Surface Chemical Analysis of Solid-Electrolyte Interphase Layer on Germanium Thin Films and the Effect of Vinylene Carbonate Electrolyte Additive

Jayasree, Silpasree S.; Nair, Shantikumar; Santhanagopalan, Dhamodaran

doi:10.5772/intechopen.90032

Cited by 4 publications

(4 citation statements)

References 33 publications

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“…XPS also indicated the formation of germanium carbide in the Ge–Al electrode during cycling, but not in the Ge–Cu electrode. Germanium carbide has been shown previously to develop in Ge Li-ion anodes during cycling and indicates side reactions of germanium with the electrolyte solvents or the carbon black conductive additive during cycling. Raman spectroscopy showed a lesser degree of pulverization of the germanium in the Ge–Al electrode during cycling compared to the Ge–Cu electrode.…”

Section: Resultsmentioning

confidence: 95%

“…However, predictive calculations show that for a 18650 format Li-ion cell the achievable specific energy and energy density are very similar to those achievable with current graphite-on-copper anodes. With use of advanced conductive additives such as carbon nanotubes, , as well as SEI-forming electrolyte additives that have been studied with germanium anodes like vinylene carbonate , or fluoroethylene carbonate, ,, the composite electrical percolation and conductivity can be increased, the germanium mass fraction in the composite can be increased, and stability of the SEI can be further improved. Altogether, such improvements can further increase the achievable cell specific energy and energy density as well as lead to an anode with the necessary performance stability for Li-ion cells with long cycle life.…”

Section: Resultsmentioning

confidence: 99%

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Analysis of Germanium Nanoparticle Composites with an Aluminum Current Collector toward Li-ion Battery Anodes with High Capacity and Broad Potential Stability Range

Crompton¹,

Hladky²

2021

ACS Appl. Energy Mater.

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Reduction reactions with lithium at >0.3 V vs Li/Li + make germanium prospectively compatible with aluminum current collectors to form a copper-free lithium-ion cell anode that may enable lithium-ion cells that are more tolerant to overdischarge. Targeted 2.0 mAh/cm 2 germanium nanoparticle electrodes with an aluminum foil (Ge−Al electrode) current collector were fabricated and tested versus lithium from 0.3 to 1.5 V vs Li/Li + in 1.0 M LiPF 6 1:1 ethylene carbonate/diethyl carbonate (v/v) electrolyte and demonstrated a peak reversible capacity of 342 mAh/g Ge at a targeted C/10 rate. A targeted 2.0 mAh/cm 2 germanium nanoparticle electrode with a copper current collector (Ge−Cu electrode) was also tested from 0.005 to 1.5 V vs Li/Li + , the results of which are utilized as a representative comparison of germanium tested in a conventional lithium-ion anode potential range. Compared to the Ge−Cu electrode, after 50 cycles at a targeted C/10 rate the Ge−Al electrode showed 90% vs 18% capacity retention. Post-mortem analysis with XPS, SEM/EDS, Raman spectroscopy, and FTIR showed that compared to the Ge−Cu electrode the Ge−Al electrode had (1) less oxygen, fluorine, and carbon deposition, (2) less germanium amorphization, (3) formation of Li x C y and Ge−H, and (4) less Li 2 O formation. After 150 cycles at equivalent targeted rates, the Ge−Al electrode also had significantly less mid-frequency impedance growth than the Ge−Cu electrode. Modeling of 18650 format LiNiCoAlO 2 -cathode lithium-ion cells with a Ge−Al anode predicted an achievable energy density and specific energy of up to 491 Wh/L and 198 Wh/kg. A germanium dissolution potential of 4.2 V vs Li/Li + was assigned based on voltammetry and post-mortem SEM/EDS. Cycling of a Ge−Al electrode with an upper potential cutoff of 4.2 V vs Li/Li + every tenth cycle showed 30% capacity retention after 50 cycles, an increased capacity fade attributed to solid electrolyte interphase instability up to 4.2 V vs Li/Li + based on impedance and post-mortem analysis.

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Section: Resultsmentioning

confidence: 95%

Section: Resultsmentioning

confidence: 99%

Analysis of Germanium Nanoparticle Composites with an Aluminum Current Collector toward Li-ion Battery Anodes with High Capacity and Broad Potential Stability Range

Crompton¹,

Hladky²

2021

ACS Appl. Energy Mater.

