Types Of Electrochemical Cells Research Articles

Air Cathode Design for Light-Assisted Charging of Metal–Air Batteries: Recent Advances and Perspectives

Metal–air batteries are a type of electrochemical cell that generates electrical energy by combining metal and oxygen from the air. They are a promising technology for energy storage and portable devices because of their high energy density, low cost, and environmental friendliness. However, the discharge products of these batteries are notoriously difficult to decompose, resulting in a high overpotential. Recent works have shown that semiconductors can capture solar energy and store it in batteries. When exposed to light, photocatalysts generate carriers (strong redox pairs), thereby increasing the electron migration rate and significantly reducing the overpotential of the metal–air battery reaction. Nevertheless, single photocatalysts often exhibit poor cycle performance due to serious carrier recombination. This review paper begins by briefly describing the fundamentals of photoelectrochemistry and then focuses on commonly used photocathode design principles and various reported photocatalysts. It also discusses the main challenges and issues caused by light, such as photocorrosion and electrolyte decomposition. Finally, the critical issues associated with photo electrodes, electrolytes, and electrode/electrolyte interfaces are emphasized, and perspectives on the development of high-performance light-assisted metal–air batteries are presented.

Three chambered fuel cell for desalination coupled urea oxidation and hexavalent chromium remediation

Proof-of-concept of a fuel cell type electrochemical cell is demonstrated for simultaneous wastewater treatment and desalination. The electrochemical desalination cell (EDC) utilized the potential difference and concentration gradient between three chosen waste streams to convert their inherent chemical energy into electrical energy. Urea/cow urine was chosen as a potential electron donor, Cr(VI) was an electron acceptor, and synthetic NaCl/seawater solution (in the middle chamber) established a three-compartment EDC. The effect of a wide range of brine (5 to 35 g/L) and Cr(VI) concentrations (200 to 1000 mg/L) on desalination performance and Cr(VI) reduction were comprehensively investigated. When fed with urea, Cr(VI) reduction of 96.2 ± 0.4 % (with an initial concentration of 1000 mg/L) and salt removal of 63.1 ± 0.2 % (with brine concentration of 35 g/L) were observed (in 4 h) with a maximum power of 15.2 mW (for 21 cm2 electrode). A 12 L benchtop prototype with six anode-cathode configurations was demonstrated. Cr(VI) reduction of 95.2 ± 2 % and desalination of 70.7 ± 0.2 % (in 20 h) with power generation of 55.2 mW was recorded. The economic analysis projection of the EDC presents a significant step toward the application of this technology in real systems.

Evaluation of the Accuracy of the Identified Equivalent Electrical Circuit of LiPePO4 Battery through Verified Measurements

In this paper, the system procedure for the identification of the equivalent electrical circuit diagram of electrochemical cells is being given. Due to the fact that energy storage systems (ESS) penetrate within many applications, the availability of their accurate and simple simulation models for time–domain analysis is very desirable. This paper describes the configuration of the laboratory measuring systems required for data acquisition, curation, and analysis of received measured data required for development of equivalent electrical circuit models (EECM) of electrochemical cells. Nowadays, various types of electrochemical cells are available for packaging technology. Therefore, the evaluation of presented identification methodology is validated through measurements of two different types of LiFePO4 cells. The first cell type is prismatic labeled LFP040AHA, and the second type is NPB 60 AH of the same manufacturer. The main aim of this paper is the determination of the elements of equivalent electrical circuit schematics of selected electrochemical cells. Consequently, the development of a simulation model is described, together with the evaluation of its accuracy through comparisons with experimental measurements. From achieved results, the relative error of simulation model varies at 2%, and thus the presented methodology is suitable for identification of EECM, and consequent design of accurate and fast computing simulation models of ESS systems.

