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 journalArticlepeer-review

23 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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