Degradation diagnostics for lithium ion cells

Birkl, Christoph; Roberts, Matthew; McTurk, Euan; Bruce, Peter G.; Howey, David A.

doi:10.1016/j.jpowsour.2016.12.011

Cited by 1,209 publications

(756 citation statements)

References 32 publications

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“…Stock data was used for the NE (taken from [22], cycled between 0.01 V to 1.2 V). Experimental validation supporting our simulation results based on loss of lithium inventory (LLI) and loss of active material (LAM) degradation modes has been reported by other groups [30][31][32].…”

Section: Half-cell Preparation and Testingsupporting

confidence: 87%

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Intrinsic Variability in the Degradation of a Batch of Commercial 18650 Lithium-Ion Cells

2018

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Abstract:The use of lithium batteries for power and energy-hungry applications has risen drastically in recent years. For such applications, it is necessary to connect the batteries in large assemblies of cells in series and parallel. With a large number of cells operating together, it is necessary to understand their intrinsic variabilities, not only at the initial stage but also upon aging. In this study, we studied a batch of commercial cells to address their initial cell-to-cell variations and also the variations induced by cycling. To do so, we not only tracked several metrics associated with cell performance, the maximum capacity, the resistance, and the rate capability but also the degradation mechanism via a non-invasive quantification of the loss of lithium inventory (LLI), the loss of active material (LAM) and the kinetic degradation on both electrodes. We found that, even with small initial cell-to-cell variations, significant variations will be observed upon aging because the cells degrade at a different pace. We also observed that these variations were not correlated with the initial variations.

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Section: Half-cell Preparation and Testingsupporting

confidence: 87%

“…Energies 2018, 11, x 4 of 14 lithium inventory (LLI) and loss of active material (LAM) degradation modes has been reported by other groups [30][31][32].…”

Section: Initial Characterizationmentioning

confidence: 89%

Intrinsic Variability in the Degradation of a Batch of Commercial 18650 Lithium-Ion Cells

2018

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“…ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 34.214.212.150 Downloaded on 2018-05-11 to IP transitions, 26 which corresponds to the number of phases used to define N in Equation 1. Equation 1 can thus be written for the PE and the NE as…”

Section: Methodsmentioning

confidence: 99%

“…26, to identify and quantify the different degradation modes. The degradation modes are estimated by fitting the open circuit voltage (OCV) of Li-ion cells measured at various stages throughout the cells' cycle life.…”

mentioning

confidence: 99%

Degradation Diagnostics for Commercial Lithium-Ion Cells Tested at − 10°C

Birkl

McTurk

Zekoll

et al. 2017

J. Electrochem. Soc.

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Degradation of lithium ion (Li-ion) cells affects both performance and safety of Li-ion batteries. In order to avoid potential safety hazards, it is crucial to detect the onset and extent of critical degradation modes in commercial Li-ion cells. This work demonstrates the application of a diagnostic algorithm to identify and quantify degradation modes of commercial Li-ion pouch cells cycled at −10 • C and a C-rate of 2 C. Rapid loss of active negative electrode material was successfully identified and results were validated using 3-electrode cells, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The positive electrode material was less strongly affected by the tests, as found by the diagnostic algorithm and confirmed with EDX and SEM results. Lithium ion (Li-ion) cells degrade as a result of usage and environmental influences, typically resulting in capacity fade and increased internal resistance.1-3 Some degradation mechanisms can lead to safety hazards through increased risk of fire or explosion. The deposition of metallic lithium and dendrite formation on graphite negative electrodes (NE) are particularly dangerous mechanisms, since metallic dendrites can pierce the separator and lead to internal short-circuits resulting in thermal runaway. [4][5][6] Understanding and detecting lithium plating and dendrite formation are important milestones on the pathway to safer, more reliable Li-ion batteries. Low operating temperatures during charge increase the risk of lithium plating and dendrite formation. [7][8][9][10][11][12][13][14][15][16] This makes it important to assess and model the behavior of Li-ion batteries at low temperatures, which is undertaken in this study.Arora et al. 4 proposed a mathematical model to predict lithium deposition on the NE during charge and overcharge, which can be used to determine operational and design limitations in order to minimize safety hazards. Other authors have focused on in-situ detection of lithium plating using electrochemical calorimetry, 17 a combination of an electrochemical model with a particle filter, 18 Although in-situ detection of lithium plating is an important advance, safety hazards can be further reduced by detecting the factors leading up to lithium plating before the onset of the plating mechanism itself. Deposition of metallic lithium on graphite NEs occurs under high charging rates, at low charging temperatures and in poorly balanced cells with an excess of active positive electrode (PE) material. 4,12,24,25 These circumstances are easily avoided in new cells by appropriate cell design and observation of operational limitations such as minimal charging temperature and maximal cell voltages and current rates. However, as cells degrade, active electrode material can be lost, changing the ratio of negative to positive electrode material and the current rates and voltage limits imposed on the remaining active material. Loss of NE material leads to higher current rates on the NE and a higher ratio of active PE to NE material...

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“…either excessive external heat influx or heat generation surpassing the ability of dissipation, poses a serious threat to the integrity of the device [7,8]. Thermally induced degradation processes comprise the evolution of gas from evaporation and degradation of the electrolyte, melting of the separator leading to internal short circuits, changes of the electrodes' structure releasing oxygen and lithium respectively and other fast selfaccelerating exothermic reactions leading to thermal runaway [9][10][11][12][13][14]. Lithium ion cells not only offer a higher energy density but also more resistance towards aging than other types of electrochemical secondary cells like Pb-acid batteries and NiMH systems [15][16][17].…”

Section: Introductionmentioning

confidence: 99%