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To promote sulfur conversion kinetics by a solid auxiliary redox couple embedded in cathode for Li-S batteries


The sluggish kinetics of sulfur conversion reactions in Li-S battery is a critical challenge to its applications. Many researches have been dedicated to promote the conversion process including either functionalized matrix materials in cathodes or redox mediators in electrolytes. Here, by embedding a solid auxiliary redox species, we designed and prepared a composite which can be used as matrix for sulfur cathode. Differing from the conventional method in which all the so-called redox mediator is utilized to be dissolved in electrolyte, we employ a solid auxiliary redox species — a cobalt phthalocyanine complex supported on the graphene structures as skeleton materials of sulfur to promote the conversion kinetics in Li-S batteries. The graphene-Cobalt phthalocyanine hybrid plays a prominent role of promoting the kinetics of polysulfide conversion with multi-functions of reducing the activation energy hill, transferring electron, suppressing shuttle effect, etc. Consequently, the Li-S battery with Graphene-Cobalt phthalocyanine-sulfur cathode showed excellent electrochemical performance over the Graphene-Sulfur cathode. Typically, high initial capacity of 1400 mA h g-1 achieved at 0.1C during initial activation cycle and also, the 1st and 300th cycles capacities at 0.5C are 1116 and 860 mA h g-1 respectively. Additionally, at 0.3C rate, high capacities of 1182 and 869 mA h g-1 are obtained during the 1st and 500th cycles respectively. And, enhanced rate capability has been attained delivering a capacity of 874 mA h g-1 at 2C rate.

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Article information

07 Apr 2020
06 May 2020
First published
08 May 2020

Sustainable Energy Fuels, 2020, Accepted Manuscript
Article type

To promote sulfur conversion kinetics by a solid auxiliary redox couple embedded in cathode for Li-S batteries

G. Girma, J. Fan, P. Xu, R. Yuan, L. Cao, M. Zheng and Q. Dong, Sustainable Energy Fuels, 2020, Accepted Manuscript , DOI: 10.1039/D0SE00553C

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