Search results for "Capacitor"

From the Powder to the Electro and/or Magnetic Ceramic Component: Fine Grain Size and Properties

1997

Voltage-controlled current loops with nanofluidic diodes electrically coupled to solid state capacitors

2016

[EN] We describe experimentally and theoretically voltage-controlled current loops obtained with nanofluidic diodes immersed in aqueous salt solutions. The coupling of these soft matter diodes with conventional electronic elements such as capacitors permits simple equivalent circuits which show electrical properties reminiscent of a resistor with memory. Different conductance levels can be reproducibly achieved under a wide range of experimental conditions (input voltage amplitudes and frequencies, load capacitances, electrolyte concentrations, and single pore and multipore membranes) by electrically coupling two types of passive components: the nanopores (ionics) and the capacitors (electr…

Polyoxometalate-based metal-organic frameworks for boosting electrochemical capacitor performance

2019

Abstract Polyoxometalate-based metal-organic frameworks (POMOFs) possess promising applications as capacitors. Herein, we report the syntheses, structures and electrochemical properties of five copper-containing POMOFs: [CuI4H2(btx)5(PW12O40)2]·2H2O (1), [CuIICuI3(H2O)2(btx)5(PWVI10WV2O40)]·2H2O (2), [CuI6(btx)6(PWVI9WV3O40)]·2H2O (3), [CuI4H2(btx)5(PMo12O40)2]·2H2O (4) and [CuIICuI3(btx)5(SiMoVI11MoVO40)]·4H2O (5) (btx = 1,4-bis(triazol-1-ylmethyl) benzene) with potential applications as capacitors. Compounds 1–3 contain the same Keggin-type polyoxometalate (POM) although with different oxidation states, allowing the analysis of the effect of the electronic population on the capacitance pe…

Wood and Black Liquor-Based N-Doped Activated Carbon for Energy Application

2021

The research was funded by the Latvian Council of Science project “Nanostructured Nitrogenated Carbon Materials as Promoters in Energy Harvesting and Storage Technologies”, project No LZP-2018/1-0194, “New biomass origin materials hybrid carbon composites for energy storage” project No LZP-2020/2-0019 and postdoc project “Nitrogen and phosphorus-containing biomass based activated carbons for fuel cells and supercapacitors” project No 1.1.1.2/VIAA/4/20/596.

Exploring High-Energy Li-I(r)on Batteries and Capacitors with Conversion-Type Fe3O4-rGO as the Negative Electrode

2017

We report a microwave-assisted solvothermal process for the preparation of magnetite (Fe3O4, ca. 5 nm)-anchored reduced graphene oxide (rGO). It has been examined as a prospective conversion-type negative electrode for multiple energy storage applications, such as Li-ion batteries (LIBs) and Li-ion capacitors (LICs). A LiFePO4/Fe3O4-rGO cell is constructed and capable of delivering an energy density of approximately 139 Wh kg−1 with a notable cyclability (ca. 76 %) after 500 cycles. Prior to the fabrication of a LIB, the Fe3O4-rGO is electrochemically pretreated to eliminate the irreversible capacity loss. In addition to the LIB, a high-energy LIC is also fabricated by using the pre-lithiat…

Series and parallel resonant inverters for induction heating under short-circuit conditions considering parasitic components

1999

Series and parallel resonant inverters are the common structures in high power industrial generators for induction heating applications. In practical working conditions, short-circuit of the heating coil is very common, normally producing overvoltages that can damage the power transistors of the inverter if no special precautions are taken. The aim of the paper is to show the mechanism of how overvoltages are generated under short-circuit conditions of the heating coil for series and parallel inverters.

Giant Enhancement in the Supercapacitance of NiFe–Graphene Nanocomposites Induced by a Magnetic Field

2019

The rapid rise in energy demand in the past years has prompted a search for low-cost alternatives for energy storage, supercapacitors being one of the most important devices. It is shown that a dramatic enhancement (≈1100%, from 155 to 1850 F g-1 ) of the specific capacitance of a hybrid stimuli-responsive FeNi3 -graphene electrode material can be achieved when the charge/discharge cycling is performed in the presence of an applied magnetic field of 4000 G. This result is related to an unprecedented magnetic-field-induced metal segregation of the FeNi3 nanoparticles during the cycling, which results in the appearance of small Ni clusters (<5 nm) and, consequently, in an increase in pseudoca…

Optimizing Energy Transduction of Fluctuating Signals with Nanofluidic Diodes and Load Capacitors

2018

[EN] The design and experimental implementation of hybrid circuits is considered allowing charge transfer and energy conversion between nanofluidic diodes in aqueous ionic solutions and conventional electronic elements such as capacitors. The fundamental concepts involved are reviewed for the case of fluctuating zero-average external potentials acting on single pore and multipore membranes. This problem is relevant to electrochemical energy conversion and storage, the stimulus-response characteristics of nanosensors and actuators, and the estimation of the accumulative effects caused by external signals on biological ion channels. Half-wave and full-wave voltage doublers and quadruplers can…

Anodization and anodic oxides

2018

Anodizing is a low-temperature, low-cost electrochemical process allowing for the growth, on the surface of valve metals and valve metal alloys, of anodic oxides of tunable composition and properties. This article is an overview on theoretical aspects concerning the general aspects of the kinetics of growth of barrier and porous anodic oxides and some of their present and possibly future technological applications of anodic oxides. The first part of the article is devoted to anodic oxide growth models, from Guntherschulze and Betz work (in 1934) to the more recent results on barrier and porous oxide films. The second part is focused on industrial processes to fabricate anodic oxides and the…

Diamond Films as Support for Electrochemical Systems for Energy Conversion and Storage

2019

Many efforts have been dedicated to develop and study different catalysts supported materials for energy storage and conversion. Polymer electrolyte membranes (PEM) and capacitors have been topics of special interest for the scientific community, then, the research to find excellent catalyst-supports has constantly increased. The use of conductive diamond films has been proposed due to their mechanical and chemical stability properties. In this context, the application of BDD-catalyst surfaces for PEM fuel cells as well as the production of electrochemical capacitors using BDD materials have been summarized and discussed in this chapter.