bluuebunny/crossref_metadata_2025 huggingface dataset:
AlGaN/GaN HEMT Based Biosensor
Authors: Alur Siddharth , Gnanaprakasa Tony Jefferson , Wang Yaqi , Sharma Yogesh , Dai Jing , Hong Jong , Simonian Aleksandr L. , Bozack Michael , Ahyi Claude , Park Minseo
Published: April 2010

GaN has been considered as a promising candidate for biosensing due to its chemical and thermal stability. In this work, an AlGaN/GaN high electron mobility transistor (HEMT) wafer with a 2DEG mobility of 1300 cm2/v-s and a sheet carrier density of 1×1013 cm-2 was used as a sensor platform. Ti/Al/Ni/Au were used as source and drain contacts, with Ni/Au contacts as gate electrodes. A NF3 plasma was used for device isolation. Photodefinable PDMS was used for the purpose of encapsulation. Once the encapsulation was completed using the photodefinable PDMS, the Schottky contact was exposed to a thiolated DNA in immobilization buffer for a period of 12hours. XPS was used to confirm the probe immobilization. The change in the (Id-Vds) characteristics of the device is measured during these processes, which confirm the probe immobilization and also the probe and the target DNA hybridization.
Development of Enhancement Mode AlN/Ultrathin AlGaN/GaN HEMTs by Selective Wet Etching
Authors: Anderson Travis , Tadjer Marko , Mastro Michael , Hite Jennifer , Hobart Karl , Eddy Charles , Kub Fritz
Published: April 2010

A novel recessed-gate structure involving an ultrathin AlGaN barrier layer capped by an AlN layer in the source-drain access regions has been implemented to demonstrate enhancement-mode high electron mobility transistors. A wet etch process has been developed using heated photoresist developer to selectively etch the AlN for the gate recess step, bypassing plasma etching and associated issues. The etch has been proven to be selective to AlN over AlGaN and GaN. A repeatable threshold voltage of +0.21V has been demonstrated with 4 nm AlGaN barrier layer thickness.
Etch Pits of 4H-Silicon Carbide Surface Formed Using Chlorine Trifluoride Gas
Authors: Habuka Hitoshi , Furukawa Kazuchika , Tanaka Keiko , Katsumi Yusuke , Takechi Naoto , Fukae Katsuya , Kato Tomohisa
Published: April 2010

Surface morphology of a single-crystalline 4H-silicon carbide (SiC) etched by chlorine trifluoride gas was studied over the wide temperature range of 570-1570 K at atmospheric pressure in a horizontal cold wall reactor. The etch rate of both the Si-face and C-face 4H-SiC at the substrate temperatures between 720 and 1570 K was simultaneously measured to be nearly flat at ca. 5 μm min-1. The Si-face and C-face showed pitted surfaces at low temperatures; the pits tended to become small and shallow with the increasing substrate temperature. This temperature-dependent behavior is expressed using the rate theory accounting for the slightly low activation energy at the spot causing the pit. The etch pits formed at low temperature may have relationship with crystalline defects, such as threading edge dislocation and screw dislocation.
a-Plane GaN for Hydrogen Sensing Applications
Authors: Baik Kwang Hyeon , Lim Wantae , Pearton Stephen , Wang Yu-Lin , Ren Fan , Yang Jeongyeol , Jang Soohwan
Published: April 2010

The performance of Pd/GaN Schottky diodes fabricated on a-plane GaN for hydrogen sensing was investigated. Pd Schottky diode on non-polar a-plane (11-20) GaN layers shows large increases in both forward and reverse bias current upon exposure to 4% H2 in N2. The barrier height reduction due to hydrogen exposure is 0.11 eV with long recovery times (>25 mins) at room temperature. The sensitivity to hydrogen is significantly greater than for diodes on conventional c-plane (Ga-polar) GaN.
Passivation of Deep Levels at the SiO2/SiC Interface
Authors: Basile Alberto F. , Rozen John , Chen X.D. , Dhar Sarit , Williams John R. , Feldman Leonard C. , Mooney Patricia M.
Published: April 2010

The analysis of trapping phenomena in 4H- and 6H-SiC MOS capacitors from C-V and CCDLTS measurements is presented. Three categories of defect levels are distinguished: namely, oxide traps, semiconductor bulk traps, and interface states. NO annealing results in a dramatic decrease of the density of the interface states and the oxide traps in both polytypes, but does not reduce that of the SiC bulk traps.
pnpn and npn Heterostructural Optoelectronic Devices
Authors: Guo Der-Feng
Published: April 2010

An ohmic-contact pnpn triangular-barrier optoelectronic switch (TBOS) has been fabricated. The triangular barrier is formed by inserting an InGaAs p-type delta-doped (δ(p+)) quantum well between two n--GaAs layers. Due to the hole accumulation in the δ(p+) well and the avalanche multiplication in the reverse-biased region, an S-shaped negative differential resistance (NDR) is obtained in the device characteristics. With a replacement of the ohmic-contact p-type cap layer with a Schottky-contact n-type layer in the pnpn TBOS, a Schottky-contact npn TBOS has also been proposed. A double S-shaped NDR phenomenon is observed in the npn TBOS characteristics due to the hole accumulation in the δ(p+) well and the sequential avalanche multiplications in the reverse-biased region and Schottky-contact junction. Both devices show a flexible optical function as a result of the triangular barrier heights associated with incident light.
InGaN-Based Light Emitting Diodes with an AlN Sacrificial Buffer Layer for Chemical Lift-Off Process
Authors: Lin Chia-Feng , Dai Jing-Jie , Lin Ming-Shiou
Published: April 2010

