Differential Thermal Analysis

Vold, Marjorie J.

doi:10.1021/ac60030a011

Cited by 184 publications

(71 citation statements)

References 14 publications

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“…The difference in temperature between sample and reference (T sample − T reference ) thus constitutes the DTA signal. [7][8][9] During a melting event, this difference can be represented graphically in the form of a peak when plotted against reference temperature or equivalently, time. By a thermally inert reference, the absence of phase transitions over the temperature range of interest is implied.…”

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confidence: 99%

Differential Thermal Analysis of Li-Ion Cells as an Effective Probe of Liquid Electrolyte Evolution during Aging

Day

Xia

Petibon

et al. 2015

J. Electrochem. Soc.

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A technique has been developed to allow for in-situ observation of the state of the liquid electrolyte present in an electrochemical device through exploiting the nature of solid-liquid phase transitions. An apparatus was developed to perform differential thermal analysis (DTA) on complete NMC/graphite lithium-ion pouch cells. The DTA apparatus monitored the temperature of a sample cell alongside that of a thermally inert reference cell during a controlled temperature scan through the melting point of the electrolyte in the sample cell, producing a thermal signature of the sample electrolyte without damage to the cell performance. This signature holds information pertaining to the composition and amount of liquid electrolyte present in the electrochemical device, allowing for detailed study of electrolyte evolution at various points of life and indications of the state-of-health of the device. In recent years, lithium-ion batteries have surpassed other competing technologies as the pre-eminent choice in a wide range of energy storage applications. With expansion beyond use in personal electronics into mainstream automotive applications and grid storage, a more complete understanding of the complex processes evolving in these devices over a decade of life is of utmost importance. A generic lithium-ion cell comprises two electrodes and a liquid electrolyte (itself composed of ever-increasingly complex systems of lithium-based salts, organic solvents and a blend of electrolyte additives intended to stabilize and improve the cell operation and lifetime). Parasitic reactions are known to coincide with regular operation of the device, leading to reduction and oxidation of the liquid electrolyte through development of solid electrolyte interface layers (SEI) and also other reactions at the electrodes.1-3 Depending on the specific electrolyte chemistry and cycling protocol, this may result in substantial changes to the chemistry of the electrolyte compared to that introduced to the cell at time of manufacturing, significant electrolyte consumption, or both.To date, studies of this evolution have been limited to ex situ post mortem studies of the cells. Possible methods include X-ray photoelectron spectroscopy (XPS) 2 and gas chromatography coupled with mass-spectrometry (GC/MS). 4 These studies are limited as XPS studies the SEI directly as opposed to the electrolyte itself and GC/MS is insensitive to the electrolyte salt. Furthermore, all such schemes are inherently destructive, precluding intermittent study of a single cell at arbitrary points of life.A thorough understanding of the evolution and loss of liquid electrolyte are critical to both determining chemistries for study in research programs, as well as establishing the value and remaining lifetime of an used lithium-ion cell. The strict capacity requirements for Li-ion cells in electric vehicles necessitating battery disposal at an intermediate state of life has resulted in the recent emergence of a used-battery market. 5,6 This further underscores the value of...

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confidence: 99%

Differential Thermal Analysis of Li-Ion Cells as an Effective Probe of Liquid Electrolyte Evolution during Aging

Day

Xia

Petibon

et al. 2015

J. Electrochem. Soc.

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“…Further, theoretical DTA and rate curves for special mechanisms were generated by our integration program METEX [19,21,23, and were subjected to the same routine evaluation program (comparative one-step strategy [19,32,33]) as the experiments. For the DTA experiments, the reaction enthalpy AH was calculated from the temperature difference B(t) sample/reference using VOLDs equation [34] c c , ra The assumptions for the determination of the reference rate coefJcients were [19,35,36]: 1) The bimolecular rate law for the reaction between bromate and bromide (lo-' M Br-assumed for the bromide-free experiments); 2) Arrhenius equation; 3) Proportionality of rate and heat flow; 4) First-order heat decay in the calorimeter equation (Tian-equation) [19,29,37].…”

Section: Discussionmentioning

confidence: 99%

New strategies for studies on the kinetics and energetics of the Belousov‐Zhabotinskii reaction

Koch

Nagy-Ungvárai

1987

Ber Bunsenges Phys Chem

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Catalysis / Chemical Kinetics / Computer Experiments / Oscillatory Chemical Reactions / Thermal AnalysisThe oscillatory Belousov-Zhabotinskii reaction and its subsystems were studied by z 1700 DTA and UV experiments performed at linearly increased temperature. The starting concentrations of bromate, bromide, catalyst, and malonic acid were varied in order to obtain "concentration codes" of such series. These represent the dependence of any parameters in discrete ranges of the starting concentrations of the different components. Particularly adequate for a model check are the mechanistic codes (= MCC's), which concern the shape index and reaction type index: If these mechanistic coordinates remain constant in such a concentration interval, other data, e.g. activation energies, can be attributed to a rate-determining process. -The results led to a nine-step model which is based on the FKN mechanism and is capable of roughly reproducing the influence of the initial concentrations and heating rate on 11 parameters characteristic of the envelope and of the oscillations of the experimental signals. The MCC's of the experimental and theoretical series are similar, revealing 4-5 rate-determining steps in the different concentration ranges. -The activation energies agree with values from the literature, cited for three steps; these and further resulting activation energies are consistent with our studies with subsystems.

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“…In 1939 Norton published his classical paper on differential thermal techniques where he made rather excessive claims for their value both in the identification and quantitative analysis exemplifying clay mixtures [51]. Vold (1948) [52] and Smyth (1951) [53] proposed a more advanced DTA theory, but the first detailed theories and applicability fashions, free from restrictions, became accessible by followers in 1950s [3,50,[54][55][56][57][58], e.g., Keer, Kulp, Evans, Blumberg, Erikson, Soule, Boersma, Borchard, Damiels, Deeg, Nagasawa, Tsuzuki, Barshad, Strum, Lukaszewski, etc.…”

Section: Early Scientific and Societal Parentage Of Thermal Analysismentioning

confidence: 99%

Historical Roots and Development of Thermal Analysis and Calorimetry

Šesták

Hubík

Mareš

2010

Hot Topics in Thermal Analysis and Calorimetry

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Differential Thermal Analysis

Abstract: Equations are derived which make possible the calculation of heats of transformation from differential heating curves, independent of external calibrations.

Cited by 184 publications

References 14 publications

Differential Thermal Analysis of Li-Ion Cells as an Effective Probe of Liquid Electrolyte Evolution during Aging

Differential Thermal Analysis of Li-Ion Cells as an Effective Probe of Liquid Electrolyte Evolution during Aging

New strategies for studies on the kinetics and energetics of the Belousov‐Zhabotinskii reaction

Historical Roots and Development of Thermal Analysis and Calorimetry

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