Silicon Thin Film Electrodes Research Articles

Modeling Interfacial Delamination and Critical Dimension in Patterned Silicon Thin Film Electrodes for Improved Cycling Stability

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The Roles of Intermediate Phases of Li-Si Alloy as Anode Materials for Lithium-Ion Batteries

Abstract An ab initio method of the first-principles plane-wave pseudopotentials based on the density functional theory has been used to calculate the physical character and electrochemical performance of various alloy phases in Li-Si alloy. The results show that besides the growth of solid electrolyte interphase (SEI), the formation of Li12Si7 alloy phase also partly leads to the initial irreversible capacity loss. In addition, the pure silicon thin film electrode was prepared by the radio frequency (RF) magnetic sputtering on copper foil collector as anode materials. The structural and electrochemical characteristics of Li-Si alloy were examined using X-ray diffraction (XRD), cyclic voltammogram (CV) and repeatedly constant current charge/discharge (CC). The results show that the first irreversible capacity loss is very large and amorphous structure can accommodate the large volume expansions and improve cyclic performance.

In Situ Measurements of Stress-Potential Coupling in Lithiated Silicon

An analysis of the dependence of electric potential on the state of stress of a lithiated-silicon electrode is presented. Based on the Larché and Cahn chemical potential for a solid solution, a thermodynamic argument is made for the existence of the stress-potential coupling in lithiated silicon; based on the known properties of the material, the magnitude of the coupling is estimated to be in thin-film geometry. An experimental investigation is carried out on silicon thin-film electrodes in which the stress is measured in situ during electrochemical lithiation and delithiation. By progressively varying the stress through incremental delithiation, the relation between stress change and electric-potential change is measured to be 100–120 mV/GPa, which is of the same order of magnitude as the prediction of the analysis. The importance of the coupling is discussed in interpreting the hysteresis observed in the potential vs state-of-charge plots and the role of stress in modifying the maximum charge capacity of a silicon electrode under stress.

Improved cycling stability of silicon thin film electrodes through patterning for high energy density lithium batteries

The mechanical degradation of electrodes caused by lithiation and delithiation is one of the main factors responsible for the short cycle life of lithium-based batteries employing high capacity electrodes. In this report, we introduced a simple patterning approach to improve the cycling stability of silicon electrode, which is considered as the next generation negative electrode due to its high Coulombic capacity and low cost, but is limited by the mechanical degradation associated with large volume variations during cycling. The pattern design is based on the observation of a critical size for the crack gap in continuous films. An improvement in cycle life was noted when the pattern size was below the critical (7–10 μm) size, in which case the Si electrode patches adhered well to the Cu substrate after many cycles. By taking the plastic deformation in both Si thin film and substrate into consideration, the calculated crack spacing is consistent with experimental observations. Theoretical considerations gave a feasible explanation for the failure of Si pattern above the critical size. These results suggest a new approach to extend the cycle life of Si-based electrode materials using size to control and relax the stress due to lithiation and delithiation.

Study on the Effect of an Electrolyte Additive on the Electrochemical Characteristics of Silicon Thin Film Electrode

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A study of Li-ion diffusion kinetics in the fullerene-coated Si anodes of lithium ion batteries

The diffusion coefficient of lithium ions in fullerene-coated silicon thin film electrodes, prepared by the plasma-assisted deposition technique, was estimated by a specific electrochemical measurement known as cyclic voltammetry (CV) and then compared with that of a bare silicon film used as the anode in lithium ion batteries. Based on our experimental range, the diffusion coefficient of the fullerene-coated Si thin film was found to be ∼10−9 cm2 s−1 or two orders of magnitude higher than that of the bare Si thin film (∼1011 cm2 s−1). It can be concluded that the fullerene film acts as an artificial solid electrolyte interphase (SEI) layer during charging–discharging tests.