The InGaN-based light-emitting diodes (LEDs) grown on triangle-shaped patterned sapphire substrates were separated through a chemical lift-off process by laterally etching an AlN sacrificial layer at the GaN/sapphire substrate interface. The lateral etching rate of the AlN buffer layer was calculated at 10μm/min for the 100μm-width LED chip that was lifted off from the sapphire substrate. A triangular-shaped hole structure and a hexagonal-shaped air-void structure were observed on the lift-off GaN surface that was transferred from the patterned sapphire substrate. The chemical lift-off process was achieved by using an AlN buffer layer as a sacrificial layer in a hot potassium hydroxide solution.
Electron Paramagnetic Resonance Studies of Shallow Donors Behavior in Hydrogenated ZnO Films
Authors: Larina Liudmila , Tsvetkov Nikolay , Yang Jong , Lim Koeng-Su , Shevaleevskiy Oleg
Published: April 2010

Photoassisted metalorganic chemical vapor deposition (photo-MOCVD) technique was used for depositing of as-grown (ZnO) and hydrogenated (ZnO:H) zinc oxide polycrystalline thin films under different growth and hydrogen doping conditions. The structure and morphology of the films was controlled using SEM and AFM microscopy and surface roughness measurements. The studies of paramagnetic defects behavior and magnetic susceptibility in as-grown and hydrogenated samples were provided in the temperature range 77-300 K using X-band EPR spectrometer. It was found that all the samples exhibited a single symmetric strong Lorentzian line at g = 1.96 while the line intensity was shown to increase upon H-doping. The concentration of paramagnetic defects, associated with the concentration of the hydrogen donors, was extracted. The behavior of the magnetic susceptibility curves was described by Curie and Pauli contributions. We have shown that the excess concentration of paramagnetic defects, appeared after hydrogen doping, correlated with the increase of the Pauli term of magnetic susceptibility and followed the increase of free carrier concentration
Scanning Electron Microscope Observation of Concentration Profile in Ionic Liquid Caused by Electrochemical Reaction
Authors: Kuwabata Susumu , Kondo Koshiro , Tsuda Tetsuya
Published: April 2010

We have developed a system enabling in situ electron microscope observation of electrochemical reactions using room-temperature ionic liquid (RTIL). In this study the in situ electrochemical scanning electron microscopy (ECSEM) was employed to know information of metal ions dissolved in RTIL. An energy dispersive X-ray fluorescence spectrometer (EDX) allowed quantitative detection of Ag+ dissolved in RTIL with the concentration range from 0.002 to 2 mol dm-3. When line and fixed-place EDX analysis was conducted at vicinity of an Ag electrode that was electrochemically oxidized in RTIL, concentration profile and time course concentration changes of Ag+ were able to be easily observed.
A Study of Zinc Electrodeposition From Zinc Chloride: Choline Chloride: Ethylene Glycol
Authors: Pölzler Matthias , Whitehead Adam H. , Gollas Bernhard
Published: April 2010

This work is an initial study of the zinc deposition process from a Lewis-basic choline chloride/ ethylene glycol deep eutectic solvent containing ZnCl2 at 30{degree sign}C. The system was examined by cyclic voltammetry at static and rotating glassy carbon disc electrodes and by potential step techniques. Although there was little deposition initially on sweeping or stepping the potential to -0.5 to -0.8 V vs. Zn/Zn(II) more rapid deposition was observed when the potential was raised to -0.4 to -0.2 V. The role of choline chloride was also examined by comparison with a choline-free electrolyte, which exhibited a more conventional voltammetric response. A tentative suggestion has been proposed to account for the observed deposition behaviour.
Electrochemical Deposition of Poly-Paraphenylene Using Sodium Dodecyl Sulphate in Acidic and Ionic Liquid Media
Authors: Verma Amita , Singh P. K. , Ahmad Shahzada
Published: April 2010

Poly-paraphenylene films have been electrochemically synthesized using two medium. The first route employed concentrated sulfuric acid and sodium dodecyl sulphate (SDS) as the surfactant, while the second route involved room temperature ionic liquid 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (EMITF) and SDS, using benzene as the monomer unit in both the routes. The films are amorphous in nature as revealed by XRD. FT-IR study has elucidated the presence of para linkage in the films. The sulfuric acid medium derived films exhibit high transmission (~ 77 %) compared to the ionic liquid derived films (~ 47 %) at 550 nm. The optical direct and indirect bandgaps of the films derived from acidic medium were found to be 3.85 and 3.5 eV, respectively. The films have exhibited photoluminescence emission peaks at 355 nm and an additional peak also appears at 406, 437, 453 and 470 nm. Furthermore, these films have exhibited electrochromism and the ionic liquid derived film (453 cm2C-1) shows higher coloration efficiency value, which confirms its superior electrochromic performance in comparison to the sulfuric acid derived film
Addition of PEG-Thiol to Cu Electroless Plating Bath for Realizing Perfect Conformal Deposition in Through-Si Via Holes of 3-D Integration
Authors: Inoue Fumihiro , Yokoyama Takumi , Tanaka Syukiti , Yamamoto Kazuhiro , Shingubara Shoso
Published: April 2010

Cu electroless plating is one of the most promising methods to form a seed layer of electroplating for Cu filling in TSV of 3-D integration. However, with an increase of the aspect ratio of TSV, a uniformity of Cu thickness at the sidewall of TSV becomes poor due to consumption of Cu ions and reducing agents near the entrance of TSVs. In this study, we have studied an addition of PEG-thiol to an electroless Cu plating bath with a reducing agent of glyoxylic acid. We achieved conformal deposition of Cu for TSV with diameters of 4 to 10 μm by this method. The Cu thickness of the TSV sidewall remained constant with depth even for a high aspect ratio TSVs. This method is very effective for a formation of a thin Cu seed layer prior to the Cu electroplating process of TSV-filling.
Effects of Slurry Distribution using Diaphram and Centrifugal Pumps on the Defectivity in a Cu CMP Process
Authors: Donis Robert , Fisher Matthew , Bauck Leland
Published: April 2010

