Enthalpies of combustion of toluene, benzene, cyclohexane, cyclohexene, methylcyclopentane, 1-methylcyclopentene, and n-hexane

Good, W. D.; Smith, N. K.

doi:10.1021/je60040a036

Cited by 191 publications

(97 citation statements)

References 10 publications

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“…15 While it is assumed here that the observed reduction in parasitic heat flow for FEC:TFEC is primarily a result of a decreased reaction rate, a difference in the enthalpy of reaction would also result in a difference in parasitic heat flow. No data were available for EC and FEC, but the condensed phase enthalpy of combustion for benzene and fluorobenzene are −3267.5 ± 0.4 kJ/mol 52 and −3101.6 ± 0.6 kJ/mol, 53 respectively. Therefore the reaction enthalpy may be slightly lower for the oxidation of FEC compared to EC, but it is not expected to be significantly different, such that the reduction in parasitic heat flow is believed to be primarily a result of a reduced reaction rate.…”

Section: Resultsmentioning

confidence: 99%

The Impact of Electrolyte Composition on Parasitic Reactions in Lithium Ion Cells Charged to 4.7 V Determined Using Isothermal Microcalorimetry

Downie

Hyatt

Dahn

2015

J. Electrochem. Soc.

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In an effort to better the understanding of the high voltage degradation of electrolytes in lithium ion cells, this work presents isothermal microcalorimetry results on LiNi 0.42 Mn 0.42 Co 0.16 O 2 (NMC442)/graphite pouch cells up to 4.7 V. The voltage and time dependent parasitic heat flow was determined for cells containing several electrolyte compositions based on carbonate solvents with several additive combinations, as well as a fluorinated carbonate solvent system. We have demonstrated that cells containing fluorinated carbonate-based electrolyte (1M LiPF 6 in 3:7 fluoroethylene carbonate: di-2,2,2-trifluoroethyl carbonate) showed a significantly decreased parasitic heat flow at voltages >4.4 V compared to ethylene carbonate-based cells, but limited advantage <4.4 V. However all cells, regardless of electrolyte composition, exhibited very large parasitic heat flows, and therefore parasitic reaction rates, at high voltages (>4. Existing and emerging applications using lithium ion batteries are demanding increased energy densities, decreased cell bulging due to gas production, fast charging capabilities, and longer lifetimes, etc, all while reducing cost. The calendar and cycle lifetimes of lithium ion cells are well known to be primarily affected by parasitic reactions between the electrodes and electrolyte.1,2 To extend these lifetimes, the rate and extent of parasitic reactions must be reduced. Therefore it is of utmost importance to be able to measure and quantify the impact of changes in cell components on these reactions in a rapid and precise manner that correlates to long term performance.One common and effective way of minimizing parasitic reactions and extending cell lifetimes is the use electrolyte of additives. Extensive studies have been carried out on such additives, and many comprehensive reviews can be found on the topic. 1,3,4 However, the role of electrolyte additives is extremely complex, is relatively poorly understood, and is the subject of much debate in the literature. Furthermore, in an effort to increase energy density, there has been a push to move to higher voltage systems. However, the typical carbonate solvents are oxidized at such high voltages, where the decomposition has been reported to begin as low at 4.0 V 5,6 and up to 4.5 V vs Li/Li + . 3,7-9 One class of solvents used to extend the stability window are fluorinated carbonates, the most common of which is fluoroethylene carbonate (FEC).3,10-15 Several other fluorinated cyclic and linear carbonates have been investigated as both full solvent systems and cosolvents.1,14-17 One such fluorinated linear carbonate investigated in this work is di-2,2,2-trifluoroethyl carbonate (TFEC) which has been shown to improve the protective passivation film that forms on the negative electrode. [17][18][19] It is clear that the voltage dependent impact of electrolyte additives and unconventional solvents on parasitic reactions is of particular interest, especially at high voltages.Recently, Downie et al. demonstrated that isothermal microc...

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Section: Resultsmentioning

confidence: 99%

The Impact of Electrolyte Composition on Parasitic Reactions in Lithium Ion Cells Charged to 4.7 V Determined Using Isothermal Microcalorimetry

Downie

Hyatt

Dahn

2015

J. Electrochem. Soc.

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“…(15)(16)(17) A rotating-bomb calorimeter (laboratory designation BMR II) (18) and two platinum-lined bombs (laboratory designation Pt-3b and Pt-5b) (19) with internal volumes of 0.393 4 dm 3 and 0.395 4 dm 3 , respectively, were used without rotation. For each experiment, a volume 1.0·10 −3 dm 3 of water was added to the bomb, and the bomb was flushed and charged to the pressure 3.04 MPa with pure oxygen.…”

Section: Methodsmentioning

confidence: 99%

The standard enthalpies of formation of 2-methylbiphenyl and diphenylmethane,

Steele¹

1995

The Journal of Chemical Thermodynamics

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“…Anhydrous lithium hydroxide was used as adsorbent (7). The combustion products were checked for unburned carbon and other products of incomplete combustion, but none was detected.…”

Section: Methodsmentioning

confidence: 99%