Discharging a Li-S battery with ultra-high sulphur content cathode using a redox mediator

Kwi Ryong Kim, Kug Seung Lee, Chi Yeong Ahn, Seung-Ho Yu, Yung Eun Sung

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

Lithium-sulphur batteries are under intense research due to the high specific capacity and low cost. However, several problems limit their commercialization. One of them is the insulating nature of sulphur, which necessitates a large amount of conductive agent and binder in the cathode, reducing the effective sulphur load as well as the energy density. Here we introduce a redox mediator, cobaltocene, which acts as an electron transfer agent between the conductive surface and the polysulphides in the electrolyte. We confirmed that cobaltocene could effectively convert polysulphides to Li 2 S using scanning electron microscope, X-ray absorption near-edge structure and in-situ X-ray diffraction studies. This redox mediator enabled excellent electrochemical performance in a cathode with ultra-high sulphur content (80 wt%). It delivered 400 mAh g -1 cathode capacity after 50 cycles, which is equivalent to 800 mAh g -1 S in a typical cathode with 50 wt% sulphur. Furthermore, the volumetric capacity was also dramatically improved.

Original languageEnglish
Article number32433
JournalScientific Reports
Volume6
DOIs
Publication statusPublished - 2016 Aug 30
Externally publishedYes

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