A Modeling Study of Discharging Li-O2 Batteries With Various Electrolyte Concentrations

2020 ◽  
Vol 18 (1) ◽  
Author(s):  
Fangzhou Wang ◽  
Xianglin Li ◽  
Xiaowen Hao ◽  
Jianyu Tan
Keyword(s):  
Mass Transfer ◽  
Discharge Capacity ◽  
Electrolyte Concentration ◽  
Tetraethylene Glycol ◽  
Isothermal Model ◽  
Discharge Performance ◽  
Cathode Electrode ◽  
Lithium Peroxide ◽  
Current Densities ◽  
O2 Supply

Abstract The mass transfer in the cathode electrode plays an important role in operating Li-O2 batteries. In this study, a two-dimensional, transient, and isothermal model is developed to investigate the mass transfer in discharging Li-O2 batteries. This model simulates the discharge performance of Li-O2 batteries with various electrolyte concentrations (0.1−1.0M) at various current densities (0.1, 0.3, and 0.5 mA/cm2). The O2 diffusivity and the ionic conductivity and diffusivity of Li+ are altered as the bis(trifluoromethane)sulfonimide lithium salt (LiTFSI) concentration in the electrolyte of tetraethylene glycol dimethyl ether (TEGDME) changes. The distributions of O2, Li+, and lithium peroxide (Li2O2) in the cathode electrode after discharge are calculated using this model. Modeling results show that when the concentration decreases from 0.5 to 0.25M, the discharge capacity of Li-O2 sharply drops at various current densities. The mass transfer of Li+ determines the discharge capacity of Li-O2 batteries with dilute electrolytes (≤0.25 M). In contrast, the O2 supply is dominant regarding the discharge capacity when the electrolyte concentration is larger than 0.5M. The highest discharge capacity (e.g., 6.09 mAh at 0.1 mA/cm2) is achieved using 0.5M electrolyte since it balances mass transfer of O2 and Li+.

scholarly journals Photoluminescence of Anodic Oxide Films on Aluminium

1976 ◽  
Vol 3 (2) ◽  
pp. 91-95 ◽  
Author(s):  
Sakae Tajima ◽  
Nobuyoshi Baba ◽  
Kenichi Shimizu ◽  
Issei Mizuki
Keyword(s):  
Electrolyte Concentration ◽  
Oxide Films ◽  
Anodic Oxide ◽  
Point Of View ◽  
High Current ◽  
Anodic Oxide Films ◽  
Inorganic Acids ◽  
Purity Aluminium ◽  
High Purity Aluminium ◽  
Current Densities

A wide variety of anodic oxide films were investigated from the photoluminescent point of view. It was found that the phenomenon of photoluminescence appears only on the films anodically formed in organic acids instead of inorganic acids. In particular, thick oxalic acid films formed in low electrolyte concentration, with high current densities on high purity aluminium, gave intense photoluminescence. The luminescent centres were presumed to be the carboxylate ions which had been incorporated in the films during anodisation.

Performance Optimization for Lithium–Oxygen Batteries

2012 ◽  
Vol 519 ◽  
pp. 160-163 ◽  
Author(s):  
Fang Wang ◽  
Da Liang Xu ◽  
Chun Sheng Liang ◽  
Hong Yuan Sun ◽  
Zhong Kuan Luo
Keyword(s):  
Discharge Capacity ◽  
Current Density ◽  
Performance Optimization ◽  
Cathode Surface ◽  
High Capacity ◽  
Argon Atmosphere ◽  
Pure Oxygen ◽  
Discharge Performance ◽  
Lithium Oxygen Batteries ◽  
Carbon Loading

Lithium–oxygen coin cells without catalyst were assembled in argon atmosphere and tested in pure oxygen. Results showed that the first discharge performance of the batteries was strongly affected by the carbon loading, electrolyte amount and current density. At the carbon loading (0.4 mg/cm2), the electrolyte amount (160 μL/cell) and the current density (0.05 mA/cm2), a high capacity of 4586.5 mAh/g was obtained. The capacity decreased when the carbon loading or current density was increased. And the capacity would have a decrease when the amount of electrolyte was decreased. The highest capacity of 6010.2 mAh/g was obtained by optimizing the combination of carbon loading and electrolyte amount at current density of 0.01mA/cm2. However, the discharge capacity sharply decreased from the second cycle. It may be partly due to the fact that the pores of cathode surface were blocked by discharge products at the end of discharge.

