Electrical Charge Storage Research Articles

(Dielectric Science and Technology Division Thomas D. Callinan Award Address) Colorful Adventures in the Field of Dielectrics Science: Some Highs and Lows with a Touch of a Chilly Forecast

Dielectric materials are utilized throughout semiconductor microelectronic devices for a variety of applications ranging from passive electrical isolation and charge storage to more functional etch stopping and diffusion barriers and more active layers such as humidity sensing and solid state electrolyte materials. Just in the past two decades alone, the semiconductor industry has researched and adopted a vast array of new dielectric materials with exceptionally high or low values of dielectric permittivity (k). While scaling of these so called high-k and low-k dielectrics may have reached their limits, numerous additional applications for dielectric materials continue to emerge as the industry seeks to adopt new methods for patterning nanoscale features and considers a dizzying array of beyond CMOS devices. In this talk, I will discuss my colorful adventures over these past two decades as a dielectric materials scientist starting with molecular beam and atomic layer epitaxy of III-N nitrides to plasma enhanced chemical vapor deposition of low-k dielectrics and back to atomic layer deposition of high-k dielectrics (various misadventures in between will also not be neglected!). It has been an exciting journey and I will use it to highlight the multi-disciplinary nature of dielectric science as well as illustrate how something that was once old can be reimagined to fulfill the needs of future beyond CMOS devices. I will further address some of the future challenges and opportunities presented for dielectric materials that have been created by the new patterning methods and beyond CMOS devices now under consideration. We will conclude by reviewing the unique obstacles that dielectric materials present for the realization of advanced cryogenic quantum computing architectures and the necessary associated research vectors to prevent dielectrics from becoming quantum computing’s Achilles heel.

Electric charge accumulation and storage in Nafion and graphene oxide films

• Electric charge accumulation and storage. • Proton conductivity of Nafion and grafene oxide films. • Effect of dry charged battery. In this work, the possibility of accumulation and storage of electric charge in 400–500 nm thick films formed by proton conductors was shown for the first time by the example of Nafion and graphene oxide. Current-voltage characteristics were studied in the humidity range of 53–80.7%. The process of charge accumulation is regulated by the humidity of the environment. In a dry atmosphere, the charge is preserved even when the potential is applied to the electrodes - the current appears only in a humid atmosphere. Charge accumulation occurs directly in the Nafion or graphene oxide film without chemical transformation, unlike batteries, electrical capacitors and liquid batteries.

Effect of a global warming model on the energetic performance of a typical solar photovoltaic system

This study provides insight into how the energetic performance of a typical photovoltaic solar system (PV) will change in a warmer world with increased levels of greenhouse gases. It was considered a photovoltaic system disconnected from the distribution grid, similar to those available in the market. The methodology covers systems without batteries and with the use of batteries with finite electric charge storage. The climatic change is accessed from a scenario predicted from the HadCM3(Hadley Centre Coupled Model, version 3) major global circulation model reported in the International Panel for Climatic Change (IPCC). The outputs from a future weather scenario were used as inputs for the long-term performance simulations for the typical PV solar system. The results encompass predictions for the decades of 2020, 2050 and 2080, and are presented in terms of monthly average daily energy output, fraction of the load supplied for a system with and without battery, and energetic efficiency. Seven cities in different climatic zones were evaluated. The cities and regions presented distinct behaviors, such that in some cases the PV system generated less energy, while in others an increase in photovoltaic generation was observed. However, regarding the energetic efficiency of the system, all scenarios presented increasing losses throughout the decades.

Thermal analysis of erbium charge storage nanoparticles embedded in organic MIS structure

We report on the self-heating characteristics of fabricated organic MIS structures using rare earth erbium nanoparticle as electrical charge storage elements. The organic MIS structure consists of a semiconductive polymer synthesized by means of doping two non-conductive polymers with an ionic liquid, glycerol. SEM images revealed that the rare earth nanoparticles are charging. A Zeta analyzer was used to determine the size of the nanoparticles with an average diameter size of 92 nm. The capacitance versus voltage hysteresis loops of the MIS structure revealed large window gates with a voltage span of 33 V when a ±20 V sweep scan was performed. FLIR thermograph showed an increase in temperature of 1.3 °C of the MIS structure when connected to an AC power generator at 60 Hz. Doing so increased the time constant of the device by 47% when the device is connected the a power source for 15 min. We also assessed on the relationship of increasing the temperature of the Er nanoparticles increases the amount of charges stored in the MIS capacitor.

