In situ x-ray diffraction and electrochemical studies of Li1−xNiO2

Li, W.; Reimers, J. N.; Dahn, J. R.

doi:10.1016/0167-2738(93)90317-v

Cited by 720 publications

(520 citation statements)

References 8 publications

Supporting

Mentioning

463

Contrasting

Unclassified

Order By: Relevance

“…29 The last anodic peak observed at 4.13 V belongs to the H2-H3 phase transition, which leads to a significant unit cell volume reduction and contributes to structural instability. 30 Recent studies also suggest that oxygen could be redox-active during this phase transition. 17 As the cycling proceeded, all redox peaks from NMC811 shifted further apart, which is consistent with increasing impedance and polarization.…”

Section: Resultsmentioning

confidence: 99%

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

Mao

Wood

David

et al. 2018

J. Electrochem. Soc.

View full text Add to dashboard Cite

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...

show abstract

Section: Resultsmentioning

confidence: 99%

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

Mao

Wood

David

et al. 2018

J. Electrochem. Soc.

View full text Add to dashboard Cite

show abstract

“…In order to describe the complex relationship existing in these materials between structure, chemical composition (nature of the transition metal, sodium content) and the physical properties, several systems have to be investigated. Exploring new systems would involve synthesizing each composition and characterizing its structure, however, an alternative and possibly efficient method to characterize phase diagrams is the use of electrochemistry to change the alkali ion content and hence M oxidation state while simultaneously collecting structural data 12 . The result of which is a map of the phase diagram of the NaxMO2 systems studied under the electrochemical conditions employed.…”

Section: Introductionmentioning

confidence: 99%

The Na_xMoO₂ Phase Diagram (¹/₂ ≤ x < 1): An Electrochemical Devil’s Staircase

Vitoux¹,

Guignard²,

Suchomel³

et al. 2017

Chem. Mater.

View full text Add to dashboard Cite

Layered sodium transition metal oxides represent a complex class of materials that exhibit a variety of properties, e.g. superconductivity, and can feature in a range of applications, e.g. batteries. Understanding the structure-function relationship is key to developing better materials. In this context, the phase diagram of the NaxMoO2 system has been studied using electrochemistry combined with in situ synchrotron X-ray diffraction experiments. The many steps observed in the electrochemical curve of Na2/3MoO2 during cycling in a sodium battery suggests numerous reversible structural transitions during sodium (de)intercalation between Na0.5MoO2 and Na~1MoO2. In situ X-ray diffraction confirmed the complexity of the phase diagram within this domain, thirteen single phase domains with minute changes in sodium contents. Almost all display superstructure or modulation peaks in their X-ray diffraction patterns suggesting the existence of many NaxMoO2 specific phases that are believed to be characterized by sodium/vacancy ordering as well as Mo-Mo bonds and subsequent Mo-O distances patterning in the structures. Moreover, a room temperature triclinic distortion was evidenced in the composition range 0.58 ≤ x < 0.75, for the first time in a sodium layered oxide system. Monoclinic and triclinic subcell parameters were refined for every NaxMoO2 phase identified. Reversible [MoO2] slab glidings occur during the sodium (de)intercalation. This level of structural detail provides unprecedented insight on the phases present and their evolution which may allow each phase to be isolated and examined in more detail.

show abstract

“…43,47 It was shown that Ni-rich materials have poor charge-discharge capacity retention, which could be related to the electrolyte oxidization at the positive electrode surface [7][8][9]48,49 and/or structural changes of the material, such as large c-axis shrinkage, at high potentials. 43,46,50,51 This work is therefore aimed at determining the failure mechanism of NMC811 as a function of the potential range chosen for cycle testing, the results of which will aid in further developments.In this work, half cells (coin cells) with control electrolyte and full cells (pouch cells) with control electrolyte plus additives such as vinylene carbonate (VC) and a prop-1-ene-1,3-sultone (PES) based blend were tested over four different upper cutoff potential ranges. Isothermal microcalorimetry was used to explore the parasitic reactions and their potential dependence while in-situ and ex-situ X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to investigate the structural degradation of the materials during cycling.…”

mentioning

confidence: 99%

mentioning

confidence: 99%

Study of the Failure Mechanisms of LiNi_0.8Mn_0.1Co_0.1O₂Cathode Material for Lithium Ion Batteries

