Three-Dimensional Visualization of Gas Evolution and Channel Formation inside a Lithium-Ion Battery

Sun, Fu; Markötter, Henning; Manke, Ingo; Hilger, André; Kardjilov, Nikolay; Banhart, John

doi:10.1021/acsami.6b00708

Cited by 39 publications

(37 citation statements)

References 61 publications

(124 reference statements)

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“…Unfortunately, the repeated volume change or even pulverization of silicon during cycling would break down a previously formed SEI layer and re‐expose fresh Si surface to the electrolyte. As a result, the thickness of the surface interface increases and the irreversible charge “loss” derived from the unceasing development of the SEI layer finally brings about gas generation, low cycling efficiency, and ongoing capacity decay . Fundamentally, the continuous development of SEI layer is mainly induced by the repeated pulverization of silicon.…”

Section: Introductionmentioning

confidence: 75%

In situ and Operando Tracking of Microstructure and Volume Evolution of Silicon Electrodes by using Synchrotron X‐ray Imaging

et al. 2018

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The internal microstructure of a silicon electrode in a lithium ion battery was visualized by operando synchrotron X‐ray radioscopy during battery cycling. The silicon particles were found to change their sizes upon lithiation and delithiation and the changes could be quantified. It was found that volume change of a particle is related to its initial size and is also largely determined by the changing surrounding electron‐conductive network and internal interface chemical environment (e.g., electrolyte migration, solid–electrolyte interphase propagation) within fractured particles. Moreover, an expansion prolongation phenomenon was discovered whereby some particles continue expanding even after switching the battery current direction and shrinkage would be expected, which is explained by assuming different expansion characteristics of particle cores and outer regions. The study provides new basic insights into processes inside Si particles during lithiation and delithiation and also demonstrates the unique possibilities of operando synchrotron X‐ray imaging for studying degradation mechanisms in battery materials.

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Section: Introductionmentioning

confidence: 75%

In situ and Operando Tracking of Microstructure and Volume Evolution of Silicon Electrodes by using Synchrotron X‐ray Imaging

et al. 2018

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“…In addition, for the standard electrode at 45% DOD, some pores initially filled with electrolyte becomegas‐filled. This indicates that the gas, present in the pristine electrode (2.1% v , Table ) or likely to be produced during the SEI formation, can move freely through the global porous network of the electrode. At 100% DOD, the large Si particle is nearly no longer distinguishable from its surrounding matrix (because highly lithiated) for both electrodes.…”

Section: Resultsmentioning

confidence: 99%

Dynamics of the Morphological Degradation of Si‐Based Anodes for Li‐Ion Batteries Characterized by In Situ Synchrotron X‐Ray Tomography

Vanpeene

Villanova

King

et al. 2019

Advanced Energy Materials

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different anode materials with high theoretical capacities have been investigated. [1,2] Among them, silicon has drawn a lot of attention due to its gravimetric capacity ten times higher than graphite (3579 mAh g −1 for Li 15 Si 4 vs 372 mAh g −1 for LiC 6 ). Si is also earth abundant, low cost, and nontoxic. However, its use in commercial Li-ion batteries is challenging because the capacity retention and coulombic efficiency of Si electrodes are much lower than for graphite electrodes. [3,4] This is related to the important volume change of Si during its lithiation (up to 280% for Li 15 Si 4 vs ≈10% for LiC 6 ), which deteriorates the electrode architecture and destabilizes the solid electrolyte interphase (SEI). The optimization of the mechanical properties of Si-based electrodes is thus a key issue to improve their electrochemical performance. This optimization must be done at the Si particle scale as well as at the composite electrode scale.The use of nanosized Si materials (nanoparticles, nanowires, nanopillars, nanocomposites) has demonstrated a great efficiency for limiting the pulverization of the Si active material upon cycling as its fracturing resistance is size-dependent. [5] One must, however, note that the synthesis of such nanosized materials at industrial scale and competitive cost remains an issue, in addition to their low tap density and high surface reactivity. It thus appears more relevant to use micrometric particles, for example, ball-milled nanocrystalline/amorphous Si [6] or nanostructured Si alloys [1,7] able to prevent the formation of crystalline Li 15 Si 4 , which is known to promote particle fracture due to its large phase boundary stress with amorphous Li x Si during delithiation.The mechanical properties (compliance) of the SEI layer must also be optimized to be able to tolerate the large volume variation of the Si particles. To date, the use of appropriate electrolytes or electrolyte additives such as fluoroethylene carbonate (FEC) [8] appears as the most judicious strategy. [9] However, this interfacial issue is still not fully resolved and is probably the most important obstacle for the implementation of Si-rich based anodes in commercial Li-ion batteries.At a larger spatial scale, the volume change of the electrode is likely to induce its macrocracking, collapsing, and/or delamination from the current collector, leading to electrical disconnection of some Si particles. [10] In order to limit these morphological degradations, the cohesion and adhesion strength of the Si electrodes needs to be improved. These have The alloying reaction of silicon with lithium in negative electrodes for lithiumion batteries causes brutal morphological changes that severely degrade their cyclability. In this study, the dynamics of their expansion and contraction, of their cracking in the bulk and of their debonding at the interface with the current collector are visualized by in situ synchrotron X-ray computed tomography and quantified from appropriate 3D imaging analyses. Two electrodes made with s...

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“…[46][47][48] An electrochemical validation of the presently designed cell can be found in our previous reports. [49][50] SEM images of the surface and a cross-section of the employed trilayer Celgard ® 2325 separator are shown in Figure 2. From Figure 2a, the distinct slit-pore structure that results from extrusion and unidirectional stretching during the dry-process manufacture method is clearly observed.…”

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Study of the Mechanisms of Internal Short Circuit in a Li/Li Cell by Synchrotron X-ray Phase Contrast Tomography

et al. 2016

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Knowledge about degradation and failure of Li-ion batteries (LIBs) is of paramount importance especially because failure can be accompanied by severe hazards. To contribute to the understanding of such phenomena synchrotron in-line phase contrast Xray tomography was employed to investigate internal cell deformation and degradation caused by an internal short circuit (ISC). The tomographic images taken from an uncycled Li/Li cell and a short-circuited Li/Li cell reveal how lithium microstructures (LmS) develop during electrochemical stripping and plating during discharge and charge and how the three-layer separator used is damaged by growing LmSs and delaminates and melts as a consequence of an ISC. Previously unknown insights into the internal cell degradation and deformation mechanisms caused by an ISC are obtained and provide hints of how the properties of the separator could be modified in order to improve the reliability and safety of current and next-generation LIBs.

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Three-Dimensional Visualization of Gas Evolution and Channel Formation inside a Lithium-Ion Battery

Cited by 39 publications

References 61 publications

In situ and Operando Tracking of Microstructure and Volume Evolution of Silicon Electrodes by using Synchrotron X‐ray Imaging

In situ and Operando Tracking of Microstructure and Volume Evolution of Silicon Electrodes by using Synchrotron X‐ray Imaging

Dynamics of the Morphological Degradation of Si‐Based Anodes for Li‐Ion Batteries Characterized by In Situ Synchrotron X‐Ray Tomography

Study of the Mechanisms of Internal Short Circuit in a Li/Li Cell by Synchrotron X-ray Phase Contrast Tomography

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