Graphene quantum dots: Structural integrity and oxygen functional groups for high sulfur/sulfide utilization in lithium sulfur batteries

Jungjin Park, Joonhee Moon, Chunjoong Kim, Jin Hyoun Kang, Eunhak Lim, Jaesung Park, Kyung Jae Lee, Seung-Ho Yu, Jung Hye Seo, Jouhahn Lee, Jiyoung Heo, Nobuo Tanaka, Sung Pyo Cho, Jeffrey Pyun, Jordi Cabana, Byung Hee Hong, Yung Eun Sung

Research output: Contribution to journalArticlepeer-review

54 Citations (Scopus)

Abstract

Lithium-sulfur (Li-S) batteries are expected to overcome the limit of current energy storage devices by delivering high specific energy with low material cost. However, the potential of Li-S batteries has not yet been realized because of several technical barriers. Poor electrochemical performance is mainly attributed to the low electrical conductivity of the fully charged and discharged species, the irreversible loss of polysulfide anions and the decrease in the number of electrochemically active reaction sites during battery operation. Here, we report that the introduction of graphene quantum dots (GQDs) into the sulfur cathode dramatically enhanced sulfur/sulfide utilization, yielding high performance. In addition, the GQDs induced structural integrity of the sulfur-carbon electrode composite by oxygen-rich functional groups. This hierarchical architecture enabled fast charge transfer while minimizing the loss of lithium polysulfides, which is attributed to the physicochemical properties of GQDs. The mechanisms through which excellent cycling and rate performance are achieved were thoroughly studied by analyzing capacity versus voltage profiles. Furthermore, experimental observations and theoretical calculations further clarified the role played by GQDs by proving that C-S bonding occurs. Thus, the introduction of GQDs into Li-S batteries will provide an important breakthrough allowing their use as high-performance and low-cost batteries for next-generation energy storage systems.

Original languageEnglish
Article numbere272
JournalNPG Asia Materials
Volume8
Issue number5
DOIs
Publication statusPublished - 2016 May 27
Externally publishedYes

ASJC Scopus subject areas

  • Modelling and Simulation
  • Materials Science(all)
  • Condensed Matter Physics

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