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About: Capacitance is a(n) research topic. Over the lifetime, 69666 publication(s) have been published within this topic receiving 1039557 citation(s). The topic is also known as: electrostatic capacity & electric capacitance. more


Open accessJournal ArticleDOI: 10.1126/SCIENCE.1200770
Yanwu Zhu1, Shanthi Murali1, Meryl D. Stoller1, K. J. Ganesh1  +9 moreInstitutions (3)
24 Jun 2011-Science
Abstract: Supercapacitors, also called ultracapacitors or electrochemical capacitors, store electrical charge on high-surface-area conducting materials. Their widespread use is limited by their low energy storage density and relatively high effective series resistance. Using chemical activation of exfoliated graphite oxide, we synthesized a porous carbon with a Brunauer-Emmett-Teller surface area of up to 3100 square meters per gram, a high electrical conductivity, and a low oxygen and hydrogen content. This sp 2 -bonded carbon has a continuous three-dimensional network of highly curved, atom-thick walls that form primarily 0.6- to 5-nanometer-width pores. Two-electrode supercapacitor cells constructed with this carbon yielded high values of gravimetric capacitance and energy density with organic and ionic liquid electrolytes. The processes used to make this carbon are readily scalable to industrial levels. more

Topics: Supercapacitor (60%), Carbon (59%), Graphite oxide (58%) more

4,976 Citations

BookDOI: 10.1002/0471716243
04 Apr 2005-
Abstract: Preface. Preface to the First Edition. Contributors. Contributors to the First Edition. Chapter 1. Fundamentals of Impedance Spectroscopy (J.Ross Macdonald and William B. Johnson). 1.1. Background, Basic Definitions, and History. 1.1.1 The Importance of Interfaces. 1.1.2 The Basic Impedance Spectroscopy Experiment. 1.1.3 Response to a Small-Signal Stimulus in the Frequency Domain. 1.1.4 Impedance-Related Functions. 1.1.5 Early History. 1.2. Advantages and Limitations. 1.2.1 Differences Between Solid State and Aqueous Electrochemistry. 1.3. Elementary Analysis of Impedance Spectra. 1.3.1 Physical Models for Equivalent Circuit Elements. 1.3.2 Simple RC Circuits. 1.3.3 Analysis of Single Impedance Arcs. 1.4. Selected Applications of IS. Chapter 2. Theory (Ian D. Raistrick, Donald R. Franceschetti, and J. Ross Macdonald). 2.1. The Electrical Analogs of Physical and Chemical Processes. 2.1.1 Introduction. 2.1.2 The Electrical Properties of Bulk Homogeneous Phases. Introduction. Dielectric Relaxation in Materials with a Single Time Constant. Distributions of Relaxation Times. Conductivity and Diffusion in Electrolytes. Conductivity and Diffusion-a Statistical Description. Migration in the Absence of Concentration Gradients. Transport in Disordered Media. 2.1.3 Mass and Charge Transport in the Presence of Concentration Gradients. Diffusion. Mixed Electronic-Ionic Conductors. Concentration Polarization. 2.1.4 Interfaces and Boundary Conditions. Reversible and Irreversible Interfaces. Polarizable Electrodes. Adsorption at the Electrode-Electrolyte Interface. Charge Transfer at the Electrode-Electrolyte Interface. 2.1.5 Grain Boundary Effects. 2.1.6 Current Distribution, Porous and Rough Electrodes- the Effect of Geometry. Current Distribution Problems. Rough and Porous Electrodes. 2.2. Physical and Electrochemical Models. 2.2.1 The Modeling of Electrochemical Systems. 2.2.2 Equivalent Circuits. Unification of Immitance Responses. Distributed Circuit Elements. Ambiguous Circuits. 2.2.3 Modeling Results. Introduction. Supported Situations. Unsupported Situations: Theoretical Models. Unsupported Situations: Equivalent Network Models. Unsupported Situations: Empirical and Semiempirical Models. Chapter 3. Measuring Techniques and Data Analysis. 3.1. Impedance Measurement Techniques (Michael C. H. McKubre and Digby D. Macdonald). 3.1.1 Introduction. 3.1.2 Frequency Domain Methods. Audio Frequency Bridges. Transformer Ratio Arm Bridges. Berberian-Cole Bridge. Considerations of Potentiostatic Control. Oscilloscopic Methods for Direct Measurement. Phase-Sensitive Detection for Direct Measurement. Automated Frequency Response Analysis. Automated Impedance Analyzers. The Use of Kramers-Kronig Transforms. Spectrum Analyzers. 3.1.3 Time Domain Methods. Introduction. Analog-to-Digital (A/D) Conversion. Computer Interfacing. Digital Signal Processing. 3.1.4 Conclusions. 3.2. Commercially Available Impedance Measurement Systems (Brian Sayers). 3.2.1 Electrochemical Impedance Measurement Systems. System Configuration. Why Use a Potentiostat? Measurements Using 2, 3 or 4-Terminal Techniques. Measurement Resolution and Accuracy. Single Sine and FFT Measurement Techniques. Multielectrode Techniques. Effects of Connections and Input Impedance. Verification of Measurement Performance. Floating Measurement Techniques. Multichannel Techniques. 