In Situ Quantification of the Swelling of Graphite Composite Electrodes by Scanning Electrochemical Microscopy

Bülter, Heinz; Peters, Fabian; Schwenzel, Julian; Wittstock, Günther

doi:10.1149/2.1061514jes

Cited by 30 publications

(44 citation statements)

References 32 publications

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“…This region had not caused large currents in Figure a–g and was interpreted as a large crack in the HOPG surface because of the following reasons. (i) This region provided i T values that are characteristic for graphite composites not passivated by a SEI . (ii) The crack appeared suddenly and was accompanied by significant gas formation due to electrolyte reduction as indicated by the small i T regions.…”

Section: Resultssupporting

confidence: 79%

“…Figure a–c shows a series of SECM feedback images of an identical region of the HOPG basal plane using DBDMB as redox mediator at a ME–sample distance of d =7 μm. In contrast to earlier studies on graphite composites, metallic Li, and Si from this laboratory, we used Au MEs here because, as Pt MEs approached the HOPG, deactivation of the ME occurred instantaneously. This was prevented by the use of Au MEs.…”

Section: Resultssupporting

confidence: 55%

“…However, local electron transfer rate constants changed over hours as shown qualitatively in Figure a–c (more images are show in SI‐7 in the Supporting Information) and quantitatively in Figure , which displays i T ( x , y )/< i T >; here, < i T > is the average current of the selected image and i T ( x , y ) refers to the ME current at a specific location ( x , y ). The analysis of i T ( x , y )/< i T > (instead of i T ) compensates the slow deactivation of the ME in 1 m LiPF 6 ethylene carbonate/diethyl carbonate (EC/DEC, 50:50 wt %) solution reported before . The positions for which i T ( x , y )/< i T > is shown in Figure are marked in Figure a–c by roman numbers.…”

Section: Resultsmentioning

confidence: 76%

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Scanning Electrochemical Microscopy for the In Situ Characterization of Solid–Electrolyte Interphases: Highly Oriented Pyrolytic Graphite versus Graphite Composite

2016

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The solid–electrolyte interphase (SEI) is of key importance for the performance and safety of lithium‐ion batteries. Recently, scanning electrochemical microscopy (SECM) has been used to study in situ the SEI. Here, we compare the SEI of graphite composite electrodes to the SEI at macroscopic samples of binder‐free, highly oriented pyrolytic graphite (HOPG) where effects of mechanical processing and particle–particle as well as electrolyte–binder interactions should be absent. Both, short‐term changes of SEI passivity on the timescale of seconds and minutes and long‐term changes over hours are found on HOPG as well as on graphite composite electrodes, but the SEI at HOPG is more stable compared to graphite composite electrodes. In addition, the microelectrode probe of the SECM is used to induce local SEI damage to monitor its reformation. Subsequently, secondary processes such as local crack formation, gas formation due to electrolyte reduction, and HOPG expansion are studied.

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Section: Resultssupporting

confidence: 79%

Section: Resultssupporting

confidence: 55%

Section: Resultsmentioning

confidence: 76%

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Scanning Electrochemical Microscopy for the In Situ Characterization of Solid–Electrolyte Interphases: Highly Oriented Pyrolytic Graphite versus Graphite Composite

2016

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“…Compared with the techniques listed in Table , there are several advantages of SEI characterization using the FB mode of SECM. ( i ) Usually, imaging is performed with d =5–15 μm . Hence, it is a contact‐less interrogation thus avoiding damage to the SEI and sample.…”

Section: Sei Investigation By the Feedback Mode Of Scanning Electrocmentioning

confidence: 99%

Review of Local In Situ Probing Techniques for the Interfaces of Lithium‐Ion and Lithium–Oxygen Batteries

et al. 2016

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Electrodes in lithium‐ion and post‐lithium‐ion batteries are made of composite materials exposing a variety of different surfaces towards the electrolyte. This causes a distribution of current densities and consequently locally different changes of interfaces and bulk materials that might be critical for the performance and durability of secondary batteries. The optimization of local structures of battery materials is hindered by a lack of local techniques that provide in situ reactivity information from such hidden interfaces. A variety of new electrochemical scanning probe techniques are currently adapted to the investigation of battery materials under near‐realistic environmental conditions. The review provides a critical assessment of this development with a particular emphasis on the assessment of the passivating properties of solid–electrolyte interphases, the extension of the concepts to lithium–oxygen cells, and attempts to image ion intercalation reactions.