Slurry health has been shown to impact defectivity in the chemical mechanical planarization (CMP) process. Improper mechanical handling is known to form large agglomerates in CMP slurries that can lead to increased scratching of the surface. The foremost cause of slurry damage occurs from shear stresses placed on the slurry particles as they pass through the motive force in a distribution system. This paper is a study of two common slurry pumping methods and their contribution to post CMP micro-scratch defects measured on TEOS, Black Diamond l (BD l), Cu blanket wafers, and low-k/Cu integrated patterned wafers. The two specific slurry handling methods studied were the recirculation of slurry in a distribution system by positive displacement (diaphragm) pumps and bearingless centrifugal pump systems.
(Invited) Reliability of Through Silicon Via Technologies
Authors: Klumpp Armin , Ramm P.
Published: April 2010

A lot of technologies are suggested to build up 3-dimensional integrated systems. Due to the relatively short history of 3D-integration attempts most of these technologies are still far away of being mature modules. After a period of time with public relation for 3D-integration by presenting new technological results, now it is necessary to turn attention towards practicability and value for products. The key word is reliability
The Functional Group Effect of Complexing Agent on Cu CMP in the Neutral Environment
Authors: Bae Jae Han , Kim Yung Jun , Kim Jae Jeong
Published: April 2010

Chemical mechanical planarization (CMP) makes it possible to fabricate the reliable and speedy Cu interconnection with high integration. Through general Cu CMP process causes the surface defects, such as corrosion, dishing, and erosion, in high acidic and basic conditions, extensive research about CMP in neutral condition is needed. It is well known that the removal rate of Cu with neutral pH slurry is relatively lower than acidic and basic slurries. To improve the removal rate in neutral pH condition, complexing agents which dissolve Cu surface by complexing with Cu metal or Cu oxide have been used. In the present study, we investigate the effective functional group and complexing agent in neutral pH condition.
First Principles Simulations of Li Ion Migration in Materials Related to LiPON Electrolytes
Authors: Du Yaojun , Holzwarth Natalie
Published: April 2010

In an effort to understand stability and ionic conduction mechanisms in the LiPON family of solid electrolytes, we have carried out first principles calculations of several related crystalline materials. Simulation results include heats of formation, zone center lattice vibrational modes, and activation energies for Li ion migration. In the course of this work, we discovered new stable crystalline forms of Li2PO2N, based on the previously known phosphate chain structure of LiPO3.
Studies on Complexing Properties of 2,4,6-Trifluorophenylboronic Acid Pinacol Ester in PEODME Based Polymer Electrolyte
Authors: Kryczka Jolanta , Drzewiecki Stanisław , Szczypińska Joanna , Żukowska Zofia , Adamczyk Woźniak Agnieszka , Syzdek Jarosław S. , Marcinek Marek , Sporzyński Andrzej , Wieczorek Władysław
Published: April 2010

In this paper we present our systematic studies on the application of new organoboron compound as anion complexing additive in poly(ethylene oxide) dimethyl ether PEGDME-lithium salt. The anion trapping ability of this compounds is discussed regarding the type of various compounds, both triarylboranes as well as arylboronic esters. A possible mechanism of interactions is verified by the impedance spectroscopy, differential scanning calorimetry and vibrational spectroscopy methods.
Anode Reactions of a Tin Thin Film Electrode Modified with an Ion-Conductive Polymer in a Room-Temperature Ionic Liquid Electrolyte
Authors: Kaga Yoshiaki , Katayama Yasushi , Miura Takashi , Komaba Shin-ichi
Published: April 2010

The anode reaction of a tin thin film electrode modified with poly(ethyleneoxide) containing lithium bis(trifluoromethylsulfonyl)amide (LiTFSA) has been investigated in an ionic liquid electrolyte, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide (BMPTFSA). Lithium dope and undope were found possible for the modified electrode, indicating the lithium ion conductive polymer acts as an artificial solid-electrolyte interphase film. The cycle performance of the modified electrode was slightly improved compared with the unmodified one, suggesting the polymer film prevent the active material from falling off from the current collector.
Negative Electrode Properties of Sn and Si Leaf Powder for Li-ion Batteries
Authors: Saito Morihiro , Nakai Kenta , Hagiwara Makoto , Tasaka Akimasa , Takenaka Toshio , Hirota Masato , Kamei Akika , Inaba Minoru
Published: April 2010

Two kinds of metal thin platelets (Leaf Powder, Oike Co., Ltd.) based on Sn and Si were prepared, and their charge/discharge properties were investigated as alternative negative electrode materials to graphite for Li-ion batteries. One was simple metal platelets (M-LP, thickness: 100 nm) and the other was laminated platelets with an inactive Ni layer (M/Ni/M-LP, thickness: 30/30/30 nm). For both Sn and Si platelets, the shape of thin platelets effectively relieved the stress by volume expansion and shrinkage during the alloying and de-alloying processes, and improved their charge/discharge cycleabilities. Particularly, the Si platelets suppressed their agglomeration and pulverization, and much more remained the shapes than the Sn platelets. The lamination with the inactive Ni layer further improved the cycleability, though the specific capacity decreased by its presence. The alloying and de-alloying reaction with Li+ ion was substantially smooth, which was due to a decrease in the diffusion distance of Li+ ion by using the thin platelets. As a result, the Si/Ni/Si-LP exhibited a good capability over ca. 400 mAh g-1 up to 3C rate.
Electrochemical Properties of Fullerene Coated Silicon Thick Film for Anode Material of Lithium Secondary Batteries
Authors: Arie Arenst Andreas , Lee Joong-Kee
Published: April 2010