Detailed analysis of electrochemical behavior of high–performance solid oxide fuel cell using DRT technique

The study of anodic and cathodic reactions separately in a fuel cell with a thin electrolyte is difficult due to the problem in manufacturing a reference electrode because the potential of the reference electrode will depend on the potential of the anode and cathode. This paper presents the results of tests of five types of electrochemical cells. Three of the cells were fuel cells with a supporting nickel–ceramic anode. Two cells were with a supporting electrolyte and symmetrical electrodes similar to the cathode of a fuel cell. A detailed analysis of the impedance spectra of fuel cells using the distribution of relaxation times (DRT) technique, comparison of the obtained data with the DRT functions of symmetrical cells, as well as the use of simple oxides with high electrochemical activity for electrodes impregnation, made it possible to determine separately the polarization resistance of the cathode and anode of the fuel cell and to determine the reasons limiting the power of the cells. It was found that in the case of a high–performance fuel cell (power density more than 2 W cm−2 at 900 °C) its performance was mainly limited by gas diffusion in the pores of the anode.

Effect of carbon support on the catalytic activity of copper-based catalyst in CO2 electroreduction

Climate change caused by carbon dioxide anthropogenic emissions has turned into one of the most important environmental concerns of our society. Among the different actions proposed for mitigation of CO2 emissions, electrocatalytic reduction appears as a very promising technology for recycling CO2 to synthetic fuels and other valuable products. One of the most important challenges of this technology is the development of catalysts that allow obtaining high efficiencies in the reduction of the CO2 molecule. This work is focused in the development of Cu based nanostructured catalysts deposited on carbon supports. Supercritical fluid deposition (SFD) technique has been used for the copper deposition on three different carbon supports: carbon black (CB), carbon nanotubes (CNT) and reduced graphene oxide (rGO). SFD is an environmentally friendly technology that has demonstrated good results in the synthesis of nanomaterials.Results obtained in this work show that SFD technique allows a homogeneous deposition of copper nanoparticles on the different carbon supports used with deposition yields close to 90%. The average size of copper nanoparticles formed is between 13 and 19 nm.The activity of these catalysts (Cu/CB, Cu/CNT and Cu/rGO) in the electrocatalytic reduction of carbon dioxide has been carried out in gas phase in a PEM type electrochemical cell. Results show a higher CO2 conversion rate (around 40%) when using Cu/CNT catalyst. In every case, CO, formic acid and methane are the main reaction products obtained from the CO2 reduction. Nevertheless, Cu/CNT and Cu/CB catalysts promote the formation of CO, whereas formic acid is the main reaction product with Cu/rGO. This could be attributed to the presence of oxygenated groups observed in the rGO based catalyst. These results point out that the interaction between the copper nanoparticles and the carbon support plays an important role in the CO2 electrocatalytic reduction process.

Rethinking Electrochemical Science and Engineering Education

Electrochemical Science and Engineering is a particularly challenging subject to teach at the undergraduate/graduate level. The students need a substantial background in the physics of electrostatics, fields, potentials, and electrical circuits, solution chemistry, thermodynamics, mass transport and kinetics. They must also be versed in the underlying mathematics of differential and integral calculus. A lack of knowledge or retention of any of the aforementioned prerequisite subject areas can pose significant barriers to advanced learning. A minority of the students at The University of New Mexico have had some prior training in electrochemical research from internships at UNM, and National and Defense laboratories. The performance of the student interns was largely superior to the students with no direct laboratory experience. These students were generally much more engaged at achieving a better understanding of the underlying science behind their laboratory work. A major goal of the School of Engineering at UNM is to improve the comprehension and retention of key fundamental concepts and skills in the aforementioned areas for all students in the chemical engineering field and provide more opportunities for “hands on” learning and skills development. The Department of Chemical and Biological Engineering (CBE) at the University of New Mexico is engaged in a program to revolutionize engineering education by launching FACETS: Formation of Accomplished Chemical Engineers for Transforming Society. FACETS will revolutionize CBE by: (1) introducing "CIRE" design challenges in the core curriculum that are Community-, Industry-, Research-, and/or Entrepreneurship-based; (2) conducting professional development institutes that will train and mentor faculty and graduate students; workshops will be led by experts from industry and national laboratories, from the learning sciences, from engineering education and multicultural studies, for example the directors of UNM Native American Studies and Chicano/a Studies, and (3) create a digital badging system that will help students take ownership of their competencies and develop engineering identities and enable faculty to monitor and assess student outcomes and to engage in research on their teaching. We believe that this comprehensive approach towards modular learning and digital validation will improve our teaching of Electrochemistry and Electrochemical Engineering and heighten our student’s understanding of the subject material. We have prepared core concept modules with supporting experimentation in the subject areas of: Types of Electrochemical Cells, Solution Theory, Electrostatics, Electrolytes, Ionic Transport, Charged Interfaces, Electrochemical Thermodynamics, Batteries, Fuel Cells, Electrolysis, Electrodeposition, Electroanalysis and Environmental Electrochemistry.

