Constant Current Method Research Articles

A closed-loop constant deposition current control method based on MCED circuit model

Meniscus-confined electrodeposition (MCED) is a simple and economical fabrication method for micro/nanoscale three-dimensional metal printing. In most applications of MCED of copper pillars using a deposition pipette probe, there exists a certain probe retraction speed range that can ensure successful pillar deposition. If the probe retraction speed exceeds this range, however, the morphological changes in the contact meniscus droplet bridge between the probe tip and substrate induce deposition current fluctuations. These fluctuations result in uneven pillar diameters (i.e., beaded wire deposition) and can even lead to nanowire breakage and growth termination. To analyze the MCED process, therefore, this paper first proposes a circuit model for the MCED process and then, based on this model, analyzes the mechanism underlying the deposition current fluctuations present as the probe retracts at higher speeds. To effectively suppress these deposition current fluctuations and improve the stability and quality of deposited copper pillars, a closed-loop constant-deposition-current control method is proposed. Compared with deposition using no control strategy, the constant-deposition-current control method is shown by simulations and experiments to significantly suppress the fluctuation of the deposition current and increase the stability of copper pillar growth. In addition, the constant-deposition-current control method is used for the rapid fabrication of copper pillars with high aspect ratios.

Chemically Crosslinked Sulfonated Polyphenylsulfone (CSPPSU) Membranes for PEM Fuel Cells.

Sulfonated polyphenylsulfone (SPPSU) with a high ion exchange capacity (IEC) was synthesized using commercially available polyphenylsulfone (PPSU), and a large-area (16 × 18 cm2) crosslinked sulfonated polyphenylsulfone (CSPPSU) membrane was prepared. In addition, we developed an activation process in which the membrane was treated with alkaline and acidic solutions to remove sulfur dioxide (SO2), which forms as a byproduct during heat treatment. CSPPSU membranes obtained using this activation method had high thermal, mechanical and chemical stabilities. In I-ViR free studies for fuel cell evaluation, high performances similar to those using Nafion were obtained. In addition, from the hydrogen (H2) gas crossover characteristics, the durability is much better than that of a Nafion212 membrane. In the studies evaluating the long-term stabilities by using a constant current method, a stability of 4000 h was obtained for the first time. These results indicate that the CSPPSU membrane obtained by using our activation method is promising as a polymer electrolyte membrane.

Add-On Type Pulse Charger for Quick Charging Li-Ion Batteries

In this paper, an add-on type pulse charger is proposed to shorten the charging time of a lithium ion battery. To evaluate the performance of the proposed pulse charge method, an add-on type pulse charger prototype is designed and implemented. Pulse charging is applied to 18650 cylindrical lithium ion battery packs with 10 series and 2 parallel structures. The proposed pulse charger is controlled by pulse duty, frequency and magnitude. Various experimental conditions are applied to optimize the charging parameters of the pulse charging technique. Battery charging data are analyzed according to the current magnitude and duty at 500 Hz and 1000 Hz and 2000 Hz frequency conditions. The proposed system is similar to the charging speed of the constant current method under new battery conditions. However, it was confirmed that as the battery performance is degraded, the charging speed due to pulse charging increases. Thus, in applications where battery charging/discharging occurs frequently, the proposed pulse charger has the advantage of fast charging in the long run over conventional constant current (CC) chargers.

Al2O3 nanostructured gas sensitive material for silicon based low power thermocatalytic sensor

Micro-catalytic gas sensors are essential devices for detection of combustive gases up to lower explosion limit (LEL). Micro-catalytic gas sensors capable to detect hydrocarbons below 50 mW power consumption at 550 °C operation temperature were developed by using a novel gas sensing material technique. Experiments were aiming at deposition of controlled volume and structure of the catalyst. Constant current method in a Wheatstone-bridge configuration was applied in functional tests of developed Al2O3 catalysts.

