Electrolyte Plate Research Articles

Preparation of high density garnet electrolytes by impregnation sintering for lithium-ion batteries

The conductivity of solid state electrolyte is closely connected with its chemical composition, crystal structure and density. High density Ta-doped Li7La3Zr2O12 (LLZTO) plates were synthesized by impregnation sintering. The density of electrolyte plates increased when the impregnating solution concentration increased from 5 to 35%. The LLZTO electrolyte plates showed a highest ionic conductivity of 6.47 × 10−4 S/cm when the impregnating solution concentration was 35%. The LLZTO electrolyte plates presented a highest relative density of 97% when the impregnating solution concentration was 40%, meanwhile, the activation energy of this electrolyte plate was calculated to be 0.35 eV, lower than the other samples.

Fabrication of an anode functional layer for an electrolyte-supported solid oxide fuel cell using electrohydrodynamic jet printing**Report presented at 9th International Workshop on Advanced Materials Science and Nanotechnology (IWAMSN2018), 7–11 November 2018, Ninh Binh City, Vietnam

Electrohydrodynamic jet (E-jet) printing is an advanced printing technique using an electric field to create the flow of inks from a nozzle via electrohydrodynamics. This technique can deliver very small droplets or flows of inks for high resolution printing. Here, we describe the fabrication of an anode functional layer for an electrolyte-supported solid oxide fuel cells using E-jet printing technique. An ink containing nickel oxide and 10% scandia-stabilized zirconia (10ScSZ) was used to print on an electrolyte plate. Different printing parameters were investigated to vary the structure and morphology of the printed layer. A multiple anode functional layer was fabricated following the optimal printing parameters. The results showed that the thickness of the lines of the printed grid-structured layer could be altered by changing the printing speed. In addition, the grid interval could be easily adjusted. Moreover, multiple overlapped grid layers could be quickly fabricated by printing another layer on a printed dried layer. This anode structure is very beneficial for fuel cell since it possesses a high porosity for quick diffusion of fuel gas and an increased active surface area for enhancing electrochemical reactions. The results showed that the open-circuit voltage (OCV) values of both cells were approximately 1.1 V although the anode functional layer fabricated by using E-jet printing was 7–10 times thinner than that using screen printing.

Ti/PbO2-Sm2O3 composite based electrode for highly efficient electrocatalytic degradation of alizarin yellow R

In this work, a novel Ti/PbO2-Sm2O3 composite electrode with high electrocatalytic activity is successfully fabricated via simple electrodeposition method and further investigated for electrochemical degradation of alizarin yellow R (AYR) wastewater. The test results of X-ray diffraction, field-emission scanning electron microscopy and energy-dispersive X-ray spectroscopy confirm that Sm2O3 is successfully composited with PbO2. The coating of Ti/PbO2-Sm2O3 composite electrode stacked by typical pyramid-like micro-particles exhibits smooth and compact surface morphology which is conducive to enhancing the corrosion resistance of electrode. Furthermore, electrochemical performance tests indicate that Ti/PbO2-Sm2O3 composite electrode has advantages of higher oxygen evolution potential, lower charge transfer resistance and longer lifetime over Ti/PbO2 electrode. Electrolyte concentration, plate space, initial pH and cell voltage are assessed to optimize the degradation condition of AYR. The results show that COD removal efficiency and degradation efficiency of AYR on Ti/PbO2-Sm2O3 composite electrode reach up to 79.90% and 80.00% under the optimal conditions (Na2SO4 electrolyte concentration 9.0 g L−1, plate space 3.0 cm, initial pH 5, cell voltage 3.0 V and electrolysis time 150 min), respectively. The degradation of AYR follows pseudo-first-order reaction kinetics, and a plausible mineralization pathway of AYR is proposed on the basis of the identification of major intermediate products. These results suggest that Ti/PbO2-Sm2O3 composite electrode is a promising candidate for electrocatalytic degradation of AYR wastewater.