Effect of Mass Transfer on the Performance of Selective Catalytic Reduction (SCR) Systems

2010 ◽  
Vol 133 (3) ◽  
Author(s):  
Nimrod Kapas ◽  
Tariq Shamim ◽  
Paul Laing
Keyword(s):  
Mass Transfer ◽  
Selective Catalytic Reduction ◽  
Single Channel ◽  
Catalytic Reduction ◽  
Mass Transfer Rate ◽  
Isothermal Model ◽  
One Dimensional ◽  
Scr Catalysts ◽  
Fast Scr ◽  
Conversion Performance

This paper presents a computational investigation of the effect of mass transfer on the performance of selective catalytic reduction (SCR) catalysts, which are employed to reduce NOx emissions from diesel engines. The paper employs a single-channel based, one-dimensional, isothermal model. The heterogeneous surface chemistry is modeled by considering standard and fast SCR mechanisms, and the mass transfer rate is described by using a one-dimensional film model and dimensionless Sherwood (Sh) number. The paper investigates the effect of Sh numbers on the catalyst conversion performance at various temperatures and space velocities. The results show that the effect of the Sh number on the SCR catalyst performance is temperature dependent and is more pronounced at high space velocities. In general, higher Sh numbers lead to increased conversion efficiencies.

Hydrogenation and Corrosion Properties of LaNi4.5Co0.5-Based Alloy Doped with 1.7 at% Sn

2015 ◽  
Vol 227 ◽  
pp. 263-266 ◽  
Author(s):  
Martyna Dymek ◽  
Henryk Bala ◽  
Henryk Drulis ◽  
Alicja Hackemer
Keyword(s):  
Discharge Capacity ◽  
Room Temperature ◽  
Parent Compound ◽  
Exchange Current ◽  
Corrosion Properties ◽  
Equilibrium Pressure ◽  
Sn Doping ◽  
Cobalt Substitution ◽  
Current Densities ◽  
Discharge Capacities

Effect of small addition of tin (1.7 at.%) into LaNi4.5Co0.5 alloy on gas phase and cathodically charged hydrogen absorption ability as well as its corrosion resistance in 6M KOH solution is discussed. To reveal the effect of Sn doping three alloys have been selected: LaNi4.5Co0.5 (precursor), LaNi4.5Co0.5Sn0.1 and LaNi5 - as a parent compound. The room temperature p-C isotherms indicate to beneficial effect of Sn addition which causes decrease of H2 equilibrium pressure and does not limit atomic hydrogen solubility. Discharge capacities (Qdisch), exchange current densities of H2O/H2 system () as well as corrosion rates () have been determined for the tested alloys on the basis of cyclic galvanostatic measurements (at –0.5C/+0.5C rates). It has been shown that for N > 3 cycle the discharge capacity of LaNi4.5Co0.5 is ca twofold greater than that for LaNi5 reference. Addition of 1.7 at.% Sn into Co-containing alloy expands the discharge capacity by 30-40%. The Co containing alloys reveal twice as great exchange current densities of H2O/H2 system compared to LaNi5, however, Sn addition slightly decreases the , especially for latest cycles. The partial cobalt substitution for Ni accelerates alloy corrosion in alkaline solution, however, tin addition fully eliminates this effect.

scholarly journals Nanoconfined growth of lithium-peroxide inside electrode pores: A noncatalytic strategy toward mitigating capacity-rechargeability trade-off in Lithium–Air battery

2021 ◽  
Author(s):  
Arghya Dutta ◽  
Kimihiko Ito ◽  
Yoshimi Kubo
Keyword(s):  
Discharge Capacity ◽  
Practical Realization ◽  
Trade Off ◽  
Lithium Peroxide ◽  
Air Battery

Capacity-rechargeability trade-off in Lithium–Air battery remains as one of the major challenges before its practical realization. As the discharge capacity increases, an uncontrolled growth of lithium-peroxide leads to passivation of...

