Effects of Surface Coating on Gas Evolution and Impedance Growth at Li[NixMnyCo1-x-y]O2Positive Electrodes in Li-Ion Cells

Xiong, Deijun; Hynes, Toren; Ellis, L. D.; Dahn, J. R.

doi:10.1149/2.0991713jes

Cited by 25 publications

(28 citation statements)

References 49 publications

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“…In addition to the high frequency semicircle observed after formation cycles, a second semicircle appeared at lower frequency for all cathodes after aging cycles, which could be attributed to the development of charge-transfer impedance of slower process. 31,32 As summarized in Figure S6b, all cycled cathodes had significantly higher impedance after aging cycles. The strong cathode impedance growth may come from side reactions that occur at the cathode surface during cycling 33,34 and the formation of surface reconstruction layers.…”

Section: Resultsmentioning

confidence: 94%

Selecting the Best Graphite for Long-Life, High-Energy Li-Ion Batteries

Mao

Wood

David

et al. 2018

J. Electrochem. Soc.

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Most lithium-ion batteries still rely on intercalation-type graphite materials for anodes, so it is important to consider their role in full cells for applications in electric vehicles. Here, we systematically evaluate the chemical and physical properties of six commerciallyavailable natural and synthetic graphites to establish which factors have the greatest impact on the cycling stability of full cells with nickel-rich LiNi0.8Mn0.1Co0.1O2 (NMC811) cathodes. Electrochemical data and post-mortem characterization explain the origin of capacity fade. The NMC811 cathode shows large irreversible capacity loss and impedance growth, accounting for much of full cell degradation. However, six graphite anodes demonstrate significant differences with respect to structural change, surface area, impedance growth, and SEI chemistry, which impact overall capacity retention. We found long cycle life correlated most strongly with stable graphite crystallite size. In addition, graphites with lower surface area generally had higher coulombic efficiencies during formation cycles, which led to more stable long-term cycling. The best graphite screened here enables a capacity retention around 90% in full pouch cells over extensive long-term cycling compared to only 82% for cells with the lowest performing graphite. The results show that optimal graphite selection improves cycling stability of high energy lithium-ion cells. With the booming demands for electric vehicles and electronic devices, high energy density lithium-ion batteries with long cycle life are highly desired. Despite the recent progress in Si 1 and Li metal 2 as future anode materials, graphite still remains the active material of choice for the negative electrode. 3,4 Lithium ions can be intercalated into graphite sheets at various stages like Li x C 12 and Li x C 6 , providing a high specific capacity of 372 mAh/g (∼2.5 times higher than LiCoO 2 ) and high volumetric capacity (similar to LiCoO 2 ) corresponding to LiC 6 . 5,6 In addition to its low cost and non-toxicity, graphite has a lowest average voltage (150 mV vs. Li/Li + ) and the flat voltage profile, rendering a high overall cell voltage. 7 Graphite also displays a very low voltage hysteresis, which in turn results in high energy efficiency. 8 For applications in lithium-ion batteries, many properties of the graphite powders must be optimized including crystallinity, particle size, morphology, and surface chemistry. However, most research effort has been placed on the development and characterization of high performance cathodes, while the impact of the graphite anode on full cell performance has been largely unexplored.Compared to widely used battery cathodes such as LiCoO 2 (140 mAh/g), LiFePO 4 (160 mAh/g), LiNi 1/3 Mn 1/3 Co 1/3 O 2 (160 mAh/g), and LiNi 0.5 Mn 0.3 Co 0.2 O 2 (175 mAh/g), 9-11 nickel-rich LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811) is delivers a higher specific capacity (180-220 mAh/g), which increases the battery life on a single charge. 12,13 The high capacity arises because Ni is the main red...

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Section: Resultsmentioning

confidence: 94%

Selecting the Best Graphite for Long-Life, High-Energy Li-Ion Batteries

Mao

Wood

David

et al. 2018

J. Electrochem. Soc.

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“…For example, the degradation of NMC811 cells was studied by using different electrolyte additives including VC and PES211 to suppress side reactions and it was revealed that NMC442/graphite cells and NMC111/graphite cells showed better performances with PES211, whereas NMC811/graphite cells aged slower with VC (with slower capacity fading and impedance growth) [79]. Here, PES was also reported to be a viable additive for the suppression of gas evolution [91] and impedance growth during cycling to higher voltages (above 4.3 V), and rocksalt surface layers formed with the use of VC but not with PES211, concluding that electrolyte additives can significantly affect the rate of parasitic reactions and that parasitic reactions were the main reason for capacity fading [7,92].…”

Section: Parasitic Reaction: Effects Of Nimentioning

confidence: 99%

“…Li-free coatings on the outer surface of NMC cathodes have been extensively investigated due to a unique advantage over doping in which the valence of transition metal ions remains unaffected and so does the theoretical capacity. Here, materials used for Li-free coating include transition metal phosphates [187], metal oxides [99,188,189], fluorides [143,190], silicon oxide [91,100] and organic coating layers [138,191] in which the general concept is to prevent cathode surfaces containing highly reactive Ni 4+ from contacting the electrolyte and therefore to reduce side reactions. Here, coating layer thicknesses are usually between 5 and 40 nm and similar to doping, XRD measurements usually do not show new characteristic peaks and instead, existing peak widths/positions may change slightly.…”