Experiment Improvement of “Determination of Copper by Constant Current Electrolysis Method”

Experiment Improvement of “Determination of Copper by Constant Current Electrolysis Method”

Design and implementation of adaptive battery charging method considering the battery temperature

Today, batteries are widely used in mobile devices, vehicles and military applications. Batteries meet the energy needs of the equipment on the vehicle in military vehicles which is one of the application areas. During the military vehicle is stationary, the vehicle engine must not work for camouflage. Therefore, it needs a battery charge circuit. Controlled charging/discharging of the batteries is very important for the cycle life and safety of the batteries. Many conventional battery chargers units charge it without considering the battery temperature. In this study, adaptive battery charging method design and circuit is taken into consideration, considering the battery temperature. The adaptive battery charging algorithm has been applied to charge the batteries of military vehicles and in accordance with military standards (MIL-STD-1275-E voltage surges and MIL-HDBK-454B electronic equipment standard). In this study, experiments with different charge rates have been made and conventional constant current and constant voltage method and proposed adaptive battery charging method result are compared. Experimental results show that the battery temperature decreases 15°C with the proposed charging method. This adaptive battery charging method has been shown to prevent overheating of the battery.

New Temperature-Compensated Multi-Step Constant-Current Charging Method for Reliable Operation of Battery Energy Storage Systems

Battery lifetime represents a significant concern for the techno-economical operation of several applications based on energy storage. Moreover, the charging method is considered as one of the main critical elements in defining and influencing the operating lifetime of batteries. Several charging techniques have been addressed in the literature, however almost all of them are suffering from lack of temperature feedback in order to maintain battery lifetime. This paper presents a new high-reliable charging method for battery energy storage systems (ESSs). The proposed temperature compensated multi-step constant current (TC-MSCC) method is developed based upon the modified (MSCC) charging method. It enhances the operating lifetime of batteries by employing a feedback from the battery temperature to control the duration and starting time of each charging current step. Compared with the traditional charging methods addressed in the literature, the proposed TC-MSCC method achieves faster charging than the conventional constant current (CC) and the constant-current constant-voltage (CC-CV) methods. Moreover, the proposed TC-MSCC method possesses longer operating battery lifetime with reduced thermal stresses compared to the traditional MSCC methods. The proposed charging method is verified by simulation and experimental results using 9 Ah lead-acid battery. However, the new proposed TC-MSCC method is generalized and can be applied to various types of batteries. The detailed performance comparisons and results show the superiority of the proposed methods over the most widespread charging methods in the literature.

Smoothing Control Scheme Of Photovoltaic Module Through A Battery Energy Storage System

The battery energy storage system (BESS) is basically used to smooth wind / solar power controlling. The constant current controller method is employed in order to eliminate the output fluctuation of Photovoltaic/ BESS power generation system. In this presented paper, the detailed description of the Grid associated PV structure along with battery and load is modeled and simulated in MATLAB / SIMULINK software.

Excellent cyclic performance of electrolytic MnO2 in Li/MnO2 rechargeable batteries

The electrolytic MnO2 particles with α∙γ-MnO2 is successfully prepared using one-step acid constant current electrodeposition method. Scanning electron microscope, N2 adsorption/desorption method and X-ray diffraction are employed for the material characterization. Scanning electron microscope result shows that the diameter of MnO2 particle is about 350–500 nm. A lot of mesoporous exist in the as-prepared MnO2 particles, which exhibit high specific surface area and can provide significantly more electrochemical active sites for the redox reaction. The as-prepared MnO2 particles as cathode in rechargeable Li/MnO2 battery displays high discharge capacity of 202 mAh g−1 in the 1st cycle at a current density of 46 mA g−1, and its discharge capacity retention ratio can achieve 82% over 100 cycles. The discharge capacities of the 100th cycle are 152, 127 and 114 mAh g−1 at different current densities of 151, 350 and 755 mA g−1, respectively, indicating excellent rate capability. The promising electrochemical performance of α∙γ-MnO2 can make researchers focus again on using metal oxide as the cathode materials in the rechargeable Li-ion batteries.

Fabrication of gold nanorod arrays on a cylindrical surface of optical fibers by using in-situ electrodeposition

Optical fiber is an excellent light-coupled substrate, which has the characteristics of large a length-diameter ratio with a cylindrical surface. Recently, various methods have been reported in order to improve the ability of local optical fields. In particular, methods aimed to address the efficient coupling and optical resonances by modifying metal nanostructures on the light-coupled substrate have been developed. However, existing methods are largely applicable to planar or tip substrates, and it remains a significant challenge to prepare metal nanostructures on a cylindrical substrate. In this study, we proposed a novel strategy to fabricate gold nanorods arrays (AuNRs) by electrodepositing them in anodized aluminum oxide (AAO) templates on the cylindrical surface of optical fibers. Briefly, AAO templates were prepared in-situ by using a constant current density secondary oxidation method on the cylindrical surface of optical fibers, and then the AuNRs were in-situ deposited in the AAO templates by electrodeposition. The features of the AuNRs such as diameter, nanorod pitch, and height could be easily regulated by adjusting the parameters of electrodeposition and the anode oxidation. The SEM images demonstrates that AuNRs exhibit a satisfactory consistency with a uniform diameter and favorable self-supporting properties. The relationships between the current density, pore diameter and pore distribution were explored, combined with the voltage-time curve during anodic oxidation. Furthermore, the surface plasmon resonance (SPR) optical properties of the AuNRs on the cylindrical surface were analyzed using the Finite-difference Time-domain Algorithm (FDTD) method. Results suggest that this alternative in-situ electrodeposition strategy has the potentials to be applied to SPR optical fiber sensing.