In Situ Raman Microscopy for Redox Mechanism of Cathode Materials

Raman spectroscopy has been used to study structural information is a vibrational technique which is very sensitive to the metallic oxidation state, and it is very suitable for electrode materials due to several characteristics; fast, nondestructive method, measurement of the same electrode and even on the same spot with various laser, and analysis using another techniques. Moreover, the Raman imaging technique is powerful tool to study the charge of structure, surface morphology, and phase transition accompanying crack propagation. Here, we introduce Raman micro-spectroscopy installed at Advanced Nano-Surface Research Group in KBSI which is especially set up in glove box to measure various materials without air exposure, which can exhibit a sample from another surface contamination when exposure to atmosphere. Additionally, we designed and fabricated two types of electrochemical cells (plane cell and cross cell) developed for in situ Raman micro-spectroscopy for studying electrode materials in operating battery during battery operation. This approach simultaneously characterizes phase transition and facilitates uncovering the relationships between surface structure and activity during battery operation. This result provides a method for visualizing chemical structure of phase transition and the changed surface morphology.

Oxygen Reduction Reactions in Low-Viscosity Ionic Liquids Based on Phosphonium Cations

There is high expectation for the lithium-oxygen (Li-O2) battery due to its high energy density because the cathodic active material is O2 in the air. The oxygen reduction reaction (ORR) at the cathode is of great importance, and it is strongly influenced by types of electrolytes. In particular, mass transport of oxygen molecules and its parameter, i. e. the solubility and the diffusion coefficient, are important for high performance of Li-O2 battery. Ionic liquids (ILs) have drawn attentions as an electrolyte for Li-O2 battery, because of their unique properties like incombustibility, low vapor pressure, good ionic conductivity and wide electrochemical potential window [1]. Major ILs used for such electrochemical devices include imidazolium, pyridinium, quaternary ammonium, pyrrolidinium and piperidinium derivatives. On the other hand, phosphonium ILs have the remarkable features such as their chemical and thermal stabilities, and lower viscosity, compared to the ammonium counterparts [2]. Therefore, we focused on the phosphonium ILs. Recently, much lower viscosity was reported that based on small phosphonium cation such as triethylalkylphosphonium cation or tri-n-butylalkylphosphonium cation [2,3]. All electrochemical measurements such as cyclic voltammetry (CV) and potential-step chronoamperometry (CA) were performed using a three electrode type electrochemical cell at 25oC. A glassy carbon (GC) disk electrode (d = 1 mm) or a carbon fiber (CF) microdisk electrode (d = 33 μm) were used as the working electrode. Counter electrode and reference electrode were Pt wire and Ag+/Ag in 0.1 M Ag-OTf / EMI-TFSA , respectively. CAs were performed on the CF microdisk electrode to estimate the solubility and the diffusion coefficient of oxygen in the ILs, individually, by the micro-electrode technique [4]. Two typical groups which consisted of triethylalkyl or tri-n-butylalkyl phosphonium cation were observed in the solubility correlated with molar volume. Moreover, two linear relationship between the diffusion coefficient and the viscosity of ILs were observed. In addition, the diffusion coefficients were correlated to occupied molar volumes which were calculated by the oxygen solubility in each IL. These result suggested that diffusion coefficient was not only affected the viscosity but also diffusion path originated from the cation structure. [1] A. Khan, C. Zhao, ACS sustainable Chem. Eng. 4, 506 (2016) [2] K. Tsunashima, M. Sugiya, Electrochem. Commun. 9, 2353 (2007) [3] K. Tsunashima, M. Sugiya, Electrochemistry, (2007), in press. [4] J. Maruyama, M. Inaba, T. Morita, Z. Ogumi, J. Electroanal. Chem. 504, 208 (2001)

