Electrochemical Behavior of Symmetric Electrical Double-Layer Capacitors and Pseudocapacitors and Identification of Transport Anomalies in the Interconnected Ionic and Electronic Phases Using the Impedance Technique.

A double-channel transmission line impedance model was applied to the study of supercapacitors to investigate the charge transport characteristics in the ionic and electronic conductors forming the electrode/solution interface. The macro homogeneous description of two closely mixed phases (Paasch-Micka-Gersdorf model) was applied to study the influence of disordered materials on the charge transport anomalies during the interfacial charge-discharge process. Different ex situ techniques were used to characterize the electrode materials used in electrical double-layer (EDLC) and pseudocapacitor (PC) devices.

New Insights on the Sodium Water-in-Salt Electrolyte and Carbon Electrode Interface from Electrochemistry and Operando Raman Studies.

Comprehensive electrochemical and operando Raman studies are performed to investigate the electrochemical stability window (ESW) of supercapacitors filled with normal (salt-in-water) and highly concentrated (water-in-salt, WiSE) electrolytes. Impedance and chronoamperometric experiments are employed and combined with cyclic voltammetry to correctly define the ESW for a WiSE-based device. The total absence of water-splitting resulted in phase angles close to -90° in the impedance data.

Charge-storage mechanism of highly defective NiO nanostructures on carbon nanofibers in electrochemical supercapacitors.

An electrode composed of highly defective nickel oxide (NiO) nanostructures supported on carbon nanofibers (CNFs) and immersed in an Li+-based aqueous electrolyte is studied using Raman spectroscopy under dynamic polarization conditions to address the charge-storage phenomenon. By this operando technique, the formation of Li2SO4·H2O during the discharge process is verified. At the same time, we observed the phase transformation of NiO to NiOOH.

A rational experimental approach to identify correctly the working voltage window of aqueous-based supercapacitors.

It is common to find in the literature different values for the working voltage window (WVW) range for aqueous-based supercapacitors. In many cases, even with the best intentions of the widening the operating voltage window, the measured current using the cyclic voltammetry (CV) technique includes a significant contribution from the irreversible Faradaic reactions involved in the water-splitting process, masked by fast scan rates. Sometimes even using low scan rates is hard to determine precisely the correct WVW of the aqueous-based electrochemical capacitor.

How to Measure and Calculate Equivalent Series Resistance of Electric Double-Layer Capacitors.

Electric double-layer capacitors (EDLCs) are energy storage devices that have attracted attention from the scientific community due to their high specific power storage capabilities. The standard method for determining the maximum power () of these devices uses the relation = /4, where stands for the cell voltage and for the equivalent series resistance. Despite the relevance of , one can observe a lack of consensus in the literature regarding the determination of this parameter from the galvanostatic charge-discharge findings.

Epidemiological profile of leishmaniasis at a reference service in the state of Alagoas, Brazil, from January 2000 to September 2008.

Leishmaniasis is a parasitic disease found in the continents of Europe, Asia, Africa and the Americas. In Brazil, the disease is an important public health problem, occurring in most states, but mainly in the Northeast region of the country, with the state of Alagoas having a significant number of confirmed cases. The present study establishes and discusses the epidemiological profile of cases of leishmaniases treated at the Reference Center of Alagoas, Hospital Escola Hélvio de Farias Auto, between January 2000 and October 2008.

Effects of chlorhexidine and sodium hypochlorite on the microhardness of root canal dentin.

Objective: The purpose of this study was to evaluate the effects of endodontic irrigants on the microhardness of root canal dentin.

Study Design: Thirty extracted single-rooted human teeth were used. The crowns were sectioned at the cementoenamel junction.