Ultrasonication-assisted fabrication of hierarchical architectures of copper oxide/zinc antimonate nanocomposites based supercapacitor electrode materials

In this work, a new nanohybrid consisting of copper oxide and zinc antimonate was designed using ultrasonication assisted homogenous magnetic stirring approach and investigated their performance as an electrode material for supercapacitors. Combination of the duo could enhance the electrical conductivity and charge storage capacity of whole nanostructured electrode, which is very much essential for supercapacitor application. Primarily, the prepared nanohybrid electrode material was investigated through XRD, FT-IR, FE-SEM, HR-TEM, UV-DRS, PL and XPS to determine their structural, morphological, optical and compositional characteristics. Thereafter, the electrochemical properties of the nanohybrid electrode were investigated using CV, GCD and EIS studies in 1.0 M KOH solution. The fabricated nanohybrid electrode material exhibits exceptional electrochemical performance by delivering maximum specific capacitance of 257.14 F g−1 at a current density of 12.5 A g−1. The nanocomposite showed high cycling stability of 102.0% even after 2000 cycles at a current density of 10.0 A g−1. These exceptional electrochemical characteristics of CuO/ZnSb2O6 nanocomposites are due to their dual nanorod morphology, influence of ultrasonication on non-aggregated nanocomposite formation, presence of more number of electrochemical active sites, and their synergistic interactions. The obtained results confirmed that CuO/ZnSb2O6 nanocomposites could be a potential candidate as electrode materials for supercapacitors.

Photosynthetic apparatus of Rhodobacter sphaeroides exhibits prolonged charge storage

Photosynthetic proteins have been extensively researched for solar energy harvesting. Though the light-harvesting and charge-separation functions of these proteins have been studied in depth, their potential as charge storage systems has not been investigated to the best of our knowledge. Here, we report prolonged storage of electrical charge in multilayers of photoproteins isolated from Rhodobacter sphaeroides. Direct evidence for charge build-up within protein multilayers upon photoexcitation and external injection is obtained by Kelvin-probe and scanning-capacitance microscopies. Use of these proteins is key to realizing a ‘self-charging biophotonic device’ that not only harvests light and photo-generates charges but also stores them. In strong correlation with the microscopic evidence, the phenomenon of prolonged charge storage is also observed in primitive power cells constructed from the purple bacterial photoproteins. The proof-of-concept power cells generated a photovoltage as high as 0.45 V, and stored charge effectively for tens of minutes with a capacitance ranging from 0.1 to 0.2 F m−2.

The effect of alkyl chain of the imidazolium ring on the poly(o-methoxyaniline)/ionic liquid supercapacitor performance

New materials can be developed using a known compound with enhanced properties modifying and controlling its microstructure, morphology, and density of defects. In this work, a new material was produced by the addition of ionic liquid (IL) to the poly(o-methoxyaniline) (POMA) conductive polymer, in the form of esmeraldine salt. The polymer impregnated with IL was tested as an electrode for use in supercapacitors. The results show that the charge storage properties of the materials are dependent on the length of the alquil substituent of imidazolium ring of ionic liquid cation. The best results, obtained by the addition of 1-butyl-3-methylimidazolium triflate IL to the polymer, improved electrical charge storage and electrochemical stability, making the material a promising electrode for supercapacitor devices. This compound has specific capacitance of 205 F/g, five times larger than pure POMA and was stable for 3000 cycles of charge/discharge experiments carried out at 1.0 A/g.

