Hierarchical hollow microspheres grafted with Co nanoparticle-embedded bamboo-like N-doped carbon nanotube bundles as ultrahigh rate and long-life cathodes for rechargeable lithium-oxygen batteries

Jung Hyun Kim, Seung Keun Park, Yeon Jong Oh, Yun Chan Kang

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

Rational design of efficient, affordable, and durable electrocatalysts for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is essential for rechargeable lithium-oxygen (Li–O2) batteries. We present for the first time hierarchical hollow microspheres grafted with metallic Co-embedded bamboo-like N-doped carbon nanotube bundles (Co-b-NCNTs hollow microspheres) as oxygen electrodes for Li-air batteries. Hierarchical composite microspheres are prepared via a facile two-step process involving synthesis of Co3O4-MgO hollow microspheres by spray pyrolysis, followed by internal and external growth of bamboo-like NCNTs in the shells. During post-treatment, metallic Co and MgO nanoparticles play key respective roles in catalyzing in-situ growth of NCNTs and maintaining structural integrity of the composites. The hierarchical composite structure with Co and N doping not only provides ample active sites for the OER and ORR, but also sufficient space for storing produced Li2O2. Thus, Co-b-NCNTs hollow microspheres exhibit high initial round-trip efficiency, long-term cycling and ultrahigh rate performances when applied as oxygen electrodes for Li–O2 batteries. The initial discharge capacity and round-trip efficiency at a current density of 200 mA g−1 are 28,968 mA h g−1 and 78.2%, respectively. Specific capacities at cutoff capacities of 500 and 1000 mA h g−1 are stable for 201 and 157 cycles, respectively.

Original languageEnglish
Pages (from-to)2500-2510
Number of pages11
JournalChemical Engineering Journal
Volume334
DOIs
Publication statusPublished - 2018 Feb 15

Keywords

  • Carbon nanotubes
  • Cathode material
  • Hierarchical structure
  • Li-O batteries
  • Nanostructured material
  • Spray pyrolysis

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry
  • Chemical Engineering(all)
  • Industrial and Manufacturing Engineering

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