Portugaliae
Electrochimica Acta

Editorial

Personal opinion of the author on the use of mercury and amalgam electrodes for determination of trace amounts of biologically active organic compounds is expressed. This view is supported by references to numerous reviews and original papers from UNESCO Laboratory of environmental electrochemistry supporting the claim that both mercury and amalgam electrodes can play useful role in modern practically oriented analytical laboratories.

The article deals with preparing of lithiated graphite material. The lithiated graphite material can be used as active electrode material in lithium-ion batteries. Most of the commercially produced lithium-ion batteries have the negative electrode based on graphite. The capacity losses which are caused by irreversible capacity of graphite may reduce the potential capacity of the battery from 15 % up to 45 %. These losses arise on negative electrode interphase (solid graphite electrode and liquid electrolyte), where during the formation process is created the SEI (Solid-Electrolyte Interphase) layer. The layer is composed from lithium atoms and the decomposition products of electrolyte solvents. The SEI layer is indispensable for correct function of lithium-ion battery. In this article are presented experimental methods for synthesis of lithiated graphite material. The article describes the three concepts of preparing lithiated material and its using like a precursor for preparing of negative electrode. The first method is based on using n-butyllithium (C4H9Li) reagent, its behaviour as the donor of lithium atoms, and graphite acts as the acceptor of lithium atoms. The second concept follows the first one only with adding an ionic compound to graphite, in our case FeCl3. The last concept presents the electroless lithiation process, which is based on different electrochemical potential between lithium and graphite.

The organic-inorganic hybrid sol-gel films, the structure of which comprises interconnected inorganic and organic networks have been reported as an environmentally friendly anti-corrosion pre-treatment for several metals, including aluminium alloys. In this paper, an epoxy-silica-zirconia hybrid sol-gel coating was synthesized from glycidoxypropyltrimethoxysilane (GPTMS) and zirconium n-propoxide (TPOZ) precursors and applied to EN AW-6063 alloy by dip-coating. To promote the organic network formation through the epoxy group polymerization at room temperature, two types of amine crosslinkers were added during synthesis: diethylenetriamine (DETA), in different concentrations, and a tri-functional amino-silane. The evolution of the curing process and the corrosion behaviour of the coated aluminium alloy specimens were evaluated by Electrochemical Impedance Spectroscopy (EIS) in 0.5 M NaCl. The morphology and surface chemistry of the hybrid coatings were characterized by Energy Dispersive Spectroscopy (EDS) coupled with Scanning Electron Microscopy (SEM) and by Fourier Transform Infrared Spectroscopy (FTIR). The results obtained revealed that the sol-gel coatings with lower amine ratios required longer curing times, but showed the best anticorrosive performance with time. The increase in amine concentration has led to a more cross linked organic network, resulting in higher initial coatings resistance; however it has turned coatings more hydrophilic, prone to rapid degradation in water.

The article deals with description of rheological and electrical properties of solvents for electrolytes of lithium-ion batteries. Solvents mixture of dimethyl sulfone and sulfolane at different volume ratios and with a lithium salt (LiClO4) appears as a potentially suitable electrolyte. In this work, we investigate the influence of different solvents and their mixtures in order to find a solvent which increases the fire safety of such battery. The aim of this experiment is to investigate the rheological properties, particularly density and dynamic viscosity of solvents with lithium salt in temperature dependence and to find the optimal composition of the electrolyte from the perspective of achieving the lowest dynamic viscosity and better electrical conductivity, because both quantities are closely related with Walden’s rule. The vibration method is used to determine the values of dynamic viscosity.

The aim of this study was to improve the properties of cathodic material for lithium-ion batteries based on LiCoO2. The solid phase reaction method was chosen as a manufacturing method of the doped base material. This method has already been tested for the production of basic material. Materials selected from the group of alkali metals were chosen as the doping elements. The main objective was to use these added elements for stabilizing the structure of the LiCoO2 material and for limiting the process of their degeneration.