Comprehensive Study of Li<sup>+</sup>/Ni<sup>2+</sup> Disorder in Ni-Rich NMCs Cathodes for Li-Ion Batteries
The layered oxides LiNi<sub>x</sub>Mn<sub>y</sub>Co<sub>z</sub>O<sub>2</sub> (NMCs, x + y + z = 1) with high nickel content (x ≥ 0.6, Ni-rich NMCs) are promising high-energy density-positive electrode materials for Li-ion batteries. Their electrochemic...
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MDPI AG
2021-09-01
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| author | Elena D. Orlova Aleksandra A. Savina Sergey A. Abakumov Anatolii V. Morozov Artem M. Abakumov |
| author_facet | Elena D. Orlova Aleksandra A. Savina Sergey A. Abakumov Anatolii V. Morozov Artem M. Abakumov |
| author_sort | Elena D. Orlova |
| collection | DOAJ |
| description | The layered oxides LiNi<sub>x</sub>Mn<sub>y</sub>Co<sub>z</sub>O<sub>2</sub> (NMCs, x + y + z = 1) with high nickel content (x ≥ 0.6, Ni-rich NMCs) are promising high-energy density-positive electrode materials for Li-ion batteries. Their electrochemical properties depend on Li<sup>+</sup>/Ni<sup>2+</sup> cation disordering originating from the proximity of the Li<sup>+</sup> and Ni<sup>2+</sup> ionic radii. We synthesized a series of the LiNi<sub>0</sub>.<sub>8</sub>Mn<sub>0</sub>.<sub>1</sub>Co<sub>0</sub>.<sub>1</sub>O<sub>2</sub> NMC811 adopting two different disordering schemes: Ni for Li substitution at the Li site in the samples finally annealed in air, and close to Ni↔Li antisite disorder in the oxygen-annealed samples. The defect formation scenario was revealed with Rietveld refinement from powder X-ray diffraction data, and then the reliability of semi-quantitative parameters, such as <i>I</i><sub>003</sub>/<i>I</i><sub>104</sub> integral intensity ratio and <i>c</i>/(2√6<i>a</i>) ratio of pseudocubic subcell parameters, was verified against the refined defect concentrations. The <i>I</i><sub>003</sub>/<i>I</i><sub>104</sub> ratio can serve as a quantitative measure of g(Ni<sub>Li</sub>) only after explicit correction of intensities for preferred orientation. Being normalized by the total scattering power of the unit cell, the <i>I</i><sub>003</sub>/<i>I</i><sub>104</sub> ratio depends linearly on g(Ni<sub>Li</sub>) for each disordering scheme. The <i>c</i>/(2√6<i>a</i>) ratio appears to be not reliable and cannot be used for a quantitative estimate of g(Ni<sub>Li</sub>). In turn, the volume of the <i>R</i><inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mover accent="true"><mn>3</mn><mo>¯</mo></mover></semantics></math></inline-formula><i>m</i> unit cell correlates linearly with g(Ni<sub>Li</sub>), at least for defect concentrations not exceeding 5%. The microscopy techniques such as high-resolution high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and electron diffraction tomography (EDT) allow us to study the materials locally, still, there is no proper quantitative approach for comprehensive analysis of defects. In the present work, the TEM-assisted quantitative Li<sup>+</sup>/Ni<sup>2+</sup> disordering analysis with EDT and HAADF-STEM in six Ni-rich NMC samples with various defects content is demonstrated. Noteworthy, while PXRD and EDT methods demonstrate overall defect amounts, HAADF-STEM allows us to quantitatively distinguish regions with various disordering extents. Therefore, the combination of mentioned PXRD and TEM methods gives the full picture of Li<sup>+</sup>/Ni<sup>2+</sup> mixing defects in Ni-rich NMCs. |
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| last_indexed | 2024-03-10T07:10:45Z |
| publishDate | 2021-09-01 |
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| spelling | doaj.art-95c37e3cf7cc4ad08aaaf0419881ed052023-11-22T15:27:39ZengMDPI AGSymmetry2073-89942021-09-01139162810.3390/sym13091628Comprehensive Study of Li<sup>+</sup>/Ni<sup>2+</sup> Disorder in Ni-Rich NMCs Cathodes for Li-Ion BatteriesElena D. Orlova0Aleksandra A. Savina1Sergey A. Abakumov2Anatolii V. Morozov3Artem M. Abakumov4Center for Energy Science and Technology, Skolkovo Institute of Science and Technology, Nobel Str. 3, 121205 Moscow, RussiaCenter for Energy Science and Technology, Skolkovo Institute of Science and Technology, Nobel Str. 3, 121205 Moscow, RussiaLaboratory for Molecular Imaging and Photonics, KU Leuven, Celestijnenlaan 200F, B-3001 Leuven, BelgiumCenter for Energy Science and Technology, Skolkovo Institute of Science and Technology, Nobel Str. 3, 121205 Moscow, RussiaCenter for Energy Science and Technology, Skolkovo Institute of Science and Technology, Nobel Str. 3, 121205 Moscow, RussiaThe layered oxides LiNi<sub>x</sub>Mn<sub>y</sub>Co<sub>z</sub>O<sub>2</sub> (NMCs, x + y + z = 1) with high nickel content (x ≥ 0.6, Ni-rich NMCs) are promising high-energy density-positive electrode materials for Li-ion batteries. Their electrochemical properties depend on Li<sup>+</sup>/Ni<sup>2+</sup> cation disordering originating from the proximity of the Li<sup>+</sup> and Ni<sup>2+</sup> ionic radii. We synthesized a series of the LiNi<sub>0</sub>.