Charge-discharge Characteristics Research Articles

Novel carbonaceous ZnO composite prepared through inert-ambient pyrolysis of the zinc anthranilate complex

In this work we present the analysis of products of the pyrolysis, at 600 °C, of zinc anthranilate complex in open air and in the nitrogen ambient of a sealed tube. The resulting powder samples were characterized by x-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (FESEM), and transmittance electron microscopy (HR-TEM). Open-air pyrolysis (OAP) yields well-crystallized ZnO, whereas sealed-tube pyrolysis (STP) produces a black powder that is found to be a composite (ZnO/C) of graphitic carbon and nanocrystalline, nearly monodisperse ZnO. The composite is carbon-rich. The relatively large size of ZnO crystallites from OAP and their much smaller size in the STP product suggest that carbon formation in the sealed tube restricts the growth of ZnO nanocrystals. When ZnO/C was annealed in air at 650 °C for 1 h, the oxide crystallites retained their average size, with all carbon removed. To investigate the possibility of using ZnO/C as electrode material in capacitors, electrochemical investigations electrode were carried out using cyclic voltammetry and galvanostatic charge-discharge, with 0.5 M KOH as electrolyte. The specific capacitance of the ZnO/C composite was found to be 124.7 F g−1 at 5 mV s−1 scan rate, indicating the suitability of ZnO/C as electrode material because of the measured voltammograms and charge-discharge characteristics.

Statistical Study on Space Charge effects and Stage Characteristics of Needle-Plate Corona Discharge under DC Voltage

The air’s partial discharges (PD) under DC voltage are obviously affected by space charges. Discharge pulse parameters have statistical regularity, which can be applied to analyze the space charge effects and discharge characteristics during the discharge process. Paper studies air corona discharge under DC voltage with needle-plate model. Statistical rules of repetition rate (n), amplitude (V) and interval time (∆t) are extracted, and corresponding space charge effects and electric field distributions in PD process are analyzed. The discharge stages of corona discharge under DC voltage are divided. Furthermore, reflected space charge effects, electric field distributions and discharge characteristics of each stages are summarized to better explain the stage discharge mechanism. This research verifies that microcosmic process of PD under DC voltage can be described based on statistical method. It contributes to the microcosmic illustration of gas PD with space charges.

Systematic Characterizations of All-Vanadium Redox Flow Battery Employing Pore-Filled Ion-Exchange Membranes

Recently, the interest in high-performance energy storage system (ESS) is increasing since it is a very essential part of the smart grid for stable and efficient electricity supply. At present, diverse battery technologies such as lithium ion batteries, redox flow batteries (RFBs), and sodium–sulfur batteries are competing with each other to be applied to commercial ESS. Among them, RFBs are considered to be the most promising for a large-scale ESS application. Meanwhile, all-vanadium redox flow batteries (VRBs) utilizing vanadium ions in different oxidation states as the active redox species have been considered as one of the most promising RFBs owing to the controlled crossover rate of the redox species through membranes. Since an ionomer membrane separator is one of the most dominant components determining the charge-discharge characteristics of RFB systems, the development of highly efficient membranes has been considered to be very essential for successful commercialization of VRBs. Among various kinds of membranes, pore-filled ion-exchange membranes (PFIEMs) fabricated by combining a porous substrate and an ionomer are known to have excellent characteristics including high chemical and dimensional stabilities, low manufacturing cost, low mass transfer resistance, etc. In this work, we have developed novel PFIEMs by using a polyethylene (PE)- or a polytetrafluoroethylene (PTFE)-based porous substrate for VRB applications. Especially, we have designed the filling ionomer to possess the high crosslinking degree and ion-exchange capacity, simultaneously. In addition, the prepared PFIEMs and the RFB employing them have been systematically analyzed by various electrochemical methods for evaluating their performances exactly. The detailed results will be presented and discussed at the conference. This work was supported by a grant (No.2017000140002/ RE201702218) from the Environmental Industry Advancement Technology Development Project of Korea Environmental Industry & Technology funded by Korea Ministry of Environment.

Charge-Discharge Characteristics of Li/CuCl_2 Batteries with LiPF_6/Methyl Difluoroacetate Electrolyte

Charge-Discharge Characteristics of Li/CuCl_2 Batteries with LiPF_6/Methyl Difluoroacetate Electrolyte

Charge-Discharge and Interfacial Properties of Ionic Liquid-Added Hybrid Electrolytes for Lithium-Sulfur Batteries.

