Chemical versus Electrochemical Electrolyte Oxidation on NMC111, NMC622, NMC811, LNMO, and Conductive Carbon

Jung, Roland; Metzger, Michael; Maglia, Filippo; Stinner, Christoph; Gasteiger, Hubert A.

doi:10.1021/acs.jpclett.7b01927

Cited by 415 publications

(595 citation statements)

References 47 publications

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“…[219,220] Complementary results were obtained by Bak et al [226] via combined synchrotron-based (time-resolved) XRD and mass spectroscopy. [219,220] Complementary results were obtained by Bak et al [226] via combined synchrotron-based (time-resolved) XRD and mass spectroscopy.…”

Section: In Situ Gas Analyticssupporting

confidence: 59%

“…Apparently, there is a correlation between the oxygen release and the H2-H3 phase transformation, occurring in Ni-rich NCM CAMs at potentials above 4.1 V. Consistent results were also reported for the pure Ni endmember LNO. [101,219,220] During initial high-voltage charging up to 4.5-4.6 V vs Li + /Li of HE-NCM CAMs, Li 2 MnO 3 -like domains are supposed to be activated by extraction of Li and O atoms from the lattice. [227] For Li-rich layered oxides, the O 2 evolution usually occurs at high potentials.…”

Section: In Situ Gas Analyticsmentioning

confidence: 99%

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Chemical, Structural, and Electronic Aspects of Formation and Degradation Behavior on Different Length Scales of Ni‐Rich NCM and Li‐Rich HE‐NCM Cathode Materials in Li‐Ion Batteries

et al. 2019

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costs are required. Current state-of-theart LIBs using, e.g., well-established LiNi 1/3 Co 1/3 Mn 1/3 O 2 (NCM111) cathode material are yet not able to fulfill all these demands. In order to increase the energy density of LIBs, battery produ cers and researchers pursue various strategies. Substitution of expensive Co by Ni to achieve LiNi 1−x−y Co x Mn y O 2 compounds with x < 0.3 in order to increase the structural stability at high state-of-charge (SOC) is one possible approach. Another promising material class is represented by Li-rich high-energy NCM (HE-NCM) materials (cLi 2 MnO 3 ⋅[1 − c]LiTMO 2 [TM = Ni, Co, Mn, etc.]). All of these subgroups of layered oxides have in common a crystal structure that is prone to irreversible changes and fatigue during continuous Li (de-)intercalation. The relevant changes in electronic and crystal structure strongly depend on the particular cathode composition and micro/nanostructure. The development of a target-oriented roadmap to improved LIBs that meet the above requirements must address the underlying mechanisms on different cell levels, i.e., from the atomic level to the electrode level. A comprehensive summary of the properties and developments in the field of Ni-rich NCM [1][2][3][4][5][6][7][8][9] and Li-rich HE-NCM [10][11][12][13][14][15][16] has been presented recently In order to satisfy the energy demands of the electromobility market, both Ni-rich and Li-rich layered oxides of NCM type are receiving much attention as high-energy-density cathode materials for application in Li-ion batteries. However, due to different stability issues, their longevity is limited. During formation and continuous cycling, especially the electronic and crystal structure suffers from various changes, eventually leading to fatigue and mechanical degradation. In recent years, comprehensive battery research has been conducted at Karlsruhe Institute of Technology, mainly aiming at better understanding the primary degradation processes occurring in these layered transition metal oxides. The characteristic process of formation and mechanisms of fatigue are fundamentally characterized and the effect of chemical composition on cell chemistry, electrochemistry, and cycling stability is addressed on different length scales by use of state-of-the-art analytical techniques, ranging from "standard" characterization tools to combinations of advanced in situ and operando methods. Here, the results are presented and discussed within a broader scientific context. by several authors. Here, we focus on the detailed characterization of these materials on different length scales, including the processes during formation and fatigue.After a brief introduction of the different materials addressed here, their characteristic process of formation and mechanisms of fatigue are discussed with respect to cell chemistry, electrochemistry, and cycling stability. Based on the fundamental results of our experimental studies on the material level, the effect of formation and fatigue on different cell levels is evalu...

