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Articles 751 - 780 of 914
Full-Text Articles in Chemical Engineering
Electrowinning Of Nonnoble Metals With Simultaneous Hydrogen Evolution At Flow-Through Porous Electrodes Iii. Time Effects, Mahmoud M. Saleh, John W Weidner, Bahgat E. El-Anadouli, Badr G. Ateya
Electrowinning Of Nonnoble Metals With Simultaneous Hydrogen Evolution At Flow-Through Porous Electrodes Iii. Time Effects, Mahmoud M. Saleh, John W Weidner, Bahgat E. El-Anadouli, Badr G. Ateya
Faculty Publications
The electrowinning of zinc from a recirculating alkaline zincate solution at a flow-through porous electrode was investigated. Experimental results were obtained to test the predictions of a mathematical model. The effects of electrolyte flow rate, cell current, and electrode thickness on the concentration-time relations and coulombic efficiency-time relations were studied. The experimental results show that the highest recovery rate was obtained at both high flow rates and cell currents. There is, however, a practical limit for increasing both the cell current and the electrolyte flow rate. Reasonable agreement between the model predictions and experimental results was obtained. A case study …
An Electrochemical Route For Making Porous Nickel Oxide Electrochemical Capacitors, Venkat Srinivasan, John W. Weidner
An Electrochemical Route For Making Porous Nickel Oxide Electrochemical Capacitors, Venkat Srinivasan, John W. Weidner
Faculty Publications
Porous nickel oxide films were prepared by electrochemically precipitating nickel hydroxide and heating the hydroxide in air at 300°C. The resulting nickel oxide films behave as an electrochemical capacitor with a specific capacitance of 59 F/g electrode material. These nickel oxide films maintain high utilization at high rates of discharge (i.e., high power density) and have excellent cycle life. Porous cobalt oxide films were also synthesized. Although the specific capacitances of these films are approximately one-fifth that of the nickel oxide films, the results demonstrate the versatility of fabricating a wide range of porous metal oxide films using …
Molecular-Level Modeling Of The Viscoelasticity Of Crosslinked Polymers: Effect Of Time And Temperature, Philip P. Simon, Harry J. Ploehn
Molecular-Level Modeling Of The Viscoelasticity Of Crosslinked Polymers: Effect Of Time And Temperature, Philip P. Simon, Harry J. Ploehn
Faculty Publications
We present a new molecular-level picture of chain dynamics for describing the viscoelasticity of crosslinked polymers. The associated mathematical model consists of a time-dependent momentum balance on a representative polymer segment in the crosslinked network, plus phenomenological expressions for forces acting on the segments. These include a cohesive force that accounts for intermolecular attraction, an entropic force describing the thermodynamics governing chain conformations, and a frictional force that captures the temperature dependence of relative chain motion. We treat the case of oscillatory uniaxial deformation. Solution of the model equations in the frequency domain yields the dynamic moduli as functions of …
The Effect Of Ultrasonic Frequency Upon Enhanced Killing Ofp. Aeruginosa Biofilms, Zhen Qian, Richard D. Sagers, William G. Pitt
The Effect Of Ultrasonic Frequency Upon Enhanced Killing Ofp. Aeruginosa Biofilms, Zhen Qian, Richard D. Sagers, William G. Pitt
Faculty Publications
It is widely recognized that the bacteria sequestered in a biofilm on a medical implant are much more resistant to antibiotics than their planktonic counterparts. Recent studies have shown that application of antibiotic along with low power ultrasound significantly increases the killing of planktonic bacteria by the antibiotic. Herein is reported a similar application of antibiotic and ultrasound to sessile bacteria in biofilms of Pseudomonas aeruginosa on a polyethylene substrate. Biofilm viability was measured after exposure to 12 μg/ml gentamicin sulfate and 10 mW/cm2 ultrasound at frequencies of 70 kHz, 500 kHz, 2.25 MHz, and 10 MHz. The results …
Characterization Of The Si/Sio2 Interface Formed By Remote Plasma Enhanced Chemical Vapor Deposition From Sih4/N2O With Or Without Chlorine Addition, Young-Bae Park, Xiaodong Li, Shi-Woo Rhee