Redox Mechanisms and Film Formation at Interfaces in Lithium-sulfur Battery System

The lithium-sulfur battery is widely considered as one of the most perspective post lithium-ion systems. However, the high theoretical capacity of 1672 mAh g-1 is difficult to attain in practice. Also, the typical power capability lags behind that of the Li-ion rivals. We will present extensive experimental work using many different types of electrochemical cells and different measuring techniques with the aim to elucidate the main processes taking place at two interfaces: lithium/electrolyte and electrolyte/carbon cathode. We will identify the main electrochemical reaction show how they directly or indirectly limited the performance of state-of-the-art Li-S systems. Selected typical results will be interpreted based on modeling using the transmission line approach. New insights into well known mechanisms such as deposition of solid film, depletion of polysulfides in bulk electrolyte, the shuttle effect etc. will be presented and discussed.

Cu oxide/ZnO-based surfaces for a selective ethylene production from gas-phase CO2 electroconversion

In this work, the application of Cu oxides/ZnO-based electrocatalytic surfaces for the continuous and selective gas-phase electroreduction of CO2 to ethylene in a filter-press type electrochemical cell is studied. The prepared catalytic materials are characterized by transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Then, the Cu oxides/ZnO-based gas diffusion electrodes are electrochemically characterized by cyclic voltammetry and Tafel plot analyses. The ethylene formation rate and Faradaic efficiency are as high as 487.9 μmol m−2s−1 and 91.1% when a current density of 7.5 mAcm−2 (-2.5 V vs. Ag/AgCl) is applied to the system, with an ethylene/methane production ratio of 139, showing a better performance than previous electrocatalytic systems for the production of ethylene from CO2 conversion. Consequently, the use of Cu oxides/ZnO-based electrocatalysts for gas-phase CO2 reduction is a step forward in the production of C2 products, such as ethylene.

Batteries in a vehicle – conditions, capabilities and limitations

Electric buses are now seen as the primary means of public transport in cities. However, their exploitation is associated with a number of limitations. The article presents the problem of battery use in buses. The design differences between the vehicle with the internal combustion engine and the electric motor are discussed. In particular, authors compared the number of passengers that both types of buses can take, as well as the difference in vehicle mass and range, and the reasons for these differences. The types of electrochemical cells that can be used to power vehicles and their basic features are presented. The article focuses on the NMC, LFP, LTO and LIC type cells. Next, the battery pack structure and its components were described. The specific energies of cells and batteries constructed from these cells were compared. Next, the most important features of the vehicle equipped with batteries with various types of cells are discussed. The mass, range, charging time and cycle lifetime of the batteries were compared. The basic dependence was noted: the greater the specific energy, the smaller the number of battery cycles. So if the bus has to take more passengers, it must have light batteries, which should be frequently charged, which requires high cyclic lifetimes.

Comparison of cathode catalyst binders for the hydrogen evolution reaction in microbial electrolysis cells