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“…Appropriate formation of the SEI through electrolyte modification is a promising strategy to address this issue. , Previous studies have evaluated the effectiveness of electrolyte additives such as fluoroethylene carbonate (FEC) − and vinylene carbonate (VC) ,− on the SEI. These reports show an advantageous additive effect on long-term cycling, through introduction of fluorinated species. − Previous reports have noted the synergy between the Si morphology and electrolyte additives to achieve extended cyclability with more than 2000 mAh g –1 over 50 cycles, where the use of FEC leads to surface film compositions leading to lower impedance throughout (de)lithiation …”

Section: Introductionmentioning

confidence: 82%

Interfacial Reactivity of Silicon Electrodes: Impact of Electrolyte Solvent and Presence of Conductive Carbon

Vila

Bernardez

et al. 2022

ACS Appl. Mater. Interfaces

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Silicon (Si) is a promising high-capacity material for lithium-ion batteries; however, its limited reversibility hinders commercial adoption. Approaches such as particle and crystallite size reduction, introduction of conductive carbon, and use of different electrolyte solvents have been explored to overcome these electrochemical limitations. Herein, operando isothermal microcalorimetry (IMC) is used to probe the influence of silicon particle size, electrode composition, and electrolyte additives fluoroethylene carbonate and vinylene carbonate on the heat flow during silicon lithiation. The IMC data are complemented by X-ray photoelectron and Raman spectroscopies to elucidate differences in solid electrolyte interphase (SEI) composition. Nanosized (∼50 nm, n-Si) and micrometer-sized (∼4 μm, μ-Si) silicon electrodes are formulated with and without amorphous carbon and electrochemically lithiated in ethylene carbonate (EC), fluoroethylene carbonate (FEC), or vinylene carbonate (VC) based electrolytes. Notably, n-Si electrodes generate 53−61% more normalized heat relative to their μ-Si counterparts, consistent with increased surface area and electrode/electrolyte reactivity. Introduction of amorphous carbon significantly alters the heat flow profile where multiple exothermic peaks and increased normalized heat dissipation are observed for all electrolyte types. Notably, the VC-containing electrolyte demonstrates the greatest normalized heat dissipation of the electrode compositions tested showing as much as a 50% increase compared to the EC or FEC counterparts. The results are relevant to the understanding of silicon negative electrode function in the presence of electrolyte additives and provide insight relative to silicon containing cell reactivity and safety.

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“…For bulk Si, electrolyte additives such as fluoroethylene carbonate (FEC), vinylene carbonate, and propylene carbonate have improved long‐term cyclability through their reduction or stabilization of surface fluorinated species. [ 21–23 ] Specifically, the improved cycle life of cells utilizing FEC as an electrolyte additive has been attributed to the formation of a more homogenous and robust SEI. [ 24 ] It has also been demonstrated that FEC leads to superior surface film compositions causing an overall lower impedance.…”

Section: Introductionmentioning

confidence: 99%

Low‐Oxidized Siloxene Nanosheets with High Capacity, Capacity Retention, and Rate Capability in Lithium‐Based Batteries

Arnot

Bock

et al. 2022

Adv Materials Inter

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The mechanical degradation experienced by Si electrodes during Li (de)alloying reactions can potentially be mitigated by using Si‐based materials with layered 2D geometries. Such materials are expected to exhibit favorable mechanical properties and be capable of buffering the volume change associated with (de)lithitation. In this work, 2D siloxene nanosheets are synthesized using a facile topotactic reaction followed by ultrasonication as an exfoliation step. Detailed structural and chemical characterization via electron microscopy, X‐ray photoelectron spectroscopy (XPS), and Raman spectroscopy is conducted, revealing a low‐oxidized siloxene nanosheet material with only 15% surface Si‐oxide. The obtained siloxene nanosheets are tested as Li‐ion negative electrodes in lithium‐based electrochemical cells. The cells exhibit high rate capability with a capacity of 935 mAh g–1 at 3200 mA g–1 and ≈99.5% coulombic efficiency. The inclusion of fluoroethylene carbonate (FEC) in the electrolyte improves capacity retention over 200 cycles from 13% to 77% at 1000 mA g–1. This behavior is attributed to the FEC decomposition forming a solid electrolyte interphase (SEI) with higher ion conductivity and robust LiF/LixPOyFz content, as characterized via XPS Raman spectroscopy.

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Surface Chemical Analysis of Solid-Electrolyte Interphase Layer on Germanium Thin Films and the Effect of Vinylene Carbonate Electrolyte Additive

Cited by 4 publications

References 33 publications

Analysis of Germanium Nanoparticle Composites with an Aluminum Current Collector toward Li-ion Battery Anodes with High Capacity and Broad Potential Stability Range

Analysis of Germanium Nanoparticle Composites with an Aluminum Current Collector toward Li-ion Battery Anodes with High Capacity and Broad Potential Stability Range

Interfacial Reactivity of Silicon Electrodes: Impact of Electrolyte Solvent and Presence of Conductive Carbon

Low‐Oxidized Siloxene Nanosheets with High Capacity, Capacity Retention, and Rate Capability in Lithium‐Based Batteries

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