A non‐nucleophilic Hauser base hexamethyldisilazide (HMDS) magnesium electrolyte possesses inherent properties required for a magnesium–sulfur battery. However, the development of full cell batteries using HMDSCl‐based electrolytes is still hampered by a low coulombic efficiency. A new electrolyte formulation of non‐nucleophilic HMDS magnesium containing bromide as a halide instead of chloride was obtained through a simple and straightforward synthesis route. The electrochemistry of magnesium was investigated through plating and stripping in three different HMDSBr‐based electrolytes: Mg(HMDS)Br, Mg(HMDS)Br‐BEt3, and Mg(HMDS)Br‐AlEt3 dissolved in tetrahydrofuran. The different magnesium species present in the electrolytes were determined using NMR. Weak electron‐withdrawing Lewis acids, BEt3 and AlEt3 were used intentionally and their impact was investigated. Contrary to expectation, the substitution of chloride by bromide does not drastically narrow the electrochemical stability window. HMDSBr‐based electrolytes demonstrated long‐term (1000 cycles) stable reversibility and highly efficient (≈99 %) magnesium plating/tripping without a high ratio of bromide compared with the MgHMDSCl‐based electrolytes. The aprotic electrolyte shows comparatively high anodic stability (≈2.4 V vs. Mg/Mg2+) and high ionic conductivity of 1.16 mS cm−1 at room temperature. Plating of magnesium with low overpotential (<188 mV) revealed a morphology dependence on the electrolyte type with a shiny metallic homogenous layer, suggesting a rational balance between the nucleation and growth process in HMDSBr‐based 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)3Mg(Carb)Br] (1) which shows a Schlenk‐type equilibrium with formation of [(thf)3Mg(Carb)2] 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(μ‐Br/X)2Li(thf)2] (X=Br (2) and Cl (3)) which show a significantly higher solubility in ethereal solvents. The THF solvation energies increase from (thf)xMgBr2 over (thf)xMg(Carb)Br to (thf)xMg(Carb)2 for an equal number x of ligated THF molecules.

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.

Lithium-ion batteries (LIBs) have an impact on our daily life since the turn of the nineties as the most important and widespread electrochemical energy storage systems.Nowadays, there is a continuously growing demand for higher energy density storage devices and for new sustainable battery technologies. [1] Moreover, the development and implementation of new sustainable energy systems could become the ultimate bridge to a definitive energy transition, addressing increasingly pressing climate change problems. Magnesium (Mg) possesses the highest volumetric capacity (3850 mAh cm À3 ) compared to Li (2060 mAh cm À3 ), Na (1130 mAh cm À3 ), and Ca (2050 mAh cm À3 ), which makes a Mg metal-based battery cell a promising candidate to envision a future shift of the current battery field to a postlithium age. [2,3] Moreover, depending on the experimental conditions, electrodeposition of metallic Mg can be free of dendrites. [2,[4][5][6][7] Abundancy, low cost, and eco-friendliness are additional appealing features that render Mg metal an attractive choice. [2,3,[5][6][7][8][9] The first proof-of-concept of a rechargeable Mg metal battery was demonstrated by Aurbach et al., with the most impressive cycle life ever reported so far. [10] Stripping and deposition of a magnesium metal anode were enabled for >3500 cycles using a Chevrel phase (CP) cathode. [11] The organomagnesium chloroaluminate complex, Mg(AlCl 2 BuEt) 2 / tetrahydrofuran (THF) was used as electrolyte, even if it presents now well-known corrosivity of the current collector and a limited anodic stability. [12] The electrolyte contained Grignard reagents, making it nucleophilic in nature, and thus unsuitable for electrophilic-type cathode materials. [13] This remarkable breakthrough of the first Mg battery prototype ignited a great interest in the development of suitable electrolytes and cathodes to improve the cell voltage. Intensive research has been carried out on the development of new electrolytes, which can enable reversible deposition and stripping at low overpotentials, are noncorrosive and nonnucleophilic in nature, possess high anodic stability, and are easy-to-make. However, the strategy to design compatible electrolytes that fulfill all these requirements seems not to be an easy task. A good compromise was found in the hexamethyldisilazide magnesium chloride (HMDSMgCl) electrolyte, as the addition of aluminum chloride (AlCl 3 ) improved the anodic stability up to 3.6 V versus Mg/Mg 2þ on Pt. [14] Worth noting that a high ratio of AlCl 3 Lewis acid and/or MgCl 2 in (HMDS)MgCl-based electrolytes leads not only to higher anodic stability but also to high Mg deposition

Owing to the low cost and high abundance of sodium, sodium‐based batteries, especially those employing metallic sodium anodes, are considered for post‐lithium energy storage. In order to develop high‐performance and long‐lasting sodium‐metal batteries, however, the reversible Na‐metal stripping and plating challenge must be addressed. Most organic electrolytes suffer from non‐uniform 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 2.2 V vs. Na/Na+ and an ionic conductivity of 1.36 mS cm−1 at 25 °C. Furthermore, the plated electrodes showed a remarkable morphology of the Na deposits, that is, no dendrite formation, whereby the above‐mentioned electrolyte could overcome the aforementioned cycling issues, thus suggesting suitability for further studies.