The formation and stability of the solid electrolyte interface on the graphite anode

Agubra, Victor; Fergus, Jeffrey W.

doi:10.1016/j.jpowsour.2014.06.024

Cited by 427 publications

(341 citation statements)

References 131 publications

(174 reference statements)

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“…The SEI acts as a protective layer to impede continuous electrolyte decomposition and solvent co-intercalation into graphitic layers during subsequent cycles. 24,25 The large charge capacity and low coulombic efficiency in the first formation cycle seen here is directly associated mainly with anode SEI formation as well as irreversible capacity loss on the cathode ( Figure S2). For example, the NMC811/SLC 1520T cell delivered a charge and discharge capacity of 224 mAh/g NMC and 192 mAh/g NMC , respectively, yielding a coulombic efficiency (CE) of 86.1% for the first formation cycle.…”

Section: Resultsmentioning

confidence: 90%

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: 90%

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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“…Based upon [51][52][53], the cycled cell is likely to experience an initially faster rate of SEI growth compared to the cell held at constant potential due to the exposure of fresh electrode surface to the electrolyte as a result of cracks in the surface film caused by cycling [54]. However, the rate of degradation was expected to slow down as the SEI layer thickened [55].…”

Section: Cycled Cellmentioning

confidence: 99%

Novel application of differential thermal voltammetry as an in-depth state-of-health diagnosis method for lithium-ion batteries

Merla

Yufit

et al. 2016

Journal of Power Sources

127

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 Accelerated ageing of lithium-ion cells under various storage/loading conditions.  Degradation analysis was performed using various in-situ diagnosis methods.  Differential thermal voltammetry (DTV) suitable for electric vehicle application.  State-of-health estimation through quantitative analyses of DTV peak evolution. AUTHOR E-MAIL ADDRESSYu Merla -yu.merla09@imperial.ac.uk Billy Wu -billy.wu@imperial.ac.uk Vladimir Yufit -v.yufit@imperial.ac.uk Nigel P. Brandon -n.brandon@imperial.ac.uk Ricardo F. Martinez-Botas -r.botas@imperial.ac.uk Gregory J. Offer -gregory.offer@imperial.ac.uk ABSTRACT Understanding and tracking battery degradation mechanisms and adapting its operation have become a necessity in order to enhance battery durability. A novel use of differential thermal voltammetry (DTV) is presented as an in-situ state-of-health (SOH) estimator for lithium-ion batteries.Accelerated ageing experiments were carried on 5Ah commercial lithium-ion polymer cells operated and stored at different temperature and loading conditions. The cells were analysed regularly with various existing in-situ diagnosis methods and the novel DTV technique to determine their SOH. The diagnosis results were used collectively to elaborate the degradation mechanisms inside the cells. The DTV spectra were decoupled into individual peaks, which each represent particular phases in the negative and positive electrode combined. The peak parameters were used to quantitatively analyse the battery SOH. 2A different cell of the same chemistry with unknown degradation history was then analysed to explore how the cell degraded. The DTV technique was able to diagnose the cell degradation without relying on supporting results from other methods nor previous cycling data. KEYWORDS:

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“…13 Actually, significant evolution of gaseous products such as CO 2 , CO, O 2 , H 2 , CH 4 , C 2 H 4 , C 2 H 6 , C 3 H 6 and C 3 H 8 from the decomposition of carbonate solvents and lithium during battery operation has been detected by various characterization techniques. [14][15][16][17][18][19][20][21] In addition, utilizing isotope analysis, Onuk et al have unambiguously identified the origin of gases evolving in LIBs. 22 Furthermore, by adopting in situ transmission electron microscopy (TEM) 23 and neutron radiography (NR), 9,11 the generation of gaseous bubbles channels formed by the gas have recently been visualized.…”

Section: Introductionmentioning

confidence: 99%

Three-Dimensional Visualization of Gas Evolution and Channel Formation inside a Lithium-Ion Battery

Sun

Markötter

Manke

et al. 2016

ACS Appl. Mater. Interfaces

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Gas generation within lithium ion batteries (LIBs) gives rise to safety concerns that question their applicability. By employing synchrotron X-ray imaging, the gas and channel evolution occurring in an operating LIB have been directly visualized in their inherent 3D state as a function of discharge and charge. Using the spatial 3D distribution of gas bubbles and channels, the active particles that dictate the performance of a functional LIB were identified and visualized in 3D. Delithiation and lithiation are interpreted as the process of activating particles continuously in a step-bystep way. The present work not only demonstrates the generation and evolution of gas within LIB in 3D, but also reveals the distribution of active particles for the first time. These fundamentally findings presented here shed light on a range of processes that could not previously be characterized in 3D and can provide practical guidance for the

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The formation and stability of the solid electrolyte interface on the graphite anode

Cited by 427 publications

References 131 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

Novel application of differential thermal voltammetry as an in-depth state-of-health diagnosis method for lithium-ion batteries

Three-Dimensional Visualization of Gas Evolution and Channel Formation inside a Lithium-Ion Battery

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