Even though lithium–sulfur batteries possess higher theoretical capacity and energy density than conventional lithium-ion batteries, the challenging issues such as poor electronic conductivity of sulfur, dendrite formation and subsequent polysulfide shuttling, and the undesirable interfacial properties of the lithium metal anode with an electrolyte impede this system from commercialization. To circumvent the dissolution of lithium polysulfides and to improve the interfacial properties of the electrolyte with the lithium metal anode, numerous tactics have been employed. Therefore, in this work, hybrid electrolytes composed of room-temperature ionic liquids of different cations with the bis(trifluoromethanesulfonyl)imide (TFSI) anion and a nonaqueous liquid electrolyte [1 M LiTFSI in tetraethylene glycol dimethyl ether/1,3-dioxolane 1:1 (v/v)] have been prepared, and their physicoelectrochemical properties were thoroughly investigated. The lithium surface upon cycling was characterized by Raman, Fourier transform infrared, and X-ray photoelectron spectroscopy analyses. The dendrite and shuttle current measurements also indicated the formation of a stable solid electrolyte interphase and lower polysulfide shuttling between the electrodes. Among the systems examined, the hybrid electrolyte composed of 1-methyl-1-propylpyrrolidinium TFSI exhibited appreciable charge–discharge characteristics, better interfacial properties with the lithium metal anode, and increased ionic conductivity which were attributed to the enhanced ion-pair interaction that is present between the 1-methyl-1-propylpyrrolidinium cation and the TFSI anion in the electrolyte which was substantiated by Raman analysis.

Charge-Discharge Characteristics of Textile Energy Storage Devices Having Different PEDOT:PSS Ratios and Conductive Yarns Configuration.

Conductive polymer PEDOT:PSS, sandwiched between two conductive yarns, has been proven to have capacitive behavior in our textile energy storage devices. Full understanding of its underlying mechanism is still intriguing. The effect of the PEDOT to PSS ratio and the configuration of the electrode yarns are the focus of this study. Three commercial PEDOT:PSS yarns, Clevios P-VP-AI-4083, Ossila AI 4083, and Orgacon ICP 1050, as well as stainless steel and silver-coated polybenzoxazole (Ag/PBO) yarns, in various combinations, were used as solid electrolytes and electrodes, respectively. Analyses with NMR, ICP-OES, TGA, and resistivity measurement were employed to characterize the PEDOT:PSS. The device charge-discharge performance was measured by the Arduino microcontroller. Clevios and Ossila were found to have identical characteristics with a similar ratio, that is, 1:5.26, hence a higher resistivity of 1000 Ω.cm, while Orgacon had a lower PEDOT to PSS ratio, that is, 1:4.65, with a lower resistivity of 0.25–1 Ω.cm. The thermal stability of PEDOT:PSS up to 250 °C was proven. Devices with PEDOT:PSS having lower conductivity, such as Clevios P-VP-AI-4083 or Ossila AI 4083, showed capacitive behavior. For a better charge-discharge profile, it is also suggested that the PEDOT to electrode resistance should be low. These results led to a conclusion that a larger ratio of PEDOT to PSS, having higher resistivity, is more desirable, but further research is needed.

Performance Analysis of Li-ion Battery Under Various Thermal and Load Conditions

In the recent years, with the rapid advancements made in the technologies of electric and hybrid electric vehicles, selecting suitable batteries has become a major factor. Among the batteries currently used for these types of vehicles, the lithium-ion battery leads the race. Apart from that, the energy gained from regenerative braking in locomotives and vehicles can be stored in batteries for later use for propulsion thus improving the fuel consumption and efficiency. But batteries can be subjected to a wide range of temperatures depending upon the operating conditions. Thus, a thorough knowledge of the battery performance over a wide range of temperatures and different load conditions is necessary for their successful employment in future technologies. In this context, this study aims to experimentally analyze the performance of Li-ion batteries by monitoring the charge–discharge rates, efficiencies, and energy storage capabilities under different environmental and load conditions. Sensors and thermal imaging camera were used to track the environment and battery temperatures, whereas the charge–discharge characteristics were analyzed using CADEX analyzer. The results show that the battery performance is inversely proportional to charge–discharge rates. This is because, at higher charge–discharge rates, the polarization losses increase thus increasing internal heat generation and battery temperature. Also, based on the efficiency and energy storage ability, the optimum performing conditions of the Li-ion battery are 30–40 °C (temperature) and 0.5 C (C-rate).