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Section: In Situ Gas Analyticssupporting

confidence: 59%

Section: In Situ Gas Analyticsmentioning

confidence: 99%

Chemical, Structural, and Electronic Aspects of Formation and Degradation Behavior on Different Length Scales of Ni‐Rich NCM and Li‐Rich HE‐NCM Cathode Materials in Li‐Ion Batteries

et al. 2019

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“…However, Jung et al 8,10,44 and Strehle et al 25 proposed another concept for stochiometric and overlithiated layered oxides, respectively, suggesting that CO 2 evolution starting at 4.2 V vs. Li + /Li before the onset of oxygen release is produced by the oxidation of surface impurities, while the released oxygen is suggested to react with the carbonate electrolyte causing CO 2 evolution, consistent with the concomitant rapid increase in CO 2 concentration. While the exact mechanism leading to CO 2 evolution is still subject to ongoing discussions, we will here adopt the mechanistic view proposed by Strehle et MnO 3 , and 2350 μmol/g for 0.50 Li 2 MnO 3 ), bulk oxygen release does not seem to be a feasible mechanism for these overlithiated materials.…”

Section: Resultsmentioning

confidence: 99%

“…6,7 However, it has been shown that all NCM materials show structural instabilities at high state-of-charge (SOC), i.e., at a high degree of delithiation, leading to oxygen release from the near-surface region accompanied by the formation of a resistive surface layer; ultimately, this leads to rapid capacity fading and limits the practical capacity of NCM materials to <200 mAh/g. [8][9][10] * Electrochemical Society Member. * * Electrochemical Society Fellow.…”

mentioning

confidence: 99%

Oxygen Release and Surface Degradation of Li- and Mn-Rich Layered Oxides in Variation of the Li₂MnO₃Content

Teufl

Strehle

Müller³

et al. 2018

J. Electrochem. Soc.

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In this study, we will show how the oxygen release depends on the Li 2 MnO 3 content of the material and how it affects the actual voltage fading of the material. Thus, we compared overlithiated NCMs (x Li 2 MnO 3 • (1-x) LiMeO 2 ; Me = Ni, Co, Mn) with x = 0.33, 0.42 and 0.50, focusing on oxygen release and electrochemical performance. We could show that the oxygen release differs vastly for the materials, while voltage fading is similar, which leads to the conclusion that the oxygen release is a chemical material degradation, occurring at the surface, while voltage fading is a bulk issue of these materials. We could prove this hypothesis by HRTEM, showing a surface layer, which is dependent on the amount of oxygen released in the first cycles and leads to an increase of the charge-transfer resistance of these materials. Furthermore, we could quantitatively deconvolute capacity contributions from bulk and surface regions by dQ/dV analysis and correlate them to the oxygen loss. As a last step, we compared the gassing to the base NCM (LiMeO 2 , Me = Ni, Co, Mn), showing that surface degradation follows a similar reaction pathway and can be easily To face future issues, as global warming, air pollution, as well as the consumption of fossil fuels, an alternative is required to cover the future demand of energy and mobility in an environmentally friendly and sustainable way. In this context, lithium-ion batteries are viable options for large scale energy storage and for electric vehicles, as they have been used to power consumer electronics for many years. 1,2Since graphite is an excellent anode material at potentials of ≈0.1 V vs. Li + /Li with a roughly 2-fold higher specific capacity of about 360 mAh/g compared to currently used cathode active materials (CAMs), many efforts have been undertaken to increase the specific capacity and energy density of CAMs. As first practical cathode active material Lithium-Cobalt-Oxide (LCO) was investigated by Goodenough et al. in the 1980s, exhibiting a specific capacity of about 140 mAh/g and having a layered structure composed of lithium and transition metal layers.3 As these layered structures showed good structural stability during lithium extraction and insertion, and therefore good capacity retention, many attempts have been undertaken to further develop alternative layered structures which would offer higher capacity. One promising attempt that led to the currently used Lithium-NickelCobalt-Manganese-Oxides (NCMs) is to change the occupancy of the transition metal layer by not using exclusively cobalt, but also introducing nickel and manganese into the transition metal layer; hereby it was found that nickel shows a high redox activity, while manganese helps to stabilize the structure during lithium extraction.4-6 By using different transition metals and metal compositions, a playground has been created that allows to tune the properties of the material: while initially a Ni:Co:Mn ratio of 1:1:1 was used (also referred to as NCM-111), trends nowadays favor the so-called Ni...