Silicon thick films were coated by fullerene thin film using plasma assisted thermal evaporation technique at plasma power of 50 and 100 W. The fullerene coated silicon films were then used as anode materials of lithium secondary batteries. The coated electrodes demonstrated a lower initial irreversible capacity and a better interfacial property, as shown by the cyclic voltammetry (CV) measurements and impedance analysis. It was attributed to the fullerene coating layer which could maintain the mechanical stability of electrodes by suppressing the side reaction with the electrolyte during the repeated charge-discharge tests.
Effect of Carbon Coating on Electrochemical properties of LiCoO2/Nanocarbon Composites
Authors: Uno Yusuke , Tachimori Koji , Tsujikawa Tomonobu , Hirai Toshiro
Published: April 2010

We fabricated LiCoO2/helical nanocarbon (HCN) composites by forming HCNs on LiCoO2 coated with acetylene black (AB) (LiCoO2/AB) to inhibit LiCoO2 degradation, and estimated its electrochemical properties. HCNs were successfully formed on LiCoO2/AB and there was no significant difference in the HCN formation from HCNs formed on bare LiCoO2. However, XRD measurements indicated that AB coating provided insufficient protection against LiCoO2 degradation. This resulted in a low specific capacity for a cell containing LiCoO2/AB/HCN composite.
The Novel Ionic Transfer Detecting Methodology of Lithium Polymer Battery by Positron Annihilation Studies
Authors: Wang Fu Ming , Wang Yung-Yun , Wan Chi-Chao
Published: April 2010

A new method for ionic transfer detection is called Doppler Broadening S parameter of Positron Annihilation Spectroscopy (PAS) is used to study polysiloxane electrolytes with ethylene oxide (EO) side chains and carbonate electrolytes. First, the polymer electrolytes are modified to enhance contact with an acrylate, and an increase in the lengths of the EO chains is shown to decrease the resistance of the transition interface layer at the pristine electrode surface. Second, an ionic transfer study of the electrode surface after electrochemical reactions showed that the polymer electrolytes have a greater effect on the interface transition layers than did the carbonate electrolytes. In addition, a continuity phase including a chemical membrane that is formed from carbonate electrolytes during electrochemical reactions and the enhancing ionic transfer benefits is found by this new detecting methodology.
Thermal Stability of Ionic Liquids as an Electrolyte for Lithium-Ion Batteries
Authors: Hori Mariko , Aoki Yasuhiro , Maeda Seiji , Tatsumi Ryouta , Hayakawa Seiichirou
Published: April 2010

We have examined the thermal stability of several ionic liquids contacted with a charged cathode material Li0.5CoO2 by DSC and TG as the easy model-method to estimate the safety of ionic liquids as an electrolyte. From the results of DSC, it was found that the thermal stability depended on the type of ionic liquid, especially the chemical structure of the anion. The introduction of F atom to anion improved the thermal stability, but C=O groups in anion reduced the stability. For EMI·BF4 with Li0.5CoO2, DSC profile showed the exothermic peak from 200 degree C to 300 degree C and TG profile showed the weight loss in the same temperature area, though neither exothermic peak nor weight loss was observed up to 350 degree C for sole EMI·BF4. From the analysis of generated gas, the main gas was CO2 in the area of exothermic heat.
Thin Film Lithium Battery using Stable Solid Electrolyte Li4SiO4 Fabricated by PLD
Authors: Nakagawa Atsuyoshi , Kuwata Naoaki , Matsuda Yasutaka , Kawamura Junichi
Published: April 2010

The Li4SiO4 thin film was successfully deposited by pulsed laser deposition (PLD) technique using an ArF excimer laser. The morphology, the micro structure and the ionic conductivity of the Li4SiO4 film were investigated. The ionic conductivity was 4.1×10-7Scm-1 at 25{degree sign}C. A solid-state thin film battery (TFB) consisting of the amorphous Li4SiO4 electrolyte with LiCoO2 positive electrode and Li metal negative electrode was fabricated and characterized. The TFB exhibited good reversibility on CV cycles for more than 50 cycles between 3.0 and 4.4V.
Low Energy of Activation Lithium-ion Conducting Channel
Authors: Scanlon Lawrence , Lucente Leah , Lawson Milissa , Lawson Jacob , Fellner Joseph P. , Feld William , Balbuena Perla B. , Munichandraiah Nookala , Xiao Haiming
Published: April 2010

The specific ionic conductivities for a thin film of dilithium phthalocyanine (Li2Pc) dried at 160°C and for a pressed pellet of single crystals of Li2Pc have been determined via impedance analysis as a function of temperature. The specific ionic conductivity of the thin film is on the order of mS/cm from -50 to +50°C with an energy of activation of 0.063 eV. The specific ionic conductivity for the pressed pellet is on the order of 10-4 S/cm from 0 to +50°C with an energy of activation of 0.038 eV. The results suggest that lithium ion conduction takes place between the planes of the complex anions of Li2Pc, parallel to the a-axis.
The Influence of Additives on Lithium Dope/Undope Reactions for a Tin Film Electrode in a Room-Temperature Ionic Liquid Electrolyte
Authors: Miyashita Soudai , Katayama Yasushi , Miura Takashi , Komaba Shin-ichi
Published: April 2010