A modelling and simulation study of soluble lead redox flow battery: Effect of presence of free convection on the battery characteristics

In this paper, we develop a mathematical model for soluble lead redox flow battery. The model accounts for simultaneous effect of forced convection and induced free convection in electrolyte domain of the battery. It predicts existence of dominant free convection over the forced convection in vicinity of the electrodes. The predictions suggests that both, electrode kinetics and ion transfer assisted by free convection alone, controls charge-discharge characteristics of the battery. The free convection augments ion transfer rate to the electrodes. By virtue of this, limiting current density at the electrodes increases to twice the theoretical limit under forced convection. The predictions coherently explains Collins et al. [1]‘s observations of high charge efficiencies when charging currents are higher than the theoretical limit. Also, the model consistently explains Pletcher et al. [2]‘s observation of insensitivity of the battery characteristics to the electrolyte flow rate. The model predicts satisfactory battery performance even at microscopic (μL s−1) flow rates which opens up the possibility for significant reduction in electrolyte pumping cost.

Charge-Discharge Characteristics Improvement Through Optimization of Voltage Range for LiNiCoMnO2 Electrode for High Energy Density Lithium-Ion Batteries

The development of suitable electrode materials for lithium ion batteries (LIBs) to enhance the performance of LIBs in order to meet increasingly demand globally is one of the challenges. Thus, for almost three decades since 1980, continuous study for high performance LIBs electrode has been done. In this report, the optimization charge-discharge characteristic of LiNiCoMnO2 (LNCM) cathode – layered structured material with lithium metal as anode has been evaluated. The electrode was assembled together with Celgard as separator and organic electrolyte Lithium hexafluorophosphate (1M LiPF6, EC:DEC 1:1) in coin cells (CR2032) under argon atmosphere inside a glove box. The charge-discharge performance test was conducted using Neware battery testing system. The discussion in this paper is focusing on the characteristic features of the charge-discharge profile, optimize charge-end voltage and rate capability (C-rate). The studies discovered the voltage range has been optimized up to 3.3-4.5 V at a constant current of 0.35 mA (0.1 C) with voltage plateau of 4.0 V. The result indicated the optimized range has the highest specific capacity of 118 mAh/g and most stable coulombic efficiency (94.3%).

An Iodide-Based Complexing Agent for the Zinc-Iodide Flow Battery

The effect of iodide-based complexing agent on the electrochemical performance of zinc-iodide flow battery was investigated. The addition of a complexing agent that will stabilize triiodide during charging can reduce the self-discharge and increase the charge and voltaic efficiency. The hydrogen evolution and kinetics of the both electrode reactions in the presence of the complexing agent was assessed. Cyclic voltammetry and Tafel analysis were performed to evaluate the influence of complexing agent on zinc electrochemical kinetics. The results indicated that the complexing agent enhances the cell performance by increasing the kinetics, which will enable operation of the battery at increased current density, or increases in the charge-discharge efficiency. At the positive electrode a deposit was observed on the electrode surface. The deposit was characterized by SEM and EDS and the deposition process was found to change significantly in the presence of the complexing agent. The charge-discharge characteristics of the electrolyte system were investigated in an H-type glass cell, and polarization curves were obtained for the two half-cell reactions.

A Highly Tunable Fabrication Process for Binder-Free Three-Dimensional Carbon Nanoarchitectures for Supercapacitor Electrode Via Nanotransfer Printing Technique

Among various energy storage systems, supercapacitors are known to be excellent candidates with inherent fast charge-discharge characteristics and outstanding cycle stability, but are known to be mediocre in the energy density aspect. In order to realize their full potential, the electrode nanostructure needs to be carefully designed and fabricated, maximizing the surface area for electrochemically active sites while maintaining the conductivity and stability. Here, we report a novel and straightforward fabrication method for a binder-free carbon nanoarchitecture that meets these conditions. Using a solvent-assisted nanotransfer printing technique, a three-dimensional nanoarchitecture is assembled with highly controllable and consistent pore sizes, applicable in both EDLC and pseudocapacitor electrodes. In this study, arrays of carbon nanowires were transfer-printed using polymer replicas of silicon substrates with linear trenches of various widths and periods, ranging from few hundred nanometers to micrometers. The printing process was repeated multiple times to assemble mesh-like carbon nanoarchitectures with desirable thicknesses. Due the simplicity of the process, the fabrication method is highly versatile, modifiable in numerous elements such as thickness and width of the carbon, pattern size, intersection angles, and so forth. The patterns were fabricated in a wide range of dimensions to investigate the effect of pattern sizes in the electrode performance. Such tunability enables comprehensive analysis of effect of the electrode pore size and structure in supercapacitor performance. The electrochemical performances of the electrodes were tested by manufacturing a series of supercapacitor on CR2032 coin cells. Two symmetric electrodes were isolated using an ion-porous separator and organic solvent was used as the electrolyte. All coin cell assembly was conducted in a dry room with relative humidity lower than 2% to prevent any contamination in the electrolyte. Furthermore, we report additional processes to widen the application capability of the described fabrication method. Hierarchical structures have been fabricated by printing alternating layers of patterns of different dimensions. Larger nanowires provide apertures that act as pathways for efficient access of electrolyte to the active material, while smaller nanowires contribute to increase the surface area. Moreover, this nanoarchitecture can be modified for pseudocapacitors or other energy storage applications. Metallic nanoparticles can be dispersed and embedded on the carbon surface to form carbon-metal or carbon-metal oxide composite materials, allowing the aforementioned advantages of this structure to be similarly applied in other devices. This three-dimensional nanoarchitecture fabrication process provides a highly tunable and straightforward method based on transfer-printing technique, and further investigations and optimizations can be expected from the high versatility. Figure 1