3.2.2 Materials Impedance Measurement Systems. System Configuration. Measurement of Low Impedance Materials. Measurement of High Impedance Materials. Reference Techniques. Normalization Techniques. High Voltage Measurement Techniques. Temperature Control. Sample Holder Considerations. 3.3. Data Analysis (J. Ross Macdonald). 3.3.1 Data Presentation and Adjustment. Previous Approaches. Three-Dimensional Perspective Plotting. Treatment of Anomalies. 3.3.2 Data Analysis Methods. Simple Methods. Complex Nonlinear Least Squares. Weighting. Which Impedance-Related Function to Fit? The Question of "What to Fit" Revisited. Deconvolution Approaches. Examples of CNLS Fitting. Summary and Simple Characterization Example. Chapter 4. Applications of Impedance Spectroscopy. 4.1. Characterization of Materials (N. Bonanos, B. C. H. Steele, and E. P. Butler). 4.1.1 Microstructural Models for Impedance Spectra of Materials. Introduction. Layer Models. Effective Medium Models. Modeling of Composite Electrodes. 4.1.2 Experimental Techniques. Introduction. Measurement Systems. Sample Preparation-Electrodes. Problems Associated With the Measurement of Electrode Properties. 4.1.3 Interpretation of the Impedance Spectra of Ionic Conductors and Interfaces. Introduction. Characterization of Grain Boundaries by IS. Characterization of Two-Phase Dispersions by IS. Impedance Spectra of Unusual Two-phase Systems. Impedance Spectra of Composite Electrodes. Closing Remarks. 4.2. Characterization of the Electrical Response of High Resistivity Ionic and Dielectric Solid Materials by Immittance Spectroscopy (J. Ross Macdonald). 4.2.1 Introduction. 4.2.2 Types of Dispersive Response Models: Strengths and Weaknesses. Overview. Variable-slope Models. Composite Models. 4.2.3 Illustration of Typical Data Fitting Results for an Ionic Conductor. 4.3. Solid State Devices (William B. Johnson and Wayne L. Worrell). 4.3.1 Electrolyte-Insulator-Semiconductor (EIS) Sensors. 4.3.2 Solid Electrolyte Chemical Sensors. 4.3.3 Photoelectrochemical Solar Cells. 4.3.4 Impedance Response of Electrochromic Materials and Devices (Gunnar A. Niklasson, Anna Karin Johsson, and Maria Stromme). Introduction. Materials. Experimental Techniques. Experimental Results on Single Materials. Experimental Results on Electrochromic Devices. Conclusions and Outlook. 4.3.5 Time-Resolved Photocurrent Generation (Albert Goossens). Introduction-Semiconductors. Steady-State Photocurrents. Time-of-Flight. Intensity-Modulated Photocurrent Spectroscopy. Final Remarks. 4.4. Corrosion of Materials (Digby D. Macdonald and Michael C. H. McKubre). 4.4.1 Introduction. 4.4.2 Fundamentals. 4.4.3 Measurement of Corrosion Rate. 4.4.4 Harmonic Analysis. 4.4.5 Kramer-Kronig Transforms. 4.4.6 Corrosion Mechanisms. Active Dissolution. Active-Passive Transition. The Passive State. 4.4.7 Point Defect Model of the Passive State (Digby D. Macdonald). Introduction. Point Defect Model. Electrochemical Impedance Spectroscopy. Bilayer Passive Films. 4.4.8 Equivalent Circuit Analysis (Digby D. Macdonald and Michael C. H. McKubre). Coatings. 4.4.9 Other Impedance Techniques. Electrochemical Hydrodynamic Impedance (EHI). Fracture Transfer Function (FTF). Electrochemical Mechanical Impedance. 4.5. Electrochemical Power Sources. 4.5.1 Special Aspects of Impedance Modeling of Power Sources (Evgenij Barsoukov). Intrinsic Relation Between Impedance Properties and Power Sources Performance. Linear Time-Domain Modeling Based on Impedance Models, Laplace Transform. Expressing Model Parameters in Electrical Terms, Limiting Resistances and Capacitances of Distributed Elements. Discretization of Distributed Elements, Augmenting Equivalent Circuits. Nonlinear Time-Domain Modeling of Power Sources Based on Impedance Models. Special Kinds of Impedance Measurement Possible with Power Sources-Passive Load Excitation and Load Interrupt. 4.5.2 Batteries (Evgenij Barsoukov). Generic Approach to Battery Impedance Modeling. Lead Acid Batteries. Nickel Cadmium Batteries. Nickel Metal-hydride Batteries. Li-ion Batteries. 4.5.3 Impedance Behavior of Electrochemical Supercapacitors and Porous Electrodes (Brian E. Conway). Introduction. The Time Factor in Capacitance Charge or Discharge. Nyquist (or Argand) Complex-Plane Plots for Representation of Impedance Behavior. Bode Plots of Impedance Parameters for Capacitors. Hierarchy of Equivalent Circuits and Representation of Electrochemical Capacitor Behavior. Impedance and Voltammetry Behavior of Brush Electrode Models of Porous Electrodes. Impedance Behavior of Supercapacitors Based on Pseudocapacitance. Deviations of Double-layer Capacitance from Ideal Behavior: Representation by a Constant-phase Element (CPE). 4.5.4 Fuel Cells (Norbert Wagner). Introduction. Alkaline Fuel Cells (AFC). Polymer Electrolyte Fuel Cells (PEFC). Solid Oxide Fuel Cells (SOFC). Appendix. Abbreviations and Definitions of Models. References. Index. more

