Total Amount Of Charge Research Articles

Characteristics of a Kapton triboelectric nanogenerator-based touch button’s voltage output

Since the Triboelectric Nanogenerator (TENG) was invented in 2012, Its potential in the area of energy generation and self-powered sensors has been very obvious, one of the uses of TENGs is as self-powered touch buttons, which are usually single-electrode TENGs, single-electrode TENGs are made of a layer of a material (which is to be triboelectrified) attached to an electrode which is connected to an electrical ground or a reference electrode, in this study, a cheap triboelectric button was made with Kapton and tested in contact and separation with aluminum and a human finger while varying parameters such as the grounding state of the person touching the button and the touch force. It was found that the tested button gave easily detectable signals if touched with aluminum foil or a human finger, however, the signal to noise ratio was low in case of being pressed by a human finger with the person touching the button also being grounded, this is due to an increased capacitance between the person pressing the button and the environment, it was also found that the output voltage of the TENG increased after pressing it lots of times consecutively due to an increased amount of total charge on the Kapton layer when pressed at slightly different spots, these output characteristics could help in better integration of such buttons in human-machine interaction applications.

Simulation of Anodic Current and Optimization of the Fitting Equation and the Fitting Algorithm during Constant Voltage Anodization

To investigate the formation mechanism of anodization and to clarify the relationship between the reaction process and the actual structure, we fitted the current density–time curve based on MATLAB. A time-varying function C(t) is introduced to optimize the total current fitting equation used to describe the constant voltage anodization process, which makes the equation more in line with the real reaction process based on the kinetic model of ionic and electronic current. Besides, a new fitting algorithm is developed based on the trust region method, which can effectively improve the fitting effect through iteration. In our work, the initial values of the parameters in the equation were calculated, and finally, the fitting degree of the constant voltage anodization under 40, 50, and 60 V was improved to 0.9842, 0.9693, and 0.9305, respectively. According to the new equation, the fitting degree of the total amount of charge transferred by ions during the reaction and the volume of oxides according to a proportional function can reach 0.9972.

Formulation for the Performance Analysis of a Lithium-Carbon Monofluoride Cell

The formulation presented in this paper is for the performance analysis of a primary lithium-carbon monofluoride cell. The formulation can also be used to compute the theoretical cell open-circuit voltage; the fractional conversion of the limiting reactant, carbon monofluoride and hence, the cell fractional state-of-charge; total amount of charge required to be involved for the complete utilization of the cell cathode active material, carbon monofluoride as well as the transient specific amount of charge involved; the ratio of the thermal energy production to the electric energy production; and the rate of heat exchange between the cell exterior surface and its surroundings required for the determination of the cell average temperature.

Investigation of internal gas pressure and internal temperature of cylindrical Li-ion cells to study thermodynamical and mechanical properties of hard case battery cells

This study is the first to measure the relationship between gas pressure, internal gas temperature and state of charge of cylindrical Li-ion battery cells. For this purpose, a new, simple and affordable setup for in-situ investigation of internal gas pressure and internal temperature of commercial cylindrical Li-ion cells is designed and tested. Setups to investigate the internal gas pressure have so far only been performed on pouch and prismatic cells or require complex and expensive measurement equipment. In this work, the mechanical effects of an increasing gas pressure in cylindrical Li-ion cells are addressed for the first time. It is shown that the measurement of internal gas pressure and internal temperature over multiple charging and discharging cycles is possible. Measurements at different current rates show the dependency of the gas pressure to the total amount of charge transferred and the temperature of the cell. The pressure, which depends on the degree of lithiation of the electrodes, relaxes after the Li-ion cells have been exposed to a high current. Additionally, phases of the phase transition are visible via differential capacity analysis. The differential pressure analysis shows an equivalent trend to the differential capacity. Thus demonstrates the predominant phase transformations, namely the restructuring of lithiated graphite, the lithiation of silicon, and the phase transformation of nickel–cobalt–manganese (NCM) oxide. These effects contribute significantly to the pressure change, as they cause electrode expansion, which results in a reduction of the gas volume of the Li-ion cell, leading to an increase in pressure.

Far-Field Electrostatic Signatures of Macromolecular 3D Conformation.