Nafion is commonly used as a catalyst binder in many types of electrochemical cells, but less expensive binders are needed for the cathodes in microbial electrolysis cells (MECs) which are operated in neutral pH buffers, and reverse electrodialysis stacks (RED),which use thermolytic solutions such as ammonium bicarbonate. Six different binders were examined based on differences in ion exchange properties (anionic: Nafion, BPSH20, BPSH40, S-Radel; cationic: Q-Radel; and neutral: Radel, BAEH) and hydrophobicity based on water uptake (0%, Radel; 17–56% for the other binders). BPSH40 had similar performance to Nafion based on steady-state polarization single electrode experiments in a neutral pH phosphate buffer, and slightly better performance in ammonium bicarbonate. Three different Mo-based catalysts were examined as alternatives to Pt, with MoB showing the best performance under steady-state polarization. In MECs, MoB/BPSH40 performed similarly to Pt with Nafion or Radel binders. The main distinguishing feature of the BPSH40 was that it is very hydrophilic, and thus it had a greater water content (56%) than the other binders (0–44%). These results suggest the binders for hydrogen evolution in MECs should be designed to have a high water content without sacrificing ionic or electronic conductivity in the electrode.

Time resolved impedance spectroscopy analysis of lithium phosphorous oxynitride - LiPON layers under mechanical stress

Abstract In this paper we present investigations on the morphological and electrochemical changes of lithium phosphorous oxynitride (LiPON) under mechanically bent conditions. Therefore, two types of electrochemical cells with LiPON thin films were prepared by physical vapor deposition. First, symmetrical cells with two blocking electrodes (Cu/LiPON/Cu) were fabricated. Second, to simulate a more application-related scenario cells with one blocking and one non-blocking electrode (Cu/LiPON/Li/Cu) were analyzed. In order to investigate mechanical distortion induced transport property changes in LiPON layers the cells were deposited on a flexible polyimide substrate. Morphology of the as-prepared samples and deviations from the initial state after applying external stress by bending the cells over different radii were investigated by Focused Ion Beam- Scanning Electron Microscopy (FIB-SEM) cross-section and surface images. Mechanical stress induced changes in the impedance were evaluated by time-resolved electrochemical impedance spectroscopy (EIS). Due to the formation of a stable, ion-conducting solid electrolyte interphase (SEI), cells with lithium show decreased impedance values. Furthermore, applying mechanical stress to the cells results in a further reduction of the electrolyte resistance. These results are supported by finite element analysis (FEA) simulations.

The Chemical Capacitance as a Fingerprint of Defect Chemistry in Mixed Conducting Oxides.

The oxygen stoichiometry of mixed conducting oxides depends on the oxygen chemical potential and thus on the oxygen partial pressure in the gas phase. Also voltages may change the local oxygen stoichiometry and the amount to which such changes take place is quantified by the chemical capacitance of the sample. Impedance spectroscopy can be used to probe this chemical capacitance. Impedance measurements on different oxides ((La,Sr)FeO3-δ = LSF, Sr(Ti,Fe)O3-δ = STF, and Pb(Zr,Ti)O3 = PZT) are presented, and demonstrate how the chemical capacitance may affect impedance spectra in different types of electrochemical cells. A quantitative analysis of the spectra is based on generalized equivalent circuits developed for mixed conducting oxides by J. Jamnik and J. Maier. It is discussed how defect chemical information can be deduced from the chemical capacitance.

(Invited) Development of Transformational Technologies

The Advanced Research Projects Agency (ARPA-E) funds high risk, high reward transformational research to reduce energy related emissions, reduce imports of energy from foreign sources, improve energy efficiency across all economic sectors, and ensure US technological lead in advanced energy technologies, including electrochemical energy storage and transformation for grid scale and automotive applications. Storing energy in the form of liquid fuels has numerous advantages compared to conventional methods of energy storage (ES) such as batteries (high cost, short cycle life), pumped hydro and compressed air (low energy density). Low costs of storage and transportation of liquid fuels enables long-time ES and effective energy transportation using existing infrastructure technologies. Electrochemical synthesis of fuels allows for direct conversion of renewable electricity to chemical energy, which simplifies the process and increases the process efficiency. ARPA-E funds several projects targeting electrochemical synthesis of liquid fuels via OPEN and focused programs. The Reliable Electricity Based on Electrochemical Systems (REBELS) program aiming at distributed generation for more reliable and flexible smart grid focuses on intermediate temperature fuel cells that operate between 200-500oC and includes cell capable to produce liquid fuels along with electricity. The Renewable Electricity to Fuels through Utilization of Energy-dense Liquids (REFUEL) program seeks to fund the development of transformational technologies to reduce the barriers to widespread adoption of intermittent renewable energy sources by enabling the conversion of energy from these sources, water and air to energy-dense zero-carbon liquid fuels. This presentation will also highlight flow battery technologies using organic active materials including funded by ARPA-E. A comparison of organic and inorganic active materials in aqueous and non-aqueous electrolytes for flow battery applications will be presented. Compatibility of fuels, electrocatalysts and membranes will be discussed. State-of-the-art technologies for electrochemical synthesis of fuels and organic active materials using different types of electrochemical cells will be presented.