Characterization Of The Si/Sio2 Interface Formed By Remote Plasma Enhanced Chemical Vapor Deposition From Sih4/N2O With Or Without Chlorine Addition, Young-Bae Park, Xiaodong Li, Shi-Woo Rhee
Faculty Publications
The Si/SiO2interface formed by remote plasma enhanced chemical vapor deposition (RPECVD) at low temperature with SiH4/N2O or SiH4/N2O/Cl2 was studied and compared with thermal oxidation. The interface of the CVD SiO2 without chlorine addition is rougher than that with chlorine addition. But the surface roughness of CVD SiO2 films increases with chlorine addition. The thermal oxidation induces strong interface strains, and the strains generated by the CVD SiO2 without chlorine addition are stronger and are distributed more nonuniformly than those by the chlorinated SiO2. …
Nitrogen Release During Coal Combustion, Thomas H. Fletcher, Larry L. Baxter, Reginald E. Mitchell, Robert H. Hurt
Nitrogen Release During Coal Combustion, Thomas H. Fletcher, Larry L. Baxter, Reginald E. Mitchell, Robert H. Hurt
Faculty Publications
Experiments in entrained flow reactors at combustion temperatures are performed to resolve the rank dependence of nitrogen release on an elemental basis for a suite of 15 U.S. coals ranging from lignite to low-volatile bituminous. Data were obtained as a function of particle conversion, with overall mass loss up to 99 % on a dry, ash-free basis. Nitrogen release rates are presented relative to both carbon loss and overall mass loss. During devolatilization, fractional nitrogen release from low-rank coals is much slower than fractional mass release and noticeably slower than fractional carbon release. As coal rank increases, fractional nitrogen release …
Effects Of Pyrolysis Heating Rate On Intrinsic Reactivities Of Coal Chars, Thomas K. Gale, Calvin H. Bartholomew, Thomas H. Fletcher
Effects Of Pyrolysis Heating Rate On Intrinsic Reactivities Of Coal Chars, Thomas K. Gale, Calvin H. Bartholomew, Thomas H. Fletcher
Faculty Publications
The main objective of this work was to determine the effects of pyrolysis heating rate on intrinsic O2 reactivity of coal chars. Relationships of intrinsic reactivity to other pyrolysis conditions and char physical and chemical structure were also investigated, and empirical correlations were obtained. Two different entrained flow reactors (a flat flame methane/air burner and a drop tube reactor) were used to prepare chars under a variety of different pyrolysis conditions at maximum particle temperatures and heating rates of 840-1627 K and 104 to 2x105 K/s, respectively. Intrinsic reactivities of a lignite and two bituminous coal chars …
Galvanostatic Pulse And Pulse Reverse Plating Of Zinc–Nickel Alloys From Sulfate Electrolytes On A Rotating Disc Electrode, Branko Popov, M. Ramasubramanian, S. N. Popova, Ralph E. White, Ken-Ming Yin
Galvanostatic Pulse And Pulse Reverse Plating Of Zinc–Nickel Alloys From Sulfate Electrolytes On A Rotating Disc Electrode, Branko Popov, M. Ramasubramanian, S. N. Popova, Ralph E. White, Ken-Ming Yin
Faculty Publications
Galvanostatic pulse and pulse reverse techniques have been used to study the plating of zinc–nickel alloys in the presence of nonyl phenyl polyethylene oxide. The effects of average current density, rotation speed of disc electrode and the presence of nonyl phenyl polyethylene oxide in the electrolyte on deposition of zinc–nickel alloys were evaluated. Zinc–nickel plating bath solution chemistry was studied by determining the equilibrium concentrations at various pH levels. It was found that the alloy composition was determined by solution equilibria, mass transfer of the electroactive species within the diffusion layer and by the surface coverage of nonyl phenyl polyethylene …
Anodic Oxidation Of Ethylenediaminetetraacetic Acid On Platinum Electrode In Alkaline Medium, S. N. R. Pakalapati, Branko N. Popov, Ralph E. White
Anodic Oxidation Of Ethylenediaminetetraacetic Acid On Platinum Electrode In Alkaline Medium, S. N. R. Pakalapati, Branko N. Popov, Ralph E. White
Faculty Publications
