Oxidation-reduction assisted exfoliation of LiCoO2 into nanosheets and reassembly into functional Li-ion battery cathodes

Qian Cheng, Ting Yang, Ying Li, Man Li, Candace Chan

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

A common approach used to obtain 2D nanosheet materials is through the exfoliation of layered compounds by osmotic, chemical/electrochemical, or mechanical means, with a proton exchange step usually implemented for materials characterized by strong interlayer ionic bonding. However, in lithium metal oxides, due to the strong adsorption of protons at Li+ sites, this approach is less effective for obtaining nanosheets with good electrochemical properties that can be used in Li-ion battery applications. Here LiCoO2 (LCO) was exfoliated into nanosheets using electrochemical oxidation followed by intercalation of tetraethylammonium cations. The nanosheets were purified using dialysis and electrophoresis. The nanosheets were successfully restacked into the O2-polytype of LCO with microwave hydrothermal assistance, indicating that non-equilibrium structures can be obtained by reassembling nanosheets. After high temperature annealing, the materials exhibited electrochemical properties characteristic of O3-type LCO with good capacity retention when passivated with atomic layer deposition Al2O3 coatings. This work shows that the proton exchange step usually required for the exfoliation of layered metal oxides can be circumvented, and moreover, that the obtained nanosheets could be restacked into functional electrode materials. This could pave the way for the synthesis of materials with novel structures and electrochemical properties, as well as facilitate the fabrication of hybrid and composite structures from different nanosheets as building blocks.

Original languageEnglish
Pages (from-to)6902-6910
Number of pages9
JournalJournal of Materials Chemistry A
Volume4
Issue number18
DOIs
Publication statusPublished - 2016

Fingerprint

Nanosheets
Cathodes
Electrochemical properties
Protons
Oxides
Ion exchange
Metals
Tetraethylammonium
Dialysis
Oxidation-Reduction
Lithium-ion batteries
Atomic layer deposition
Electrochemical oxidation
Intercalation
Composite structures
Electrophoresis
Lithium
Cations
Positive ions
Microwaves

ASJC Scopus subject areas

  • Chemistry(all)
  • Renewable Energy, Sustainability and the Environment
  • Materials Science(all)

Cite this

Oxidation-reduction assisted exfoliation of LiCoO2 into nanosheets and reassembly into functional Li-ion battery cathodes. / Cheng, Qian; Yang, Ting; Li, Ying; Li, Man; Chan, Candace.

In: Journal of Materials Chemistry A, Vol. 4, No. 18, 2016, p. 6902-6910.

Research output: Contribution to journalArticle

@article{d9a5606f651a448fa9f14a14e7489f65,
title = "Oxidation-reduction assisted exfoliation of LiCoO2 into nanosheets and reassembly into functional Li-ion battery cathodes",
abstract = "A common approach used to obtain 2D nanosheet materials is through the exfoliation of layered compounds by osmotic, chemical/electrochemical, or mechanical means, with a proton exchange step usually implemented for materials characterized by strong interlayer ionic bonding. However, in lithium metal oxides, due to the strong adsorption of protons at Li+ sites, this approach is less effective for obtaining nanosheets with good electrochemical properties that can be used in Li-ion battery applications. Here LiCoO2 (LCO) was exfoliated into nanosheets using electrochemical oxidation followed by intercalation of tetraethylammonium cations. The nanosheets were purified using dialysis and electrophoresis. The nanosheets were successfully restacked into the O2-polytype of LCO with microwave hydrothermal assistance, indicating that non-equilibrium structures can be obtained by reassembling nanosheets. After high temperature annealing, the materials exhibited electrochemical properties characteristic of O3-type LCO with good capacity retention when passivated with atomic layer deposition Al2O3 coatings. This work shows that the proton exchange step usually required for the exfoliation of layered metal oxides can be circumvented, and moreover, that the obtained nanosheets could be restacked into functional electrode materials. This could pave the way for the synthesis of materials with novel structures and electrochemical properties, as well as facilitate the fabrication of hybrid and composite structures from different nanosheets as building blocks.",
author = "Qian Cheng and Ting Yang and Ying Li and Man Li and Candace Chan",
year = "2016",
doi = "10.1039/c5ta09069e",
language = "English",
volume = "4",
pages = "6902--6910",
journal = "Journal of Materials Chemistry A",
issn = "2050-7488",
publisher = "Royal Society of Chemistry",
number = "18",

}

TY - JOUR

T1 - Oxidation-reduction assisted exfoliation of LiCoO2 into nanosheets and reassembly into functional Li-ion battery cathodes

AU - Cheng, Qian

AU - Yang, Ting

AU - Li, Ying

AU - Li, Man

AU - Chan, Candace

PY - 2016

Y1 - 2016

N2 - A common approach used to obtain 2D nanosheet materials is through the exfoliation of layered compounds by osmotic, chemical/electrochemical, or mechanical means, with a proton exchange step usually implemented for materials characterized by strong interlayer ionic bonding. However, in lithium metal oxides, due to the strong adsorption of protons at Li+ sites, this approach is less effective for obtaining nanosheets with good electrochemical properties that can be used in Li-ion battery applications. Here LiCoO2 (LCO) was exfoliated into nanosheets using electrochemical oxidation followed by intercalation of tetraethylammonium cations. The nanosheets were purified using dialysis and electrophoresis. The nanosheets were successfully restacked into the O2-polytype of LCO with microwave hydrothermal assistance, indicating that non-equilibrium structures can be obtained by reassembling nanosheets. After high temperature annealing, the materials exhibited electrochemical properties characteristic of O3-type LCO with good capacity retention when passivated with atomic layer deposition Al2O3 coatings. This work shows that the proton exchange step usually required for the exfoliation of layered metal oxides can be circumvented, and moreover, that the obtained nanosheets could be restacked into functional electrode materials. This could pave the way for the synthesis of materials with novel structures and electrochemical properties, as well as facilitate the fabrication of hybrid and composite structures from different nanosheets as building blocks.

AB - A common approach used to obtain 2D nanosheet materials is through the exfoliation of layered compounds by osmotic, chemical/electrochemical, or mechanical means, with a proton exchange step usually implemented for materials characterized by strong interlayer ionic bonding. However, in lithium metal oxides, due to the strong adsorption of protons at Li+ sites, this approach is less effective for obtaining nanosheets with good electrochemical properties that can be used in Li-ion battery applications. Here LiCoO2 (LCO) was exfoliated into nanosheets using electrochemical oxidation followed by intercalation of tetraethylammonium cations. The nanosheets were purified using dialysis and electrophoresis. The nanosheets were successfully restacked into the O2-polytype of LCO with microwave hydrothermal assistance, indicating that non-equilibrium structures can be obtained by reassembling nanosheets. After high temperature annealing, the materials exhibited electrochemical properties characteristic of O3-type LCO with good capacity retention when passivated with atomic layer deposition Al2O3 coatings. This work shows that the proton exchange step usually required for the exfoliation of layered metal oxides can be circumvented, and moreover, that the obtained nanosheets could be restacked into functional electrode materials. This could pave the way for the synthesis of materials with novel structures and electrochemical properties, as well as facilitate the fabrication of hybrid and composite structures from different nanosheets as building blocks.

UR - http://www.scopus.com/inward/record.url?scp=84968733007&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84968733007&partnerID=8YFLogxK

U2 - 10.1039/c5ta09069e

DO - 10.1039/c5ta09069e

M3 - Article

VL - 4

SP - 6902

EP - 6910

JO - Journal of Materials Chemistry A

JF - Journal of Materials Chemistry A

SN - 2050-7488

IS - 18

ER -