Influence of surface modification on electrochemical performance of high voltage spinel ordered-LiNi0.5Mn1.5O4 exposed to 5.3 v for 100 h before and after surface modification with ALD method

Chae Ah Kim, Hyung Jong Choi, Jung Hwa Lee, Sun Young Yoo, Jun Woo Kim, Joon Hyung Shim, Byoungwoo Kang

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

To quantify the effect of high voltage on the electrochemical properties of high-potential spinel ordered-LiNi0.5Mn1.5O4, it was intentionally exposed to 5.3 V for 100 h that can ensure the decomposition of electrolyte. After this treatment, the bulk structure did not change, but electrochemical properties of the sample were severely degraded; polarization became large and capacity loss was substantial. Polarization was caused by formation of a thick insulating passivation layer on the surface of the sample that was measured by impedance spectroscopy. The capacity loss can be partially caused by incomplete phase transformation during discharging as a result of loss of electrical contact due to the presence of the thick passivation layer on the surface of particles. This indicates that the phase transformation depends on the applied current. The other cause for the capacity loss can be from the inactiveness of transition metals in the surface that was measured by XPS. Thick passivation layer on the surface can have inactive transition metals leading to permanent capacity fading. Hence, to control the electrode stability in high voltage spinel LiNi0.5Mn1.5O4, a bare LNMO sample coated with Al2O3 by Atomic Layer Deposition (ALD) were prepared, then exposed to 5.3 V for 100 h. After this surface treatment, the Al2O3-coated sample showed much better electrochemical performance than the bare sample. During the exposure, the bare sample underwent intensive surface reactions with very large generated current density and large charge-transfer resistance. In contrast, the coated sample experienced much weaker surface reactions with low charge-transfer resistance even though the applied potential, 5.3 V was much higher than the stable upper voltage limit (∼4.5 V) of conventional electrolyte. The coating effectively protects the surface of the material from surface reactions such as oxidation of the electrolyte; therefore Al2O3-coated LNMO shows reasonable electrochemical properties after exposing at 5.3 V for 100 h. This finding demonstrates that detrimental effects of the exposure at high potential on the electrochemical properties strongly depends on surface characteristics. This understanding can be used to stabilize high-voltage positive electrode materials.

Original languageEnglish
Pages (from-to)134-142
Number of pages9
JournalElectrochimica Acta
Volume184
DOIs
Publication statusPublished - 2015 Dec 1

Fingerprint

Atomic layer deposition
Surface treatment
Electrochemical properties
Surface reactions
Electric potential
Passivation
Electrolytes
Transition metals
Charge transfer
Phase transitions
Polarization
Electrodes
spinell
Current density
X ray photoelectron spectroscopy
Spectroscopy
Decomposition
Coatings
Oxidation

Keywords

  • ALD coating
  • electrolyte reactions
  • high-potential LiNiMnO spinel
  • high-voltage exposure

ASJC Scopus subject areas

  • Electrochemistry
  • Chemical Engineering(all)

Cite this

Influence of surface modification on electrochemical performance of high voltage spinel ordered-LiNi0.5Mn1.5O4 exposed to 5.3 v for 100 h before and after surface modification with ALD method. / Kim, Chae Ah; Choi, Hyung Jong; Lee, Jung Hwa; Yoo, Sun Young; Kim, Jun Woo; Shim, Joon Hyung; Kang, Byoungwoo.

In: Electrochimica Acta, Vol. 184, 01.12.2015, p. 134-142.

Research output: Contribution to journalArticle

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abstract = "To quantify the effect of high voltage on the electrochemical properties of high-potential spinel ordered-LiNi0.5Mn1.5O4, it was intentionally exposed to 5.3 V for 100 h that can ensure the decomposition of electrolyte. After this treatment, the bulk structure did not change, but electrochemical properties of the sample were severely degraded; polarization became large and capacity loss was substantial. Polarization was caused by formation of a thick insulating passivation layer on the surface of the sample that was measured by impedance spectroscopy. The capacity loss can be partially caused by incomplete phase transformation during discharging as a result of loss of electrical contact due to the presence of the thick passivation layer on the surface of particles. This indicates that the phase transformation depends on the applied current. The other cause for the capacity loss can be from the inactiveness of transition metals in the surface that was measured by XPS. Thick passivation layer on the surface can have inactive transition metals leading to permanent capacity fading. Hence, to control the electrode stability in high voltage spinel LiNi0.5Mn1.5O4, a bare LNMO sample coated with Al2O3 by Atomic Layer Deposition (ALD) were prepared, then exposed to 5.3 V for 100 h. After this surface treatment, the Al2O3-coated sample showed much better electrochemical performance than the bare sample. During the exposure, the bare sample underwent intensive surface reactions with very large generated current density and large charge-transfer resistance. In contrast, the coated sample experienced much weaker surface reactions with low charge-transfer resistance even though the applied potential, 5.3 V was much higher than the stable upper voltage limit (∼4.5 V) of conventional electrolyte. The coating effectively protects the surface of the material from surface reactions such as oxidation of the electrolyte; therefore Al2O3-coated LNMO shows reasonable electrochemical properties after exposing at 5.3 V for 100 h. This finding demonstrates that detrimental effects of the exposure at high potential on the electrochemical properties strongly depends on surface characteristics. This understanding can be used to stabilize high-voltage positive electrode materials.",
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AU - Choi, Hyung Jong

AU - Lee, Jung Hwa

AU - Yoo, Sun Young

AU - Kim, Jun Woo

AU - Shim, Joon Hyung

AU - Kang, Byoungwoo

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AB - To quantify the effect of high voltage on the electrochemical properties of high-potential spinel ordered-LiNi0.5Mn1.5O4, it was intentionally exposed to 5.3 V for 100 h that can ensure the decomposition of electrolyte. After this treatment, the bulk structure did not change, but electrochemical properties of the sample were severely degraded; polarization became large and capacity loss was substantial. Polarization was caused by formation of a thick insulating passivation layer on the surface of the sample that was measured by impedance spectroscopy. The capacity loss can be partially caused by incomplete phase transformation during discharging as a result of loss of electrical contact due to the presence of the thick passivation layer on the surface of particles. This indicates that the phase transformation depends on the applied current. The other cause for the capacity loss can be from the inactiveness of transition metals in the surface that was measured by XPS. Thick passivation layer on the surface can have inactive transition metals leading to permanent capacity fading. Hence, to control the electrode stability in high voltage spinel LiNi0.5Mn1.5O4, a bare LNMO sample coated with Al2O3 by Atomic Layer Deposition (ALD) were prepared, then exposed to 5.3 V for 100 h. After this surface treatment, the Al2O3-coated sample showed much better electrochemical performance than the bare sample. During the exposure, the bare sample underwent intensive surface reactions with very large generated current density and large charge-transfer resistance. In contrast, the coated sample experienced much weaker surface reactions with low charge-transfer resistance even though the applied potential, 5.3 V was much higher than the stable upper voltage limit (∼4.5 V) of conventional electrolyte. The coating effectively protects the surface of the material from surface reactions such as oxidation of the electrolyte; therefore Al2O3-coated LNMO shows reasonable electrochemical properties after exposing at 5.3 V for 100 h. This finding demonstrates that detrimental effects of the exposure at high potential on the electrochemical properties strongly depends on surface characteristics. This understanding can be used to stabilize high-voltage positive electrode materials.

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