Three-dimensional modeling of frequency- and time-domain electromagnetic methods with induced polarization effects

Electrical conduction describes the ability of porous media to conduct electrical charges and induced polarization (IP) describes their ability to reversibly store electrical charges. An effective conductivity can be defined as a complex number with frequency-dependent components (i.e., the conductivity is also dispersive). Although IP effects have been observed in frequency- and time-domain electromagnetic (FDEM and TDEM, respectively) data for years, most FDEM and TDEM studies still treat the earth using the conductivity alone (therefore neglecting IP effects). Electromagnetic field data inversion and interpretation require a quantitative three-dimensional modeling with dispersive conductivities, which is still a challenging problem. Using the generic partial-differential-equation solver Comsol Multiphysics's application program interface (API) with Matlab, we have successfully developed three-dimensional FDEM and TDEM modeling with IP effects. Benchmarks are performed using analytical solutions and other numerical techniques. Results with and without IP effects are also compared and analyzed to illustrate the importance of taking IP effects into account. Our modeling could be of great importance in quantitatively studying IP effects in the FDEM and TDEM methods, in developing new field configurations, and also in educational purposes.

Computational Modeling of Particle Hydrodynamics and Charging Process for the Flowable Electrodes of Carbon Slurry

Slurry of activated carbon particles mixed with an aqueous electrolyte solution has been used as “flowable electrode” in a few recent electrochemical systems, e.g., electrochemical flow capacitors (EFCs) for energy storage, and flow-electrode capacitive deionization (FCDI) for water treatment. In these applications, the porous carbon particles with very large specific surface area adsorb ions from the electrolyte and meanwhile store electrical charges when a voltage source is added in the charging process. Under the flow condition, the motion of the particles and their mutual contact form a dynamically varying electrical network for the charge transport through the bulk material. We introduce a novel particle-based computational model using the Stokesian dynamics to simulate the hydrodynamic interaction of the carbon particles and the charge transport. An analogous electrical circuit model is developed by approximating the particles with many interconnected resistor-capacitor units, and the circuit’s topology is temporally changing depending on the instantaneous particle configuration. The Stokesian model and the circuit model are solved simultaneously to study how the hydrodynamic interaction and cluster formation affect the charge transport process of the slurry. The presence of the stationary current collector can be included to incorporate the near-wall effects on particle mobility. In the simulation, we vary the particle concentration as well as the ratio of the particle charging time to the hydrodynamic interaction time. The results shows that the charge transport in the carbon slurry is enhanced by increasing the concentration of the particles and faster particle charging. In addition, cluster formation of the particles plays an important role for the electronic transport process. After scaling, the transient electrical current from the present study generally agrees with that from previous experimental and modeling studies.

Enhancement of the supercapacitive properties of laser deposited graphene-based electrodes through carbon nanotube loading and nitrogen doping.

Several technological routes are being investigated for improving the energy storage capability and power delivery of electrochemical capacitors. In this work, ternary hybrid electrodes composed of conducting graphene/reduced graphene oxide (rGO), which store charge mainly through electric double-layer mechanisms, covered by NiO nanostructures, for adding pseudocapacitance, were fabricated through a matrix assisted pulsed laser evaporation technique. The incorporation of multiwall carbon nanotubes (MWCNTs) provokes an increase of the porosity and thus, a substantial enhancement of the electrodes' capacitance (from 4 to 20 F cm-3 at 10 mV s-1). Volumetric capacitances of 34 F cm-3 were also obtained with electrodes containing just carbon nanotubes coated with NiO nanostructures. Moreover, the use of nitrogen containing precursors (ammonia, urea) for laser-induced N-doping of the nanocarbons also provokes a notable increase of the capacitance. Remarkably, N-containing groups in rGO-MWCNTs mainly add electric double layer charge storage, pointing to an increase of electrode porosity, whereas redox reactions contribute with a minor diffusion fraction. It was also observed that the loading of carbon nanotubes leads to an increase of diffusion-controlled charge storage mechanisms versus capacitive ones in rGO-based electrodes, the opposite effect being observed in graphene electrodes.

