Carbon nanotube-encapsulated noble metal nanoparticle hybrid as a cathode material for Li-oxygen batteries

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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Author(s)

  • Xin Huang
  • Hong Yu
  • Huiteng Tan
  • Jixin Zhu
  • Wenyu Zhang
  • Chengyuan Wang
  • Jun Zhang
  • Yuxi Wang
  • Yunbo Lv
  • Zhi Zeng
  • Dayong Liu
  • Jun Ding
  • Madhavi Srinivasan
  • Pulickel M. Ajayan
  • Huey Hoon Hng
  • Qingyu Yan

Detail(s)

Original languageEnglish
Pages (from-to)6516-6523
Journal / PublicationAdvanced Functional Materials
Volume24
Issue number41
Online published22 Aug 2014
Publication statusPublished - 5 Nov 2014
Externally publishedYes

Abstract

Although Li-oxygen batteries offer extremely high theoretical specific energy, their practical application still faces critical challenges. One of the main obstacles is the high charge overpotential caused by sluggish kinetics of charge transfer that is closely related to the morphology of discharge products and their distribution on the cathode. Here, a series of noble metal nanoparticles (Pd, Pt, Ru and Au) are encapsulated inside end-opened carbon nanotubes (CNTs) by wet impregnation followed by thermal annealing. The resultant cathode materials exhibit a dramatic reduction of charge overpotentials compared to their counterparts with nanoparticles supported on CNT surface. Notably, the charge overpotential can be as low as 0.3 V when CNT-encapsulated Pd nanoparticles are used on the cathode. The cathode also shows good stability during discharge-charge cycling. Density functional theory (DFT) calculations reveal that encapsulation of "guest" noble metal nanoparticles in "host" CNTs is able to strengthen the electron density on CNT surfaces, and to avoid the regional enrichment of electron density caused by the direct exposure of nanoparticles on CNT surface. These unique properties ensure the uniform coverage of Li2O2 nanocrystals on CNT surfaces instead of localized distribution of Li2O2 aggregation, thus providing efficient charge transfer for the decomposition of Li2O2. Encapsulation of noble metal nanoparticles significantly strengthens the surface electron density of carbon nanotubes (CNTs) without causing regional enrichment of electron density on CNT surface. Accordingly, the entire surfaces of CNTs serve as catalytic regions for the oxygen reduction reaction (ORR), which ensures uniform covering of Li2O2 nanocrystals on the CNT surface, thus facilitating the decomposition of Li2O2 with low charge overpotential.

Research Area(s)

  • carbon nanotubes, cathode materials, charge overpotential, encapsulation, Li-oxygen batteries, surface electron distribution

Citation Format(s)

Carbon nanotube-encapsulated noble metal nanoparticle hybrid as a cathode material for Li-oxygen batteries. / Huang, Xin; Yu, Hong; Tan, Huiteng; Zhu, Jixin; Zhang, Wenyu; Wang, Chengyuan; Zhang, Jun; Wang, Yuxi; Lv, Yunbo; Zeng, Zhi; Liu, Dayong; Ding, Jun; Zhang, Qichun; Srinivasan, Madhavi; Ajayan, Pulickel M.; Hng, Huey Hoon; Yan, Qingyu.

In: Advanced Functional Materials, Vol. 24, No. 41, 05.11.2014, p. 6516-6523.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review