Demonstrating oxygen loss and associated structural reorganization in the lithium battery cathode Li[Ni0.2Li0.2Mn0.6]O2

The cathode in rechargeable lithium-ion batteries operates by conventional intercalation; Li+ is extracted from LiCoO2 on charging accompanied by oxidation of Co3+ to Co4+; the process is reversed on discharge. In contrast, Li+ may be extracted from Mn4+-based solids, e.g., Li2MnO3, without oxidation of Mn4+. A mechanism involving simultaneous Li and O removal is often proposed. Here, we demonstrate directly, by in situ differential electrochemical mass spectrometry (DEMS), that O2 is evolved from such Mn4+ -containing compounds, Li[Ni(0.2)Li(0.2)Mn(0.6)]O2, on charging and using powder neutron diffraction show that O loss from the surface is accompanied by diffusion of transition metal ions from surface to bulk where they occupy vacancies created by Li removal. The composition of the compound moves toward MO(2). Understanding such unconventional Li extraction is important because Li-Mn-Ni-O compounds, irrespective of whether they contain Co, can, after O loss, store 200 mAhg(-1) of charge compared with 140 mAhg(-1) for LiCoO(2).     

Some aspects of the charging effect in monochromatized focused XPS

Summary The charging effect in XPS, especially in MONO-XPS, relates not only to insulators but also to certain types of conductive and semiconductive systems as defined by the measurement of the resistance with a conventional Ohmmeter. The following facts are discussed: (1) the presence of a pressure dependence of the charging effect for samples with high insulation; (2) the presence of the vertical differential charging for samples consisting of ultra-thin insulating overlayers on a conductive substrate and for resistive materials; and (3) the features of a focusing neutralizer with adjustable beam current, energy, and position. It is proposed to divide the charging effect into the two groups of simple charging and differential charging; the latter is further divided into two sub-groups of lateral and vertical differential charging. A general survey of the charging effect in XPS is also given.     

Continuum Field Charging of Dielectric Spheroids

Classical continuum theory for field charging is applied in an analysis of the ionic charging of spheroidal dielectrics. Assuming that the particle orientation is fixed during the charging process, the saturation charge and charging rate are determined as functions of the orientation and aspect ratio of spheroids. For spheroids of small dielectric constants the saturation charge becomes the largest when the electric field is directed perpendicular to the major axis of the spheroid. For an ensemble of randomly oriented spheroids the average saturation charge can be approximated as the arithmetic average of the saturation charges for the spheroid with the electric field directed along the three principal axes of the spheroid. In addition, the ensemble average of the dimensionless charging rate of randomly oriented spheroids of moderate axial ratio approximates the dimensionless charging rate of a sphere. Copyright 2000 Academic Press.     

The charging of a liquid dielectric upon its flow past a flat-plate

The charging of a liquid dielectric upon its flow past a flat-plate is considered. Analytical expressions for the density distribution of electric charge and charging current are derived. The dependences of the current and charge density distribution on the system parameters are investigated. The effect of the electric field that emerges owing to charge separation on the charging process is taken into account. Consideration of the electric field is shown to lead to lower values of the electric charge density and charging current. As the Debye number decreases, the charge density also decreases. The charging current increases with an increase in the Debye number.     

In-situ Study of Charge and Discharge of Ni-MH Battery Using the Combined Method of Electrochemistry and Microcalorimetry

An apparatus to study the battery system has been set up. The thermal effects of charge and discharge of Ni-MH batteries have been studied. The calorimetric measurements indicate that the net heat dissipation during charging is larger than that during discharging. It is observed that the ratio of heat dissipation to charging energy varies with charging capacity, and almost 90 percent of charging energy is lost as heat dissipation near the end of the charging process at 97.7 mA. A jump of thermal curve near the end of discharge due to a secondary electrode reaction has been observed.This revised version was published online in November 2005 with corrections to the Cover Date.     

The origin of potential rise during charging of Li-O_2 batteries

When aprotic Li-O_2 batteries recharge, the solid Li_2O_2 in the positive electrode is oxidized, which often exhibits a continuous or step increase in the charging potential as a function of the charging capacity, and its origin remains incompletely understood.Here, we report a model study of electro-oxidation of a Li_2O_2 film on an Au electrode using voltammetry coupled with in situ Raman spectroscopy. It was found that the charging reaction initializes at the positive electrode|Li_2O_2 interface, instead of the previously presumed Li_2O_2 surface, and consists of two temporally and spatially separated Li_2O_2 oxidation processes, accounting for the potential rise during charging of Li-O_2 batteries. Moreover, the electrode surface-initialized oxidation can disintegrate the Li_2O_2 film resulting in a loss of Li_2O_2 into electrolyte solution, which drastically decreases the charging efficiency and highlights the importance of using soluble electro-catalyst for the complete charging of Li-O_2 batteries.     