An Investigation of Electrolytic Jet Polishing at High Current Densities

1963 ◽  
Vol 85 (4) ◽  
pp. 395-401 ◽  
Author(s):  
Reno R. Cole ◽  
Yoram Hopenfeld
Keyword(s):  
Mass Transfer ◽  
Flow Rate ◽  
Mathematical Analysis ◽  
High Current ◽  
Electrolyte Flow ◽  
Current Densities ◽  
Relationship Of ◽  
The Relationship ◽  
Modified Theory ◽  
Fundamental Mass

A method of polishing metals by means of an electrolytic jet at extremely high current densities (to 1750 amps per sq in.) is described. Data are presented on the relation of polishing effect on various metals to current density and electrolyte flow rate for several electrolytes. An experimental method is described whereby the relationship of the above factors can be determined. It was found that all metals investigated could be polished at high enough current densities. Previous theories of electrolytic polishing are discussed and shown to not fully account for the process investigated. A modified theory to account for polishing at the high current densities observed is presented and is supported by mathematical analysis based on fundamental mass transfer considerations.

scholarly journals Effect of Operating Parameters on Performance of Alkaline Water Electrolysis

2015 ◽  
Vol 09 (2) ◽  
Keyword(s):  
Electrolyte Concentration ◽  
Operating Temperature ◽  
Water Electrolysis ◽  
Operating Parameters ◽  
Alkaline Water Electrolysis ◽  
Alkaline Water ◽  
Electrode Location ◽  
Cathode Electrode ◽  
Fundamental Research ◽  
Higher Temperature

In this fundamental research investigation, the simple fundamental experimental design with two platinum wire as anode/cathode electrode and KOH solution as electrolyte were used throughout the experiments. The effect of electrolyte volume and concentration, electrode location and submerged length into the electrolyte, distance between two electrode and operating temperature on efficiency of water electrolysis was investigated. The results showed that the performance of alkaline water electrolysis is significantly affected by distance between electrode, electrolyte concentration and operating temperature. Higher rate of hydrogen production can be possible at smaller gap between electrodes with higher concentration of electrolyte operating at higher temperature.

scholarly journals Polypyrrole|zinc supercapattery with the aqueous electrolyte

2017 ◽  
Vol 71 (6) ◽  
pp. 479-485
Author(s):  
Marija Janackovic ◽  
Milica Gvozdenovic ◽  
Branimir Grgur
Keyword(s):  
Discharge Capacity ◽  
Current Density ◽  
Discharge Current ◽  
Aqueous Electrolyte ◽  
Constant Current ◽  
Charge Capacity ◽  
Columbic Efficiency ◽  
Specific Discharge ◽  
Current Densities ◽  
Charge Discharge