In situ measurements of stress evolution in silicon thin films during electrochemical lithiation and delithiation

We report in situ measurements of stress evolution in a silicon thin-film electrode during electrochemical lithiation and delithiation by using the multi-beam optical sensor (MOS) technique. Upon lithiation, due to substrate constraint, the silicon electrode initially undergoes elastic deformation, resulting in rapid rise of compressive stress. The electrode begins to deform plastically at a compressive stress of ca. −1.75 GPa; subsequent lithiation results in continued plastic strain, dissipating mechanical energy. Upon delithiation, the electrode first undergoes elastic straining in the opposite direction, leading to a tensile stress of ca. 1 GPa; subsequently, it deforms plastically during the rest of delithiation. The plastic flow stress evolves continuously with lithium concentration. Thus, mechanical energy is dissipated in plastic deformation during both lithiation and delithiation, and it can be calculated from the stress measurements; we show that it is comparable to the polarization loss. Upon current interruption, both the film stress and the electrode potential relax with similar time constants, suggesting that stress contributes significantly to the chemical potential of lithiated silicon.

Effect of succinic anhydride as an electrolyte additive on electrochemical characteristics of silicon thin-film electrode

The effect of an electrolyte additive, succinic anhydride (SA), on the electrochemical performances of a silicon thin-film electrode, which is prepared by radio-frequency magnetron sputtering, is investigated. The introduction of SA into a liquid electrolyte consisting of ethylene carbonate/diethyl carbonate/1 M LiPF 6 significantly enhances the capacity retention and coulombic efficiency of the electrode. This improvement in the electrochemical performance of the electrode is attributed to modification of the solid/electrolyte interphase (SEI) layer by the introduction of SA. The differences in the characteristic properties of SEI layers, with or without SA, are explained by analysis with scanning electron microscopy, electrochemical impedance spectroscopy, and X-ray photoelectron spectroscopy.

Silicon–glass instrumented solid-phase extraction–zone electrophoresis microchip with thin amorphous silicon film electrodes: performance in immunoaffinity analysis

Silicon–glass microchips were designed and fabricated for on-chip solid phase extraction (SPE) and zone electrophoresis studies. The solvent channels for extraction and the separation channels for analyses were fabricated sequentially on the silicon device. Electrical contacts were integrated in a fused silica glass lid. Amorphous silicon thin film electrodes were fabricated for high voltage and conductivity detection. A chip installation rack with electrical and fluidic contacts was constructed to facilitate the experiments. Simulation was used to elucidate both the liquid flow and the electric field distribution. The operational performance of the microchips was demonstrated by using a fluorescein isothiocyanate (FITC)-labelled testosterone derivative as the model analyte and fluorescein as both the negative control and the calibration compounds. In SPE an immunosorbent, based on recombinant anti-testosterone Fab-fragments, was immobilized to activated Sepharose gel. Simultaneous monitoring of the movement of FITC-testosterone from SPE cavity through the channel to the detection point was performed with a laser-induced fluorescence detector. The observed limit of detection for FITC-testosterone was 2 μM.

Electrochemical Behaviors of Silicon Electrode in Lithium Salt Solution Containing Alkoxy Silane Additives

The electrochemical behaviors of a silicon thin-film electrode in organic lithium salt solution were explored with focus on irreversible reactions of the first lithium charge and discharge cycling by using electrochemical quartz crystal microbalance (EQCM) combined with various electrochemical techniques. A considerable increase in mass of the silicon electrode was observed during lithium charging even before lithium absorption into the electrode, which is ascribed to the buildup of electrolyte reduction products on the silicon surface. Galvanostatic charge–discharge experiments combined with ac impedance spectroscopy demonstrate a significant overpotential growth and an aggravating capacity for the lithium charge and discharge cycling, and suggest they are due to the sedimentation of electrolyte reduction product. Additives containing alkoxy silane functional groups were evaluated as a passivation agent for lithium rechargeable batteries utilizing a silicon anode. The presence of additives in electrolyte suppressed the mass accumulation to the silicon electrode caused by irreversible electrolyte reductions and improved the electrode for cycle life. Electrochemical analyses associated with EQCM as a function of the number of alkoxy functional groups of the additives illustrate that the silicon electrode is passivated by chemical reaction of the alkoxy silane functional group of the additives with hydroxyl groups at the electrode/electrolyte interface, and this passivation improves the cycle life.

