Differential voltage analyses of high-power, lithium-ion cells

Bloom, Ira; Jansen, Andrew N.; Abraham, Daniel P.; Knuth, J.; Jones, Shannon; Battaglia, Vincent; Henriksen, G. L.

doi:10.1016/j.jpowsour.2004.07.021

Cited by 471 publications

(314 citation statements)

References 36 publications

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“…This influence becomes apparent when the full cell is almost in a completely discharged state, as there is a dip in the shallower voltage slope (indicated with arrow A in Figure 5a) when the graphite electrode is almost completely delithiated at the plateau around 0.22 V (see also Figure 1). These potential shifts can be estimated through a dV/dQ analysis of the full cells after aging; descriptions of this method can be found elsewhere [41][42][43][44] and a representative example is shown in Figure 6a. In order to properly reference the contribution of each electrode to the full cell dV/dQ profiles, half cells (vs. Li metal) were assembled using the same positive NCM523 and negative graphite electrodes and cycled at a ∼C/50 rate.…”

Section: Resultsmentioning

confidence: 99%

Transition Metal Dissolution, Ion Migration, Electrocatalytic Reduction and Capacity Loss in Lithium-Ion Full Cells

Gilbert

Shkrob

Abraham

2017

J. Electrochem. Soc.

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419

513

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Continuous operation of full cells with layered transition metal (TM) oxide positive electrodes (NCM523) leads to dissolution of TM ions and their migration and incorporation into the solid electrolyte interphase (SEI) of the graphite-based negative electrode. These processes correlate with cell capacity fade and accelerate markedly as the upper cutoff voltage (UCV) exceeds 4.30 V. At voltages ≥4.4 V there is enhanced fracture of the oxide during cycling that creates new surfaces and causes increased solvent oxidation and TM dissolution. Despite this deterioration, cell capacity fade still mainly results from lithium loss in the negative electrode SEI. Among TMs, Mn content in the SEI shows a better correlation with cell capacity loss than Co and Ni contents. As Mn ions become incorporated into the SEI, the kinetics of lithium trapping change from power to linear at the higher UCVs, indicating a large effect of these ions on SEI growth and implicating (electro)catalytic reactions. We estimate that each Mn II ion deposited in the SEI causes trapping of ∼10 2 additional Li + ions thereby hastening the depletion of cyclable lithium ions. Using these results, we sketch a mechanism for cell capacity fade, emphasizing the conceptual picture over the chemical detail. Increasing the energy and power density of Li-ion batteries (LIBs) for transportation applications is desirable for extending driving range and for providing the burst of power required for vehicle acceleration.1-3 Layered transition metal (TM) oxides containing Co, Mn, and Ni are promising high-energy electrode materials, as they exhibit theoretical oxide-specific capacities >200 mAh/g and can be cycled to potentials exceeding 4.50 V vs. Li/Li + . 4,5 However, the performance deterioration of full cells, in which these oxides are paired with a graphite (Gr) negative electrode, increases markedly at potentials exceeding 4.30 V, limiting their wider use as high-energy cathode materials.6,7 Therefore, it is imperative to examine the causes for their performance loss at high voltages. In this study we aim at understanding both the phenomenology and mechanism of capacity loss; mitigation of this loss will be the focus of future articles.Several possible causes for cell performance degradation have been identified over the years. These causes include, but are not limited to (i) TM oxide structure changes leading to voltage fade, 8 (ii) buildup of electrode surface films, especially the solid-electrolyte interphases (SEIs) 9,10 at the negative electrode, leading to Li + inventory depletion and/or impedance rise, 11-13 (iii) decomposition of the electrolyte, [14][15][16] (iv) pitting corrosion of aluminum current collectors, 17-19 (v) binder destabilization leading to delamination of electrode coatings, and (vi) dissolution of electrode-active materials. [20][21][22][23] This last source, especially the dissolution of Mn and its deposition in the negative electrode SEI, has been shown to be particularly detrimental to cell performance. [24][25][26] All steps o...