Preparation of Pd/GO/ITO composite electrode and degradation of 2,4-chlorophene

2,4-Dichlorophenol (2,4-DCP) is a kind of toxic organic compound listed as a priority pollutant by the environmental protection agency, which will endanger the environment and human health. The accumulation of 2,4-DCP in the environment has become a serious problem today since 2,4-DCP is difficult to be degraded by traditional methods. In this study, a novel palladium/graphene oxide/indium tin oxide (Pd/GO/ITO) composite electrode was prepared by constant current electrodeposition method. And the surface morphology, crystal structure and surface element valence state of the electrode were observed and analyzed by SEM, XRD and XPS, respectively. Finally, by studying the influence of different conditions on the performance of the electrodes, the electrochemical degradation efficiency of the new electrodes on 2,4-DCP was investigated. It was found that the degradation of the Pd/GO/ITO electrodes on 2,4-DCP followed a quasi-first-order reaction under different conditions.

Improved Performance of Zinc Composite//Secondary Doped Li-PANI Composite Film for Rechargeable Batteries

To improve the conductivity of pure polyaniline (PANI), compact scale-like PANI secondary doped with lithium chloride (Li-PANI) was prepared after the in-situ synthesis of PANI powder using the constant current method and 4,4’-diaminobiphenyl (DABP) as an additive in hydrochloric acid (HCl) solution. The compact morphology of obtained Li-PANI was feasible for improvement the charge transfer in the PANI chains and inter-molecular. The oxidation peak currents of Li-PANI with DABP additive were nearly three times higher than those of the Li-PANI and much higher than those of in-situ doped PANI in only HCl solution. Both the LiCl-PANI/TiO2/C/DABP composite ( Li-PANI composite) and Zn/ZnO/MgO/CMC-Na composite (Zn composite) were prepared by homogeneously coating at controlled thicknesses (0.20 mm and 0.04 mm, respectively). A Zn composite was used as cathode and Li-PANI composite as anode for the fabrication of improved Zn//PANI battery, with an open voltage of approximately 1.5 V in ZnCl2+LiCl electrolyte solution. The battery charge/discharge cycle performance was determined between 0.7 V and 1.7 V. The discharge capacity of the cathode reached 131.4 mAh·g-1 at a current density of 2 mA·cm-2. During 35 charge/discharge cycles, the average decrease in the discharge capacity of each cycle was 0.07%, indicating that the cycle performance and stability of the designed battery revealed the feasible competition potential with traditional batteries.

Study on Anion Doped Polypyrrole As Anode Material for Aqueous Sodium Ion Battery

In order to meet the growing demand for large-scale energy storage, low-cost sodium-based aqueous capacitor battery has received people's attention. Polypyrrole is an inexpensive conductive polymer. In this paper, polypyrrole nanowires with anionic structure were prepared by chemical oxidation and doping ions during the preparation. They could be used as negative electrode material for sodium ion capacitor cells.The sodium ion storage mechanism of polypyrrole doped with anions was studied by cyclic voltammetry, AC impedance method and constant current charge-discharge method. Morphology and structure were analyzed by X-ray diffraction, infrared spectroscopy and scanning electron microscopy. Anions doped polypyrrole can reach a steady capacity of 200 mAh / g in 1 mol / L NaNO3 solution. After 500 cycles, the capacity retention is 70% at a current density of 0.1 A / g.The specific capacity of 120 mAh / g can still be achieved at a current density of 5 A / g. The polypyrrole doped with ions has two kinds of sodium ion intercalation mechanism, has the advantages of batteries and capacitors, has a larger capacity and excellent rate performance, good cycle performance. Figure 1

Pulse Electroplating of Zinc/Nickel Alloy from a Deep Eutectic Solvent (DES)

