"Knees" in lithium-ion battery aging trajectories

Attia, Peter M.; Bills, Alexander; Planella, Ferran Brosa; Dechent, Philipp; Reis, Gonçalo dos; Dubarry, Matthieu; Gasper, Paul; Gilchrist, Richard; Greenbank, Samuel; Howey, David; Liu, Ouyang; Khoo, Edwin; Preger, Yuliya; Soni, Abhishek; Sripad, Shashank; Stefanopoulou, Anna G.; Sulzer, Valentin

doi:10.48550/arxiv.2201.02891

Cited by 3 publications

(4 citation statements)

References 162 publications

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“…This effect is also known as sudden death and can be triggered by different mechanisms and/or their combinations. [85] Therefore, it cannot be excluded that this transition point is reached earlier in the cells with gradient and inhomogeneous aging effects despite similar aging with and without temperature gradients. So even with the temperature-dependent alterations during aging revealed by the postmortem analysis, a maximum temperature difference over the length of the cell cannot be defined.…”

Section: Correlation Of Resultsmentioning

confidence: 98%

Inhomogeneous Aging in Lithium‐Ion Batteries Caused by Temperature Effects

2022

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Lithium‐ion batteries (LIBs) are widely used as electrochemical energy storage devices due to their advantages in energy and power density as well as their reliability. One research focus is the cyclic lifetime of LIB, where the influence of thermal conditions during cycling is not yet completely understood. In previous publications, investigations on the cyclic aging behavior of LIB under various thermal boundary conditions are presented, including defined temperature gradients and temperature transients. Thereupon, herein, the results of cell openings and an extensive postmortem study with analyses of scanning electron micrographs, electrode thickness, X‐ray diffraction, and inductively coupled plasma optical emission spectroscopy are presented, evaluated, and correlated with the thermal conditions. The results reveal significant variations on the electrode and atomic scale for the different thermal boundary conditions during cycling. The electrodes exposed to a temperature gradient exhibit an inhomogeneous distribution of aging behavior that directly correlates with the local temperature. Cycling with superimposed transient temperatures reveals fundamentally different aging effects. With this knowledge, critical temperature conditions can be avoided in applications to prolong cyclic lifetime.

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Section: Correlation Of Resultsmentioning

confidence: 98%

Inhomogeneous Aging in Lithium‐Ion Batteries Caused by Temperature Effects

2022

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“…After the formation cycles, degradation accumulates while preferring smaller particles. The observed heterogeneous degradation accumulation on the smaller particles from the autocatalytic behavior between fitness and degradation contributes to the eventual death of the battery [13]. This overall trend causes the smaller particles to lose their usable capacity faster and contribute to the failure of the battery before the larger particles do.…”

Section: Discussionmentioning

confidence: 99%

“…Electrode level degradation phenomena is seen in capacity loss curves and in voltage-capacity curves [11]. In experiments, impedance growth has been found to be mainly from the cathode side [12][13][14][15], while anode degradation is generally motivated by solid electrolyte interphase formation and lithium plating [5,16]. Understanding the increase of cathode impedance is a critical step of understanding electrode level degradation.…”

Section: Introductionmentioning

confidence: 99%

Population Effects Driving Active Material Degradation in Intercalation Electrodes

Zhuang¹,

Bazant²

2023

Preprint

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Single particle modeling, used in most battery simulations to describe intercalation and degradation, lacks the accurate physics to describe interactions between particles. To remedy this, we formulate a model that describes the evolution of degradation of a population of battery active material particles using ideas in population genetics of fitness evolution, where the state of a system depends on the health of each particle that contributes to the system. With the fitness formulation, the model incorporates effects of particle size and heterogeneous degradation effects which accumulate in the particles as the battery is cycled, accounting for different active material degradation mechanisms. At the particle scale, degradation progresses non-uniformly across the population of active particles, observed from the autocatalytic relationship between fitness and degradation. Electrode level degradation is formed from various contributions of the particle level heterogeneous degradation, especially from smaller particles. It is shown that specific mechanisms of particle level degradation can be associated with characteristic signatures in the capacity-loss and voltage profiles. Conversely, certain features in the electrode level phenomena can also give insights into the relative importance of different particle level degradation mechanisms.

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“…This requires an understanding of the (electro)chemical signatures of degradation. Although the microscopic origins of degradation are numerous and complex [6,7,8], on a macroscopic level performance loss manifests as capacity reduction and build-up of resistance [9,10]. While the former is related to loss of storage capability and associated with lost lithium inventory (LLI) and/or change of active material microstructure (LAM), the latter results from increased impedance at all interfaces within the individual cells and across pack connections.…”

mentioning

confidence: 99%

Entropy profiling for the diagnosis of NCA/Gr-SiOx Li-ion battery health

Wojtala¹,

Zulke²,

Burrell³

et al. 2022

Preprint

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Graphite-silicon (Gr-Si) blends have become common in commercial Li-ion battery negative electrodes, offering increased capacity over pure graphite. Lithiation/delithiation of the silicon particles results in volume changes, which may be associated with increased hysteresis of the open circuit potential (OCP). The OCP is a function of both concentration and temperature. Entropy change measurement--which probes the response of the OCP to temperature--offers a unique battery diagnostics tool. While entropy change measurements have previously been applied to study degradation, the implications of Si additives on the entropy profiles of commercial cells have not been explored.Here, we use entropy profiling to track ageing markers in the same way as differential voltage analysis. In addition to lithiation/delithiation hysteresis in the OCP of Gr-Si blends, cells with Gr-Si anodes also exhibit differences in entropy profile depending on cycling direction, reflecting degradation-related morphological changes. For cycled cells, entropy change decreased during discharge, likely corresponding to graphite particles breaking and cracking. However, entropy change during charge increased with cycling, likely due to the volume change of silicon. Over a broad voltage range, these combined effects led to the observed rise in entropy hysteresis with age. Conversely, for calendar aged cells entropy hysteresis remained stable.

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"Knees" in lithium-ion battery aging trajectories

Cited by 3 publications

References 162 publications

Inhomogeneous Aging in Lithium‐Ion Batteries Caused by Temperature Effects

Inhomogeneous Aging in Lithium‐Ion Batteries Caused by Temperature Effects

Population Effects Driving Active Material Degradation in Intercalation Electrodes

Entropy profiling for the diagnosis of NCA/Gr-SiOx Li-ion battery health

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