Development of Aluminum Air Battery Using an Ionic Liquid Electrolyte Solution

Introduction. Metal air batteries are attracting attention as an automobile power.There is a use track record of already zinc as an electrode for air battery, but the light metal such as Li and Mg also has been attracting attention as an electrode for air battery. Al as the metal active material is attractive because it is rich in resources and the energy density of Al is high. In alkaline aqueous solution, Al is dissolved and emits electrons. But It would be self-discharge by the corrosion reaction with hydrogen occurs even at no load. This reaction is independent of the cell reaction, resulting in extra material loss. Therefore, by limiting the water content using a hydrophobic ionic liquid, we consider a mechanism for controlling the self-discharge reaction of Al. In this study, since the air electrode didn’t work in hydrophobic ionic liquid, we aimed to develop a new metal-air battery incorporating a mechanism for controlling the self-discharge of the Al with a hydrophobic ionic liquid. Experiment. Al plates (purity 99%, thickness 0.5 mm) was used and cut into an appropriate size. Air electrode supported carbon powder to nickel and sealed with silicon sheet was used . Hydrophobic ionic liquids ( Emim-TFSI,1-Ethyl-3-methylimidazoliumbis(trifluoromethylsulfonyl)imide ) and hydrophilic ionic liquid(EMISE, 1-Ethyl-3-methylimidazolium ethyl sulfate ) was used in the experiment and vacuum dried it for 24h. In addition, the electrolytic solution was also used DMSO. The electrochemical cell was self-made. This cell is composed of two tanks and the ion exchange membrane. It is composed of Tank A and Tank B, and using a cation exchange membrane as a partition. Tank A is where to put the ionic liquid or DMSO in and put KOH pellet in. Also Al plate was immersed in the A tank. Tank B is where to put 1M KOH or 8M KOH solution in. In this experimental system, it is possible to take out current by adding water to the A tank. However, when the experiments using ionic liquid, temperature of Tank A was maintained at approximately 50 degrees using a heater and a thermocouple. In case of DMSO, the temperature of Tank A was room temperature. It was measured voltage-current characteristic curve of the total of six types of electrochemical cells by the combination of the electrolyte of the tankA and tankB. Moreover, we carried out Electrochemical impedance measurements for an electrochemical cell with EMIM-TFSI and 8M KOH and carried out an analysis of the electrochemical cell. Results. We were able to obtain 6 kinds of current-voltage characteristic curve. Judging from the Current-voltage characteristic curve, we can obtain the non-ideal curve, namely ohmic curves. Among the results obtained, The electrochemical cell were found to show high performance when we used the hydrophilic ionic liquid (EMISE) or hydrophobic ionic liquid (EMIM-TFSI) in the A tank and the 8M KOH in the B tank. However, while the fluidity of the EMIM-TFSI was maintained, the fluidity of EMISE was lost after the experiments. From the results of impedance measurement, We were able to measure the magnitude of the resistance component of the anion permeable membrane.