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Section: Resultsmentioning

confidence: 99%

Transition Metal Dissolution, Ion Migration, Electrocatalytic Reduction and Capacity Loss in Lithium-Ion Full Cells

Gilbert

Shkrob

Abraham

2017

J. Electrochem. Soc.

Self Cite

419

513

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“…Impedance growth can reduce cell capacity at high rate. Dahn et al, 27 among others 28,29 showed that differential voltage analysis allows the active masses of both electrodes and the relative capacity slippages of each electrode to be determined. In this work, these parameters were obtained using reference differential voltage curves measured in NMC442/Li and graphite/Li half cells for fit dV/dQ vs. Q of the full cells.…”

Section: Resultsmentioning

confidence: 99%

A Guide to Ethylene Carbonate-Free Electrolyte Making for Li-Ion Cells

Glazier

Petibon

et al. 2016

J. Electrochem. Soc.

130

119

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Li [Ni 0.42 Mn 0.42 Co 0.16 ]O 2 (NMC442)/graphite pouch cells demonstrate superb performance at high voltage when ethylene carbonate (EC)-free electrolytes, using a solvent mixture that is >95% ethyl methyl carbonate (EMC) and between 2 and 5% of an "enabler", are used. The "enablers", required to passivate graphite during formation, can be vinylene carbonate (VC), methylene-ethylene carbonate (MEC), fluoroethylene carbonate (FEC) or difluoro ethylene carbonate (DiFEC), among others. In order to optimize the amount of "enabler" added to EMC, gas chromatography coupled with mass spectrometry (GC-MS) was used to track the consumption of "enabler" during the formation step. Storage tests, electrochemical impedance spectroscopy (EIS), ultrahigh precision coulometry (UHPC), long-term cycling, differential voltage analysis and isothermal microcalorimetry were used to determine the optimum amount of enabler to add to the cells. It was found that the graphite negative electrode cannot be fully passivated when the amount of "enabler" is too low resulting in gas production and capacity fade. Using excess "enabler" can cause large impedance and gas production in most cases. The choice of "enabler" also impacts cell performance. A solvent blend of 5% FEC with 95% EMC (by weight) provides the best combination of properties in NMC442/graphite cells operated to 4.4 V. It is our opinion that the experiments and their interpretation presented here represent a primer for the design of EC-free electrolytes. Lithium-ion batteries (LIB) are now widely used in electrified vehicles and energy storage systems.1 These applications require longer calendar and cycle lifetime as well as higher energy density. In order to increase the energy density of LIB, researchers focus on developing electrode materials with high specific capacity that may involve charging to increased upper cutoff potentials.2,3

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“…Similar information as in the case of a differential-voltage plot (i.e., Q-dV/dQ) can be derived from such a representation. It is useful to visualize the transitions between the different stages of the graphite electrode [42][43][44] and consequently to identify cyclable lithium loss as well as active material loss in a more quantitative manner. …”

Section: °Cmentioning

confidence: 99%

Calendar aging of a graphite/LiFePO4 cell

Kassem

Bernard

Revel

et al. 2012

Journal of Power Sources

281

124

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Graphite/LFP commercial cells are stored under 3 different conditions of temperature (30°C, 45°C, and 60°C) and SOC (30, 65, and 100%) during up to 8 months. Several non-destructive electrochemical tests are performed at different storage times in order to understand calendar aging phenomena. After storage, all the cells except those stored at 30°C exhibited capacity fade. The extent of capacity fade strongly increases with storage temperature and to a lesser extent with the state of charge. From in-depth data analysis, cyclable lithium loss was identified as the main source of capacity fade. This loss arises from side reactions taking place at the anode, e.g. solvent decomposition leading to the growth of the solid electrolyte interphase. However, the existence of reversible capacity loss also suggests the presence of side reactions occurring at the cathode, which are less prominent than those at the anode. The analyses do not show any evidence about active-material loss in the electrodes. The cells do not suffer substantial change in internal resistance. According to EIS analysis, the overall impedance increase is 70% or less.

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Differential voltage analyses of high-power, lithium-ion cells

Cited by 471 publications

References 36 publications

Transition Metal Dissolution, Ion Migration, Electrocatalytic Reduction and Capacity Loss in Lithium-Ion Full Cells

Transition Metal Dissolution, Ion Migration, Electrocatalytic Reduction and Capacity Loss in Lithium-Ion Full Cells

A Guide to Ethylene Carbonate-Free Electrolyte Making for Li-Ion Cells

Calendar aging of a graphite/LiFePO4 cell

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