The anodic oxidation of ethylenediaminetetraacetic acid (EDTA) was studied in alkaline medium on a smooth platinum electrode. Bulk electrolysis indicated that stable organic intermediates (formaldehyde and glyoxal) are formed during the oxidation of EDTA and that complete oxidation to CO2 can be achieved. The proposed pathway suggests that the acetate groups in EDTA are initially oxidized, generating formaldehyde and ethylenediamine. The rest potential of EDTA (0.066 to 0.164 V vs. Hg/HgO) was observed to be higher than for other organic species. In alkaline medium, very little EDTA oxidation was found to occur on bare platinum. Limiting-current behavior due to …
The Effects Of Multiple Electroplated Zinc Layers On The Inhibition Of Hydrogen Permeation Through An Iron Membrane, D. H. Coleman, G. Zheng, Branko N. Popov, Ralph E. White
The Effects Of Multiple Electroplated Zinc Layers On The Inhibition Of Hydrogen Permeation Through An Iron Membrane, D. H. Coleman, G. Zheng, Branko N. Popov, Ralph E. White
Faculty Publications
The Devanathan-Stachurski permeation technique was used to investigate the rate of hydrogen permeation through an iron membrane with consecutively electroplated zinc layers. Hydrogen evolution rates and hydrogen permeation rates were followed as functions of time at different applied potentials. Hydrogen evolution and permeation decreased with each successive zinc layer until finally reaching an average decrease of 93 and 96%, respectively, as compared with bare iron. Hydrogen surface coverage, exchange current density, absorption-adsorption reaction constant, and hydrogen recombination constant were estimated on bare iron and on zinc-plated iron. It was found that the decrease in the permeation rate of hydrogen through …
Anomalous Codeposition Of Fe-Ni Alloys And Fe-Ni-Sio2 Composites Under Potentiostatic Conditions, M. Ramasubramanian, S. N. Popova, Branko N. Popov, Ralph E. White, K. M. Yin
Anomalous Codeposition Of Fe-Ni Alloys And Fe-Ni-Sio2 Composites Under Potentiostatic Conditions, M. Ramasubramanian, S. N. Popova, Branko N. Popov, Ralph E. White, K. M. Yin
Faculty Publications
A mathematical model has been developed to describe the electrodeposition of Fe-Ni alloys and Fe-Ni-SiO2 composites under potentiostatic conditions. This model can be used to predict the polarization behavior, partial current densities, and alloy composition of each of the components as a function of the applied potential. Fe-Ni-SiO2 samples were deposited on platinum rotating disk electrodes from sulfate electrolytes under potentiostatic conditions, and the results obtained were compared to the model. The model predictions were found to agree well with the experimental observations for the Fe-Ni and Fe-Ni-SiO2 systems.
Determination Of Transport And Electrochemical Kinetic Parameters Of Bare And Copper-Coated Lani4.27Sn0.24 Electrodes In Alkaline Solution, G. Zheng, Branko N. Popov, Ralph E. White
Determination Of Transport And Electrochemical Kinetic Parameters Of Bare And Copper-Coated Lani4.27Sn0.24 Electrodes In Alkaline Solution, G. Zheng, Branko N. Popov, Ralph E. White
Faculty Publications
Electrochemical properties of bare and copper-coated LaNi4.27Sn0.24 electrodes were investigated in alkaline solution. The exchange current density, polarization resistance, and equilibrium potential were determined as functions of the state of charge in the electrodes. The symmetry factors for bare and copper-coated electrodes were estimated to be 0.53 and 0.52, respectively. By using a constant current discharge technique, the hydrogen diffusion coefficient in bare and coated LaNi4.27Sn0.24 was estimated to be 6.75 × 10–11 cm2/s.
Application Of Porous Electrode Theory On Metal Hydride Electrodes In Alkaline Solution, G. Zheng, Branko N. Popov, Ralph E. White
Application Of Porous Electrode Theory On Metal Hydride Electrodes In Alkaline Solution, G. Zheng, Branko N. Popov, Ralph E. White
Faculty Publications
Porous electrode theory was applied to estimate the exchange current density, the polarization resistance, and symmetry factor for LaNi4.27Sn0.24 hydride electrode in alkaline solution. The exchange current density, polarization resistance, and symmetry factor were determined from polarization curves which were obtained at low overpotentials.
Linear Algebra Used To Determine Independent Half‐Cell Equations, D. H. Coleman, Ralph E. White
Linear Algebra Used To Determine Independent Half‐Cell Equations, D. H. Coleman, Ralph E. White
Faculty Publications
No abstract provided.