In solution as in vacuum, the electrostatic field distribution in the vicinity of a charged object carries information on its three-dimensional geometry. We report on an experimental study exploring the effect of molecular shape on long-range electrostatic interactions in solution. Working with DNA nanostructures carrying approximately equal amounts of total charge but each in a different three-dimensional conformation, we demonstrate that the geometry of the distribution of charge in a molecule has substantial impact on its electrical interactions. For instance, a tetrahedral structure, which is the most compact distribution of charge we tested, can create a far-field effect that is effectively identical to that of a rod-shaped molecule carrying half the amount of total structural charge. Our experiments demonstrate that escape-time electrometry (ETe) furnishes a rapid and facile method to screen and identify 3D conformations of charged biomolecules or molecular complexes in solution.

The influence of leader charge on current intensity and spectral characteristics of return strokes

The characteristic parameters reflecting the current intensity in lightning return stroke discharge channel are the primary concern in the field of lightning physics research and protection. Based on the spectrum and the corresponding fast electric field change waveforms for 9 natural cloud-to-ground lightnings including multiple return strokes, part of the total charge quantity in the corresponding leader channel was estimated by different methods, and its influence on current intensity and spectral characteristics of return strokes were further investigated. The results show, that for the same lightning, part of the leader charge quantity estimated by using the two methods according to the electric field change waveforms is in good agreement with the electron number per channel length calculated by basing on leader spectrum, it is also found that part of the neutralized leader charges is positively correlated with the peak current, the radius of the core current-carrying channel and the total intensity of ionic lines in the spectrum. These results mean that the current intensity of the lightning return stroke discharge mainly depends on the charge quantity being stored in the previous leader process. The radius of the core current-carrying channel is closely related to the current intensity. Moreover, the intensity of the ionic line in the spectrum can directly reflect the current intensity, which is an ideal observable parameter for studying the current characteristics.

(Digital Presentation) Water Oxidation in Acid with Earth-Abundant Electrocatalysts

Green hydrogen production from renewable energy can help overcome difficult energy challenges worldwide. It can help decarbonize hard-to-abate sectors such as steel, chemicals, and ammonia fertilizer. Polymer Electrolyte Membrane (PEM) water electrolyzer serves as a promising technology when coupled with the fluctuating renewable energies for hydrogen production, with the advantages of fast response, dynamic operation, and excellent overload capacity. However, the only technically feasible anode catalysts for PEM are built on scarce iridium and require more than 40 years of annual production for 1 TW-scale. The scarce metal iridium has become a bottleneck limiting the scale development of PEM water electrolysis technology. Therefore, identifying earth-abundant catalysts with high activity and acid tolerance is essential to realizing large-scale hydrogen production via water electrolysis. Various 3d transition metals have been investigated as potential OER catalysts. In 2019, we reported how manganese oxide shows exceptional stability among earth-abundant materials for oxygen evolution reaction (OER) in acid. At the time, non-precious metal catalysts had difficulty maintaining activity for more than a week at 10 mA cm-2. In comparison, manganese oxide (γ-MnO2) was able to electrolyze water for over 11 months at 10 mA cm-2. This was made possible by identifying a stable potential window for γ-MnO2 in which the OER can be catalyzed efficiently while simultaneously suppressing deactivation pathways. After that, a binary spinel oxide catalyst (Co2MnO4) was synthesized by mixing stable manganese with active cobalt using a thermal decomposition method. Cobalt oxides were shown to be active for the OER but unstable in acid. By incorporating Mn into the Co3O4 spinel lattice, the lifetime was extended by two orders of magnitude while maintaining the activity. The water electrolysis with Co2MnO4 in acid can be sustained over 1500 hours at 200 mA cm-2. The activation barrier of the obtained spinel Co2MnO4 is comparable to state-of-the-art iridium oxides, which are reported to have activation energies of 25-30 kJ mol-1 in acidic conditions. The catalyst dissolution was experimentally analyzed by spectroscopy methods. It is clarified that the tetrahedral Co is the preferable dissolution site and the dissolution rate is suppressed in Co2MnO4 compared to Co3O4, resulting in outstanding stability. The active working time of Co2MnO4 as a function of current density for the OER reaction and other earth-abundant electrocatalysts reported in the literature were summarized. The marked improvement of the activity and stability in acid makes cobalt manganese spinel materials an intriguing candidate for non-noble metal water electrolysis. Acknowledgments: This work was supported by the New Energy and Industrial Technology Development Organization (NEDO). Figure caption: Long-term stability of Co2MnO4 during the OER in acid. a, Time dependence of the electrochemical potential necessary to perform OER at 100, 200, 500 and 1,000 mA cm-2 geo in H2SO4 (pH 1) and H3PO4 (pH 1), respectively. The stabilities of Co3O4 and γ-MnO2 in H2SO4 (pH 1) are shown for comparison. All the experiments were performed at 25 °C using an FTO substrate except for curve IX, for which a Pt/Ti mesh was used. b, A comparison of the stability of Co2MnO4 with Co3O4 and other Earth-abundant OER catalysts reported in the literature12-28 (Please refer Nat Catal 5, 109–118 (2022)) (upwards and downwards triangles represent lifetime and operation time, respectively). The measurements were performed under acidic conditions. Data points with roman numerals (I to XI) correspond to curves I to XI in a. Diagonal lines indicate the total amount of charge transferred before deactivation. Only studies that report stability at pH < 3 were included in the literature survey. Figure 1

