5 research outputs found
Sodium Cyclopentadienide as a New Type of Electrolyte for Sodium Batteries
Owing to the low cost and high abundance of sodium, sodiumâbased batteries, especially those employing metallic sodium anodes, are considered for postâlithium energy storage. In order to develop highâperformance and longâlasting sodiumâmetal batteries, however, the reversible Naâmetal stripping and plating challenge must be addressed. Most organic electrolytes suffer from nonâuniform and continuous formation of the solid electrolyte interphase as well as unfavorable dendritic growth. The use of sodium cyclopentadienide dissolved in tetrahydrofuran as the electrolyte reveals an improved reversibility of sodium dissolution and electrodeposition combined with an electrochemical stability window of around 2.2â
V vs. Na/Na+ and an ionic conductivity of 1.36â
mSâcmâ1 at 25â°C. Furthermore, the plated electrodes showed a remarkable morphology of the Na deposits, that is, no dendrite formation, whereby the aboveâmentioned electrolyte could overcome the aforementioned cycling issues, thus suggesting suitability for further studies
Suitability of Carbazolyl Hauser and TurboâHauser Bases as MagnesiumâBased Electrolytes
Lithium-ion batteries pose certain drawbacks and alternatives are highly demanded. Requirements such as low corrosiveness, electrochemical stability and suitable electrolytes can be met by magnesium-ion batteries. Metalation of carbazole with Mg in THF in the presence of ethyl bromide yields the sparingly soluble Hauser base [(thf)Mg(Carb)Br] (1) which shows a Schlenk-type equilibrium with formation of [(thf)Mg(Carb)] and [(thf)4MgBr2]. A THF solution of 1 shows a low over-potential and a good cyclability of electrodeposition/-stripping of Mg on a Cu current collector. An improved performance is achieved with the turbo-Hauser bases [(thf)(Carb)Mg(Ό-Br/X)Li(thf)] (X=Br (2) and Cl (3)) which show a significantly higher solubility in ethereal solvents. The THF solvation energies increase from (thf)MgBr over (thf)Mg(Carb)Br to (thf)Mg(Carb) for an equal number x of ligated THF molecules
An Electrochemical Route for Hot Alkaline Blackening of Steel: A Nitrite Free Approach
Blackening belongs to the predominant technological processes in preserving steel surfaces from corrosion by generating a protective magnetite overlayer. In place of the commonly used dipping-procedure into nitrite-containing blackening baths at boiling temperatures that are far above 100 °C, here we describe a more environmentally friendly electrochemical route that operates at temperatures, even below 100 °C. After an investigation of the electrochemical behavior of steel samples in alkaline solutions at various temperatures, the customarily required bath temperature of more than 130 °C could be significantly lowered to about 80 °C by applying a DC voltage that leads to an electrode potential of 0.5−0.6 V vs. Pt. Thus, it was possible to eliminate the use of hazardous sodium nitrite economically and in an optimum way. Electrochemical quantification of the corrosion behavior of steel surfaces that were in contact with 0.1 M KCl solution was carried out by linear sweep voltammetry and by Tafel slope analysis. When comparing these data, even the corrosion rates of conventional blackened surfaces are of the same magnitude as a blank steel surface. This proves that magnetite overlayers represent rather poor protective layers in the absence of additional sealing. Moreover, cyclic voltammetry (CV), atomic force microscopy (AFM), scanning electron microscopy (SEM) and auger electron spectroscopy (AES) characterized the electrochemically blackened steel surfaces
Sodium Cyclopentadienide as a New Type of Electrolyte for Sodium Batteries
Owing to the low cost and high abundance of sodium, sodiumâbased batteries, especially those employing metallic sodium anodes, are considered for postâlithium energy storage. In order to develop highâperformance and longâlasting sodiumâmetal batteries, however, the reversible Naâmetal stripping and plating challenge must be addressed. Most organic electrolytes suffer from nonâuniform and continuous formation of the solid electrolyte interphase as well as unfavorable dendritic growth. The use of sodium cyclopentadienide dissolved in tetrahydrofuran as the electrolyte reveals an improved reversibility of sodium dissolution and electrodeposition combined with an electrochemical stability window of around 2.2â
V vs. Na/Na+ and an ionic conductivity of 1.36â
mSâcmâ1 at 25â°C. Furthermore, the plated electrodes showed a remarkable morphology of the Na deposits, that is, no dendrite formation, whereby the aboveâmentioned electrolyte could overcome the aforementioned cycling issues, thus suggesting suitability for further studies