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“…Electrolyte (EC/DEC) is electrochemically stable until ~4.8 V with a blank electrode composed of conductive carbon and PVDF. 52, 53 We do not attempt to ascribe a capacity to the CO 2 evolution, as CO 2 is likely evolved from surface Li 2 CO 3 that remains after synthesis. Of note, any non-volatile electrolyte decomposition products that cannot be detected using DEMS could contribute to the irreversible capacity on charge.…”

Section: Resultsmentioning

confidence: 99%

Elucidating anionic oxygen activity in lithium-rich layered oxides

et al. 2018

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Recent research has explored combining conventional transition-metal redox with anionic lattice oxygen redox as a new and exciting direction to search for high-capacity lithium-ion cathodes. Here, we probe the poorly understood electrochemical activity of anionic oxygen from a material perspective by elucidating the effect of the transition metal on oxygen redox activity. We study two lithium-rich layered oxides, specifically lithium nickel metal oxides where metal is either manganese or ruthenium, which possess a similar structure and discharge characteristics, but exhibit distinctly different charge profiles. By combining X-ray spectroscopy with operando differential electrochemical mass spectrometry, we reveal completely different oxygen redox activity in each material, likely resulting from the different interaction between the lattice oxygen and transition metals. This work provides additional insights into the complex mechanism of oxygen redox and development of advanced high-capacity lithium-ion cathodes.

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Chemical versus Electrochemical Electrolyte Oxidation on NMC111, NMC622, NMC811, LNMO, and Conductive Carbon

Cited by 415 publications

References 47 publications

Chemical, Structural, and Electronic Aspects of Formation and Degradation Behavior on Different Length Scales of Ni‐Rich NCM and Li‐Rich HE‐NCM Cathode Materials in Li‐Ion Batteries

Chemical, Structural, and Electronic Aspects of Formation and Degradation Behavior on Different Length Scales of Ni‐Rich NCM and Li‐Rich HE‐NCM Cathode Materials in Li‐Ion Batteries

Oxygen Release and Surface Degradation of Li- and Mn-Rich Layered Oxides in Variation of the Li₂MnO₃Content

Elucidating anionic oxygen activity in lithium-rich layered oxides

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Chemical versus Electrochemical Electrolyte Oxidation on NMC111, NMC622, NMC811, LNMO, and Conductive Carbon

Cited by 415 publications

References 47 publications

Chemical, Structural, and Electronic Aspects of Formation and Degradation Behavior on Different Length Scales of Ni‐Rich NCM and Li‐Rich HE‐NCM Cathode Materials in Li‐Ion Batteries

Chemical, Structural, and Electronic Aspects of Formation and Degradation Behavior on Different Length Scales of Ni‐Rich NCM and Li‐Rich HE‐NCM Cathode Materials in Li‐Ion Batteries

Oxygen Release and Surface Degradation of Li- and Mn-Rich Layered Oxides in Variation of the Li2MnO3Content

Elucidating anionic oxygen activity in lithium-rich layered oxides

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Oxygen Release and Surface Degradation of Li- and Mn-Rich Layered Oxides in Variation of the Li₂MnO₃Content