Investigating phase transformation in the Li1.2Co0.1Mn0.55Ni0.15O2 lithium-ion battery cathode during high-voltage hold (4.5 V) via magnetic, X-ray diffraction and electron microscopy studies

Debasish Mohanty; Athena S. Sefat; Sergiy Kalnaus; Jianlin Li; Roberta A. Meisner; E. Andrew Payzant; Daniel P. Abraham; David L. Wood; Claus Daniel

doi:10.1039/C3TA10304H

Investigating phase transformation in the Li_1.2Co_0.1Mn_0.55Ni_0.15O₂ lithium-ion battery cathode during high-voltage hold (4.5 V) via magnetic, X-ray diffraction and electron microscopy studies†

Debasish Mohanty,*^a Athena S. Sefat,^a Sergiy Kalnaus,^a Jianlin Li,^b Roberta A. Meisner,^a E. Andrew Payzant,^c Daniel P. Abraham,^d David L. Wood^a and Claus Daniel^be

Author affiliations

* Corresponding authors

^a Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37931-6083, USA
E-mail: mohantyd@ornl.gov

^b Energy and Transportation Science Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA

^c Chemical and Engineering Materials Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee-37831-6083, USA

^d Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, Illinois-60439, USA

^e Bredesen Centre for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville, Tennessee 37996, USA

Abstract

This study is the first that provides evidence of phase transformation in a Li-rich Li_1.2Co_0.1Mn_0.55Ni_0.15O₂ cathode material for lithium-ion batteries (LIBs) during constant voltage charging. Diffraction and magnetic measurement techniques were successfully implemented to investigate the structural transformation in this cathode material during holding a half-cell at 4.5 V in a charged state. The results from X-ray diffraction showed a decrease in c-lattice parameters during high-voltage hold. Magnetic data revealed an increase in average effective magnetic moments of transition metal (TM) ions at constant voltage corresponding to a change in electronic states of TM ions. Analysis showed the reduction of Ni⁴⁺ to Ni²⁺, which was attributed to charge compensation due to oxygen loss. The appearance of the strong {10 [1 with combining macron] 0} forbidden reflection in the single-crystal selected area electron diffraction (SAED) data was attributed to migration of transition metal ions to the octahedral vacancy sites in the lithium layer during high-voltage hold, which was in agreement with the magnetization results. After prolonged hold at 4.5 V, high-resolution transmission electron microscopy (TEM) images along with SAED results showed the presence of spinel phases in the particles, indicating a layered to spinel like phase transformation at constant voltage in agreement with the magnetic data. The results obtained from these magnetic and diffraction studies furnish the fundamental understanding of the structural transformation pathways in Li-rich cathodes at constant voltage and will be instrumental for modifying the parent structure to achieve greater stability.

$Graphical abstract: Investigating phase transformation in the Li1.2Co0.1Mn0.55Ni0.15O2 lithium-ion battery cathode during high-voltage hold (4.5 V) via magnetic, X-ray diffraction and electron microscopy studies$

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Article information

DOI: https://doi.org/10.1039/C3TA10304H
Article type: Paper
Submitted: 21 Jan 2013
Accepted: 21 Mar 2013
First published: 21 Mar 2013

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J. Mater. Chem. A, 2013,1, 6249-6261

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Investigating phase transformation in the Li_1.2Co_0.1Mn_0.55Ni_0.15O₂ lithium-ion battery cathode during high-voltage hold (4.5 V) via magnetic, X-ray diffraction and electron microscopy studies

D. Mohanty, A. S. Sefat, S. Kalnaus, J. Li, R. A. Meisner, E. A. Payzant, D. P. Abraham, D. L. Wood and C. Daniel, J. Mater. Chem. A, 2013, 1, 6249 DOI: 10.1039/C3TA10304H

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Journal of Materials Chemistry A