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“…ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 34.213.227.119 Downloaded on 2018-05-09 to IP and uncharged pristine graphite composite electrodes 21 in 5 mM DB-DMB 1 M LiPF 6 ethylene carbonate (EC):diethyl carbonate (DEC) 1:1 solution. In case of graphite composite electrodes, local swelling of the uncharged graphite composite electrodes due to binder-solvent interactions complicates the image interpretation.…”

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confidence: 99%

Investigation of the Electron Transfer at Si Electrodes: Impact and Removal of the Native SiO₂Layer

Bülter

Sternad

Sardinha

et al. 2015

J. Electrochem. Soc.

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Silicon is considered as one of the promising alternatives to graphite as negative electrode material in lithium-ion batteries. The electron transfer at uncharged microstructured and planar Si was characterized using the feedback mode of scanning electrochemical microscopy (SECM) and 2,5-di-tert-butyl-1,4-dimethoxybenzene as redox mediator. Approach curves and images demonstrate that the electron transfer rate constants at pristine Si are relatively small due to the native SiO 2 surface layer. In addition, the electron transfer rate constants show local variations because of the heterogeneous coverage of SiO 2 . The SiO 2 layer is at least partially removed by mechanical contact and abrasion with the microelectrode probe. After SiO 2 removal by the microelectrode or by a hydrofluoric acid dip, the electron transfer rate constants increase strongly and remain heterogeneous. Moreover, the surface of the Si electrodes is at least stable over hours after SiO 2 removal. The consequences for investigating the formation of the solid electrolyte interphase (SEI) on Si are discussed. Silicon is considered as one of the promising alternatives to graphite as negative electrode material in lithium-ion batteries (LIBs). This is due to its wide abundance, low voltage and high theoretical gravimetric capacity of 3579 mAh g −1 .1 During the lithiation, the electrochemical potential of the Si electrode exceeds the stability window of the electrolyte and, consequently, the electrolyte is reductively decomposed.2 The decomposition products form a solid electrolyte interphase (SEI) covering the Si material lying beneath.3 A major challenge of Si as negative battery electrodes is the large volume change of ca. 270% 4 upon lithiation. Recurring lithiation/delithiation causes the electrode material to crack leading, in the worst case, to irreversible loss of active material. During the volume expansion non-passivated Si surfaces are expected to be exposed which are immediately covered by a SEI layer because of ongoing electrolyte decomposition. 5 Thus, similar to metallic Li electrodes the SEI layer is continuously re-formed and remains instable during each lithiation process. 6 The properties of the SEI are important for the performance of Si negative electrodes. 5,7 In order to evaluate the Si electrode performance, reliable in situ characterization of the SEI is definitely a key issue for the progress in this field. In general, scanning probe techniques are frequently applied for various aspects of battery research. 8,9 Especially atomic force microscopy (AFM) has been used to characterize in situ and ex situ the SEI at amorphous Si (a-Si) thin films, [10][11][12][13][14] Si-based thin films, 11,15 a-Si nanopillars 16 and Si nanowires. 17,18 AFM provides information about the morphology evolution and physical properties of the SEI. The present study aims at characterizing the functional properties of Si electrodes in situ by the feedback mode of scanning electrochemical microscopy (SECM), which probes the local electron transfer ra...

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In Situ Quantification of the Swelling of Graphite Composite Electrodes by Scanning Electrochemical Microscopy

Cited by 30 publications

References 32 publications

Scanning Electrochemical Microscopy for the In Situ Characterization of Solid–Electrolyte Interphases: Highly Oriented Pyrolytic Graphite versus Graphite Composite

Scanning Electrochemical Microscopy for the In Situ Characterization of Solid–Electrolyte Interphases: Highly Oriented Pyrolytic Graphite versus Graphite Composite

Review of Local In Situ Probing Techniques for the Interfaces of Lithium‐Ion and Lithium–Oxygen Batteries

Investigation of the Electron Transfer at Si Electrodes: Impact and Removal of the Native SiO₂Layer

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In Situ Quantification of the Swelling of Graphite Composite Electrodes by Scanning Electrochemical Microscopy

Cited by 30 publications

References 32 publications

Scanning Electrochemical Microscopy for the In Situ Characterization of Solid–Electrolyte Interphases: Highly Oriented Pyrolytic Graphite versus Graphite Composite

Scanning Electrochemical Microscopy for the In Situ Characterization of Solid–Electrolyte Interphases: Highly Oriented Pyrolytic Graphite versus Graphite Composite

Review of Local In Situ Probing Techniques for the Interfaces of Lithium‐Ion and Lithium–Oxygen Batteries

Investigation of the Electron Transfer at Si Electrodes: Impact and Removal of the Native SiO2Layer

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Product

Resources

About

Investigation of the Electron Transfer at Si Electrodes: Impact and Removal of the Native SiO₂Layer