Polypyrrole (PPY) electrode was obtained by electrochemical oxidative polymerization of pyrrole on graphite electrode from aqueous electrolyte containing 0.1 mol dm?3 pyrrole monomer and 1.0 mol dm?3 HCl. Polymerization was achieved at the constant current density of 2 mA cm?2 during 1 h. The estimated active mass of PPY (assuming that the maximal doping degree of 0.33 was achieved and the polymerization efficiency of 100%) was 14 mg. Electrochemical characterization of PPY electrode was performed by galvanostatic experiments of charge (doping) and discharge (dedoping) with different current densities in the range between 0.5 and 1.5 mA cm?2. The experiments were performed in aqueous electrolyte containing 2.0 mol dm?3 NH4Cl and 1.1 mol dm?3 ZnCl2. Based on galvanostatic charge/discharge curves, following parameters of PPY electrode were evaluated: discharge capacity, specific discharge capacity, charge capacity, specific charge capacity, and Columbic efficiency. Both charge and discharge capacities were dependent on charge/discharge currents. The values decreased by increasing charge/discharge current, except for the lowest current density where Columbic efficiency exceeded 100%, which was explained by involvement of cations, from the electrolyte, in the doping process. An electrochemical cell in which PPY electrode served as a cathode and zinc electrode as the anode with an aqueous electrolyte containing 2.0 mol dm?3 NH4Cl and 1.1 mol dm?3 ZnCl2, was formed and relevant electrochemical and electrical parameters of the cell were estimated and discussed. Charge of the Zn|PPY cell was dependent on the charge/discharge current. Charge of the cell started between 0.5 and 0.7 V and proceeded up to 1.5 V, while the open circuit voltage of the fully discharged cell was 1.3 V. Specific discharge capacity of Zn|PPY cell, calculated based on discharge times, ranged from 95 to 70 mA h g?1, decreasing linearly with increasing discharge current density. On the other hand, calculated values of the theoretical capacity of the Zn|PPY cell was 105 mA g?1, meaning that practically 90% of the theoretical capacity can be achieved by discharging the cell with low current densities, while 67% of the theoretical capacity was obtained with the highest used current density. Based on Ragon parameters, the estimated values of specific energy that ranged between 46 and 68 W h kg?1, and the specific power between 125 and 380 W kg?1, Zn|PPY cell might be classified as a ?supercapattery?.

Voltage Loss Analysis of Zinc-Cerium Redox Flow Batteries

2020 ◽  
Author(s):  
Kiana Amini ◽  
Mark D. Pritzker
Keyword(s):  
Mass Transfer ◽  
Positive Electrode ◽  
Cell Reaction ◽  
Half Cell ◽  
Redox Flow Batteries ◽  
Electrode Potentials ◽  
Voltage Loss ◽  
Flow Batteries ◽  
Current Densities

Redox flow batteries (RFBs) are a relatively new generation of electrochemical devices suitable for large-scale energy storage applications. The separation between the electrolyte storage tanks and the electrochemical cell in RFBs simplifies the battery scale-up and facilitates the energy/power ratio tuning. Among the different types of RFBs investigated, those based on zinc and cerium are very attractive due to the large negative and positive electrode potentials in an aqueous media. Thus, zinc-cerium RFBs are capable of providing one of the highest cell voltages (~ 2.4 V) among flow [1]. To date, Zn-Ce RFBs have primarily been investigated galvanostatically to determine their charge, voltage and energy efficiencies and attempts have been made to suppress the rate of the hydrogen evolution side reaction [2,3]. In order to further optimize the performance of these batteries and to elucidate the future pathways to enhance their efficiency, the sources of voltage loss in the battery during discharge must be identified and the role of the positive and negative half-cells in the voltage loss determined. Toward this goal, we have conducted in situ polarization and EIS experiments on a full-cell Zn-Ce RFB with reference electrodes inserted in the system. At low and intermediate current densities, the main contributor to the voltage loss during discharge is the kinetic overpotential of the negative Zn/Zn2+ half-cell. On the other hand, at high current densities, mass transfer limitations at the positive Ce3+/Ce4+ half-cell cause a large potential drop in the system. From in situ kinetic studies, we have measured an exchange current density of ~ 7.4*10−3 A cm−2 for Zn oxidation and ~ 24.2*10−3 A cm−2 for Ce4+ reduction, which supports the findings from battery operation that the kinetics of the negative electrode reaction is slow compared to that of the positive electrode at low-to-intermediate current densities. The use of an alternative mixed methanesulfonate-chloride negative electrolyte to reduce the kinetic overpotential of the negative half-cell reaction and the influence of the flow rate on the mass-transfer rate of the positive half-cell reaction have also been investigated and will be discussed in this presentation.

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