Section: Li-free Coatingmentioning

confidence: 99%

“…For example, Chen et al have found that coating layers of Al 2 O 3 and nano-TiO 2 can suppress cation mixing (Li + and Ni 2+ ) as indicated by the ratio of I 003 -I 104 in XRD [99,188] and that Al 2 O 3 layers can reduce self-redox reactions by introducing new energy levels to prevent the reduction of Ni ions by O 2− . In addition, researchers have also found that Al 2 O 3 surface coatings can maintain stabler CEI structures [188,193] and that the atomic layer deposition (usually used to enhance coating uniformity through the precise control of coating thicknesses to several nanometers or even thinner) of Al 2 O 3 on NMC532 [101,130] can suppress parasitic reactions and phase transitions in which one study by Dahn group suggested that performance stabilizations were due to the protection of cathode surfaces to surface-oxidized species rather than the prevention of electrolyte oxidation [91]. Furthermore, researchers have also reported that the crystallization of amorphous TiO 2 applied on NMC811 surfaces can result in Li 2 TiO 3 , which can further inhibit phase transformation from H2 to H3 [96].…”

Section: Li-free Coatingmentioning

confidence: 99%

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Degradation Mechanisms and Mitigation Strategies of Nickel-Rich NMC-Based Lithium-Ion Batteries

Yuan

Zhang

et al. 2019

Electrochem. Energ. Rev.

533

383

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The demand for lithium-ion batteries (LIBs) with high mass-specific capacities, high rate capabilities and long-term cyclabilities is driving the research and development of LIBs with nickel-rich NMC (LiNi x Mn y Co 1−x−y O 2 , x ⩾ 0.5 ) cathodes and graphite (Li x C 6 ) anodes. Based on this, this review will summarize recently reported and widely recognized studies of the degradation mechanisms of Ni-rich NMC cathodes and graphite anodes. And with a broad collection of proposed mechanisms on both atomic and micrometer scales, this review can supplement previous degradation studies of Ni-rich NMC batteries. In addition, this review will categorize advanced mitigation strategies for both electrodes based on different modifications in which Ni-rich NMC cathode improvement strategies involve dopants, gradient layers, surface coatings, carbon matrixes and advanced synthesis methods, whereas graphite anode improvement strategies involve surface coatings, charge/discharge protocols and electrolyte volume estimations. Electrolyte components that can facilitate the stabilization of anodic solid electrolyte interfaces are also reviewed, and trade-offs between modification techniques as well as controversies are discussed for a deeper understanding of the mitigation strategies of Ni-rich NMC/graphite LIBs. Furthermore, this review will present various physical and electrochemical diagnostic tools that are vital in the elucidation of degradation mechanisms during operation to supplement future degradation studies. Finally, this review will summarize current research focuses and propose future research directions.

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“…The BE peaks ( Figure 4b) at 464.05 and 466.88 eV could be assigned to Ru 3 + and Ru 4 + , respectively. [22] And the major existing form of Ru in Ru/CB is Ru 3 + . The peak at 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 461.36 eV was assigned to Ru 0 .…”

Section: Resultsmentioning

confidence: 99%

Preparation and Catalytic Properties of Carbon Carrier-Supported Ruthenium Catalysts for Acetalization/Ketalization Reactions

et al. 2017

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Two kinds of supported catalysts of Ru/CNTs (CNTs=carbon nanotubes) and Ru/CB (CB=Vulcan XC‐72) were prepared with the two different carbon carrier of CNTs and CB and were well characterized. The condensation reaction of several carbonyl compounds with different diols including ethanediol, 1,2‐propandiol, 1,3‐propandiol, 1,2‐dimethylethanediol and 2,2‐ dimethylpropandiol, respectively. It was found that various aldehydes and ketones were successfully transformed to the corresponding acetals and ketals with the catalysis of the two catalysts. Recyclability tests revealed that there was no obvious decreasing of the catalytic activities after 5 runs of the catalysts.

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Effects of Surface Coating on Gas Evolution and Impedance Growth at Li[Ni_xMn_yCo_1-x-y]O₂Positive Electrodes in Li-Ion Cells

Cited by 25 publications

References 49 publications

Selecting the Best Graphite for Long-Life, High-Energy Li-Ion Batteries

Selecting the Best Graphite for Long-Life, High-Energy Li-Ion Batteries

Degradation Mechanisms and Mitigation Strategies of Nickel-Rich NMC-Based Lithium-Ion Batteries

Preparation and Catalytic Properties of Carbon Carrier-Supported Ruthenium Catalysts for Acetalization/Ketalization Reactions

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