Effect of Al2O3 Coating on Stabilizing LiNi0.4Mn0.4Co0.2O2 Cathodes

Wise, Anna M.; Ban, Chunmei; Weker, Johanna Nelson; Misra, Supriya; Cavanagh, Andrew S.; Wu, Zhuangchun; Li, Zheng; Whittingham, M. Stanley; Xu, Ke; George, Steven M.; Toney, Michael F.

doi:10.1021/acs.chemmater.5b02952

Cited by 195 publications

(133 citation statements)

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“…21,22 Arumugam et al showed the benficial impact of an Al 2 O 3 coating on NMC622 in cells tested to 4.4 V. 23 In all electrolytes tested, cells with the Al 2 O 3 -coated NMC622 had larger coulombic efficiency, lower charge end point capacity slippage and better capacity retention than cells using uncoated NMC622. The impact of two different coatings on NMC622 will be explored in this preliminary work.…”

Section: 12mentioning

confidence: 98%

Using the Charge-Discharge Cycling of Positive Electrode Symmetric Cells to Find Electrolyte/Electrode Combinations with Minimum Reactivity

Shen

Xiong

Ellis

et al. 2017

J. Electrochem. Soc.

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The effects of solvents, salts, electrolyte additives and surface coatings on LiNi 0.4 Mn 0.4 Co 0.2 O 2 (NMC442) or LiNi 0.6 Mn 0.2 Co 0.2 O 2 (NMC622) have been probed using positive electrode Li-ion symmetric cells coupled with dV/dQ analysis. A robust symmetric cell design is presented which prevents hardware corrosion for over at least 800 hours of testing to 4.5 V vs. Li/Li + at 40 • C. Positive electrode symmetric cells using uncoated positive electrode materials and 1M LiPF 6 EC:EMC 3:7 or 1M LiPF 6 EMC electrolyte rapidly developed high impedance and showed poor capacity retention. However, if 1% pyridine boron trifluoride (PBF) was added to these electrolytes, cell performance was dramatically improved. Replacing LiPF 6 by LiBF 4 in the electrolytes above, with or without PBF, yielded positive electrode symmetric cells with good capacity retention. Two types of surface coatings were explored on NMC622 positive electrodes. Cells using surface-coated positive electrodes demonstrated better capacity retention for all electrolytes compared to cells without surface coatings. This work can be used as a guide by those attempting to find electrolyte/electrode pairs suitable for use in NMC/graphite cells that can operate with long lifetime to 4. 1-4 The energy density of NMC/graphite cells can be easily improved if the cells can be charged to higher potential, for example to 4.4 or 4.5 V at which point the positive electrode is at about 4.48 or 4.58 V vs. Li/Li + . However, charging NMC/graphite cells to such potentials normally leads to impedance growth and a reduction in cycle and calendar life. 5,6 Increasing the charging cutoff voltage to 4.40 V can cause some problems: 1) Parasitic reactions like electrolyte oxidation can create harmful products and damage the surface of the electrodes. 7,8 In addition, in some cases, thick SEI layers on the positive electrode can be created.2) The layered surface structure of NMC (R3m) can change into a spinel-like framework (Fd3m) and then to the disordered rocksalt structure (Fm3m). 9,10 This is thought to be one cause of impedance growth at the positive electrode.3) The unit cell volume of most NMC materials begins to contract rapidly, by about 4%, when the potential is raised above 4.4 V vs Li/Li + as the lithium content is decreased below about z = 0.25 in Li x Ni 1-y-z Mn y Co z O 2 . This could induce a detachment between binder and active particles along with cracks forming inside the secondary particles. 11,12A number of strategies have been used to protect the positive electrode surface from parasitic reactions. These include the use of electrolyte additives, different salts, different solvents and electrode material coatings. Some of these strategies will be used in the work here. For example, Petibon et al. and Ma et al. 13,14 showed that ethylene carbonate (EC)-free electrolytes, like 1M LiPF 6 in 95% ethyl methyl carbonate with 5% fluoroethylene carbonate was very effective in allowing NMC/graphite cells to operate to 4.4 V. EC-free electrolytes will be expl...