Use of Electrochemical Impedance Spectroscopy for the Evaluation of Performance of PEM Fuel Cells Based on Carbon Cloth Gas Diffusion Electrodes

Polymer electrolyte membrane fuel cells (PEMFCs) have attracted great attention in the last two decades as valuable alternative energy generators because of their high efficiencies and low or null pollutant emissions. In the present work, two gas diffusion electrodes (GDEs) for PEMFCs were prepared by using an ink containing carbon-supported platinum in the catalytic phase which was sprayed onto a carbon cloth substrate. Two aerograph nozzles, with different sizes, were used. The prepared GDEs were assembled into a fuel cell lab prototype with commercial electrolyte and bipolar plates and tested alternately as anode and cathode. Polarization measurements and electrochemical impedance spectroscopy (EIS) were performed on the running hydrogen-fed PEMFC from open circuit voltage to high current density. Experimental impedance spectra were fitted with an equivalent circuit model by using ZView software which allowed to get crucial parameters for the evaluation of fuel cell performance, such as ohmic resistance, charge transfer, and mass transfer resistance, whose trends have been studied as a function of the applied current density.

Process related effects upon formation of composite electrolyte interfaces: Nitridation and reduction of NASICON-type electrolytes by deposition of LiPON

Commercial NASICON-type electrolyte plates are coated with a thin film of LiPON to obtain a composite electrolyte system with high conductivity at room temperature that can be used in contact with metallic Lithium. The formation of the interface between the NASICON substrate and the LiPON coating is studied using an in-situ X-ray photoemission spectroscopy (XPS) surface science approach. The process of LiPON deposition induces changes in the surface chemical structure of the NASICON substrates as observed by XPS, including the partial reduction of Ti and the incorporation of N into the NASICON. The practical impact of the interface formation is studied by impedance spectroscopy, revealing a substantial increase of resistance for LiPON coated samples.

Intraband Electron Cooling Mediated Unprecedented Photocurrent Conversion Efficiency of CdSxSe1–x Alloy QDs: Direct Correlation between Electron Cooling and Efficiency

Composition and size dependent band gap engineering with longer excited state charge carrier lifetime assist CdSxSe1–x alloy semiconductor quantum dots (QDs) as a promising candidate for quantum dot solar cell (QDSC). Colloidal CdSxSe1–x alloy QDs were synthesized using the hot injection method where a stoichiometric mixture of S-TOP and Se-TOP were injected at 270 °C in a mixture of Cd-oleate. The electron decoupled from hole in the alloyed structure due to delocalization of electron in electronically quasi type-II graded CdSxSe1–x alloyed structure. As a result, intraband electron cooling time increases from 100s of fs to sub 10 ps time scale in the alloyed graded structure. Extremely slow electron cooling time (∼8 ps) and less charge recombination (∼50% in >2 ns) as compared to both CdS and CdSe QDs are found to be beneficial for charge carrier extraction in QD solar cells. Using polysulfide electrolyte and Cu2S-deposited ITO glass plates as photocathode, the efficiency of the QD solar cell was measure...

THE MONITORING AND CEMENTATION BEHAVIOR OF ELECTROKINETIC STABILISATION TECHNIQUE ON BATU PAHAT MARINE CLAY

This paper outlines the monitoring and soil fabric results from an experimental study of electrokinetic stabilisation (EKS) technique. The monitoring results were important in assessing the efficiency of the technique towards Batu Pahat marine clay. Two reactors were set up; 1.0 M of calcium chloride (CaCl2) and sodium silicate (Na2SiO3) as the electrolyte and stainless steel plates as the electrodes. EKS technique was continued for 21 days with a constant voltage gradient (50 V/m). This technique was performed in two phases where the alteration of EKS was the combination of stabilizers used. The combinations of stabilizers in phase 1 and 2 were CaCl2 - distilled water (DW) and CaCl2 - Na2SiO3, respectively. The technique was monitored using electric current, total inflow and outflow of electrolytes and pH of electrolytes. It showed fluctuated profiles of electric current for both phases, attributed by the introduction of calcium ions from the anode compartment. The inflow and outflow of electrolytes results showed that electromigration and electroosmosis occurred during EKS and it indicated the movement of anion and cation to the opposite direction. The pH of electrolytes kept constant value and balanced by electrolysis process at the cathode. Image of soil fabric for untreated and treated clay were presented where most images shows a flaky particles. The observation of those images indirectly explained the effect of cementation behavior of treated clay.

