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Title: Diffraction Analysis of the Lithium Battery Cathode Material Li(1.2)Mn(0.4)Ni(0.3)Co(0.1)O(2)

Abstract

In common with many functional materials, the composition of lithium battery cathode materials has become increasingly complex. Li{sub 1.2}Mn{sub 0.4}Ni{sub 0.3}Co{sub 0.1}O{sub 2} is a highly promising cathode material, that can have up to four cations sharing a single site. Determining the occupancies of each individual element requires more information than even a joint X-ray/neutron refinement can provide. For this material additional datasets were taken to exploit changes in elemental contrast that can be induced using resonant diffraction. Together with the actual ratios of Mn:Ni:Co determined using wavelength dispersive XRF, constraints were constructed to allow the transition metals to float across the different cation sites whilst the lithium content could be freely refined. The added complications of a C2/m monoclinic structure and anisotropic broadening made for a very complex refinement. The least squares matrices were examined in order to maintain reasonable ESDs for the variables of interest.

Authors:
; ; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
980148
Report Number(s):
BNL-93066-2010-JA
TRN: US201015%%1533
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Zeitschrift fuer Kristallographie; Journal Volume: 26
Country of Publication:
United States
Language:
English
Subject:
25 ENERGY STORAGE; CATHODES; CATIONS; DIFFRACTION; ELEMENTS; FUNCTIONALS; LITHIUM; MATERIALS; MATRICES; TRANSITION ELEMENTS; WAVELENGTHS; national synchrotron light source

