Amorphous GeOx-Coated Reduced Graphene Oxide Balls with Sandwich Structure for Long-Life Lithium-Ion Batteries

Seung Ho Choi, Kyeong Youl Jung, Yun Chan Kang

Research output: Contribution to journalArticlepeer-review

47 Citations (Scopus)

Abstract

Amorphous GeOx-coated reduced graphene oxide (rGO) balls with sandwich structure are prepared via a spray-pyrolysis process using polystyrene (PS) nanobeads as sacrificial templates. This sandwich structure is formed by uniformly coating the exterior and interior of few-layer rGO with amorphous GeOx layers. X-ray photoelectron spectroscopy analysis reveals a Ge:O stoichiometry ratio of 1:1.7. The amorphous GeOx-coated rGO balls with sandwich structure have low charge-transfer resistance and fast Li+-ion diffusion rate. For example, at a current density of 2 A g-1, the GeOx-coated rGO balls with sandwich and filled structures and the commercial GeO2 powders exhibit initial charge capacities of 795, 651, and 634 mA h g-1, respectively; the corresponding 700th-cycle charge capacities are 758, 579, and 361 mA h g-1. In addition, at a current density of 5 A g-1, the rGO balls with sandwich structure have a 1600th-cycle reversible charge capacity of 629 mA h g-1 and a corresponding capacity retention of 90.7%, as measured from the maximum reversible capacity at the 100th cycle. (Chemical Equation Presented).

Original languageEnglish
Pages (from-to)13952-13959
Number of pages8
JournalACS Applied Materials and Interfaces
Volume7
Issue number25
DOIs
Publication statusPublished - 2015 Jul 1

Keywords

  • anode material
  • germanium oxide
  • graphene composite
  • lithium-ion battery
  • spray pyrolysis

ASJC Scopus subject areas

  • Materials Science(all)

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