A Dual-Mode Rechargeable Lithium-Bromine/Oxygen Fuel Cell

Increasing global energy demand has driven the exploitation of oil reservoirs in deep oceans. The high risk of oil spill due to unexpected failures of undersea facilities urges the deployment of autonomous underwater vehicles (AUV) for frequent and thorough inspections in these extreme environments that humans cannot easily access. To meet the long endurance and occasionally high power requirements of the AUV, we propose a lithium-bromine/oxygen fuel cell with a protected lithium metal anode to provide high specific energy at either low-power mode with seawater (oxygen) or high-power mode with bromine catholytes. The proof-of-concept fuel cell with a flat catalyst-free graphite electrode can discharge at 3mW/cm2 with seawater, and 9mW/cm2 with dilute bromine catholytes. The fuel cell can also be recharged with LiBr catholytes efficiently to recover the lithium metal anode. Scanning electron microscopy images reveal that both the organic electrolye and the bromine electrolyte corrode the solid electrolyte plate quickly, leading to nanoporous pathways that can percolate through the plate, thus limiting the cell performance and lifetime. With improved solid electrolytes or membraneless flow designs, the dual-mode lithium-bromine/oxygen system could enable not only AUV but also land-based electric vehicles, by providing a critical high-power mode to high-energy-density (but otherwise low-power) lithium-air batteries.

Effect of Calcium and Sodium Ions in Soft Clay Using Electrokinetic Stabilisation Technique

Electrokinetic Stabilisation (EKS) technique is a combination process of electroosmosis and chemical grouting. This study involves the investigation on the EKS technique performances in stabilising soft clay soils. Stabilising agents will assist the EKS technique by inducing it to the soil under direct current and its movements which is governed by the principle of electrokinetic (EK). The objective of this research is to study the effectiveness of EKS technique in increasing the strength of soft clays. Two reactors were set up by using 1.0 M of calcium chloride (CaCl2), sodium silicate (Na2SiO3) as the electrolyte and stainless steel plates as the electrodes. EKS technique was being performed for 21 days period of time with a constant voltage gradient (50 V/m). This technique was carried out in two phases where the difference between them is a combination of the stabilising agent. The two combinations of stabilising agents in phase 1 and phase 2 were CaCl2 – distilled water (DW) and CaCl2 – Na2SiO3, respectively. The difference was, one was using distilled water while the other was using Na2SiO3. Results of the strength, liquid limit (LL), plastic limit (PL), plasticity index (PI), pH and ion concentration test towards untreated and treated soil were presented. Showing the strength of treated soil for both phases was increasing near the cathode section with 27.83 kPa and 27.67 kPa. LL and PI for treated soil showed the highest value which occurred near the cathode, while PL seems consistant with the values from untreated soil. The Calcium (Ca+) and sodium (Na+) concentrations in soil were increasing compared to the untreated soil, hence it has proven that the application of stabilisers in EK treatment is more effective in increasing the strength and the stability of soils.

Chemically-induced mechanical unstability of samaria-doped ceria electrolyte for solid oxide electrolysis cells

Doped-ceria is an attractive electrolyte material for solid oxide electrolysis cells (SOECs) operated at intermediate temperatures. However, ceria is highly prone to break down under high applied voltages and low oxygen partial pressures at the fuel side. This phenomenon is analyzed for the typical Sm0.2Ce0.8O1.9−δ electrolyte based on the chemically-induced stress, which is caused by the inhomogeneous distribution of oxygen non-stoichiometry throughout the thickness of electrolyte plate. The sensitivities of the maximum tensile stresses are explored under typical SOEC operating parameters such as temperature, applied voltage and oxygen partial pressure. Varying from short-circuit of solid oxide fuel cell (SOFC) mode to high voltage of SOEC conditions, the applied voltage sharpens the maximum tensile stress by seven times and raises the minimum permitted oxygen partial pressure at the cathode-electrolyte interface by a factor of 104.5 at most. The analysis results indicate that a ceria-based electrolyte under SOEC conditions denotes a definite trend of collapse at 700 °C even 600 °C, suggesting the inapplicability of doped-ceria electrolyte in SOEC mode.

Equifield line simulation and ion migration prediction for concrete under 2-D electric field

This study attempted to find a proper method applicable to simulating practical equifield lines of two-dimensional Accelerate Lithium Migration Technique (ALMT), and evaluate the feasibility of using the theoretical ion migration model of one-dimensional ALMT to predict the ion migration behavior of two-dimensional ALMT. The result showed that the electrolyte or carbon plate can be used as matrix to draw equifield line graph similar to that by using mortar as matrix. Using electrolyte electrode module for simulation has advantages of simple production, easy measurement, rapidness, and economy. The electrolyte module can be used to simulate the equifield line distribution diagram in practical two-dimensional electrode configuration firstly. Then, several equifield line zones were marked, and several subzones under one-dimensional ALMT were separated from various equifield line zones. The theoretical free content distribution of alkali in concrete under two-dimensional electric field effect could be obtained from duration analysis.