Use Of A Hydrogen Anode For Nitrate Waste Destruction, E. E. Kalu, Ralph E. White, D. T. Hobbs
Use Of A Hydrogen Anode For Nitrate Waste Destruction, E. E. Kalu, Ralph E. White, D. T. Hobbs
Faculty Publications
No abstract provided.
A Multiphase Mathematical Model Of A Nickel/Hydrogen Cell, Pauline De Vidts
A Multiphase Mathematical Model Of A Nickel/Hydrogen Cell, Pauline De Vidts
Faculty Publications
No abstract provided.
Galvanostatic Pulse And Pulse Reverse Plating Of Zinc-Nickel Alloys From Sulfate Electrolytes On A Rotating Disc Electrode, Branko N Popov, M. Ramasubramanian, S. N. Popova, Ralph E. White, K-M. Yin
Galvanostatic Pulse And Pulse Reverse Plating Of Zinc-Nickel Alloys From Sulfate Electrolytes On A Rotating Disc Electrode, Branko N Popov, M. Ramasubramanian, S. N. Popova, Ralph E. White, K-M. Yin
Faculty Publications
Galvanostatic pulse and pulse reverse techniques have been used to study the plating of zinc–nickel alloys in the presence of nonyl phenyl polyethylene oxide. The effects of average current density, rotation speed of disc electrode and the presence of nonyl phenyl polyethylene oxide in the electrolyte on deposition of zinc–nickel alloys were evaluated. Zinc–nickel plating bath solution chemistry was studied by determining the equilibrium concentrations at various pH levels. It was found that the alloy composition was determined by solution equilibria, mass transfer of the electroactive species within the diffusion layer and by the surface coverage of nonyl phenyl polyethylene …
A Model For The Galvanostatic Deposition Of Nickel Hydroxide, Mahesh Murthy, Gowri S. Nagarajan, John W. Weidner, John W. Van Zee
A Model For The Galvanostatic Deposition Of Nickel Hydroxide, Mahesh Murthy, Gowri S. Nagarajan, John W. Weidner, John W. Van Zee
Faculty Publications
A mathematical model is presented for the galvanostatic deposition of Ni(OH)2 films in stagnant Ni(NO3)2 solutions. The objective is to quantify the anomalous deposition behavior reported previously in which the utilization of the electrochemically generated OH– species decreased drastically as the concentration of Ni(NO3)2 increased beyond 0.1 M. For example as the Ni(NO3)2 concentration increased from 0.1 to 2.0 M, the deposition rate decreased by a factor of ten at 2.5 mA/cm2. At this high ratio of concentration to current density, a comparison with Faraday's …
Analysis Of Transient Hydrogen Uptake By Metal Alloy Particles, Wenlin Zhang, Supramaniam Srinivasan, Harry J. Ploehn
Analysis Of Transient Hydrogen Uptake By Metal Alloy Particles, Wenlin Zhang, Supramaniam Srinivasan, Harry J. Ploehn
Faculty Publications
This paper describes a new approach to solving the equations comprising the shrinking core model for diffusion and reaction of a chemical species in a solid spherical particle. The reactant adsorbs on the particle surface, diffuses into the particle's interior, and reacts with the particle to form a solid product. The shrinking core model assumes a fast reaction rate compared to reactant diffusion so that the reaction is localized in the interfacial zone between the unreacted solid core and the surrounding shell of reacted product. Analytical solutions of the governing conservation equations usually invoke the pseudo-steady state (PSS) approximation which …
Conversion Of Coal Tar To Soot During Coal Pyrolysis In A Post-Flame Environment, Thomas H. Fletcher, Jinliang Ma, Brent W. Webb
Conversion Of Coal Tar To Soot During Coal Pyrolysis In A Post-Flame Environment, Thomas H. Fletcher, Jinliang Ma, Brent W. Webb
Faculty Publications
Coal pyrolysis experiments were performed in the postflame region of a CH4/H2/air flat-flame burner operating under fuel-rich conditions, where the temperature and gas compositions were similar to those in the near-burner region of a large-scale coal-fired furnace. Volatiles released from the coal particles formed a cloud of soot particles at high temperatures in the absence of oxygen. The soot particles in the cloud were collected at different residence times using a water-cooled, nitrogen-quenched suction probe. Test variables included the reaction temperature and coal type. Soot yields in terms of weight percentage of dry ash-free coal were measured based on bulk …
Chemical Structure Of Coal Tar During Devolatilization, Thomas H. Fletcher, Mathew Watt
Chemical Structure Of Coal Tar During Devolatilization, Thomas H. Fletcher, Mathew Watt
Faculty Publications