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Section: 12mentioning

confidence: 98%

Using the Charge-Discharge Cycling of Positive Electrode Symmetric Cells to Find Electrolyte/Electrode Combinations with Minimum Reactivity

Shen

Xiong

Ellis

et al. 2017

J. Electrochem. Soc.

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“…These findings lead to the application of coating techniques and other surface treatments to stabilize vulnerable surfaces on the cathode materials. Such coating and surface treatments have been frequently verified as effective methods for improving cathode cycling stability19202122232425262728. Besides chemical instability, another degradation mechanism is associated with the volume change of the material upon lithium (Li) ion extraction and reinsertion.…”

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confidence: 99%

Intragranular cracking as a critical barrier for high-voltage usage of layer-structured cathode for lithium-ion batteries

et al. 2017

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LiNi1/3Mn1/3Co1/3O2-layered cathode is often fabricated in the form of secondary particles, consisting of densely packed primary particles. This offers advantages for high energy density and alleviation of cathode side reactions/corrosions, but introduces drawbacks such as intergranular cracking. Here, we report unexpected observations on the nucleation and growth of intragranular cracks in a commercial LiNi1/3Mn1/3Co1/3O2 cathode by using advanced scanning transmission electron microscopy. We find the formation of the intragranular cracks is directly associated with high-voltage cycling, an electrochemically driven and diffusion-controlled process. The intragranular cracks are noticed to be characteristically initiated from the grain interior, a consequence of a dislocation-based crack incubation mechanism. This observation is in sharp contrast with general theoretical models, predicting the initiation of intragranular cracks from grain boundaries or particle surfaces. Our study emphasizes that maintaining structural stability is the key step towards high-voltage operation of layered-cathode materials.

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“…Since B 2 O 3 oxide coating was reported to modify cathode materials for the first time byAmatucci 20 , various coating materials and methods were explored to improve the performance, chemical deposition 35 , magnetron sputtering36 and ALD[22][23] . Although these coating progresses have improved the performance, it is still difficult to ensure the homogeneity of the coating layer and avoid self-nucleation of the coating material.…”

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confidence: 99%

Enhancing the Thermal and Upper Voltage Performance of Ni-Rich Cathode Material by a Homogeneous and Facile Coating Method: Spray-Drying Coating with Nano-Al₂O₃

Xie

et al. 2016

ACS Appl. Mater. Interfaces

153

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The electrochemical performance of Ni-rich cathode material at high temperature (>50 °C) and upper voltage operation (>4.3 V) is a challenge for next-generation lithium-ion batteries (LIBs) because of the rapid capacity degradation over cycling. Here we report improved performance of LiNi0.8Co0.15Al0.05O2 materials via a LiAlO2 coating, which was prepared from a Ni0.80Co0.15Al0.05(OH)2 precursor by spray-drying coating with nano-Al2O3. Investigations by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and transmission electron microscopy revealed that an Al2O3 layer is uniformly distributed on the precursor and a LiAlO2 layer on the as-prepared cathode material. Such a coating shell acts as a scavenger to protect the cathode material from attack by HF and serious side reactions, which remarkably enhances the cycle performance at 55 °C and upper operating voltage (4.4 and 4.5 V). In particular, the sample with a 2% Al2O3 coating shows capacity retentions of 90.40%, 85.14%, 87.85%, and 81.1% after 150 cycles at a rate of 1.0C at room temperature, 55 °C, 4.4 V, and 4.5 V, respectively, which are significantly higher than those of the pristine one. This is mainly due to the significant improvement of the structural stability led by the effective coating technique, which could be extended to other cathode materials to obtain LIBs with enhanced safety and excellent cycling stability.

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Effect of Al₂O₃ Coating on Stabilizing LiNi_0.4Mn_0.4Co_0.2O₂ Cathodes

Cited by 195 publications

References 46 publications

Using the Charge-Discharge Cycling of Positive Electrode Symmetric Cells to Find Electrolyte/Electrode Combinations with Minimum Reactivity

Using the Charge-Discharge Cycling of Positive Electrode Symmetric Cells to Find Electrolyte/Electrode Combinations with Minimum Reactivity

Intragranular cracking as a critical barrier for high-voltage usage of layer-structured cathode for lithium-ion batteries

Enhancing the Thermal and Upper Voltage Performance of Ni-Rich Cathode Material by a Homogeneous and Facile Coating Method: Spray-Drying Coating with Nano-Al₂O₃

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Effect of Al2O3 Coating on Stabilizing LiNi0.4Mn0.4Co0.2O2 Cathodes

Cited by 195 publications

References 46 publications

Using the Charge-Discharge Cycling of Positive Electrode Symmetric Cells to Find Electrolyte/Electrode Combinations with Minimum Reactivity

Using the Charge-Discharge Cycling of Positive Electrode Symmetric Cells to Find Electrolyte/Electrode Combinations with Minimum Reactivity

Intragranular cracking as a critical barrier for high-voltage usage of layer-structured cathode for lithium-ion batteries

Enhancing the Thermal and Upper Voltage Performance of Ni-Rich Cathode Material by a Homogeneous and Facile Coating Method: Spray-Drying Coating with Nano-Al2O3

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Product

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Effect of Al₂O₃ Coating on Stabilizing LiNi_0.4Mn_0.4Co_0.2O₂ Cathodes

Enhancing the Thermal and Upper Voltage Performance of Ni-Rich Cathode Material by a Homogeneous and Facile Coating Method: Spray-Drying Coating with Nano-Al₂O₃