Search results for "capacitors"

Ruthenium Oxide Nanotubes Via Template Electrosynthesis

2011

Ruthenium oxide nanotubes were fabricated by a single-step galvanostatic deposition using porous anodic alumina membrane as template. For the electrodeposition process, we used a electrochemical cell specifically designed in order to employ only 0.5 ml of 0.02 M RuCl3•xH2O solution. The deposition from a very small volume was specifically addressed owing to the high cost of ruthenium compounds, which could be of some relevance from an applicative point of view. Several techniques were used to characterize the samples prior to and after thermal treatment, which was carried out at different temperatures in order to study the crystallization process of the deposit. Raman spectroscopy of as-dep…

ELECTROCHEMICAL FABRICATION OF METAL/OXIDE/CONDUCTING POLYMER JUNCTIONS FOR ELECTRONIC DEVICES

2014

A suitable control technique for fault-tolerant converters in Distributed Generation

2011

The penetration of Distributed Generation (DG) in power systems is deeply changing the existing distribution networks which is becoming a very sophisticated and complex systems incorporating both active (generators) and passive systems (distribution systems, converters and loads). The necessary simplification can be obtained dealing with small networks, namely Micro-Grids, reproducing, in a smaller scale, the structure and the problems of large networks including production, transmission and distribution of the electrical energy. In order to achieve an adequate level of reliability, fault-tolerant operations of micro-grids become very important. This result can be achieved only using power …

Heat-to-current conversion of low-grade heat from a thermocapacitive cycle by supercapacitors

2015

Thermal energy is abundantly available, and especially low-grade heat is often wasted in industrial processes as a by-product. Tapping into this vast energy reservoir with cost-attractive technologies may become a key element for the transition to an energy-sustainable economy and society. We propose a novel heat-to-current converter which is based on the temperature dependence of the cell voltage of charged supercapacitors. Using a commercially available supercapacitor, we observed a thermal cell-voltage rise of around 0.6 mV K-1 over a temperature window of 0 degrees C to 65 degrees C. Within our theoretical model, this can be used to operate a Stirling-like charge-voltage cycle whose eff…

A Hybrid Storage Systems for All Electric Aircraft

2021

A hybrid energy storage system specifically designed for a fully electric aircraft is presented in the paper. The analysis of the time evolution of the power demand of the electric propulsion system during a test mission of Maxwell X-57, an all-electric aircraft developed by NASA, has pointed out the presence of significant peak power during take-off and air tack. Considered the issues related to weight and the volume of the energy storage systems (ESSs) in all-electric aircraft, a hybridization of aircraft ESS with a Supercapacitors (SCs) bank, devoted to smooth peak power demand, has been investigated. A comparison between the simulation results of an electrochemical battery and hybrid ES…

Analysis and design of bi-directional DC-DC converters for ultracapacitors management in EVs

2018

The on-board energy-storage system of an electric vehicle (EV) should be able to collect large amounts of energy and to deal with fast load variations. The use of hybrid power sources as storage devices is an attractive solution, aiming at maximizing both energy and power density. The battery/ultracapacitors (UCs) combination promises to provide significant benefits. An accurate design of bi-directional converters, capable of proplery managing the charge/discharge of the UCs from/to a voltage bus, is essential. In this paper, a bi-directional DC-DC converter connected to a bank of UCs is described and the simulation results are given as well. The designed converter is a buck-boost type, abl…

Modelling, Simulation and Characterization of a Supercapacitor in Automotive Applications

2022

In the energy storage field, supercapacitors (SCs) are gaining more and more attention thanks to features such as high-power density, high life cycles and lack of maintenance. In this article, an improved SC three-branches model which considers the residual charge phenomenon is presented. The procedure to estimate the model parameters and the related experimental set-up are presented. The parameter estimation procedure is repeated for several SCs of the same type. The average parameters are then obtained and used as initial guesses for a recursive least square optimization algorithm, to increase the accuracy of the model. The model of a single SC is then extended to SC banks, testing differ…

Donor–Acceptor Polymers for Electrochemical Supercapacitors: Synthesis, Testing, and Theory

2014

Donor–acceptor polymers can store both a positive and negative charge allowing them to function as both the positive and negative charge storage material in a supercapacitor device, however few have been explored for this application. Here, we describe the synthesis of several donor–acceptor polymers and their electrodeposited polymer electrodes. We use differing molecular structures to examine the effect of electron acceptor concentration and show that device stability can be improved significantly by increasing the acceptor concentration. Further, we provide computational insight into the important chemical requirements for achieving even higher performance supercapacitors based on donor–…

Physico-chemical Characterization of Aluminium Oxide Films Grown on Etched Foils for Electrolytic Capacitors

2012

Hybrid magnetic materials based on layered double hydroxides: from the chemistry towards the applications

2014

Layered double hydroxides (LDHs) are the leitmotiv of this dissertation. Contradicting the assertion that “any past was better”, LDHs have been continuously revisited from the middle of the twentieth century, and represent an excellent example of the never-ending beauty of Chemistry. New synthetic perspectives are giving a new impetus to LDH chemistry, which among hybrid materials, are finding their heyday. This is resulting in novel materials and also paving the way for new fundamental and practical insights. This dissertation is focused on magnetic LDHs, and for the sake of clarity it is organized in three main parts: we will move from basic synthetic and physical aspects of LDHs, through…