Precision dynamic equivalent circuit model of a Vanadium Redox Flow Battery and determination of circuit parameters for its optimal performance in renewable energy applications

In this work it is established for the first time that the internal parameters of the electrical equivalent circuit of vanadium redox flow battery (VRFB) are variable not only with flow rate and stack current but also the state of charge (SOC) and operational cycle number. The dynamic internal circuit parameters are extracted by using the charge-discharge characteristics of a practical 1 kW 6 h VRFB system as input to the proposed model. The role of temperature on the VRFB internal parameters is also discussed. It is further demonstrated that the average error in estimation of VRFB stack voltage using dynamic parameters reduces by 28% (charging) and 14% (discharging) compared to that of using static internal parameters. The proposed model exhibits robustness and validity for large scale applications as evidenced by further extracting the internal parameters of a 125 kW 2 h VRFB system. Another significant contribution of this paper is the optimization of flow rate by considering both the stack internal power loss and pump power loss simultaneously to achieve optimal performance of the VRFB system. The proposed model involving dynamic parameter extraction and loss optimization is very useful for designing suitable battery management system (BMS) for interfacing VRFB with renewable energy sources.

Stress Dispersed Cu Metal Anode by Laser Multiscale Patterning for Lithium-Ion Batteries with High Capacity

Electric power production continues to increase as the industry advances, and the demand for high-capacity batteries for efficient operation of the electric power produced is higher than ever before. Si has been attracting a great deal of attention recently as an anode electrode material because of its high theoretical capacity. However, it suffers from significant capacity-loss, resulting from the volume-expansion of Si during charge and discharge cycles. Inspired by the multiscale structures commonly found in nature, we attempt to solve this problem by patterning the surface of the Cu current-collector. To this end, we develop a direct, one-step method using laser patterning to manufacture a multiscale structure on the surface of the current-collector. The inherent exfoliation characteristic of the Cu current-collector allows the spontaneous formation of the multiscale structure while being irradiated with a laser. A micro/nano structure, with a different surface area, is fabricated by varying the laser output at three levels, and the batteries prepared with the fabricated Cu current-collector are tested to evaluate their charge-discharge characteristics and electrochemical impedance. The results show that the multiscale structure reduces mechanical stress. The initial capacity of the Cu current-collector is proportional to the laser output, and the initial capacity of the coin cell prepared with the Cu current-collector, fabricated at the highest laser output, is 396.7% higher than that of the coin cell prepared with a bare Cu current-collector. The impedance is inversely proportional to the laser output. The charge transfer resistance of the coin cell prepared with the Cu current-collector and irradiated with the highest laser output is 190.2% lower than that of the coin cell prepared with the bare Cu current-collector.

Mesoporous Nanostructured Materials for the Positive Electrode of a Lithium–Oxygen Battery

Nanostructured carbon materials (CMs), the structure can vary widely, are promising materials for the positive electrode of a lithium–oxygen battery (LOB). The electrochemical characteristics of CMs studied in model conditions and their porous structure, as well as testing them as an active material for the positive electrode in an LOB sample, show that nanotubes (CNTs) and Super P carbon black possess the highest charge–discharge characteristics in an aprotic solvent (DMSO). Mono- and bimetallic systems containing Pt, Pd, and Ru and synthesized on CNT and Super P allow one to reduce discharge and charge overvoltage. In the presence of catalytic systems, an improvement in the energy-conversion efficiency of up to 73–76.7% is achieved for the LOB positive electrode. The possibility of achieving a stable cycling process in an LOB with a positive electrode on the basis of developed catalysts and with a LiClO4/DMSO electrolyte is shown. For the first time, the positive influence of iodine (reducing the charge voltage to about 0.8–1.0 V as compared to the characteristics of an LOB using an electrolyte without additives) on the electrode characteristics of a Li–O2 cell with the highly electron-donating solvent DMSO is demonstrated.