Electrodeposition of metal coatings such as nickel, zinc, tin, chromium and cadmium for the purposes of corrosion protection has been a core interest of the electrochemical community for more than one hundred years. Cadmium has been a favourite for military and aerospace applications because of the combination of good corrosion protection and lubricity. However, cadmium salts are very toxic and hazardous and so the use of cadmium coatings is now proscribed in all but the most demanding of applications. Alternatives to cadmium coatings have included aluminium and more recently zinc nickel alloys. The latter is more accessible via aqueous methods but requires rigorous control and monitoring of bath conditions in order to maintain the composition and quality of the coating. An alternative to aqueous electrolytes is a derivative of ionic liquids that feature eutectic mixtures of quaternary ammonium salt and hydrogen bond donor. These have become known as deep eutectic solvents (DSE). Here we have used a DES to produce coherent and adherent coatings of zinc nickel alloy in an electrochemical study and in pre-commercialisation scale-up trials. In a digital controlled pulse-plating method, alternative forward (deposition) and reverse (stripping) currents, are applied to adjust the deposit composition and morphology, as has been demonstrated in film plating from aqueous electrolytes. This report focuses on pulse-plating γ-Zn11Ni2 alloy from a eutectic mixture of choline chloride (ChCl) and ethylene glycol (EG), also known by the commercial name of Ethaline. The effect of pulse shape and frequency on deposit morphology and crystal structure were analysed and compared with coatings derived from constant current (DC) plating methods, through Hull cell tests, XRD, and SEM/EDX measurement. The deposit composition is shown here to be dependent on the average current density, the surface morphology is not sensitive to the pulse frequency, while dendritic growth is shown to be suppressed by pulsed current. We show that the crystal grain size can be controlled according to the pulse shape and frequency. By choosing a certain shape and frequency, the pulse-plating in the DES can provide improved coating qualities and improved process control. Additionally, we have extended the laboratory investigation to pre-commercial scale-up trials with a commercial electroplating company (EC Williams, UK). This project is funded by an Innovate UK action and is entitled Cadmium Replacement Using Pulse-Plating and Ionic Liquids (CRUPPAIL). Barrel-plating trials using pulse and reveres pulse methods on small components such as screws have given even adherent coatings, Figure. The combination of pulse methods and DES electrolyte give a levelling effect, Figure (a), and good throwing power in confined geometries, Figure (b). Figure: Scanning electron micrographs of Zinc Nickel alloy (85:15%) deposited using DES and pulse-plating on mild steel substrates, (a) sheet, (b) screws. Figure 1

Line Width and Capping Layer Effects on Electromigration Failure of Plasma Etched Copper Lines

Reliability of molybdenum and titanium tungsten capped copper lines of various widths prepared from the plasma-based etch process has been studied using the constant current electromigration test method. The addition of the capping layer reduced the lifetime through complicated mechanisms of interface reaction, surface oxidation, copper diffusion to the capping layer, and thermal expansion coefficient mismatch, which are augmented by the Joule heating induced temperature raise. The molybdenum capped copper line has a shorter lifetime than the titanium tungsten capped copper line has. The capping layer material is critical to the lifetime of the copper line.

Long-term, real-time and multi-channel distributed temperature monitoring system for tunnels in cold regions

Tunnel frost damage is common in cold regions and is of increasing concern. Temperature monitoring is crucial to reveal the tunnel temperature change laws and distribution characteristics and to complete a reasonable frost prevention design. In this study, a distributed temperature monitoring system for tunnels in cold regions is designed by using A level platinum resistance temperature sensors (PT100 A) and a series of electronic integrated chips to complete a long-term, real-time and multi-channel automatic temperature test in different positions in the tunnel. The constant current source method is adopted to test the platinum resistance of PT100 A, and a high-precision resistor is inserted in the circuit to improve the test accuracy. The resistance test error can be approximately 0.011, that is equal to 0.03 °C. The test resistance results are linearly converted to temperature at a calculation interval of 1 °C due to the strong linear relationship between the platinum resistance and temperature. In addition, the sensor error is compensated for on the basis of the calibrated results of sensors at 0 °C. Therefore, the accuracy of the final temperature results can be enhanced. The monitoring system has been applied in the actual tunnel, which can provide accurate, adequate and comprehensive temperature data for the optimal design of the thermal insulation layer thickness and length.