Topics: High impedance (62%), Impedance parameters (61%), Input impedance (59%) more

4,888 Citations

Open accessBook
14 Feb 2013-
Abstract: 1 Introduction and Historical Perspective 2 Similarities and Differences between Supercapacitors and Batteries for Electrical Energy Storage 3 Energetics and Elements of Kinetics of Electrode Processes 4 Elements of Electrostatics Involved in Treatment of Double-Layers and Ions at Capacitors Electrode Interfaces 5 Behavior of Dielectrics in Capacitors and Theories of Dielectric Polarization 6 The Double-Layer at Capacitor Electrode Interfaces: Its Structure and Capacitance 7 Theoretical Treatment and Modeling of the Double-Layer at Electrode Interfaces 8 Behavior of the Double-Layer in Non-Aqueous Electrolytes and Non-Aqueous Electrolyte Capacitors 9 The Double-Layer and Surface Functionalities at Carbon 10 Electrochemical Capacitors Based on Pseudocapacitance 11 The Electrochemical Behavior of Ruthenium Oxide (RuO2) as a Material for Electrochemical Capacitors 12 Capacitance Behavior of Films Conducting, Electrochemically Reactive Polymers 13 The Electrolyte Factor in Supercapacitor Design and Performance: Conductivity, Ion-Pairing and Solvation 14 Electrochemical Behavior at Porous Electrodes Applications to Capacitors 15 Energy-Density and Power-Density of Electrical Energy Storage Devices 16 AC Impedance Behavior of Electrochemical Capacitors and Other Electrochemical Systems 17 Treatments of Impedance Behavior of Various Circuits and Modeling of Double-Layer Capacitor Frequency Response 18 Self-Discharge of Electrochemical Capacitors in Relation to that of at Batteries 19 Technology Development 20 Patent Survey more

Topics: Supercapacitor (67%), Electrolytic capacitor (66%), Capacitor (64%) more

4,798 Citations

Open accessBook
Emlyn Rhoderick1Institutions (1)
01 Jan 1978-
Abstract: A review is given of our present knowledge of metal-semiconductor contacts. Topics covered include the factors that determine the height of the Schottky barrier, its current/voltage characteristics, and its capacitance. A short discussion is also given of practical contacts and their application in semiconductor technology, and a comparison is made with p-n junctions. more

Topics: Schottky barrier (74%), Metal–semiconductor junction (72%), Schottky diode (69%) more

4,277 Citations

Journal ArticleDOI: 10.1016/S0013-4686(00)00354-6
Rüdiger Kötz1, M. CarlenInstitutions (1)
Abstract: Electrochemical capacitors (EC) also called ‘supercapacitors’ or ‘ultracapacitors’ store the energy in the electric field of the electrochemical double-layer. Use of high surface-area electrodes result in extremely large capacitance. Single cell voltage of ECs is typically limited to 1–3 V depending on the electrolyte used. Small electrochemical capacitors for low-voltage electronic applications have been commercially available for many years. Different applications demanding large ECs with high voltage and improved energy and power density are under discussion. Fundamental principles, performance, characteristics, present and future applications of electrochemical capacitors are presented in this communication. more

Topics: Supercapacitor (61%), Filter capacitor (61%), Film capacitor (61%) more

4,029 Citations

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