Downie

et al. 2015

J. Electrochem. Soc.

443

372

View full text Add to dashboard Cite

LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811) can deliver a high capacity of ∼200 mAh/g with an average discharge potential of ∼3.8 V (vs. Li + /Li), making it a promising positive electrode material for high energy density lithium ion batteries. However, electrochemical tests from half cells and full cells show poor cycling performance when charged to potentials above 4.2 V. The calendar and cycle lifetimes of cells are affected by the structural stability of the active electrode materials as well as the parasitic reactions that occur in lithium ion batteries. In order to explore the major failure mechanisms of the material, half cells (coin cells) with control electrolyte and full cells (pouch cells) with control electrolyte and with selected electrolyte additives were tested over four different potential ranges. Isothermal microcalorimetry was used to explore the parasitic reactions and their potential dependence. In-situ and ex-situ X-ray diffraction and scanning electron microscopy were used to investigate the structural and morphological degradation of the materials over cycling. It was found that the dramatic c-axis change of the active material during charge and discharge may not be the major problem for cells that are cycled to higher potentials. The parasitic reactions that arise from the interactions between the electrolyte and the highly reactive delithiated cathode surface at high potentials are suggested as the main reason for the failure of cells cycled above 4.2 V. It should be possible to further improve the performance of NMC811 at high potentials by modifying the cathode surface and/or identifying and using electrolyte blends which reduce parasitic reactions. High energy density lithium ion batteries (LIBs) that are cheaper, safer, and with longer lifetimes need to be developed in order to meet the increasing demand for applications such as electric vehicles and large scale stationary energy storage. The energy density of LIBs can be increased by increasing the specific capacity and average potential of the cells. The calendar and cycle lifetimes of cells are affected by the structural stability of the active electrode materials as well as the parasitic reactions that occur in lithium ion batteries. The degree of lithium utilization of LiCoO 2 is limited to ∼70% in order avoid the O3 -H1-3 -O1 phase transformation when charged above 4.45 V.1 Parasitic reactions such as electrolyte oxidation at the cathode-electrolyte interface can ultimately cause cell failure.2-5 The rate of the parasitic reactions is related to both the catalytic role of the cathode surface which depends on its composition and surface area, 3,6 as well as on the stability of the electrolyte.2-5 Methods such as the use of electrolyte additives 7-11 and core-shell positive electrode materials [12][13][14] have been developed and studied to reduce the rate and extent of parasitic reactions, and hence increase capacity retention and lifetime of high-voltage Li-ion cells. The layered lithium Ni-Mn-Co oxides Li 1+x (Ni y Mn z Co (1-y-z) ) 1...

show abstract

In situ x-ray diffraction and electrochemical studies of Li1−xNiO2

Cited by 720 publications

References 8 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

The Na_xMoO₂ Phase Diagram (¹/₂ ≤ x < 1): An Electrochemical Devil’s Staircase

Study of the Failure Mechanisms of LiNi_0.8Mn_0.1Co_0.1O₂Cathode Material for Lithium Ion Batteries

Contact Info

Product

Resources

About

In situ x-ray diffraction and electrochemical studies of Li1−xNiO2

Cited by 720 publications

References 8 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

The NaxMoO2 Phase Diagram (1/2 ≤ x < 1): An Electrochemical Devil’s Staircase

Study of the Failure Mechanisms of LiNi0.8Mn0.1Co0.1O2Cathode Material for Lithium Ion Batteries

Contact Info

Product

Resources

About

The Na_xMoO₂ Phase Diagram (¹/₂ ≤ x < 1): An Electrochemical Devil’s Staircase

Study of the Failure Mechanisms of LiNi_0.8Mn_0.1Co_0.1O₂Cathode Material for Lithium Ion Batteries