Electrochemical‐Calorimetric Studies of Lithium‐Ion Cells

Hong, Jong‐Sung; Maleki, Hossein; Hallaj, Said Al; Redey, L.; Selman, J. R.

doi:10.1149/1.1838509

Cited by 226 publications

(143 citation statements)

References 14 publications

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“…The-magnitudes of the lower temperature peaks were not correlated with the Li levels. Other work has attributed these reactions to an electroIyte/SEI layer interaction [5,6]. We believe that this interpretation is correct since no reactions are observed for the "as received" anodes.…”

Section: Cycled Anodessupporting

confidence: 58%

Degradation Reactions in SONY-Type Li-Ion Batteries

Roth

Nagasubramanian

1999

MRS Proc.

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ABSTRACT.Thermal instabilities were identified in SONY-type lithium-ion cells and correlated with interactions of cell constituents and reaction products. Three temperature regions of interaction were identified and associated with the state of charge (degree of Li intercalation) of the cell. Anodes were shown to undergo exothermic reactions as low as 100°C involving the solid electrolyte interface (SEI) layer and the LiPF6 salt in the electrolyte (EC:PC:DEC/LiPF6). These reactions could account for the thermal runaway observed in these cells beginning at 100°C. Exothermic reactions were also observed in the 200"C-300"C region between the intercalated lithium anodes, the LiPF6 salt, and the PVDF. These reactions were followed by a hghtemperature reaction region, 300"C-400"C, also involving the PVDF binder and the intercalated lithium anodes. The solvent was not directly involved in these reactions but served as a moderator and transport medium. Cathode exothermic reactions with the PVDF binder were observed above 200°C and increased with the state of charge (decreasing Li content). This offers an explanation for the observed lower thermal runaway temperatures for charged cells.

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Section: Cycled Anodessupporting

confidence: 58%

Degradation Reactions in SONY-Type Li-Ion Batteries

Roth

Nagasubramanian

1999

MRS Proc.

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“…To proceed with the discussion, instead of using the number of particles as the independent variable, we define the fractional occupation X of the lattices as: [ 9 ] and all thermodynamic properties will be discussed in terms of this quantity. Figure 2 shows the entropy of the present system as a function of the occupation, for different energy differences E = E 2 − E 1 , which are indicated in the figure.…”

Section: Resultsmentioning

confidence: 99%

Shedding Light on the Entropy Change Found for the Transition Stage II→Stage I of Li-Ion Storage in Graphite

Leiva

Perassi

Barraco

2016

J. Electrochem. Soc.

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In order to examine the controversial hypothesis put forward to explain the entropy step experimentally observed for the stage II to stage I transition for lithium intercalation in graphite, a transparent statistical mechanical model is developed. The results obtained show that the entropy increase can be explained by the change of configurational entropy occurring at occupation of half of the lattice. Comparison with experimental data shows that attractive interactions between intercalated particles in the same layer must be assumed, in agreement with the ansatz made in the original experimental work. 5,6 and graphite, 7,8 are commonly found in electrodes of commercially lithium-ion cells. In addition to the mentioned intercalation materials, there are many others that are currently being studied or used as electrodes in lithium-ion cells. In particular, graphite is the most common material found in anodes of commercial lithium-ion cells.One of the most important features of the intercalation materials is that they can have ions stored in them with little changes in their crystalline structures. This feature allows a fast ion insertion and extraction and therefore high power density cells can be obtained when used as electrodes. However, a fast ion insertion and extraction generates heat in the cell, which can produce high temperature excursions of the cell and a premature aging.It has been demonstrated that a great portion of the heat that is generated in the intercalation materials comes from the intercalation entropy during a discharge. [9][10][11] In this sense, different methods to measure the intercalation entropy have been developed. [12][13][14][15][16][17] In the case of Li-ion insertion into graphite, the experimental curve for entropy as a function of composition, Reference 12, shows a step in the transition of stage II to stage I that could not be explained in the terms presented there. In a subsequent work, 18 two of the previous authors, state that a possible mechanism of the stage I phase formation may involve a 'dilute lithium layer' (noted dil-Li) that would have an alternating 'normal' Li layer (Li) with a hexagonal structure and a dilute lithium layer following the sequence (Li)-G-(dil-Li)-G. However, in a more recent review, Fultz 19 stated that the vibrational entropy resulting from the insertion dominates the entropy, and also he added that there should be a small change in the configurational entropy when compounds are formed in stage I or II, as they are ordered.In a previous work 20 we have proposed a theoretical approach to determine the intercalation entropy, and we applied this approach to the graphite/lithium compound. In order to clarify the origin of this entropy, in the present work we have used a simplified two-level lattice gas model to analyze the configurational contribution to the intercalation entropy of the graphite/lithium compound. The main features of the intercalation entropy are elucidated. z E-mail: eze_leiva@yahoo.com.ar Model and Statistical Mechanical Backgroun...

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“…This fact was previously proven experimentally [52]. In their model Hallaj et al measured the overpotential experimentally while entropy was estimated from the entropy coefficient (dEeq/dt) that was measured experimentally in another predating investigation [53].…”

Section: Lumped Capacitance Thermal Modelsmentioning

confidence: 77%

Theoretical Modelling Methods for Thermal Management of Batteries

Shabani¹,

Biju²

2015

Energies

108

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Abstract:The main challenge associated with renewable energy generation is the intermittency of the renewable source of power. Because of this, back-up generation sources fuelled by fossil fuels are required. In stationary applications whether it is a back-up diesel generator or connection to the grid, these systems are yet to be truly emissions-free. One solution to the problem is the utilisation of electrochemical energy storage systems (ESS) to store the excess renewable energy and then reusing this energy when the renewable energy source is insufficient to meet the demand. The performance of an ESS amongst other things is affected by the design, materials used and the operating temperature of the system. The operating temperature is critical since operating an ESS at low ambient temperatures affects its capacity and charge acceptance while operating the ESS at high ambient temperatures affects its lifetime and suggests safety risks. Safety risks are magnified in renewable energy storage applications given the scale of the ESS required to meet the energy demand. This necessity has propelled significant effort to model the thermal behaviour of ESS. Understanding and modelling the thermal behaviour of these systems is a crucial consideration before designing an efficient thermal management system that would operate safely and extend the lifetime of the ESS. This is vital in order to eliminate intermittency and add value to renewable sources of power. This paper concentrates on reviewing theoretical approaches used to simulate the operating temperatures of ESS and the subsequent endeavours of modelling thermal management systems for these systems. The intent of this review is to present some of the different methods of modelling the thermal behaviour of ESS highlighting the advantages and disadvantages of each approach. OPEN ACCESSEnergies 2015, 8 10154

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Electrochemical‐Calorimetric Studies of Lithium‐Ion Cells

Cited by 226 publications

References 14 publications

Degradation Reactions in SONY-Type Li-Ion Batteries

Degradation Reactions in SONY-Type Li-Ion Batteries

Shedding Light on the Entropy Change Found for the Transition Stage II→Stage I of Li-Ion Storage in Graphite

Theoretical Modelling Methods for Thermal Management of Batteries

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