Surface layer formed on silicon thin-film electrode in lithium bis(oxalato) borate-based electrolyte

A Si thin-film electrode of 200 nm is prepared using E-beam evaporation and deposition on copper foil. The use of a lithium bis(oxalato) borate (LiBOB)-based electrolyte markedly improves the discharge capacity retention of a Si thin-film electrode/Li half-cell during cycling. The surface layer formed on Si thin-film electrode in ethylene carbonate/diethyl carbonate (3/7) with 1.3 M LiPF 6 or 0.7 M LiBOB is characterized by means of Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopic analysis. The surface morphology of the electrode after cycling is investigated using scanning electron microscopy. The relationship between the physical morphology and the electrochemical performance of Si thin-film electrode is discussed.

Effect of fluoroethylene carbonate additive on interfacial properties of silicon thin-film electrode

A silicon thin-film electrode (thickness = 200 nm) is prepared by E-beam evaporation and deposition on copper foil. The electrochemical performance of a lithium/silicon thin-film cell is investigated in ethylene carbonate/diethyl carbonate/1.3 M LiPF 6 with and without 3 wt.% fluoroethylene carbonate (FEC). The addition of FEC remarkably improves discharge capacity retention and coulombic efficiency. The surface morphology and chemical composition of the solid electrolyte interphase (SEI) formed on the surface of the silicon thin-film electrode after cycling are studied through scanning electron microscopy and X-ray photoelectron spectroscopy analysis. A smoother and more stable SEI layer structure is generated by the introduction of the FEC additive to the electrolyte.

Optoelectrical properties of four amorphous silicon thin-film transistors 200 dpi active-matrix organic polymer light-emitting display

We report on opto-electrical properties of a current-driven 200 dpi active-matrix organic polymer red light-emitting display (AM–PLED) based on four hydrogenated amorphous silicon thin-film transistor pixel electrode circuits. The AM–PLED luminance and effective light-emission efficiency were 30 cd/m2 and 0.3 cd/A, respectively, at the data current equal to 25 mA. The display electroluminescent spectrum has a peak located at and the full width at half maximum value of 644 and 95 nm, respectively, and Commission Internationale de l’Eclairage color coordinates of (0.66,0.33).

Amorphous silicon thin-film negative electrode prepared by low pressure chemical vapor deposition for lithium-ion batteries

Thin-film amorphous silicon (a-Si) microbattery anodes are fabricated by low pressure chemical vapor deposition (LPCVD) using Si 2H 6 as source gas. The high reversible capacity and cycle performance are presented. Galvanostatic charge-discharge test of half cells were performed. Thin-film amorphous silicon anodes exhibited the highest reversible capacity (4000 mAh/g), which is about 95% of the theoretical capacity in case of Li 22Si 5. The cyclability was enhanced by controlling the lower voltage limit or by reducing the amount of cycled charge quantity. The thin-film silicon anodes can successfully be coupled with thin-film LiMn 2O 4 cathodes, confirming that batteries have output voltage of 3.0–3.8 V and good cyclic durability.

Photoelectrochemical cells based on amorphous hydrogenated silicon thin film electrodes and the behavior of photoconductor electrode materials