Lithium dope-undope reactions of a tin thin film electrode were investigated in a room-temperature ionic liquid, 1-butyl-1-methyl-pyrrolidinium bis(trifluoromethylsulfonyl)amide (BMPTFSA) containing 1 M LiTFSA with and without glyme as an additive. Lithium dope-undope was possible in 1 M LiTFSA/BMPTFSA with glymes. The resistance of the electrode-electrolyte interface with glyme was smaller than that without glyme, indicating the solvation environment of Li+ affects the interfacial resistance in the ionic liquid electrolyte.
Crystalline Halide Substituted Li-Argyrodites as Solid Electrolytes for Lithium Secondary Batteries
Authors: Stadler Florian , Fietzek Christopher
Published: April 2010

Apparent lithium ionic conductivity of crystalline Li-Argyrodite materials (Li6PS5X, X = Cl, Br) was measured to be about 10 exp(-4) S/cm, which is higher than that of common solid electrolytes like LiPON. The materials are electrochemically stable at least up to 5 V vs. Li/Li+ and thus applicable as electrolyte with standard cathode active materials in lithium secondary batteries. An all-solid-state battery using Li-Argyrodite as electrolyte with lithium titanate as cathode and lithium aluminum alloy anode was fabricated, showing a specific capacity of 150 mAh/g at a current rate of C/50 at 75 degC. However, the cell shows poor rate capability and a large polarization at room temperature.
Evaluation of Synthesis Routes for Pure and Composite LiMnPO4 with Carbonaceous Additives for Li-Ion Battery
Authors: Kaymaksiz Serife , Kaskhedikar Nitin , Sato Nurio , Roth S. , Dettlaff-Weglikowska Ursula
Published: April 2010

LiMnPO4 is considered to be a potential candidate as a cathode material for the next generation of lithium ion battery. Compared to LiFePO4, it offers higher operating voltage (~4,2 V) and higher theoretical capacity. However, its practical application is strongly inhibited by its low electrical conductivity and kinetic limits of Li ion diffusion. In this research, we have investigated the low cost, low temperature synthesis methods of LiMnPO4 such as sol-gel, hydrothermal way and microemulsion and also evaluated the resulting material taking into consideration the morphology, particle size, porosity and crystallinity. In order to improve the electrical conductivity and the Li ion mobility, we have replaced the state-of-the art carbon coating by single walled carbon nanotubes.
Properties of PVdF/HFP Inorganic Al2O3 Filler Modified Gel Electrolytes
Authors: Piotrowska Karolina , Zalewska Aldona , Syzdek Jarosław S. , Niedzicki Leszek , Marcinek Marek
Published: April 2010

In the presented work we describe the effect of fumed oxide fillers (e.g. Al2O3 pure and modified with 1-8% H2SO4 on the properties of gel electrolytes based on PVdF/HFP polymer matrix. The PVdF/HFP gels were prepared via the Bellcore process. Dry membranes were immersed in LiPF6 in an propylene carbonate (PC) electrolyte solution.
Performance Demonstration of MCMB-LiNiCoO2 Cells Containing Electrolytes Designed for Wide Operating Temperature Range
Authors: Smart Marshall C. , Bugga Ratnakumar V. , Whitcanack Larry , Smith Kiah , Santee Stuart , Puglia Frank , Gitzendanner Robert
Published: April 2010

With the intent of improving the performance of Li-ion cells over a wide operating temperature range, we have investigated the use of co-solvents to improve the properties of electrolyte formulations. In the current study, we have focused upon evaluating promising electrolytes which have been incorporated into large capacity (7 Ah) prototype Li-ion cells, fabricated by Yardney Technical Products, Inc. The electrolytes selected for performance evaluation include the use of a number of esters as co-solvents, including methyl propionate (MP), ethyl propionate (EP), ethyl butyrate (EB), propyl butyrate (PB), and 2,2,2-trifluoroethyl butyrate (TFEB). The performance of the prototype cells containing the ester-based electrolytes was compared with an extensive data base generated on cells containing previously developed all carbonate-based electrolytes.
A Mathematical Model for All Solid-State Lithium-Ion Batteries
Authors: Becker-Steinberger Katharina , Funken Stefan , Landstorfer Manuel , Urban Karsten
Published: April 2010

We present a new model for all solid-state lithium ion batteries that takes into account detailed aspects of ion transport in solid solutions of crystalline metal oxides. More precisely, our model describes transient lithium ion flux through a solid electrolyte, the solid-solid interfaces and an intercalation electrode. The diffuse part of the double layer is dynamically described via the Poisson equation, while the Stern layer potential drop is modeled by a Robin boundary condition. Electrochemical reactions on the electrode/electrolyte interface are modeled via non-linear Neumann boundary conditions. After a detailed derivation of the model equations and boundary conditions, numerical results are presented and discussed.
Storage Characteristics of Lithium-Ion Cells
Authors: Bugga Ratnakumar V. , Smart Marshall C. , Whitcanack Larry
Published: April 2010

Lithium ion cells have in general shown impressive cycle life, but their durability for applications requiring long calendar is not yet demonstrated. In this paper, we carried out systematic and detailed experimental study of the storageability of Li-ion cells. Specifically, we tested two aerospace chemistries, i.e., SAFT DD cells and Yardney prismatic 7 Ah cells, at six different temperatures and at 50% state of charge. Based on the nine-year old test data, an analysis has been made on the capacity degradation upon storage. The projected capacities from such analysis reveal that the cells can provide over 80% of their initial capacities after ten years, especially when stored at low temperatures, thus asserting the durability and viability of Li-ion batteries for long-life applications.
Influence of La-Content and Microstructure on the Corrosion Properties of a New Free Machining Titanium Alloy
Authors: Benfer Sigrid , Siemers Carsten , Rösler Joachim , Fürbeth Wolfram
Published: April 2010

