Effect of Ambient Storage on the Degradation of Ni-Rich Positive Electrode Materials (NMC811) for Li-Ion Batteries

Jung, Roland; Morasch, Robert; Karayaylalı, Pınar; Phillips, Katherine R.; Maglia, Filippo; Stinner, Christoph; Shao‐Horn, Yang; Gasteiger, Hubert A.

doi:10.1149/2.0401802jes

Cited by 337 publications

(451 citation statements)

References 35 publications

(104 reference statements)

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“…For example, surface reconstruction occurs commonly in electrodes upon exposure to the electrolyte and/or during electrochemical cycling, as in recent studies, and is attributed to the reaction between organic molecules in the electrolyte and partially coordinated metal cations in MO 6 octahedra at the particle surface. [58] The consequence of surface reconstruction during storage/cycling is similar to that induced by cooling, but it should also be noted that the cooling induced surface reconstruction is more serious, especially at the high temperatures (above 350 °C), as demonstrated in this study (Figure 3d). [18,30,45,48,[53][54][55][56][57] Such surface reconstruction during storage is found to be Ni content dependent, and more serious in high-Ni NMC cathodes, as a result of high reactivity of Ni(III) at the surface.…”

supporting

confidence: 71%

Cooling Induced Surface Reconstruction during Synthesis of High‐Ni Layered Oxides

Zhang

et al. 2019

Advanced Energy Materials

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Li-ion batteries (LIBs) are now increasingly used in electric vehicles (EVs) and other large-scale applications, but a bottleneck for their mass adoption is low Li-storage capacity, which is largely constrained by cathodes, typically with a gravimetric capacity equivalent to ≈1/2 that of the graphite anode. Despite much research into candidate cathodes for LIBs, transition metal (TM) layered oxides with a hexagonal structure (space group R3m) have remained dominant over the past three decades. [1,2] In particular, high-Ni layered oxides, LiNi x Mn y Co z O 2 (NMC; x ≥ 0.7) are now attracting world-wide interest for their high theoretical capacity (≈280 mA h g −1 ), which, however, has been difficult to realize due to the issues associated with high Ni loading: [3][4][5][6][7][8] in addition to cationic disordering (Li/Ni mixing) and the resulted low electrochemical activity, [9][10][11] Transition metal layered oxides have been the dominant cathodes in lithiumion batteries, and among them, high-Ni ones (LiNi x Mn y Co z O 2 ; x ≥ 0.7) with greatly boosted capacity and reduced cost are of particular interest for largescale applications. The high Ni loading, on the other hand, raises the critical issues of surface instability and poor rate performance. The rational design of synthesis leading to layered LiNi 0.7 Mn 0.15 Co 0.15 O 2 with greatly enhanced rate capability is demonstrated, by implementing a quenching process alternative to the general slow cooling. In situ synchrotron X-ray diffraction, coupled with surface analysis, is applied to studies of the synthesis process, revealing cooling-induced surface reconstruction involving Li 2 CO 3 accumulation, formation of a Li-deficient layer and Ni reduction at the particle surface. The reconstruction process occurs predominantly at high temperatures (above 350 °C) and is highly cooling-rate dependent, implying that surface reconstruction can be suppressed through synthetic control, i.e., quenching to improve the surface stability and rate performance of the synthesized materials. These findings may provide guidance to rational synthesis of high-Ni cathode materials. (2 of 10)cycling stability and safety are often compromised due to the surface-related issues. [12][13][14][15] Significant efforts in developing high-Ni NMC cathodes have been put on studying electrochemical impact, origin of the Li/ Ni disordering, and on improving Li/Ni ordering through optimizing synthesis conditions. [9,11,16,17] It is until very recently that people started to pay close attention to the surface instability, particularly surface reconstruction, including formation of NiO-type rock salt, [11,18,19] Li 2 CO 3 species, [10,14,[20][21][22] and nickel carbonate (NiCO 3 ·2Ni(OH) 2 ·2H 2 O). [23] These surface species are electrochemically inactive and poor in electronic and ionic conductivity, so causing high impedance to Li + (de)intercalation during cycling, [24,25] and even power fade as reported in LiNi 0.8 Co 0.2 O 2 . [26] The formation of NiO and Li 2 CO 3 at the surface of prima...

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supporting

confidence: 71%

Cooling Induced Surface Reconstruction during Synthesis of High‐Ni Layered Oxides

Zhang

et al. 2019

Advanced Energy Materials

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“…A surface layer with similar impacts can also form as cathodes come into contact with electrolytes [65]. Here, researchers suggest that this reconstructed layer can be tuned through different synthesis methods of the cathode powder [63] and that in the case of NMC111, surface impurities can also grow on top of cathode particles as resistive films over the same time period for uncycled Ni-rich NMC-based LIBs [35] that contain mainly insulating hydroxides and carbonates as revealed through Raman spectroscopy ( Fig. 3a).…”

Section: Impurities and Parasitic Reactionsmentioning

confidence: 99%

“…Apart from the cathode, graphite-the anode material that has received the most attention in LIBs due to its high mass-specific capacity and economic advantages [26,31,32]-can function collaboratively with NMC-based cathodes to provide promising performances in coin cells [20,33], pouch cells [9,34], pouch bags [11] and T-cells [35]. Based on this, this review will also provide a complete picture of the aging of graphite anodes that can affect both electrodes in battery cells based on degradation mechanisms and effective mitigation strategies.…”

Section: Introductionmentioning

confidence: 99%

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

Yuan

Zhang

et al. 2019

Electrochem. Energ. Rev.

484

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 material fatigue of layered transition metal oxides is commonly the result of correlated changes in electronic and structural properties. [93] Because of particle fracture, an increasing fraction of fresh surface is continuously exposed to the electrolyte. This, in turn, can lead to accumulation of local microstructural changes and eventually to mechanical failure.…”

Section: Introductionmentioning

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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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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Effect of Ambient Storage on the Degradation of Ni-Rich Positive Electrode Materials (NMC811) for Li-Ion Batteries

Cited by 337 publications

References 35 publications

Cooling Induced Surface Reconstruction during Synthesis of High‐Ni Layered Oxides

Cooling Induced Surface Reconstruction during Synthesis of High‐Ni Layered Oxides

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

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