The behavior of intrinsic a-Si:H photoanodes has been investigated. Thin films (approx.3.9 ..mu..m) of intrinsic a-Si:H, on a stainless steel substrate coated with a very thin (approx.200 angstrom) heavily n-type doped a-Si:H layer for ohmic contacting, behave as electrodes only under greater than or equal toE/sub g/ = 1.7 eV illumination, irrespective of the E/sup 0/' of the redox couple investigated in the range -1.78 to +0.41 V vs. SCE in CH/sub 3/CN/0.1 M (n-Bu/sub 4/N)ClO/sub 4/. The nature of the contact, stainless steel/n-type a-Si:H/intrinsic a-Si:H, indicates that redox couples having E/sup 0/' more positive than the bottom of the conduction band, E/sub CB/, can result in a field across the intrinsic a-Si:H that will drive photogenerated holes to the surface in contact with the redox couple while the electrons excited to the conduction band are driven into the bulk. In cyclic voltammetry experiments, the extent to which the oxidation peak is more negative than at Pt is a measure of the photovoltage, E/sub v/, that could be obtained at open circuit in the presence of equal concentrations of the oxidized and reduced forms of the couple. Surface photocorrosion of a-Si:H is a problem at low (approx.1 mM) concentrations ofmore » redox reagents used in cyclic voltammetry, and the largest E/sub v/ found is approx.0.4 V at approx.40 mW/cm/sup 2/ of 632.8-nm light. Derivatization of a-Si:H with (1,1'-Ferrocenediyl)dichlorosilane suppresses photocorrosion, and E/sub v/ of approx.0.75 V has been obtained for this surface-confined ferrocene derivative, exceeding the E/sub v/ on single-crystal n-type Si photoanodes. Durable cells using a Pt cathode, the a-Si:H photoanode, and EtOH/0.1 M (n-Bu/sub 4/N)ClO/sub 4//10/sup -3/ M ferricenium/0.07M ferrocene solution have been studied.« less

Notes on Mud Crack and Ripple Mark in Recent Calcareous Sediments

Previous articleNext article FreeNotes on Mud Crack and Ripple Mark in Recent Calcareous SedimentsE. M. KindleE. M. Kindle Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The Journal of Geology Volume 31, Number 2Feb. - Mar., 1923 Article DOIhttps://doi.org/10.1086/622990 Views: 59Total views on this site Citations: 8Citations are reported from Crossref PDF download Crossref reports the following articles citing this article:Khoa M. Tran, Ha H. Bui, Marcelo Sánchez, Jayantha Kodikara A DEM approach to study desiccation processes in slurry soils, Computers and Geotechnics 120 (Apr 2020): 103448.https://doi.org/10.1016/j.compgeo.2020.103448Khoa M. Tran, Ha H. Bui, Jayantha Kodikara, Marcelo Sánchez Soil curling process and its influencing factors, Canadian Geotechnical Journal 57, no.33 (Mar 2020): 408–422.https://doi.org/10.1139/cgj-2018-0489Duaa Al-Jeznawi, Marcelo Sanchez, Abbas J. Al-Taie, Marcin Zielinski Experimental studies on curling development of artificial soils, Journal of Rock Mechanics and Geotechnical Engineering 11, no.66 (Dec 2019): 1264–1273.https://doi.org/10.1016/j.jrmge.2019.02.006Marcin Zielinski, Marcelo Sánchez, Enrique Romero, Alvis Atique Precise observation of soil surface curling, Geoderma 226-227 (Aug 2014): 85–93.https://doi.org/10.1016/j.geoderma.2014.02.005X. Xiao, P. Liu, M.W. Verbrugge, H. Haftbaradaran, H. Gao Improved cycling stability of silicon thin film electrodes through patterning for high energy density lithium batteries, Journal of Power Sources 196, no.33 (Feb 2011): 1409–1416.https://doi.org/10.1016/j.jpowsour.2010.08.058 Desiccation of mud in the temperate intertidal zone: studies from the Severn Estuary and eastern England, Philosophical Transactions of the Royal Society of London. B, Biological Sciences 315, no.11711171 (Jan 1997): 127–156.https://doi.org/10.1098/rstb.1987.0005 References, (Jan 1982): 561–643.https://doi.org/10.1016/S0070-4571(08)71024-0Hsi C. T'an A Comprehensive Study of Mud Cracks and Other Similar Structures*, Bulletin of the Geological Society of China 6, no.3-43-4 (May 2009): 273–330.https://doi.org/10.1111/j.1755-6724.1927.mp63-4004.x