Three coals of different rank were pyrolyzed in a drop-tube reactor at a maximum temperature of 900 K and a residence time of 160 ms. The coal and char were analyzed with solid-state 13C NMR. The tar was dissolved in deuterated methylene chloride. It was found that the tar was only partially soluble in CD2Cl2. The nonsoluble tar portion was analyzed in the same manner as the coal and char, while the soluble tar portion was analyzed using a recently developed high-resolution 13CNMRtechnique developed for liquid phases. The tar structure was found to be significantly …
Chen, W., L. D. Smoot, S. C. Hill, And T. H. Fletcher, “Global Rate Expression For Nitric Oxide Reburning. Part 2,” Energy And Fuels, 10, 1046-1052 (1996)., Wei Chen, L Douglas Smoot, Scott C. Hill, Thomas H. Fletcher
Chen, W., L. D. Smoot, S. C. Hill, And T. H. Fletcher, “Global Rate Expression For Nitric Oxide Reburning. Part 2,” Energy And Fuels, 10, 1046-1052 (1996)., Wei Chen, L Douglas Smoot, Scott C. Hill, Thomas H. Fletcher
Faculty Publications
An investigation of a global reburning-NO reaction, sum(CiHj) + NO => HCN + . . ., which is a reduction pathway of nitric oxide (NO) by reaction with gaseous hydrocarbons, was conducted. The global reburning-NO rate expression was deduced from a combination of elemental reactions. The global rate expression and its rate constants were then determined by correlating predicted species profiles from simple hydrocarbon flames. This global reburning-NO rate constant can be expressed as 2.7x106 exp(-18,800/RT) (gmol/cm3 s). This expression and constants are applicable to atmospheric pressure with an equivalence ratio range of 1.0-2.08 …
A Computational Method For Determining Global Fuel-No Rate Expressions. Part 1, Wei Chen, L Douglas Smoot, Thomas H. Fletcher, Richard D. Boardman
A Computational Method For Determining Global Fuel-No Rate Expressions. Part 1, Wei Chen, L Douglas Smoot, Thomas H. Fletcher, Richard D. Boardman
Faculty Publications
Global chemical reaction rates used in the modeling of NOx formation in comprehensive combustion codes have traditionally been obtained through correlation of experimental data. In this paper, a computational approach for obtaining global rates is presented. Several premixed flames were simulated, and sensitivity analysis of species concentration profiles was used to suggest global pathways in fuel-nitrogen conversion to NO. Based on these analyses, the global reaction rates were formulated. The predicted species concentration profiles and their derivatives were then used in the determination of the global rate constants. The correlation of rate constants for the two fuel-NO global rates …
Kinetic Analysis Of The Fate Of Nitric Oxide Synthesized By Macrophages In Vitro, Randy S. Lewis, Snait Tamir, Steven R. Tannenbaum, William M. Deen
Kinetic Analysis Of The Fate Of Nitric Oxide Synthesized By Macrophages In Vitro, Randy S. Lewis, Snait Tamir, Steven R. Tannenbaum, William M. Deen
Faculty Publications
To investigate the fate of nitric oxide (NO) synthesized by activated macrophages, the concentrations of NO and its principal reaction products, nitrite (NO2-) and nitrate (NO3-), were measured as a function of time in suspension cultures of RAW264.7 macrophages attached to microcarrier beads. Synthesis of NO became evident 2-5 h after stimulation of the cells, and steady concentrations of NO were achieved after about 9 h. The appearance of NO in the extracellular fluid coincided with the appearance of NO2- and NO3-, which were formed thereafter at approximately equal and constant rates. Using a kinetic model based on rate constants …
Structural Characterization Of Aluminum Films Deposited On Sputtered-Titanium Nitride/ Silicon Substrate By Metalorganic Chemical Vapor Deposition From Dimethylethylamine Alane, Xiaodong Li, Byoung-Youp Kim, Shi-Woo Rhee
Structural Characterization Of Aluminum Films Deposited On Sputtered-Titanium Nitride/ Silicon Substrate By Metalorganic Chemical Vapor Deposition From Dimethylethylamine Alane, Xiaodong Li, Byoung-Youp Kim, Shi-Woo Rhee
Faculty Publications
Alfilmsdeposited on sputtered‐TiN/Si substrate by metalorganic chemical vapor deposition(MOCVD) from dimethylethylamine alane (DMEAA) were characterized using x‐ray diffraction(XRD),Auger electron spectroscopy(AES),atomic force microscopy(AFM), and transmission electron microscopy (TEM). The TiN filmsputtered on the Si has a preferred orientation along the growth direction with the 〈111〉 of the film parallel to the Si〈111〉. Sputtering of the TiN film on the Si induced strains at the interface. The TiN/Si interface is flat while the Al/TiN interface is rough. There exist many dislocations at the Al/TiN interface. The Al2O3 phase was formed at the Al/TiN interface during the early stages of …
Undergraduate Engineering Ceramics Laboratory Development, Guna S. Selvaduray
Undergraduate Engineering Ceramics Laboratory Development, Guna S. Selvaduray
Faculty Publications
No abstract provided.