Chemical modification of polymers. XII. Control of triboelectric charging properties of polymers by chemical modification

Chemical modification of polymers leads to changes in triboelectric charging properties which are proportional to the degree of conversion. This contrasts to physical mixtures in which the surface energy causes one component to dominate the surface, hence the charging properties. Relationships between molecular structure and triboelectric charging have been deduced from the results. Thus the direction of change of triboelectric charging on chemical modification is governed by the nature of the reaction and the magnitude of the change is governed by the extent of reaction.     

应用于AGV自动导引车的快速充电系统

设计建立一种用于AGV自动导引车镍氢动力蓄电池的快速充电系统,该系统在充电过程中能实时监测蓄电池组的各个运行参数,完成数据运算并逻辑判断、控制充电过程至其结束,并利用去极化放电脉冲提高充电效率.     

导电环氧树脂消除扫描电子显微镜图像荷电问题的原理与实践

荷电问题常造成扫描电子显微镜(SEM)图像上产生亮度不均、条纹等伪影.提出一种利用导电环氧树脂镶嵌样品以消除SEM图像荷电的方法,并与传统导电胶粘贴制样方法对1 000℃高温混凝土、瓷土与河南双槐树考古土三种样品的适应性进行了对比研究.结果表明,利用铜粉与环氧树脂混合制备导电环氧树脂并将样品镶嵌其中所制备样品的SEM图像基本无荷电问题,而传统导电胶粘贴方法所制备样品的SEM图像存在较严重的荷电问题,通过增加导电层厚度并不能对此进行改善,且易造成微纳结构被掩盖.最后对传统制样方法导致荷电问题的原因与导电环氧树脂对荷电问题的改善原理进行了分析.     

Temperature characterization analysis of LiFePO<Subscript>4</Subscript>/C power battery during charging and discharging

In order to study the surface temperature change and distribution during charging and discharging and in the simulation working condition of LiFePO₄/C power battery at normal temperature, the surface temperature is tested by placing the battery in the incubator and fixing 10 temperature probes on the battery surface. Results show that the temperature of the upper part is higher, and the temperature at the bottom is the lowest, while around the positive electrode is the highest during charging and discharging. The maximum temperature rising rate is reached at the moment of constant current charging transforming to the constant voltage charging during charging, and at the end moment during discharging. During charging in a certain range and discharging, the relations between the maximum temperature, the average temperature rising rate, and the maximum temperature difference of all the measurement points at the same time and the current are approximately linear, respectively. In the simulation working condition, the moment of the maximum temperature is consistent with the large current discharging instantaneous in each stage.     

Review of Building Integrated Photovoltaics System for Electric Vehicle Charging

The transition to sustainable transportation has fueled the need for innovative electric vehicle (EV) charging solutions. Building Integrated Photovoltaics (BIPV) systems have emerged as a promising technology that combines renewable energy generation with the infra-structure of buildings. This paper comprehensively reviews the BIPV system for EV charging, focusing on its technology, application, and performance. The review identifies the gaps in the existing literature, emphasizing the need for a thorough examination of BIPV systems in the context of EV charging. A detailed review of BIPV technology and its application in EV charging is presented, covering aspects such as the generation of solar cell technology, BIPV system installation, design options and influencing factors. Furthermore, the review examines the performance of BIPV systems for EV charging, focusing on energy, economic, and environmental parameters and their comparison with previous studies. Additionally, the paper explores current trends in energy management for BIPV and EV charging, highlighting the need for effective integration and recommending strategies to optimize energy utilization. Combining BIPV with EV charging provides a promising approach to power EV chargers, enhances building energy efficiency, optimizes the building space, reduces energy losses, and decreases grid dependence. Utilizing BIPV-generated electricity for EV charging provides electricity and fuel savings, offers financial incentives, and increases the market value of the building infrastructure. It significantly lowers greenhouse gas emissions associated with grid and vehicle emissions. It creates a closed-loop circular economic system where energy is produced, consumed, and stored within the building. The paper underscores the importance of effective integration between Building Integrated Photovoltaics (BIPV) and Electric Vehicle (EV) charging, emphasizing the necessity of innovative grid technologies, energy storage solutions, and demand-response energy management strategies to overcome diverse challenges. Overall, the study contributes to the knowledge of BIPV systems for EV charging by presenting practical energy management, effectiveness and sustainability implications. It serves as a valuable resource for researchers, practitioners, and policymakers working towards sustainable transportation and energy systems.     

