scanning electron microscopy (FESEM) investigations of cycled batteries, Li2S/CB@NC cathode demonstrates the capability of robust core−shell
nanostructures for different rates and improved capacity retention, revealing Li2S/CB@NC designed here as an outstanding system for high-performance lithium−sulfur batteries.

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附件 1 : PVP-Assisted_Synthesis_of_Uniform_Carbon_Coated_Li2S_CB_for_HighPerformance_Lithium−Sulfur_Batteries.pdf

2016-02-26 12:00:02, 647.87 K