Numerical Simulation on the Effects of the Horizontal Charge Distribution on Lightning Types and Behaviors

AbstractPrevious studies have generally acknowledged that lightning propagation behaviors and lightning types are closely related to the unbalanced charge amount and vertical stratification of charge structure. In this study, the total charge amount remains nearly balanced (±5%) between the adjacent charge regions where discharges initiate to avoid the interference of a total charge imbalance. Significant influences on the leader propagation tendency and lightning type are revealed by investigating different horizontal charge distribution features emphasizing on the effects of the charge distribution uniformity and the relative position of the high‐density charge center. Sensitivity experiments are performed with a two‐dimensional stochastic discharge model and demonstrate the following. Under a symmetric charge distribution, the more uniform charge distribution is conducive for leaders propagate horizontally; the charge being more compact in the central zone is favorable for vertical extension of leaders. Under an asymmetric charge distribution, a horizontal shift of high‐density charge center is conducive to the extension of leaders in the offset direction. Different charge distributions will change the electrical energy of charge regions resulting in various lightning behaviors. Various charge distributions provide favorable conditions for some lightning flashes (including positive cloud‐to‐ground flashes [PCG], “bolt‐from‐the‐blue” [BFB] flashes and gigantic jets). PCGs are favorably triggered with the more compact upper positive charge (P) and more uniform middle negative charge (N), and BFB discharges can be triggered between the P and N regions when the high‐density charge center in the P region is horizontally shifted. A possible method is provided to explain various lightning behaviors.

4.5: A Low Power Consumption Display Solution Based on The Charge Sharing Technology

With the development of display technology, low power consumption of display device is popular. To drive the display panel in the unit, each sub‐pixel in the panel needs to be charged. The more amount of charge for each sub‐pixel, the greater power consumption is needed for the display panel to display images. This paper provides a method to drive the display panel, which can reduce each sub‐pixel's total charge amount in the display panel. In this way, it can reduce the power consumption needed for driving the panel to display images.

An Extrinsic Faradaic Layer on CuSn for High-Performance Electrocatalytic CO 2 Reduction

An Extrinsic Faradaic Layer on CuSn for High-Performance Electrocatalytic CO ₂ Reduction

Collapse of four-arm stars polyelectrolyte brushes under an electric field in the presence of trivalent salt coions

Langevin dynamics simulations were conducted to study the collapse of grafted partially charged 4-arm star chains onto the oppositely charged grafting electrode in the presence of trivalent salt coions. Simulation results reveal that the average charge fraction of the grafted star chains and the salt concentration play critical roles in the competitive adsorption of charged monomers and trivalent salt coions onto the oppositely charged electrode. For grafted star chains with relatively high charge fraction, charged monomers are the dominant species collapsing on the oppositely charged electrode with the emergence of charge reversal on the grafting electrode. At a low charge fraction such that the total amount of charges on a grafted star molecule is comparable to that of a trivalent salt coion, trivalent salt coions absorb more strongly onto the electrode than grafted stars even at very low salt concentration. It is found that at relatively low charge fraction of star chains, the addition of trivalent salt coions does not lead to charge overcompensation of the surface charges on the grafting electrode. The stretching of star brushes under an electric field in the presence of trivalent salt coions was also briefly investigated.