The Characteristic of Supercapacitors Circuit as a Future Electrical Energy Storage Media

Battery or accumulator is a general electrical energy storage media. The main disadvantage of the battery is the long duration during charging process, short lifetime and less environment friendly. This is one of the obstacles in the development of electric vehicles. Recently, it has been found an electrical energy storage media that uses capacitor technology. The basic principle of capacitors is similar to a battery, which can store electrical charges. The charging process of capacitor is relatively faster than battery, but the discharging process is also very fast. The advantages of capacitor are not using chemical process, cheap maintenance and longer lifetime than battery. Therefore, the researcher developed supercapacitor. The supercapacitor has bigger and larger capacity than common capacitor. This study aims to find out the performance of some types of supercapacitor circuits during the charging and discharging process.

Unveiling the Effect of the Structure of Carbon Material on the Charge Storage Mechanism in MoS2-Based Supercapacitors.

MoS2 is a 2D material that has been widely used in supercapacitor applications because of its layered structure that provides a large surface area and allows for high electric double-layer charge storage. To enhance the cycling stability and capacitance of MoS2, it is usually mixed with carbon materials. However, the dependence of the charge storage mechanism on the structure of the carbon material is still unclear in literature. Herein, the effect of the structure of the carbon material on the charge storage mechanism in 2H flower-shaped MoS2 is investigated in detail. Specifically, 2H MoS2 was mixed with either 8 nm-diameter carbon nanotubes (CNTs) or graphene nanoflakes (GNFs) in different weight ratios. Also, a composite of MoS2, CNTs, and GNFs (1:1:1) was also studied. The charge storage mechanism was found to depend on the structure and content of the carbon material. Insights into the possible storage mechanism(s) were discussed. The MoS2/CNT/GNF composite showed a predominant pseudocapacitive charge storage mechanism where the diffusion current was ∼89%, with 88.31% of the resulted capacitance being due to faradic processes.

Enhance the electrical conductivity and charge storage of nematic phase by doping 0D photoluminescent graphene was prepared with small organic molecule as a new array quantum dot liquid crystal displays

The E7 Nematic liquid crystal (NLC) doped with Graphene quantum dots (GQDs) have been obtanied by bottom-up approaches to improve thermodynamics and electrochemical properties. The NI phase transition temperature and enthalpy were increased in comparison with the pure E7. The anchoring effect plays a key role in NI phase transition Also, the Ea values was decreased in doped GQDs system comapre to pure E7. The electrical conductivity of the doped GQD system was significantly more than pure E7. GQDs doping does significantly affect the permittivity of the nematic host, it noticeably increases its charge capacitance.

Two‐dimensional π‐conjugated metal‐organic framework with high electrical conductivity for electrochemical sensing

A two‐dimensional π‐conjugated metal‐organic framework (MOF) with long‐range delocalized electrons has been prepared and applied as modified electrode material without further post‐modification. The MOF (Cu3(HHTP)2) is composed of Cu(II) centers and a redox‐active linker (2,3,6,7,10,11‐hexahydroxytriphenylene, HHTP). Compared to most MOFs, Cu3(HHTP)2 displays higher electrical conductivity and charge storage capacity owing to the collective effect of metal ions and aromatic ligands with π–π conjugation. In order to confirm the superior properties of this material, the electrochemical detection of dopamine (DA) was conducted and the satisfactory results were obtained. The currents increase linearly with the concentration of DA in the range 5.0 × 10−8 to 2.0 × 10−4 M with a detection limit of 5.1 nM. Furthermore, Cu3(HHTP)2 presents high selectivity and applicability in serum samples for electrochemical DA sensing. Overall, this material has excellent potential as a promising platform for establishing an MOF‐based electrochemical sensor.