Single molecule charging by atomic force microscopy

AFM/KPM charging and charge mapping of polyamine charge carriers in a PMMA matrix is reported. Selective charging of the designed charge carrier is demonstrated at concentrations down to a single molecule. This works constitutes electrochemical charging and detection of single redox-active organic molecules in low dielectric matrices by probe microscopy.     

以1-(2,4,7-三硝基)芴基-2,6-二甲基苯胺为电子传输材料的单层结构有机光导体的研究

系统地研究了在由1-(2,4,-三硝基)芴基-2,6-二甲基苯胺(DMTNF),4-(二乙氨基)-苯甲醛-1,1-二苯基腙(DEH)和Y晶型氧钛酞菁(Y-TiOPc)或非金属酞菁(H₂Pc)构成的单层结构有机光导体的性能,考查了电荷产生材料(CGM)浓度、电场强度和CGM的种类对光导体静电照相性能的影响.研究结果表明,光导体的量子收率和感光度与CGM浓度有很大关系,正充电时随CGM的浓度的增加而增加,负充电时随CGM的浓度增加而降低.两种光导体在近红外光谱区表现出良好的光敏性,适合LD扫描成像.Y-TiOPc光导体的最高峰在80 nm处,半衰曝光量为0.588 μJ/cm²(正充电),0.828 μJ/cm²(负充电);H₂Pc光导体正充电最高峰在800 nm处,半衰曝光量为1.50 μJ/cm²,负充电最高峰在820 nm处,半衰曝光量为1.9 μJ/cm².     

Effects of iron phthalocyanine on the inner pressure of MH/Ni battery

The inner gas pressure of the battery beyond 1.01 106 Pa can cause a release of gas from the safety valve for a normal sealed cell, leading to a drying out of electrolyte solution[1], and gradually decreasing the performance of the battery until finally destroying it. During overcharging, oxygen is produced rapidly on the nickel electrode, and it is necessary to eliminate the oxygen and restrain the rising speed of inner pres-sure so as to improve the performance of MH/Ni bat-tery. Phthalocy…     

Chemometrics assisted resolving of net faradaic current contribution from total current in potential step and staircase cyclic voltammetry

Total current in the electroanalytical data is assumed to be consisting of three main constituents: faradaic current, step charging current and induced charging current. Both charging currents can cause an interfering effect on precise determination of faradaic currents, and hence insert direct effects on sensitivity and detection limit of the electroanalytical techniques. Despite the widespread techniques introduced until now, the extraction of the net faradaic current from total current still remains a challenge. In this work, by using multivariate curve resolution-alternating least square (MCR-ALS) as a powerful curve resolution-based chemometrics method, a straightforward method has been introduced for resolving faradaic current from the two types of charging currents (step charging current and induced charging current) in single potential step and staircase cyclic voltammetric methods. By simultaneous analyses of the current data matrices for different electrochemical systems, the three sources of current were successfully identified and their contributions in the total signal were easily calculated. Also, in this manner, the cell time constant can be obtained easily. Contrary to the previously reported methods, the present method does not need any pre-determined mathematical method; particularly there is no need to know the cell time constant.     

Effects of surface site distribution and dielectric discontinuity on the charging behavior of nanoparticles: a grand canonical Monte Carlo study

The surface site distribution and the dielectric discontinuity effects on the charging process of a spherical nanoparticle (NP) have been investigated. It is well known that electrostatic repulsion between charges on neighbouring sites tends to decrease the effective charge of a NP. The situation is more complicated close to a dielectric breakdown, since here a charged site is not only interacting with its neighbours but also with its own image charge and the image charges of all its neighbours. Coexistence of opposite charges, titration sites positions, and pH dependence are systematically studied using a grand canonical Monte Carlo method. A Tanford and Kirkwood approach has been applied to describe the interaction potentials between explicit discrete ampholytic charging sites. Homogeneous, heterogeneous and patch site distributions were considered to reproduce the titration site distribution at the solid/solution interface of natural NPs. Results show that the charging process is controlled by the balance between Coulomb interactions and the reaction field through the solid-liquid interface. They also show that the site distribution plays a crucial role in the charging process. In patch distributions, charges accumulate at the perimeter of each patch due to finite size effects. When homogeneous and heterogeneous distributions are compared, three different charging regimes are obtained. In homogeneous and heterogeneous (with quite low polydispersity indexes) distributions, the effects of the NP dielectric constant on Coulomb interactions are counterbalanced by the reaction field and in this case, the dielectric breakdown has no significant effect on the charging process. This is not the case in patch distributions, where the dielectric breakdown plays a crucial role in the charging process.     