A new titanium alloy was developed at the Technische Universität Braunschweig by alloying the standard Ti6Al4V with lanthanum. Lanthanum contents between 0.9% and 2.8% lead to improved machinability by reducing the chip length up to a factor of 100. The microstructure of the alloys depends on the sample treatment. Cast alloys have a martensitic structure whereas compressed and annealed ones show a Widmannstätten structure. The corrosion properties of these new alloys were investigated by electrochemical methods and standard corrosion tests. Investigations with potentiodynamic polarization showed that lanthanum containing alloys exhibited an active passive transition near the Eoc in chloride solutions, which is attributed to the dissolution of lanthanum. All alloys showed a similar behavior in artificial saliva and sulfuric acid. Electrochemical impedance spectroscopy (EIS) measurements confirmed the results of the other methods.
Bronze Protection in Seawater
Authors: Granic Ana , Otmacic Curkovic Helena , Stupnisek-Lisac Ema , Kharshan Margarita , Furman Alla
Published: April 2010

The aim of this work was to investigate corrosion and protection of bronze in artificial seawater. The presence of high concentration of chlorides results in an extremely high level of corrosion in seawater. Possibility of bronze protection was examined by the use of three different corrosion inhibitors. One of them is benzotriazole which is very good corrosion inhibitor but it is toxic. In this study benzotriazole was used in order to compare with the efficiency of two new non-toxic corrosion inhibitors: 1-phenyl-4-methyl-imidazole and vapor phase corrosion inhibitor which is developed from the fermentation process of sugar beets. Investigation was performed by the means of electrochemical methods. Tested corrosion inhibitors show high inhibiting efficiency, which in some cases reaches 99%. These results confirmed that in highly aggressive media like seawater benzotriazole can be replaced with environmental friendly corrosion inhibitors which provide the same or even better corrosion protection of bronze.
Effect of Temperature on Galvanic Corrosion of Non-Welded/Welded AISI 316L Stainless Steel in H3PO4
Authors: Sánchez-Tovar Rita , Montañes María Teresa , Garcia-Anton José , Guenbour Abdellah
Published: April 2010

Galvanic corrosion of non-welded/welded AISI 316L SS at different temperatures (25 ºC to 60 ºC) at a Reynolds number of 1456 in phosphoric acid has been studied using polarization curves (by the mixed potential theory) and zero resistance ammeter (ZRA) measurements. Imposed potential measurements provide more active predicted coupled potentials and higher galvanic current densities than those obtained using ZRA measurements. Polarization curves show that the anode of the pair is the non-welded AISI 316L. Galvanic current density values obtained from polarization curves increase with temperature. ZRA tests present the highest iG values at 60 ºC; however, the values are very close to zero for all the temperatures studied. This is in agreement with the low value of the compatibility limit and of the parameter which evaluate the Galvanic phenomenon importance. Both techniques present the most positive potentials at the highest temperature.
Influence of Temperature on the Corrosion Behavior and the Hydrogen Evolution Reaction on Chromium in LiBr Solution
Authors: Guiñón-Pina Virginia , Igual-Muñoz Anna , Garcia-Anton José
Published: April 2010

Lithium Bromide aqueous solutions used as absorbent in refrigeration machines can cause serious corrosion problems which also facilitate the hydrogen evolution reaction (HER) in the cathodic regions. Hydrogen generation is an important problem in the operating conditions of adsorption machines because they operate under vacuum condition and the efficiency of the system decreases. Chromium is one of the alloying elements of Stainless Steels. The objective of this work is to study the anodic and cathodic behavior of chromium and the HER in 992 g/l LiBr at different temperatures (25, 50 and 75 ºC) using various electrochemical techniques: Open Circuit Potential (OCP), potentiodynamic and galvanostatic measurements and image analysis.
A Preliminary Study on Cathodic Prevention in Reinforced Mortar
Authors: Koleva Dessi , Van Breugel Klaas , Mol J.M.C. , De Wit Hans
Published: April 2010

This work presents the preliminary tests on the performance of cathodic prevention (CPre) in reinforced mortar, subjected to aggressive (10% NaCl environment). Cathodic prevention is an electrochemical technique for minimizing, actually "preventing" any eventual corrosion of the steel bars in reinforced concrete. Therefore, the main objective of this investigation is to monitor the performance of cathodic prevention (CPre) as an alternative of cathodic protection (CP) i.e. application before corrosion initiation, using low cathodic current densities (1 to 2.5 mA/m2 steel surface). The novelty here is the application of "pulse" cathodic prevention (pulse DC current), rather than the conventional steady DC technique. The paper reports on conventional monitoring (potential mapping and depolarization decay), coupled with visualization of the steel/cement paste interface, using SEM and EDX.
Mechanism of Stress Corrosion Crack Growth on SUS316L Stainless Steel
Authors: Masuda Hiyoyuki
Published: April 2010

The crack tip deformation and surface potential distribution on SUS316L stainless steels were observed by SKFM and KFM. The existence of hydrogen-induced martensite was examined by the magnetic force microscope (MFM) observations. The results showed that the less noble potential region existed near the crack tip. MFM and KFM observation showed hydrogen-induced martensite existed at the less noble potential region. Repeated SKFM observations revealed that the crack is formed by the movement of hydrogen-induced martensite.
Preliminary Evaluation of Digital Image Correlation for In-situ Observation of Low Temperature Atmospheric-Induced Chloride Stress Corrosion Cracking in Austenitic Stainless Steels
Authors: Cook Anthony B. , Duff Jonathan , Stevens Nicholas , Lyon Stuart , Sherry Andrew , Marrow James
Published: April 2010