Redox active multi-layered Zn-pPDA MOFs as high-performance supercapacitor electrode material

Metal–organic frameworks (MOFs), which combine organic and inorganic components, are promising materials for energy storage. The conjugated structure of MOFs offers excellent electrical conductivity and charge storage performance. In this study, we introduce Zn-p–phenylenediamine (Zn-pPDA) MOFs for a first time in energy storage devices, and we also use a green and facile synthesis method for the preparation of the materials. Multi-layered Zn-pPDA MOF nanostructures with a thickness of 1–5 μm and a width of ∼20 nm are synthesised using liquid–liquid interfacial reactions. Their MOF complexes are used to fabricate positive electrodes for supercapacitors. The MOF supercapacitors exhibit high energy and power densities of approximately 62.8 Wh/kg and 4500 W/kg, respectively. Additionally, excellent cyclability with ∼96% capacitive retention after 2000 cycles is obtained. We show that the synthesis method can open a new pathway for formulating pPDA-ligand-based MOFs, and that the Zn-pPDA MOF is a highly promising material for future energy storage devices.

Chargeability of Porous Rocks With or Without Metallic Particles

The chargeability of rocks de nes their ability to reversibly store electrical charges at low frequency (typically below a few kHz). We consider the case of an isotropic mixture of metallic particles embedded into a polarizable porous background composed of mineral grains and pore water. The term metallic is here used in a broad sense involving semiconductors (for instance disseminated pyrite or magnetite), semimetals (e.g., graphite), and metals (copper, steel). The chargeability of such a mixture depends on the chargeability of the background material and the volumetric amount of metallic particles. The chargeability of the background material is in turn salinity dependent and is equal to a universal dimensionless number R = 0.08 (ratio between the normalized chargeability and the surface conductivity) at low salinities. It is given by the ratio of two apparent mobilities, which are actually related to the mobility of the Stern and diffuse layers forming the so-called electrical double layer around the mineral grains. This universal number is saturation and temperature independent. The predictive model for the chargeability of the mixture is compared successfully to variety of experimental and eld data. We show that the polarization of dispersed metallic particles is due to the electrodiffusion of the charge carriers inside these particles. This work can be applied to conventional well-log analysis using the dispersion of the electrical conductivity with the frequency in order to determine the formation properties and accounting for the presence of pyrite in some formations. Our conductivity model appears as an extension of the Waxman and Smits seminal model of shaly sands extending this model to determine the chargeability and the effect of pyrite on both the electrical conductivity and the chargeability.

Theoretical Investigation of Metallic Nanolayers For Charge-Storage Applications

We report the first time that metallic homostructure of aluminene (Al) and antimonene (Sb) materials are the promising materials for the electric charge storage as a nanocapacitors. In this work, we have proposed two various phases of capacitor, namely, hexagonal (H) and trigonal (T) phases. Here, we have investigated the electronic properties, visualization of molecular orbitals, van der Waals (vdW) energy between layers, and supercapacitance properties, such as dipole moment (P), charge stored (Qs), energy stored (Es), and capacitance (C). It is found that the Sb bilayer has higher capacitance values than Al bilayer. Instead of that, we have also focused on the various pristine homobilayer of boron (B), carbon (C), silicon (Si), phosphorus (P), gallium (Ga), germanium (Ge), arsenic (As), and indium (In) and heterobilayers of pristine C and Al, pristine C and Sb, pristine C and Si, pristine C and Sn, pristine C and As, and pristine P and Si for H and T phases, respectively, and results are compared with ...

F98. Enhanced muscle evaluation using a novel impedance-electromyography (I-EMG) needle electrode