Research on Charge Accumulation Characteristics by PEA Method and Q(t) Method

This article reports the evaluation system of the insulating properties based on the pulsed electro-acoustic (PEA) method and the current integration charge $Q(t)$ method. According to the basic principles of the methods, the relationship between the charge ratio and dielectric relaxation time in $Q(t)$ data is first derived, by which a new method is proposed to calculate the material conductivity. By further analyzing the charge results of different materials, it is pointed out that the PEA method focuses on the related characteristics of the net charge distribution captured by deep traps, while the $Q(t)$ method reflects the changing process of the total charge amount and related characteristics. No single method can completely analyze all the charge characteristics of the material, and thus the necessity of the combination of the two methods is determined. Meanwhile, based on the theoretical derivation and experimental results, it is indicated that when the charge ratio of $Q(t)$ data exceeds 2, the electrical state inside the sample basically stabilizes. At this stage, the distorted electric field can be analyzed by the PEA method, and the $Q(t)$ method can calculate the leakage current, dielectric relaxation time, and conductivity. Therefore, the combination of the two methods can provide a more reasonable assessment for the insulation property and state.

Improved 4H-SiC UMOSFET with super-junction shield region* *Project supported by the National Natural Science Foundation of China (Grant Nos. 61774052 and 61904045), the Youth Foundation of the Education Department of Jiangxi Province, China (Grant No. GJJ191154), and the Youth Foundation of Ping Xiang University, China (Grant No. 2018D0230).

This article investigates an improved 4H-SiC trench gate metal–oxide–semiconductor field-effect transistor (MOSFET) (UMOSFET) fitted with a super-junction (SJ) shielded region. The modified structure is composed of two n-type conductive pillars, three p-type conductive pillars, an oxide trench under the gate, and a light n-type current spreading layer (NCSL) under the p-body. The n-type conductive pillars and the light n-type current spreading layer provide two paths to and promote the diffusion of a transverse current in the epitaxial layer, thus improving the specific on-resistance (R on,sp). There are three p-type pillars in the modified structure, with the p-type pillars on both sides playing the same role. The p-type conductive pillars relieve the electric field (E-field) in the corner of the trench bottom. Two-dimensional simulation (silvaco TCAD) indicates that R on,sp of the modified structure, and breakdown voltage (V BR) are improved by 22.2% and 21.1% respectively, while the maximum figure of merit () is improved by 79.0%. Furthermore, the improved structure achieves a light smaller low gate-to-drain charge (Q gd) and when compared with the conventional UMOSFET (conventional-UMOS), it displays great advantages for reducing the switching energy loss. These advantages are due to the fact that the p-type conductive pillars and n-type conductive pillars configured under the gate provide a substantial charge balance, which also enables the charge carriers to be extracted quickly. In the end, under the condition of the same total charge quantity, the simulation comparison of gate charge and OFF-state characteristics between Gauss-doped structure and uniform-doped structure shows that Gauss-doped structure increases the V BR of the device without degradation of dynamic performance.

Modeling and Analysis of Capacitive Relaxation Quenching in a Single Photon Avalanche Diode (SPAD) Applied to a CMOS Image Sensor.

We present an analysis of carrier dynamics of the single-photon detection process, i.e., from Geiger mode pulse generation to its quenching, in a single-photon avalanche diode (SPAD). The device is modeled by a parallel circuit of a SPAD and a capacitance representing both space charge accumulation inside the SPAD and parasitic components. The carrier dynamics inside the SPAD is described by time-dependent bipolar-coupled continuity equations (BCE). Numerical solutions of BCE show that the entire process completes within a few hundreds of picoseconds. More importantly, we find that the total amount of charges stored on the series capacitance gives rise to a voltage swing of the internal bias of SPAD twice of the excess bias voltage with respect to the breakdown voltage. This, in turn, gives a design methodology to control precisely generated charges and enables one to use SPADs as conventional photodiodes (PDs) in a four transistor pixel of a complementary metal-oxide-semiconductor (CMOS) image sensor (CIS) with short exposure time and without carrier overflow. Such operation is demonstrated by experiments with a 6 µm size 400 × 400 pixels SPAD-based CIS designed with this methodology.

Investigation of the time interval of plasma generation for a high repetition rate laser ion source.