Citation Formats

Whitfield, P., Davidson, I, Stephens, P, Cranswick, L, and Swainson, I. Diffraction Analysis of the Lithium Battery Cathode Material Li(1.2)Mn(0.4)Ni(0.3)Co(0.1)O(2). United States: N. p., 2007. Web. doi:10.1524/zksu.2007.2007.suppl_26.483.
Whitfield, P., Davidson, I, Stephens, P, Cranswick, L, & Swainson, I. Diffraction Analysis of the Lithium Battery Cathode Material Li(1.2)Mn(0.4)Ni(0.3)Co(0.1)O(2). United States. doi:10.1524/zksu.2007.2007.suppl_26.483.
Whitfield, P., Davidson, I, Stephens, P, Cranswick, L, and Swainson, I. Mon . "Diffraction Analysis of the Lithium Battery Cathode Material Li(1.2)Mn(0.4)Ni(0.3)Co(0.1)O(2)". United States. doi:10.1524/zksu.2007.2007.suppl_26.483.
@article{osti_980148,
title = {Diffraction Analysis of the Lithium Battery Cathode Material Li(1.2)Mn(0.4)Ni(0.3)Co(0.1)O(2)},
author = {Whitfield, P. and Davidson, I and Stephens, P and Cranswick, L and Swainson, I},
abstractNote = {In common with many functional materials, the composition of lithium battery cathode materials has become increasingly complex. Li{sub 1.2}Mn{sub 0.4}Ni{sub 0.3}Co{sub 0.1}O{sub 2} is a highly promising cathode material, that can have up to four cations sharing a single site. Determining the occupancies of each individual element requires more information than even a joint X-ray/neutron refinement can provide. For this material additional datasets were taken to exploit changes in elemental contrast that can be induced using resonant diffraction. Together with the actual ratios of Mn:Ni:Co determined using wavelength dispersive XRF, constraints were constructed to allow the transition metals to float across the different cation sites whilst the lithium content could be freely refined. The added complications of a C2/m monoclinic structure and anisotropic broadening made for a very complex refinement. The least squares matrices were examined in order to maintain reasonable ESDs for the variables of interest.},
doi = {10.1524/zksu.2007.2007.suppl_26.483},
journal = {Zeitschrift fuer Kristallographie},
number = ,
volume = 26,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • Layered lithium ion battery cathode materials have been extensively investigated, of which layered–layered compositesxLi 2MnO 3·(1 -x)LiMO 2(M = Mn, Co, Ni) are of particular interest, owing to their high energy density.
  • Lithium- and manganese-rich oxides undergo structural transformation and/or atomic rearrangements during the delithiation/lithiation process and ultimately suffer from several issues such as first cycle irreversible capacity and voltage fade. In order to understand the mechanism of these issues, perception of a detailed crystal structure of pristine material is obviously demanding. In this study, combined powder neutron diffraction (ND) and temperature-dependent magnetic susceptibility techniques were employed to investigate the structure of a pristine lithium- and manganese-rich Li1.2Mn0.55Ni0.15Co0.10O2 cathode oxide. Rietveld refinement on the experimental ND pattern yields good fits by considering either Li2MO3 (M = Co, Mn, Ni) type monoclinic (C2/m space group) phase with 1% of Ni residing in the 4h lithium site or a composite structure consisting of 50% of Li2MnO3 type monoclinic (C2/m space group) and 50% LiMO2 (M = Co, Mn, Ni) type trigonal (Rmore » $$\bar{3}$$m space group) structure. In the composite structure, 3% Li/Ni site exchange in the trigonal phase is also proposed. Further, temperature-dependent dc magnetic susceptibility shows Curie–Weiss paramagnetic behavior at T ≥ 100 K, and no ordering/deviation of the field cooling (FC) curve in the temperature range 2–320 K indicates the random distribution of metal ions in the transition metal (TM) layer in the trigonal phase. Bifurcation of the zero-field cooling (ZFC) curve from the FC curve showing a magnetic ordering at TN 50 K reveals the presence of cation ordering in the TM layers arising from a distinct Li2MnO3-like phase. These results suggest that the lithium- and manganese-rich oxide with a composition Li1.2Mn0.55Ni0.15Co0.10O2 is more likely a composite of monoclinic and trigonal phases. The report also highlights the unique materials diagnostic capability of combined ND and magnetic susceptibility techniques to obtain detailed structural information of complex oxide systems.« less
  • We find that the electrochemical rate performance and capacity retention of the “layered–layered” lithium rich Li 1.2Mn 0.525Ni 0.175Co 0.1O 2(Li-rich NMC) material are significantly improved by a nanometer layer coating of a lithium conducting solid electrolyte, lithium phosphorus oxynitride (LiPON). The LiPON layer is deposited on the Li-rich NMC particles by the RF-magnetron sputtering method. The presence of the LiPON layer provides interfacial stability under high current (rate) and voltage cycling conditions and thereby improves the capacity retention over cycle life compared to pristine or uncoated Li-rich NMC. Specifically, the LiPON coated Li-rich NMC composite electrode showed stable reversiblemore » capacities of >275 mAh g -1 when cycled to 4.9 V for more than 300 cycles, and showed at least threefold improvements in the rate performance compared to the uncoated electrode compositions. Increasing the LiPON layer thickness beyond a few nanometers leads to capacity fade due to increasing electronic resistance. Lastly, detailed microstructural and electrochemical impedance spectroscopy studies are undertaken to characterize and understand the role of LiPON in improving the interfacial stability and electrochemical activity at the interface.« less
  • Nanoscale Li-rich Li1.2Mn0.54Ni0.13Co0.13O2 material is synthesized by a co-precipitation combined freeze drying (CP-FD) method, and compared with a conventional co-precipitation method combined vacuum drying (CP-VD). With the combination of X-ray diffraction (XRD) and scanning electron microscopy (SEM), it is found that the sample from CP-FD method consists of a pure phase with good crystallinity and small, homogenous particles (100-300 nm) with uniform particle size distribution. Inductively coupled plasma spectroscopy (ICP) shows that the sample has a stoichiometric ratio of n((Li)): n((Mn)): n((Ni)): n((Co))=9: 4: 1: 1; and its Brunauer-Emmett-Teller (BET) specific surface area is 5.749 m(2)g(-1). This sample achieves excellentmore » electrochemical properties: its initial discharge capacities are 298.9 mAhg(-1) at 0.1C (20 mAg(-1)), 246.1 mAhg(-1) at 0.5C, 215.8 mAhg(-1) at 1C, and 154.2 mAhg(-1) at 5C (5C charge and 5C discharge), as well as good cycling performance. In addition, the Li+ chemical diffusion coefficient of Li1.2Mn0.54Ni0.13Co0.13O2 material prepared by the CP-FD method is 4.59 x 10(-11) cm(2) s(-1), which is higher than that of the Li1.2Mn0.54Ni0.13Co0.13O2 material prepared by CP-VD. This phenomenon illustrates the potential for Li1.2Mn0.54Ni0.13Co0.13O2 with good rate performance synthesized by CP-FD method.« less