Hydrogen-Atom Direct-Entry Mechanism Into Metal Membranes, G. Zheng, Branko N. Popov, Ralph E. White
Hydrogen-Atom Direct-Entry Mechanism Into Metal Membranes, G. Zheng, Branko N. Popov, Ralph E. White
Faculty Publications
The hydrogen-atom direct-entry mechanism is used to explain why the steady-state hydrogen permeation current density through a metal membrane is directly proportional to the cathodic current density, ic, and is independent of the membrane thickness when ic is small.
Electrowinning Of Non-Noble Metals With Simultaneous Hydrogen Evolution At Flow-Through Porous Electrodes Ii. Experimental, Mahmoud M. Saleh, John W. Weidner, Bahgat E. Ei-Anadouli, Badr G. Ateya
Electrowinning Of Non-Noble Metals With Simultaneous Hydrogen Evolution At Flow-Through Porous Electrodes Ii. Experimental, Mahmoud M. Saleh, John W. Weidner, Bahgat E. Ei-Anadouli, Badr G. Ateya
Faculty Publications
This paper presents an interpretation of the experimental results obtained on the electrowinning of zinc at a flow-through porous electrode in light of a mathematical model which was presented in Part I. The process is accompanied by simultaneous hydrogen evolution within the electrode, which increases the pore electrolyte resistivity and decreases the coulombic efficiency. We measured polarization curves, coulombic efficiencies, and current distributions under various conditions of zincate concentrations, flow rates, cell current, and electrode thickness. Reasonable agreement between the measured and predicted current distributions was obtained only under conditions of high electrolyte flow rates, low cell currents, and thinner …
Mathematical Modeling Of A Nickel-Cadmium Cell: Proton Diffusion In The Nickel Electrode, Pauline De Vidts, Ralph E. White
Mathematical Modeling Of A Nickel-Cadmium Cell: Proton Diffusion In The Nickel Electrode, Pauline De Vidts, Ralph E. White
Faculty Publications
In this paper we present a mathematical model of a sealed nickel-cadmium cell that includes proton diffusion and ohmic drop through the active material in the nickel electrode. The model is used to calculate sensitivity coefficients for various parameters in the model. These calculations show that the discharge voltage of the cell is affected mostly by the kinetics of the nickel reaction. Toward the end of discharge, proton diffusion also becomes important, because the proton diffusion process affects the active material utilization significantly. During charge, the cell voltage is mainly affected by the kinetics of the nickel reaction until the …
Ac Impedance Studies On Metal Hydride Electrodes, Wenlin Zhang, M. P. Sridhar Kumar, Supramaniam Srinivasan, Harry J. Ploehn
Ac Impedance Studies On Metal Hydride Electrodes, Wenlin Zhang, M. P. Sridhar Kumar, Supramaniam Srinivasan, Harry J. Ploehn
Faculty Publications
The metal hydride (MHx) electrode is the negative electrode in one of the most advanced secondary batteries (i.e.,nickel/metal hydride). The objective of this study is to obtain insight on the mechanism of the hydriding/dehydridingreaction in the battery by using the electrochemical impedance spectroscopy (EIS) technique. An equivalent circuit for the MHx electrode reaction is proposed. The rate capability of charge and discharge of the MHx electrode is determined by thekinetics of the charge-transfer reaction at the alloy surface, which is mainly represented by the EIS responses in the lowfrequency region. Transient and pseudo-steady-state analyses …