Digital image correlation has been used to observe the growth of atmospheric-induced chloride stress corrosion cracking in type 304L stainless steel under controlled conditions of temperature, relative humidity and chloride-deposition density in a non-destructive manner. The technique is capable of detecting changes in crack dimensions that are difficult to discern via conventional optical microscopy, i.e. crack growth beneath salt layers and adherent corrosion product deposits, and measurement of crack opening displacements. Our results also demonstrate that suitable specimen design, combined with digital image correlation, will provide the means of comparing the growth behaviour of short atmospheric-induced chloride stress corrosion cracks with data obtained from conventional pre-cracked compact tension specimens as a function of mechanical "driving force".
Isolating the Electrochemical Behavior of the Austenite and Ferrite Phases in a Duplex Stainless Steel
Authors: Policastro Steve , Martin Farrel J. , Rayne Roy , Auyeung Ray C. , Pique Alberto , Lewis Alexis , Geltmacher Andrew , Natishan Paul M.
Published: April 2010

An experimental technique for making electrochemical measurements on isolated individual phase regions of known crystalline orientation in a duplex stainless steel is demonstrated. An ultraviolet-sensitive photoresist is used to mask the excluded portions of the sample and a 355 nm laser exposes only portions of the ferrite matrix or cross-sections of austenite dendrites. Initial impedance measurements indicate a relatively low solution resistance in seawater and the polarization scans of the ferrite and austenite phases were consistent with bulk polarization measurements.
Investigation of Magnesium in NaCl 0.02 M using LSV Combined with Electrochemical Impedance Spectroscopy
Authors: Nascimento Maria Lucia , Fleck Claudia , Müller Wolf-Dieter
Published: April 2010

Electrochemical characterization of Magnesium and its alloys is rather difficult due to high hydrogen development and the consequent scatter of the electrochemical data in aqueous solutions. The objective of this work was to drive the system to a given point by applying linear sweep voltammetry (LSV) up to a defined potential, immediately followed by electrochemical impedance spectroscopy (EIS) on the same spot. The objective was to reduce the scatter of EIS spectra. It was used the Mini-cell System setup, with the measurement area of 0.8mm2. The materials investigated were pure Mg and the alloy AZ31. The results were reproducible and there was indication of two electrochemical processes, one corresponding to a charge transfer and the second to the formation of a surface layer. The processes were similar for both materials. The loop corresponding to the layer formation was present to potentials more negative than the corrosion potential and was stable up to 20mV above it. Therefore this layer might be related to the formation of Mg(OH)2.
Influence of Surface Conditions on the Adsorption Process of Bovine Serum Albumin (BSA) on CoCrMo Biomedical Alloy
Authors: Valero Vidal Carlos , Igual-Muñoz Anna
Published: April 2010

CoCrMo alloys are biocompatible materials widely used for orthopaedic implants. The biocompatibility of CoCrMo alloy is closely related to its excellent corrosion resistance, imparted by a passive oxide film that forms spontaneously on the alloy surface. The adsorption of organic species present in the synovial fluids may attach with this passive film and modify their surface reactions. BSA adsorption on CoCrMo surface was studied in order to determine the mechanism of protein adsorption at different surface conditions and passivation times in phosphate buffered solution (PBS). At Open Circuit Potential (OCP), adsorption kinetics were influenced by surface passivation when passivation time was lower than 1 hour, whereas, at higher passivation times, no apparent modification in the kinetic mechanisms of adsorption was observed. On the other hand, at a passive applied potential, the BSA addition decreased the passivation kinetics of the process at all the passivation times.
Corrosion Stability of Non-Precious Metal Nickel- and Cobalt-Based Alloys in Dentistry
Authors: Klostermann Annett , Rahm Elke , Holze Rudolf
Published: April 2010

Results of a comparative in vitro study of the corrosion behavior of selected non-precious metal alloys used in dentistry in the presence of substances present in foodstuffs and materials applied in dentistry yield breakthrough potentials used as indicators of relative corrosion stability. Data are only slightly worse than those previously obtained with palladium-based alloys, earlier poor data of nickel-based alloys were not observed. The influence of additives can be rationalized based on generally known accelerating or inhibiting effects of electrolyte solution constituents.
High Energy Rechargeable Li-S Cells for EV Application: Status, Remaining Problems and Solutions
Authors: Mikhaylik Yuriy V. , Kovalev Igor , Schock Riley , Kumaresan Karthikeyan , Xu Jason , Affinito John
Published: April 2010

The primary mechanisms limiting lithium sulfur (Li-S) cell cycle life and thermal stability are discussed. Two major cycle life limiting mechanisms are identified: development of rough surface morphology on the metallic lithium anode with cycling; and depletion of lithium and electrolyte components through chemical reaction. The approach taken here to mitigate these problems, by employing physical protection, including multi-functional membrane assemblies and non-isotropic pressure is presented. Sulfur utilization of 92%, at C/5 discharge rates, increased cycle life and elimination of thermal runaway in 300 mAh Li-S cells was achieved.
Localized Gap States in LiCoO2 and their Influence on the Transport Properties in Li-Ion Batteries
Authors: Schmeißer Dieter , Schmidt Stephan , Seibold Goetz , Cherkashinin Gennady , Jaegermann Wolfram
Published: April 2010