Probing photoelectrochemical processes in Au-CdS nanoparticle arrays by surface plasmon resonance: application for the detection of acetylcholine esterase inhibitors

The photoelectrochemical charging of Au-nanoparticles (NP) in a Au-nanoparticle/CdS-nanoparticle array assembled on a Au-coated glass surface is followed by means of surface plasmon resonance (SPR) spectroscopy upon continuous irradiation of the sample. The charging of the Au-NPs results in the enhanced coupling between the localized surface plasmon of the Au-NP and the surface plasmon of the bulk surface, leading to a shift in the plasmon angle. The charging effect of the Au-NPs is supported by concomitant electrochemical experiments in the dark. Analysis of the results indicates that ca. 4.2 electrons are associated with each Au-nanoparticle under steady-state irradiation. The photoelectrochemical charging effect of the Au-NPs in the Au-CdS NP array is employed to develop a SPR sensor for acetylcholine esterase inhibitors.     

Quantised charging of monolayer-protected nanoparticles

Metal nanoparticles coated with an organic monolayer, so-called monolayer protected clusters (MPCs), can show quantised charging at room temperature due to their sub-attofarad capacitance arising from the core size and the nature of the protecting monolayer. In this tutorial review, we examine the factors affecting the energetics of MPC charging. In the first section, the underlying physics of quantised charging is outlined and we give an overview of the various methods that can be used to measure single electron transfer to nanoparticles. In the subsequent sections, we discuss how electrochemical measurements can be used to give information on the quantised charging of freely diffusing and films of immobilised MPCs. The predictions of models used to determine MPC capacitance are compared with experimental data from the literature.     

The Thermal Charging Performance of Finned Conical Thermal Storage System Filled with Nano-Enhanced Phase Change Material

A latent heat thermal energy storage (LHTES) unit can store a notable amount of heat in a compact volume. However, the charging time could be tediously long due to weak heat transfer. Thus, an improvement of heat transfer and a reduction in charging time is an essential task. The present research aims to improve the thermal charging of a conical shell-tube LHTES unit by optimizing the shell-shape and fin-inclination angle in the presence of nanoadditives. The governing equations for the natural convection heat transfer and phase change heat transfer are written as partial differential equations. The finite element method is applied to solve the equations numerically. The Taguchi optimization approach is then invoked to optimize the fin-inclination angle, shell aspect ratio, and the type and volume fraction of nanoparticles. The results showed that the shell-aspect ratio and fin inclination angle are the most important design parameters influencing the charging time. The charging time could be changed by 40% by variation of design parameters. Interestingly a conical shell with a small radius at the bottom and a large radius at the top (small aspect ratio) is the best shell design. However, a too-small aspect ratio could entrap the liquid-PCM between fins and increase the charging time. An optimum volume fraction of 4% is found for nanoparticle concentration.     

Characterization of Langmuir-Blodgett film using differential charging in X-ray photoelectron spectroscopy

Differential charging is often regarded as a problem in X-ray photoelectron spectroscopy (XPS) studies, especially for insulating or partially conducting samples. Neutralization techniques have been developed to circumvent this effect. Instead of neutralizing the positive charge, which is often the technique to obtain good quality data, it is possible to exploit this phenomenon to get useful information about the sample. An attempt is made here to use this differential charging to study the mono- and multilayer Langmuir-Blodgett (LB) films of cadmium arachidate on silicon substrate. The surface potential was probed by measuring XPS line shift with respect to their neutral position and was found to have correlation with the thickness of the films. No differential charging was observed in the monolayer LB film where there was only one layer of cadmium headgroup. Significant differential charging was observed for multilayer films, the total charging as well as the differential charging in these films increase with increasing number of layers. Angle-resolved XPS measurements were performed to obtain additional information about the structure of the films. Charging of the upper layer of the films close to the vacuum interface was found to be less compared to that of the interior. The discrete cadmium layers were found to be more differentially charged compared to the continuous hydrocarbon stacks in the multilayer LB films. Charging of the discrete cadmium layers has been utilized to obtain quantitative information of the multilayer LB films.