Three- and four-electrode EIS analysis of water stable lithium electrode with solid electrolyte plate

The properties of interfaces of water-stable lithium electrode have been investigated by EIS in Li–air batteries and four-electrode test-cells. The water-stable lithium electrode was prepared with the protection of NASICON-type glass–ceramic plate [0.8Li2O·0.25Al2O3·1.5GeO2·1.5P2O5 glass–ceramic (LAGP)]. The glass–ceramic plates are water-stable and 200–500μm thick with ion-conductivity of 4×10−4Scm−1. In Li–air batteries, the AC impedance spectra of LAGP protected lithium electrode contained two semicircles and became three after one week. The composition of impedance of LAGP protected lithium electrode was analyzed, by comparison on the impedance spectra of LAGP protected lithium electrode and bare Li metal electrode in organic electrolyte. Furthermore, in four-electrode test-cell which excluded the LAGP|aqueous-solution interface, the interface impedance of LAGP plate was analyzed. And then by the analysis of impedance, the Li|organic-electrolyte interface caused the main impedance of the water-stable lithium electrode during the discharge. The impedance of water-stable lithium electrode should be decreased by the study of new electrolyte and interface modification.

Room Direct Methanol Solid Oxide Fuel Cell

Direct methanol fuel cell with solid beta alumina ceramic membrane was studied at room temperature. Membrane electrode assembly consisted of two bipolar non-blocking silver coverings applied on the electrolyte plate. Highest open circuit voltage was reached at methanol/water volumetric ratio 3:2. Energy efficiency maximum had coincided with the cell power peak and reached 75% in absence of platinum metal catalysts.

Steady-state multiplicity phenomena during the electrochemical promotion of NO reduction by C 2H 4 in presence of O 2 on thin Rh and Pt catalyst-electrodes in a monolithic electropromoted reactor

The electrochemical promotion of catalysis (EPOC) was used to promote the selective reduction of NO by hydrocarbons in presence of oxygen using thin (∼40 nm) porous Rh and Pt catalyst layers sputtered on the opposite surfaces of thin (0.25 mm) solid electrolyte (YSZ) plates serving as electrocatalytic elements of a monolithic electrochemically promoted reactor (MEPR). Using 22 Rh/YSZ/Pt type cells it was found that the reduction of NO in presence of 1.1 kPa O 2 and 0.36 kPa C 2H 4 can be efficiently electropromoted with 340% rate enhancement, reaching 95% NO conversion with 100% selectivity to N 2 in the temperature range from 280 to 340 °C. The apparent Faradaic efficiency is larger than unity for both the NO reduction and the C 2H 4 oxidation reaction. At elevated temperatures (≥300 °C) and high reactant conversions it was found that after current interruption, the catalytic rates do not return to their initial values but remain in a new highly active steady state. It appears that this highly active state is not a genuine intrinsic permanent NEMCA state but is manifestation of steady-state multiplicity in the monolithic reactor resulting from near complete gaseous O 2 consumption. Thus the low and high activity steady states corresponding to zero applied potential appear to correspond to high and low average P O 2 in the reactor. The latter is the result of the near complete reactant conversion under the preceding electropromoted operation. These highly active permanent NEMCA states may be quite useful for practical applications.

Electrochemical Promotion of NO Reduction by C2H4 in Excess O2 Using a Monolithic Electropromoted Reactor and Pt–Rh Sputtered Electrodes

The reduction of NO by ethylene in the presence of excess oxygen was investigated in a recently developed monolithic electropromoted reactor (MEPR). In this novel dismantlable monolithic-type electrochemically promoted catalytic reactor, thin (~40 nm) porous catalyst films are sputter-deposited on thin (0.25 mm) parallel solid electrolyte plates supported in the grooves of a ceramic monolithic holder and serve as electropromoted catalyst elements. Using Pt–Rh(1:1)/YSZ/Au-type catalyst elements, the 8-plate reactor operated with apparent Faradaic efficiency exceeding unity achieving significant and reversible enhancement in the rates of C2H4 and NO consumption in presence of up to 10% O2 in the feed at gas flow rates of 1,000 cc/min. The reactor, which is a hybrid between a monolithic catalytic reactor and a flat-plate solid oxide fuel cell, permits easy practical utilization of the electrochemical promotion of catalysis.