Pengaruh Variasi Arus Pengisian Pengosongan Muatan Pada Model Baterai Lead Acid Terhadap Perubahan Efisiensi Energi

This research aims to determine the energy efficiency of lead acid batteries after testing the charge-discharge process with a constant current method. Charge-discharge current variations of 0.3 A, 0.5 A, and 0.6 A. The performance voltage range when the charging process has a value in comparison with the charging current. The greater the charging electric current can change the voltage range of the greater performance. Conversely, at the discharge process. The greater the discharge electric current can change the performance voltage range the smaller. Meanwhile, in the performance voltage range the discharge process is lower if the discharge flow gets bigger. Based on the results of the charge-discharge process test, it can be determined the energy efficiency values of the current variation of 0.3 A, 0.5 A, and 0.6 A, which are 76.32%, 76.06% and 91.33%, respectively.

A new green, energy-saving, and pressing refining process for the recovery of ultrahigh-purity lead in alkaline solution from spent lead plate grids

This paper reports a novel green and energy-saving method to prepare ultrahigh-purity lead from spent lead plate grids via a pressing-electrorefining process. The lead plate grids from spent lead-acid batteries were firstly pressed into high-density crude lead plates, then the crude lead plates were electro-refined in a NaOH–NaHPbO2 solution plus additive of JZ04 to recover an ultrahigh-purity lead. This paper systematically studied the effects of electrolyte temperature, the concentration of NaOH and Pb2+, additives, and current density on the anodic stripping process, cathodic electrodeposition process, and electrorefining process via constant current electrolysis, AC impedance, and LSV methods. The lead plate grids, anodic stripping product, and cathodic electrodeposited lead were examined by field emission scanning electron microscope, EDS, XPS, and ICP analytical methods. Results show that under the optimum conditions, the energy consumption of electrodeposition is only 18 kW·h·(t Pb)−1 with the recovery efficiency of 99.7%; the purity of obtained lead reaches 99.9991%, much higher than the criteria of the European (EN 12659-1999, 99.99%) and the Chinese standard (GB/T 469-2013, 99.994%).

Effect of MEA activation method on the long-term performance of PEM fuel cell

In this paper, the influence of activation procedure on the long-term performance of membrane electrode assembly (MEA) is investigated. The MEAs are activated by most commonly used procedures; constant voltage and constant current. After activation, MEAs are implemented under 9000 aging cycles. During aging process, MEAs performance is evaluated using polarization curves, electrochemical impedance spectroscopy and cyclic voltammetry. The obtained results show that the activated MEA by constant current method shows an average voltage decay of 11.33 µV/cycle at 1 A/cm2, compared to 4.4 µV/cycle for the activated MEA by constant voltage procedure. This is due to the more reduction of electrochemical surface area for the activated MEA by constant current method (32% vs. 19%). Also, after 9000 degradation cycles, more severe platinum nanoparticles agglomeration is seen in the cathode catalyst layer of activated MEA by constant current procedure. This shows that MEA activation by constant current activation method not only need to the longer activation time, but also causes higher catalyst layer degradation.

Determination of Flow Patterns in Vertical Upward Two-Phase Flow Channel via Void Fraction Profile

Two-phase flow happens widely in the industrial plants and certain equipment. This paper attempts to study the characteristics of two-phase flow in a vertical piping system. This was achieved by comparing the void fraction, in the working fluid, by employing Constant Electric Current Method (CECM) with the actual observation using high-speed camera. The experiment requires a complete set of two-phase flow system information and was conducted based on various flow conditions. In order to carry out this experiment, the two-phase flow loop was constructed using a specific experimental apparatus and components. The flow channels were constructed using three pipes with three different inner diameters of 21.0 mm, 47.0 mm and 95.0 mm. The flow direction was vertical upward co-current flow with liquid superficial velocity range of 0.025 m/s to 3.0 m/s and gas superficial velocity range of 0.025 m/s to 3.0 m/s, depending on the size of the pipe. The flow pattern investigation focuses on experimental work, which was based on systematic observation and measurements using a high-speed camera and some measuring apparatus. The void fraction measurement using the CECM sensor was integrated into two-phase flow system with constant electric current running in the pipe and data acquisition system controlled virtually via LabVIEW software. Both result of the flow pattern and void fraction graph were then compared to determine the type of flow pattern from the void fraction graph. Information from the previous studies and experiments were collected and the assumption of any theoretical simplifications were used as a reference. According to the result, the flow pattern in pipe can be easily determined using CECM.