The charge-discharge characteristics and diffusion mechanism of Ti-Si-Al thin film anode using an electrically induced crystallization process

In this study, an Al-Si-Ti multilayer thin film structure is designed as the anode of a lithium ion battery. The novel structure restricts the expansion of Si during charge-discharge, and its battery capacity can reach 1112 mA h g−1 after a 100-cycle charge-charging test under a 0.2 C charge-discharge rate without annealing. Notably, after a 200 °C vacuum annealing process, the cyclic capacity of the anode rises to 1208 mA h g−1 through crystallization of the Al and Ti buffer layer. However, its thermal diffusion behavior in the Al/Si or Ti/Si interfaces seriously reduces the performance and restricts the expansion of Si. The electrically induced crystallization (EIC) process not only performs crystallization but also controls the interfacial stability, after which its capacity can obviously improve to 1602 mA h g−1 after 100 cycles. Using EIC, the electron flow drives the Cu and Al atoms to endow the Si matrix with doping properties and further increases the electron conductivity of the anode. This result demonstrates that the EIC process is a suitable post-treatment process for multilayer anodes and provides a reference for future battery designs.

Synthesis and application of carbon nitride enriched leady oxide as novel negative active mass for lead acid batteries

Abstract In this work, we report the synthesis and utilization of carbon nitride enriched leady oxide (CNLO) as negative active mass (NAM) which enhances the charge–discharge characteristics of the lead-acid cells. The CNLO NAM were characterized by X-ray diffraction (XRD), Raman spectroscopy, Field emission scanning electron microscopy (FE-SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), respectively. Cells constructed with CNLO NAM exhibit remarkable improvement in the rate capability, active material utilization, cycle performance and charge acceptance compared to that of the cells constructed with conventional NAM.

Block copolymer derived 3-D interpenetrating multifunctional gyroidal nanohybrids for electrical energy storage

All necessary battery components are synthesized within a three-dimensionally periodic, co-continuous nanostructure and the first reversible charge–discharge characteristics are demonstrated.

Reduction of Charge-Transfer Resistance via Artificial SEI Formation Using Electropolymerization of Borylated Thiophene Monomer on Graphite Anodes

Modification of electrode surface using borylated-thiophene monomer resulted in the formation of a pre-formed solid electrolyte interface (SEI). The obtained ready-to use anodes did not show any loss in capacity during the first few cycles of charging and discharging. Herein, we report the synthesis and utilization of boron containing monomer to form an artificial SEI to reduce the interfacial resistance at SEI. Electropolymerization was performed via two methods, i) pre-modification and ii) in-situ modification. After the modification of the anodes, modified electrodes showed increased capacities, reduced capacity fading effect, and reduced interfacial resistance. Charge-discharge characteristics of half-cell with borylated thiophene polymer over graphite was studied and compared with graphite without any modification and polythiophene coated graphite.

Research and Application of Supercapacitor Charging System

Based on the special power supply requirements of the project, the AD8210YRZ (current monitoring operational amplifier) monitors the charging current in real time, and its output is fed back to the detection pin of the TPS5430DDA to adjust the charging voltage of the capacitor. Combined with the charge-discharge characteristics of the super capacitor, the circuit realizes high current constant current charging at low voltage and constant voltage charging when the capacitor terminal voltage increases. This method can effectively and reasonably improve the charging efficiency of the super capacitor and meet the design requirements. The product has been put into use and achieved good results.

Fabrication of lithium-ion batteries based on various LiNi<SUB align="right">1-xCo<SUB align="right">xO<SUB align="right">2 cathode materials

Samples from the proposed LiNi1-xCoxO2 system were synthesised using the sol-gel method. Stoichiometric weights of LiNO3, Co(Ac)2.2H2O and Ni(COOCH3)2.4H2O, have been considered for fabrication of LixNiyCozO2. Five samples of LiNi1-xCoxO2 (x = 1, 0.8, 0.6, 0.5 and 0.3) of lithium, nickel and cobalt composition have been selected and synthesised. Charge-discharge characteristics of LiNi1-xCoxO2 (x = 1, 0.8, 0.6, 0.5 and 0.3) were investigated by performing cycle tests in the range of 2.0-4.5 V. Our results confirmed that, although these systems can help for removing the disadvantages of cobalt which are mainly is its cost and toxicity, the performance of these systems is similar to LiCoO2 cathode material.