The electronic structure of Co2O3 and LiCoO2 is analyzed in a comparative study employing synchrotron radiation. We study the Co2p and O1s core levels, the X-ray absorption spectra at the Co2p and O1s absorption edges, as well as the valence band and conduction band states of Co2O3 and LiCoO2 by resonant photoelectron spectroscopy. We notice a metallic behavior of Co2O3 while LiCoO2 has a gap. We discuss our data in terms of a band diagram in which localized states around the Fermi energy are within the gap formed from covalent O2p-Co3d contributions.
Material and Design Options for Avoiding Lithium Plating during Charging
Authors: Eberman Kevin , Gomadam Parthasarathy , Jain Gaurav , Scott Erik
Published: April 2010

A two-dimensional model presented, including the thickness and electrode edge-overlap directions, which successfully predicts the onset of lithium plating observed experimentally with carbon negative electrodes under certain conditions. Plating with Li4Ti5O12 neither occurred experimentally nor was it predicted by the model, over a wide parameter window up to 5C. High charge rate (e.g. up to 5C) with up to 1.7mm "underlap" (positive-electrode edge extending beyond that of the negative-electrode) can be accomplished with a negative-electrode open-circuit potential 0.4V vs. lithium.
Surface Modification and Fabrication of Li-Ion Battery Components for Plug-In Hybrid Electric Vehicle
Authors: Luan Ben L. , Campbell Glen , Gauthier Maxime , Liu Xing Yang , Davidson Isobel , Nagata John , Lépinay Matthieu , Bernier Fabrice , Argue Steve
Published: April 2010

This paper addresses an important issue for the practical application of lithium ion batteries in PHEV. More specifically, preliminary research results on the coating of separators, welding of battery tabs, and fabrication and surface featuring of anodic and cathodic current collectors are presented. These developments aim at improving the power performance, reliability, and safety of lithium ion batteries.
The State-of-Energy: A New Criterion for the Energetic Performances Evaluation of Electrochemical Storage Devices
Authors: Mamadou Kelli , Delaille Arnaud , Lemaire-Potteau Elisabeth , Bultel Yann
Published: April 2010

One simple question always obsesses any designer of an energetic system using electrochemical storage: is the battery able to deliver or absorb the requested power during the requested duration? Even nowadays, the battery's available reserve is considered in terms of quantity of charge (or capacity) Thus, intermediate stages are necessary to get to its energetic and power reserves. The general approach to evaluate a battery's energetic reserve consists into two modeling. One model describes the remaining capacity while the second describes its voltage variations. This global approach makes the final modeling complex and moreover it brings up multiple sources of error. We propose a new approach that allows a direct determination of battery's power and energetic performances directly from a power solicitation profile. It is based on a new criterion: the SOE as for State-Of-Energy.
The Effect of Pore Size on the Performance of the Li-O2 Battery
Authors: Younesi Reza , Singh Neelam , Urbonaite Sigita , Edström Kristina
Published: April 2010

Lithium-air batteries are complex electrochemical systems. This study deals with the composite cathode, where oxygen is reduced and different lithium-oxygen species are formed as reaction products. The amount of stored reaction product and thus the battery capacity is known to depend on surface area and pore-volume in the cathode. Here the role of pore size is studied for three different carbons and their corresponding composite cathode films. Gas adsorption studies show that film-forming Kynar polymer is blocking micropores and mesopores below ~300 Aå. This influences battery performance of the high surface area carbon, containing micropores only, where the capacity is shown to be negligible. The two other carbons, with wider pore-size distributions, show a battery capacity in the order of 1300-1500 mAh/g carbon. This shows that it is vital to consider also the pore size in the cathode film for a good battery performance.
Optimum Charging Profile for Lithium-Ion Batteries to Maximize Energy Storage and Utilization
Authors: Methekar Ravi , Ramadesigan Venkatasailanathan , Braatz Richard D. , Subramanian Venkat R.
Published: April 2010

The optimal profile of charging current for a lithium-ion battery is estimated using dynamic optimization implemented via control vector parameterization (CVP). An efficient reformulated model is used for simulating the system behavior of the Li-ion battery. Dynamic optimization is made possible due to the computationally inexpensive reformulated model. It is found that, if the battery is charged using the optimum profile estimated by dynamic optimization, more energy can be stored as compared with conventional charging of the battery. An attempt has been made to understand the dynamics of Li-ion batteries with competing transport and reaction phenomena at various scales and location inside the battery.
Supercapacitors using n and p-Type Conductive Polymers Exhibiting Metallic Conductivity
Authors: Kinlen Patrick J. , Mbugua Joseph , Kim Young-Gi , Jung June-Ho , Viswanathan Sriram
Published: April 2010

Energy storage devices such as supercapacitors require a superior, safe and reliable functioning over a broad range of temperature combined with high energy and high power densities. Development of improved high performance supercapacitors is important for fulfilling the energy and power needs of hybrid electric vehicles, portable electronics, and specialized pulse-power systems required by the military. To meet this need, Crosslink has developed supercapacitor electrodes based on inherently conductive polymers (ICPs). These electrodes combine both the beneficial pseudocapacitive behavior of the ICP coating and a low equivalent series resistance. In this developmental effort, highly-conductive (> 1000 S/cm) polyaniline (PANI) electrodes are used to fabricate high performance supercapacitors to obtain enhanced charge transfer and redox activity. We find that the high electrical conductivity of PANI leads to an enhancement in electrochemical properties such as energy and power densities. In addition, new n-type conductive polymer systems under development exhibit stable electrochemistry and high faradaic capacitance and are being used with the PANI system to build asymmetric supercapacitors. The conductive polymers may be employed as flexible free standing films or substrate coated electrodes. The conductive polymer-based supercapacitor assembly is designed to function with high energy and power densities, cycle life, and extreme temperature tolerance while keeping production costs low.