Improvement of Rate and Cycle Performence by Rapid Polyaniline Coating of a MWCNT/Sulfur Cathode

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• 作者：Feng Wu ; Junzheng Chen ; Li Li ; Teng Zhao ; Renjie Chen
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：December 15, 2011
• 年：2011
• 卷：115
• 期：49
• 页码：24411-24417
• 全文大小：980K
• 年卷期：v.115,no.49(December 15, 2011)
• ISSN：1932-7455

文摘

Rapid in situ chemical oxidation polymerization of polyaniline was carried out to coat MWCNT-core/sulfur-shell structures. The S-coated-MWCNTs were obtained by ball-milling and thermal treatment. The polymerization was carried out by adding 2.6 g of dispersed S/MWCNT and 0.65 g of aniline hydrochloride to ethanol, and then mixing in a certain amount of ammonium peroxydisulfate dissolved in 0.2 M HCl. The addition of S/MWCNT reduced the polymerization time from 60 to 21 min. The composites were characterized by elemental analysis, FTIR, XRD, SEM, TEM, and electrochemical methods. A 70.0% sulfur, 20.2% emeraldine PANi salt and 9.8% MWCNT composite gave the typical two reduction peaks and two oxidation peaks; these are due to three polysulfide species. The initial discharge capacity was 1334.4 mAh g^鈥?-S for the PANi-S/MWCNT electrode and the remaining capacity was 932.4 mAh g^鈥?-S after 80 cycles. The columbic efficiency doubled to 92.4% compared to S-MWCNT-2. The rate of the reaction upon using PANi-S/MWCNT electrode was found to be almost twice that of the S/MWCNT composites. Because of the porous polymer, the diffusion distance of the lithium ion from the bulk liquid was reduced. The gel-like cathode composites and the higher conductivities improved the kinetics of the lithium sulfur redox reaction.