Structural Factors of Sulfur Cathodes with Poly(ethylene oxide) Binder for Performance of Rechargeable Lithium Sulfur Batteries

Abstract

The structure and the room temperature performances of sulfur cathodes composed of sulfur, carbon, and poly(ethylene oxide) (PEO) binder were studied with varying preparation method and binder content. Two different methods, ball mixing and mechanical stirring, were employed for preparation of slurry to obtain morphologically different cathodes. The cathodes prepared with mechanical stirring (SC cathodes) revealed more porous structure than those with ball mixing (BC cathodes). Scanning electron microscopy observations showed that sulfur particles were covered with dense and thick PEO film in the BC cathodes, whereas sulfur particles were bonded with porous PEO film in the SC cathodes. The SC-based cells exhibited much higher discharge capacity yielding 75% of sulfur utilization than the BC-based cells. The difference of discharge behaviors with different mixing methods indicates that the porosity of the cathode and the morphology of PEO binder are highly important factors for favorable electrochemical performance of lithium sulfur batteries. The cycle life of the SC-based cell was improved with the increase of binder content and with the roll pressing due to the increase of adhesiveness and cohesiveness of the sulfur cathode. © 2002 The Electrochemical Society. All rights reserved.

New insight into the discharge process of sulfur cathode by electrochemical impedance spectroscopy

“…Although the details of the redox process of the sulfur cathode still remain unclear, it is generally accepted that the electrolyte-insoluble fully discharged product Li 2 S species which is electronically nonconductive, is responsible for the capacity fading during the charge-discharge cycles [18][19][20]. Therefore it is very important to study the details relating to the solid Li 2 S during the charge-discharge process.…”

Application of gelatin as a binder for the sulfur cathode in lithium–sulfur batteries

“…Based all the studies of lithium-sulfur battery system, PEO and PVDF are the most commonly used binder, but both of them still have revealed some problems. The PEO-based sulfur cathode usually presents poor adhesion properties [19,20] and low ionic conductivity at low temperature [21]. The PVDF binder is readily dissolved in the organic electrolytes, especially at elevated temperatures, resulting in an increase in the interfacial resistance [22].…”

Development in Lithium/Sulfur Secondary Batteries

“…The PEO-based sulfur cathode usually presents poor adhesion properties [41,42] and low ionic conductivity at low temperature [43]. The PVDF binder is readily dissolved in the organic electrolytes, especially at elevated temperatures, resulting in an increase in the interfacial resistance [44].…”