(Invited) Membrane Development for Energy Technologies

The Advanced Research Projects Agency (ARPA-E) funds high risk, high reward transformational research to reduce energy related emissions, reduce imports of energy from foreign sources, improve energy efficiency across all economic sectors, and ensure US technological lead in advanced energy technologies, including electrochemical energy storage and transformation for grid scale and automotive applications. This presentation will highlight new technologies using ion-selective membranes for energy storage (batteries and flow batteries) and generation (fuel cells) including funded by ARPA-E. Several projects on development of anion-conducting membranes for CO2 reduction and water electrolysis are supported through OPEN program. The Reliable Electricity Based on Electrochemical Systems (REBELS) program is targeting distributed generation for more reliable and flexible smart grid focuses on intermediate temperature fuel cells that operate between 200-500oC. Two types of ionic conducting membranes (proton- and oxygen-conductors) are applied in such fuel cells. The Integration and Optimization of Novel Ionic Conducting Solids (IONICS) seeks to enable transformational electrochemical cells by creating novel solid ion conductors with wide range of desirable properties such as low ionic area-specific resistance, high chemical and electrochemical stability, high selectivity, good mechanical properties and to develop and apply methods for processing of solid ion conductors at a practical scale. The presentation will highlight the use of various ion conducting membranes for separation processes including electrochemical pumps and in fuel cells and flow batteries. Compatibility of fuels, electrocatalysts and membranes will be discussed. State-of-the-art technologies for electrochemical synthesis of fuels and organic active materials using different types of electrochemical cells will be presented.

Control of calcium oxalate morphology through electrocrystallization as an electrochemical approach for preventing pathological disease

Pathological crystallization of calcium oxalate (CaOx) inside the urinary tract is called calculi or kidney stone (Urolithiasis). CaOx exhibits three crystalline types in nature: CaOx monohydrate COM, dihydrate COD and trihydrate COT. COD and COM are often found in urinary calculi, particularly COM. Electrocrystallization has been recently used to perform oriented crystallization of inorganic compounds such as Ca-salts. Although many mineralization methods exist, the mechanisms involved in the control of CaOx polymorphism still remain unclear. Herein, we induced selective electrocrystallization of COD by modifying the electrical current, time and electrochemical cell type. By combining above factors, we established an efficient method without the use of additives for stabilizing non-pathological CaOx crystals. We found notorious stabilization of CaOx polymorphisms with hierarchically complex shape with nano-organization assembly, size and aggregated crystalline particles. Our results demonstrated that, by using an optimized electrochemical approach, this technique could have great potential for studying the nucleation and crystal growth of CaOx through functionalized synthetic polymers, and to develop a novel pathway to evaluate new calculi preventing-compound inhibitors.

Synergistic production of graphene microsheets by simultaneous anodic and cathodic electro-exfoliation of graphitic electrodes in aprotic ionic liquids

Electrochemically mediated exfoliation of graphite is a promising green and high throughput approach for production of graphene sheets (GNs). Previous research focused mostly on either anode or cathode exfoliation due to restrictions imposed by the investigated intercalating ions and insufficient consideration given to the design of the electrochemical cell. Consequently, in single graphite electrode studies, at the non-graphitic counter-electrode (e.g. Pt), unwanted electrode reactions such as gas evolution and electrolyte decomposition take place, leading to significant energy and chemical losses. Here, we report the simultaneous anodic and cathodic GN production in two types of electrochemical cells (undivided and divided) using aprotic electrolytes containing ionic liquids (ILs). We demonstrate a synergistic exfoliation effect when the iso-molded graphite anode and cathode are subjected to a constant cell potential, generating up to 3times higher exfoliation yields compared to single-electrode studies on each side (∼6-fold improvement in total). Thorough characterization of the products collected from both electrode compartments confirmed the production of ultrathin GNs (<5 layers). The cathodic exfoliates were almost exclusively composed of GNs; whereas among the anodic products, in addition to the majority GNs, we detected traces of other morphologies such as nanoparticles, nanotubes, and larger rolled sheets.

Development of an electrochemical cell for in situ transmission electron microscopy observation.

A new type of electrochemical cell was developed for in situ transmission electron microscopy observation that enables the electrode materials to be conveniently changed. The electrochemical cell was used to observe the electrochemical growth or dissolution of copper islands on a gold film with simultaneous cyclic voltammetry measurements. The copper islands could be explained by three-dimensional growing model.