Introduction A wealth of advantages has made needle electromyography (EMG) the standard, “go-to” clinical test used to evaluate muscle disorders. Nevertheless, EMG has associated technological limitations. For example, EMG only characterizes muscles’ active electrical activity, namely the depolarization of myofibers’ membrane. While clearly valuable, EMG does not provide information about non-electrically active (i.e. passive) properties altered in diseased muscle, the data’s being secondary to these alterations. One example of the relationship between passive and active electrical properties of muscle are the membrane resistance Rm (passive) and the membrane capacitance Cm (passive) of myofibers which determine the propagation velocity of action potentials (active). To date, measuring in vivo Rm, Cm and EMG using the same needle electrode was not possible. Methods We created a novel needle electrode integrating impedance and EMG technologies with the capability to measure simultaneously both passive (impedance) and active (EMG) electrical properties of muscle. We then conducted in vivo measurements in five C57BL/6 J wild-type mice at 6 weeks of age (The Jackson Lab, Bar Harbor, ME). Recordings were made in the gastrocnemius muscle with the animals mildly sedated (isoflurane 0.5–1% delivered by nosecone) while providing gentle stimuli to the hind limbs such that the animals repeatedly withdrew the limb. Results With our device, we were able to detect synchronized reductions in Rm and Cm with EMG activation. Rm is the inverse of the myofiber permeability; the higher the permeability, the lower Rm and vice versa. Cm is the ability of myofibers to store electrical charge. This result indicates the possibility to detect real-time passive and active electrical changes of myofibers during activity, which can provide additional information to help with the diagnosis. Conclusion Impedance technology embedded into an EMG needle electrode can greatly extend the diagnostic capabilities of needle EMG technology. Needle I-EMG could serve as a new bedside tool to assess muscle condition without increasing the complexity or duration of the standard needle EMG. Identifying changes in membrane properties of myofibers could serve as a convenient tool to assist with primary diagnosis or the impact of the therapies in a variety of conditions, including the denervating conditions and myotonic disorders.

Pemanfaatan karbon aktif dari sabut kelapa sebagai elektroda superkapasitor

Pada penelitian ini, karbon aktif berbasis sabut kelapa telah digunakan untuk pembuatan superkapasitor. Uji daya jerap iodin dilakukan untuk mengukur tingkat serapan pori sampel karbon aktif yang ukurannya relatif kecil (mikropori). Karakteristik bahan karbon aktif yang meliputi struktur kristal dan morfologi permukaannya diuji dengan menggunakan SEM dan XRD. Bahan elektroda dengan komposisi (Karbon aktif : PVDF = 9:1 (b/b)), kolektor arus dan separator telah dirangkai untuk diuji kinerjanya sebagai perangkat penyimpanan muatan listrik. Metode siklik voltametri digunakan untuk melihat kinerja perangkat superkapasitor dengan mengukur nilai kapasitansi spesifik berdasarkan kurva voltammogram. Berdasarkan hasil perhitungan nilai kapasitansi spesifik diperoleh nilai kapasitansi spesifik tertinggi pada superkapasitor dengan elektroda sabut kelapa yang diaktivasi dengan steam 50 mL/bar yaitu sebesar 50.73 F/g.

Stainless Steel-Based Bioanodes for Applications in Bioelectrochemical Systems

The majority of studies focusing on bioelectrochemical systems (BES) report the utilization of carbon-based electrodes. However, in order to overcome the limitations related to the scale-up of Microbial Fuel Cells (MFC) and Microbial Electro Synthesis (MES) cells technologies, the utilization of metal-based electrodes need to be considered due to their conductivity, cost and robustness. Stainless steel fiber felts (SSFF) as bioanode material for BES applications was investigated in this study. The unmodified SSFF was tested alongside with electrodes modified with reduced graphene oxide (rGO), magnetite nanoparticles (Fe3O4), manganese oxide (MnO2) and flame-oxidation (FO). The performance of the metal-based electrodes as bioanodes were investigated in half-cells in terms of stability and current densities. In addition, the impact of the capacitance of the abiotic electrode materials on the performance of the bioanodes and MFCs was evaluated (Fig. a), especially to assess how these materials can increase the energy harvested compared to non-capacitive bioanodes. The results showed that the stainless steel- based electrodes studied are competitive alternatives to the carbon-based electrodes. Current densities recorded in half-cells were 1.96, 1.95 and 2.26 mA/cm2 for FO-MnO2-SS, rGO-SS and carbon cloth, respectively. In addition, charge/discharge experiments carried out with the bioanodes developed (Fig. c) showed that the modified SSFF electrodes allow the storage of electrical charge from the biofilm to the capacitive layers of the electrodes when cells are left at open circuit potential (OCP). These results demonstrate the potential of these materials for energy generation and storage applications from waste in BES. Figure 1