Direct-write microfabrication of single-chamber micro solid oxide fuel cells

Single-chamber micro solid oxide fuel cells (SC-µSOFCs) are promising systems for portable power generation. Here we report the direct-write microfabrication and electrochemical testing of SC-µSOFCs in the single-face configuration which consists of closely spaced interdigitated electrodes on an electrolyte substrate. In direct-write microfabrication, powdered electrode materials are first synthesized into inks which are subsequently extruded through a micronozzle onto an electrolyte plate mounted on a robot-controlled platform. The microfabricated structures are then sintered to remove the organic components of the inks and to obtain porous electrodes. Processing–structure relationships were obtained using systematic experimentation for the direct-write microfabrication of nickel oxide–yttria stabilized zirconia (NiO–YSZ) anodes and lanthanum strontium manganite (LSM) cathodes on an YSZ electrolyte. Single-chamber µSOFCs were fabricated with interdigitated electrodes of a few hundred microns in size. When tested in a fuel–air mixture (methane-to-oxygen ratio Rmix = 2) at a furnace temperature of 700 °C, the cells exhibited an open circuit voltage of 800 mV and a peak power density of ∼1 mW cm−2. Implications for the use of these devices for portable power generation are discussed.

Screening and Properties of New Materials for MCFC Application

A synthetic screening is given on interesting materials, dopants and protective coatings allowing a better control of the corrosion in MCFC systems and the optimization of their lifetime. After outlining the interest of MCFC systems with respect to other fuel cell devices, an analysis of the recent literature is given on electrolyte, cathode, anode and interconnection plate materials.

Technological improvements in automotive battery recycling

Recycling of automotive batteries for the recovery of secondary lead is extremely important in Brazil, for the country does not possess large reserves of this metal. Lead is one of the most widely used metals in the world, but it is highly toxic, posing risks for humans and for the environment if not utilized or treated adequately. Industrial waste containing lead in Brazil are classified by the Brazilian Residue Code (NBR—10004:2004) as hazardous. The lead recycling process employed by the recycling industry in Brazil is the pyrometallurgical process in a rotary furnace. This process consists of four stages: (1) grinding of the battery to separate plastic, electrolyte and lead plates; (2) lead reduction in a rotary furnace; (3) separation of metallic lead from slag; and (4) refining of recycled lead. The purpose of this work is to propose process improvements aimed primarily at increasing production output by reducing the loss of lead in slag and particulates, thereby providing a healthier work environment in line with Brazilian environmental and labor laws.

Application of Anodic Titanium Oxide to Dye-Sensitized Solar Cells

Dye-sensitized solar cells were fabricated using anodized titanium oxide. An aqueous solution of 0.5 wt % HF was used for the electrolyte and platinum plate was used for the counter electrode in the anodizing process at a voltage of 20 V. We obtained well-arranged titanium oxide nanotubes with diameters of 80-150 nm. The anodic titanium was coated with the dye (Ruthenium 535 bis-TBA). A dye-sensitized solar cell was fabricated with lodolyte PMI-50 (Solaronix™) as the electrolyte and a Pt (200 nm)/ Ti (50 nm)/ glass substrate as the counter electrode. The short circuit current (I SC ), open circuit voltage (V oc ), fill factor (FF) and energy conversion efficiency of this cell were 0.54 mA/cm 2 , 0.103 V, 39 % and 0.0022%, respectively. When a current density of 2.0x10 -3 mA/cm 2 was applied to the titanium oxide electrode, the I sc , V oc , FF and energy conversion efficiency were 0.24 mA/cm 2 , 0.675 V, 30 % and 0.050 %, respectively. When the cells were coated with the dye and current was applied, the I sc , V oc , FF and energy conversion efficiency were 0.88 mA/cm 2 , 0.54 V, 24 % and 0.11 %, respectively.

Monolithic electrochemically promoted reactors: A step for the practical utilization of electrochemical promotion

A novel dismantlable monolithic-type electrochemically promoted catalytic reactor and “smart” sensor-catalytic reactor unit has been constructed and tested for hydrocarbon oxidation and NO reduction by C 2H 4 in the presence of O 2. In this novel reactor, thin (∼ 40 nm) porous catalyst films made of two different materials are sputter-deposited on opposing surfaces of thin (0.25 mm) parallel solid electrolyte plates supported in the grooves of a ceramic monolithic holder and serve as sensor or electropromoted catalyst elements. The catalyst dispersion was higher than 10%. A 22 flat plate reactor operated with apparent Faradaic efficiency up to 100, at near complete reactants conversion, at gas flow rates up to 30 l/min. The novel design has only two external electrical connections and thus significantly facilitates the practical utilization of electrochemical promotion of catalysis.