To apply a laser ion source that generates a high-intensity pulsed beam to high-dose applications, such as ion implantation, a high repetition rate operation with a short pulse interval is required. However, when the pulse interval is shortened, there is a concern that a plasma, which is different from a single pulse plasma generation, may be formed due to the interaction between the preceding and following pulses. We investigated the time interval in which plasma pulses are generated without pulse-to-pulse interaction using a laser ion source with two lasers. In the experiment, a graphite target was irradiated by two laser beams (1064-nm wavelengths) with the same pulse widths (5.4 ns) and energies (15 mJ, 30 mJ, and 45 mJ) at different time intervals ranging from 1000 μs to 0 µs, and the time integrated value corresponding to the total charge amount was calculated from the measured time-of-flight signal of the generated carbon ion current. It was observed that the total charge did not change when the time interval was as low as approximately 100 µs, and the total charge rapidly decreased when the time interval was below approximately 100 µs. Thus, it was determined that the interaction occurs within a time interval of approximately 100 µs.

Numerical Investigation of Downhole Perforation Pressure for a Deepwater Well

During the production of deepwater wells, downhole perforation safety is one of the key technical problems. The perforation fluctuating pressure is an important factor in assessing the wellbore safety threat. Due to difficulty in describing the downhole perforation pressure by using the existing empirical correlations, a prediction model based on data fitting of a large number of numerical simulations has been proposed. Firstly, a numerical model is set up to obtain the dynamic data of downhole perforation, and the exponential attenuation model of perforation pressure in the wellbore is established. Secondly, a large number of numerical simulations have been carried out through orthogonal test design. The results reveal that the downhole perforation pressure is logarithmic to the total charge quantity, increases linearly to the wellbore initial pressure, shows an exponential relationship with downhole effective volume for perforation, and has a power relationship with the thickness of casing and cement as well as formation elastic modulus. Thirdly, the prediction of perforation peak pressure at different positions along the wellbore agrees well with the field measurement within a 10% error. Finally, the results of this study have been applied in the field case, and an optimization scheme for deepwater downhole perforation safety has been put forward.

Effects of 3-dimensional porous graphene oxide network on solid-state sensors

The three-dimensional porous graphene networks (3DPGN) is recently developed graphene material. They possess both the highest mobility of graphene material and the increased surface areas possessed by the porous micro 3D structure. These powerful graphene materials have been exploited to be super-capacitors, batteries, biomedical sensors and other bioengineering applications. In this work, their foundational functions for solid-state sensors are examined with the use of 3D porous graphene oxide (GO) network (3DPGON) as proof-of-concept. Its effects on the classical glass-chemical-electrodes (GCEs) and the pH-sensing light addressable potentiometric sensor are examined, respectively. It is found that the peak currents of 3DPGON film coated GCEs are increased with the increased 3DPGON, while the LAPS’ responding for pH are lowered. The increased currents of GCE are attributed to the enhanced electron transfer (ET) by GO and the enlarged surface area by micro-porous structure. While the lowered pH responding of LAPS is caused by the screen effect induced by 3DPGON coating. In conclusion, the decoration of 3DPGON on solid-state sensors should be considered seriously, it can enhance the total amount of charges exchanging at the liquid-solid interface which is propitious to forming solid-state sensor, but the drawback of 3DPGON modification does exist because the original surface sensing sites may be covered.

Application of a Novel Measurement Setup for Characterization of Graphene Microelectrodes and a Comparative Study of Variables Influencing Charge Injection Limits of Implantable Microelectrodes.

Depending on their use, electrodes must have a certain size and design so as not to compromise their electrical characteristics. It is fundamental to be aware of all dependences on external factors that vary the electrochemical characteristics of the electrodes. When using implantable electrodes, the maximum charge injection capacity (CIC) is the total amount of charge that can be injected into the tissue in a reversible way. It is fundamental to know the relations between the characteristics of the microelectrode itself and its maximum CIC in order to develop microelectrodes that will be used in biomedical applications. CIC is a very complex measure that depends on many factors: material, size (geometric and effectiveness area), and shape of the implantable microelectrode and long-term behavior, composition, and temperature of the electrolyte. In this paper, our previously proposed measurement setup and automated calculation method are used to characterize a graphene microelectrode and to measure the behavior of a set of microelectrodes that have been developed in the Fraunhofer Institute for Biomedical Engineering (IBMT) labs. We provide an electrochemical evaluation of CIC for these microelectrodes by examining the role of the following variables: pulse width of the stimulation signal, electrode geometry and size, roughness factor, solution, and long-term behavior. We hope the results presented in this paper will be useful for future studies and for the manufacture of advanced implantable microelectrodes.