<sub>8</sub>Mn<sub>0</sub>.<sub>1</sub>Co<sub>0</sub>.<sub>1</sub>O<sub>2</sub> NMC811 adopting two different disordering schemes: Ni for Li substitution at the Li site in the samples finally annealed in air, and close to Ni↔Li antisite disorder in the oxygen-annealed samples. The defect formation scenario was revealed with Rietveld refinement from powder X-ray diffraction data, and then the reliability of semi-quantitative parameters, such as <i>I</i><sub>003</sub>/<i>I</i><sub>104</sub> integral intensity ratio and <i>c</i>/(2√6<i>a</i>) ratio of pseudocubic subcell parameters, was verified against the refined defect concentrations. The <i>I</i><sub>003</sub>/<i>I</i><sub>104</sub> ratio can serve as a quantitative measure of g(Ni<sub>Li</sub>) only after explicit correction of intensities for preferred orientation. Being normalized by the total scattering power of the unit cell, the <i>I</i><sub>003</sub>/<i>I</i><sub>104</sub> ratio depends linearly on g(Ni<sub>Li</sub>) for each disordering scheme. The <i>c</i>/(2√6<i>a</i>) ratio appears to be not reliable and cannot be used for a quantitative estimate of g(Ni<sub>Li</sub>). In turn, the volume of the <i>R</i><inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mover accent="true"><mn>3</mn><mo>¯</mo></mover></semantics></math></inline-formula><i>m</i> unit cell correlates linearly with g(Ni<sub>Li</sub>), at least for defect concentrations not exceeding 5%. The microscopy techniques such as high-resolution high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and electron diffraction tomography (EDT) allow us to study the materials locally, still, there is no proper quantitative approach for comprehensive analysis of defects. In the present work, the TEM-assisted quantitative Li<sup>+</sup>/Ni<sup>2+</sup> disordering analysis with EDT and HAADF-STEM in six Ni-rich NMC samples with various defects content is demonstrated. Noteworthy, while PXRD and EDT methods demonstrate overall defect amounts, HAADF-STEM allows us to quantitatively distinguish regions with various disordering extents. Therefore, the combination of mentioned PXRD and TEM methods gives the full picture of Li<sup>+</sup>/Ni<sup>2+</sup> mixing defects in Ni-rich NMCs.https://www.mdpi.com/2073-8994/13/9/1628Li-ion batterycathodelayered oxideNi-rich NMCsLi<sup>+</sup>/Ni<sup>2+</sup> anti-site defectstransmission electron microscopy |
| spellingShingle | Elena D. Orlova Aleksandra A. Savina Sergey A. Abakumov Anatolii V. Morozov Artem M. Abakumov Comprehensive Study of Li<sup>+</sup>/Ni<sup>2+</sup> Disorder in Ni-Rich NMCs Cathodes for Li-Ion Batteries Symmetry Li-ion battery cathode layered oxide Ni-rich NMCs Li<sup>+</sup>/Ni<sup>2+</sup> anti-site defects transmission electron microscopy |
| title | Comprehensive Study of Li<sup>+</sup>/Ni<sup>2+</sup> Disorder in Ni-Rich NMCs Cathodes for Li-Ion Batteries |
| title_full | Comprehensive Study of Li<sup>+</sup>/Ni<sup>2+</sup> Disorder in Ni-Rich NMCs Cathodes for Li-Ion Batteries |
| title_fullStr | Comprehensive Study of Li<sup>+</sup>/Ni<sup>2+</sup> Disorder in Ni-Rich NMCs Cathodes for Li-Ion Batteries |
| title_full_unstemmed | Comprehensive Study of Li<sup>+</sup>/Ni<sup>2+</sup> Disorder in Ni-Rich NMCs Cathodes for Li-Ion Batteries |
| title_short | Comprehensive Study of Li<sup>+</sup>/Ni<sup>2+</sup> Disorder in Ni-Rich NMCs Cathodes for Li-Ion Batteries |
| title_sort | comprehensive study of li sup sup ni sup 2 sup disorder in ni rich nmcs cathodes for li ion batteries |
| topic | Li-ion battery cathode layered oxide Ni-rich NMCs Li<sup>+</sup>/Ni<sup>2+</sup> anti-site defects transmission electron microscopy |
| url | https://www.mdpi.com/2073-8994/13/9/1628 |
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