Space/Interface Charge Analysis of the Multi-Layer Oil Gap and Oil Impregnated Pressboard Under the Electrical-Thermal Combined Stress

In oil-paper insulation systems, it is easy to accumulate space/interface charge under a direct current (DC) electrical field. At present, direct measurement of space/interface charge for a thick multi-layer insulation system is not possible. It is necessary to study the multi-layer oil-paper insulation system via simulation method. In this paper, the space/interface charge simulation based on the bipolar charge transport model and a simulation parameter using FEM for the multi-layer oil–paper insulation system was proposed. The influence of electrical field strength, temperature, and the combined influence of the electrical field strength and temperature on the space/interface charge behaviors were analyzed, respectively. A new method for calculating the space/interface charge density and the total charge quantity of the multi-layer oil-paper insulation under the combined action of electrical field strength and temperature was presented. Results show that the interface charge density absolute value and the total charge quantity at steady state both increases with the electrical field strength and temperature in an exponential way, respectively. Besides, temperature has a more significant influence on the charge density and the total charge quantity than the electrical field strength. The electrical field strength–temperature shifting factor αT’ was introduced for the translation of the charge density curves or the total charge quantity curves to construct the charge density main curve or the total charge quantity main curve under the combined action of electrical field strength and temperature. The equations for calculating the charge density or the total charge quantity of the multi-layer oil-paper insulation was provided, which could be used to calculate the charge density or the total charge quantity under the combined action of electrical field strength and temperature.

Effects of Electrolyte Volume and Salt Concentration on SEI Stability and Cycling Performance of Lithium Metal Anodes

In order to nearly triple the driving range of electric vehicles (EV), the US Department of Energy has set a goal of achieving an energy density of 500 Wh kg-1 in EV batteries, and the use of a lithium metal anode is essential to reaching this goal.(1) A key consideration in reducing the weight (and thereby increasing the energy density) of a lithium metal battery is its electrolyte, with the volume of electrolyte used and its salt concentration both affecting the overall battery weight. Unlike with the currently-used graphite anode, the highly reactive surface of a lithium anode varies widely from cycle to cycle, which irreversibly consumes the finite amount of electrolyte and causes lithium metal to suffer from low Coulombic efficiency. To account for Coulombic inefficiency caused by electrolyte depletion, many researchers "flood" their cells with electrolyte to prolong cycle life. However, commercial batteries will require smaller amounts of electrolyte in order to achieve weight and energy density goals. Additionally, the components that make up the solid electrolyte interphase (SEI) layer on the surface of the lithium metal are soluble in the electrolyte to varying degrees. As the more soluble components selectively dissolve into the electrolyte, reparative SEI grows in its place. During non-uniform lithium plating, new SEI also forms over the freshly-exposed surface area. Both of these processes consume more of the limited electrolyte. Factors such as the volume of electrolyte used and its salt concentration affect the stability of the SEI against dissolution while also altering the composition of the SEI that forms, which can have further impacts on cell performance. Here, three electrochemically-measurable factors are used to examine the stability of the SEI: formation rate (the rate at which the SEI forms or repairs itself each cycle), degradation rate (the rate at which the SEI dissolves or degrades during rest periods), and formation capacity (the total amount of charge dedicated to forming a stable SEI). Each of these factors will affect the consumption of electrolyte and ultimately dictate the amount of excess electrolyte needed to account for these losses. Three electrolyte volumes and three salt concentrations were chosen to examine the impact that these parameters have on SEI stability and Coulombic efficiency in the standard 3:7 ethylene carbonate/ethyl methyl carbonate with 2 % vinylene carbonate electrolyte with LiPF6 salt. Higher volumes of electrolyte resulted in increased SEI formation rates and dissolution rates. Differences in these factors at low and high salt concentrations were found to result from a change in the type of SEI that formed. References Battery500 Consortium to Spark EV Innovations: Pacific Northwest National Laboratory-led, 5-year $50M effort seeks to almost triple energy stored in electric car batteries, in Office of Technology Transitions Energy.gov (2016).