Low Temperature Molten Research Articles

Secondary aluminium-iron (III) chloride batteries with a low temperature molten salt electrolyte

Secondary aluminium-iron (III) chloride batteries using a low temperature molten salt electrolyte were constructed and tested. Discharge current densities were in the range 5 to 100 mA (∼ 1 to 20 mA cm−2; ∼C/4 to 5C); charging currents were 5mA (C/4 toC/2). Utilization of the positive electrode reactant was low due to the discharge rates and loading procedure. The mode for self discharge was dissolution of the positive electrode reactant and transport to the aluminium negative electrode where it reacted.

Low Temperature Molten Salt Electrolytes Based on Quaternary Alkyl Phosphonium Salts

Low Temperature Molten Salt Electrolytes Based on Quaternary Alkyl Phosphonium Salts

Kinetic and Transport Processes for FeCl3 and CuCl2 Positive Electrodes in Low Temperature Molten Salts

Kinetic and Transport Processes for FeCl3 and CuCl2 Positive Electrodes in Low Temperature Molten Salts

Low Temperature Molten Salt Electrolytes Containing Ternary Alkyl Sulfonium Salts

A new family of low temperature molten salts has been found. These electrolytes are based on the ternary alkyl sulfonium salts in mixtures with inorganic metal halides. A typical composition is the mixture of trimethylsulfonium chloride (TMSC) and AlCl3 in a 1:2 mole ratio. This melt has a conductivity of 5.5 mS/cm, remains fluid until somewhat below −50°C, and can plate and strip aluminum. TMSC has the same electrochemically stable window as 1-methyl-3-ethylimidazolium chloride.

Electrodeposition of Ba .6K .4BiO 3

A novel, low temperature molten salt electrochemical technique has been used for the preparation of Ba .6K .4BiO 3. The resulting crystalline material has been characterized by X-Ray diffraction, scanning electron microscopy and by energy dispersive X-ray analysis.

Viscosity measurements of low temperature molten salts

Low temperature molten salts are a new class of electrolytes for battery applications (e.g. [1]). Viscosity measurements of low temperature molten salts based on mixtures of aluminium or copper halide and alkylpyridinium or dialkylimidazolium halide have been reported [1-5]. They have shown strong dependences of viscosity with changes in composition in basic (i.e. organic-rich) melts [1, 2, 4, 5]. Further, 'gaps' in the liquidus lines, i.e. regions where fusion does not occur, only a glass transition at very low temperatures, have been shown for binary melts containing 1-methyl-3-ethylimidazolium chloride (MEIC) [1] and bromide [2] as the organic salt. Finally, measurements of chemical shifts for proton and carbon nuclear magnetic resonance spectra of basic MEICA1C13 melts have been explained in terms of oligomeric structures [6, 7]. All of these measurements used viscometers based on variations of Cannon-Fenske devices [1-3, 5] or the falling ball method [4]. These methods do not provide shear stress-shear rate data, which could be used to determine whether the melts behave like non-Newtonian fluids. This paper reports viscosity measurements of MEIC-A1CI3 binary melts using a plate and cone viscometer (in order to obtain shear stress-shear rate data) and compares the viscosities measured using this technique with those of previous investigators.

Deposition of Aluminum on Graphite from Low Temperature Molten Salts

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Thermodynamic characterization of metal hydrogen systems by assessment of phase diagrams and electrochemical measurements

The formation of metal hydrides has been investigated theoretically by the use of ternary thermodynamics and experimentally by applying an electrochemical cell technique. A new theoretical method of describing and investigating metal hydrides has been developed. It involves ternary thermodynamics and interprets the hydrogenation reaction by ternary phase diagrams. This method has the advantage over the conventional “pseudobinary” model in that it allows for disproportionation reactions. Furthermore it describes in a visual way the parameters important for hydrogen storage applications, namely plateau pressure and plateau width. Finally it gives a means of predicting hydrogenation reactions. This method has been applied to the family of Mg-based alloys. A new experimental technique for investigating metal hydrides has also been developed. It involves a nonaqueous low temperature molten salt electrochemical cell. Measurements were done with a saturated solution of NaH in the organometallic salt NaAlEt 4, where the H − ions are the hydrogen transporting species. Several Mg-based alloys were investigated. The thermodynamic calculations are in very good agreement with the experimental results and are in accordance as well with data published in the literature.

ChemInform Abstract: ELECTROCHEMICAL INVESTIGATION OF HYDROGEN STORAGE IN METAL HYDRIDES

AbstractEs wird ein neues elektrochemisches Verfahren entwickelt, mit dem die H2‐Speicherung in festen Metallhydriden untersucht und kontrolliert werden kann.

Electrochemical Investigation of Hydrogen Storage in Metal Hydrides

A new technique has been developed to study and control hydrogen storage in solid metal hydrides. The formation of metal hydrides and their thermodynamic and kinetic properties have been investigated by electrochemical methods employing a low temperature molten salt galvanic cell of the typeThe choice of the electrolyte is of great importance in this method. Besides having to be thermodynamically stable when in contact with the electrodes, it must conduct charge by transport of hydrogen containing species. For this purpose, the low temperature organometallic salt (melting point 128°C) has been synthesized. It is saturated with , the hydride ions of which act as hydrogen transmitters. This electrolyte has the additional advantage that its oxygen activity is extremely low, so that no oxide layers form which could block hydrogen reaction with the alloy and thus reduce its apparent capacity. It even cleans the surface of oxide layers which may have been present initially. This technique allows easier investigation of metal hydrides than the conventional pressure‐temperature experiments and, in addition, avoids the main problems involved in using aqueous solution electrolytes, i. e., the corrosion of the metal alloys and, especially, the formation of oxide or hydroxide layers. With the aid of this cell, charge/discharge experiments have been carried out and hydrogen has been added to and deleted from the hydride forming metal alloy systems Mg‐Ni, Mg‐Cu, and Mg‐Al at 142° and 170°C. Equilibrium open‐circuit voltage measurements provide information about the thermodynamic properties as a function of the overall composition of the electrode material. Thermodynamic data for the different metal hydride systems have been determined as a function of hydrogen content and interpreted in terms of the corresponding ternary phase diagrams (Mg‐Ni‐H, Mg‐Cu‐H, and Mg‐Al‐H, respectively). The Gibbs free energies corresponding to the various reactions of hydrogen with the binary metal alloys measured in this way have been found to be in good agreement with data determined by conventional pressure‐temperature experiments. For the Gibbs free energy of formation of , for instance, we find at 142°C, whereas the data reported in literature range from −4.2 to −5.0 kcal/mol. The results are also in accordance with a model in which these systems are treated as ternaries rather than as pseudo‐binary reactions. Using this new approach, the relevant three‐phase triangles and two‐phase tie lines of the ternary phase diagrams can be calculated from the Gibbs formation energies of the phases present in these systems. The hydrogen capacities in these several metal alloy systems are also readily interpreted in terms of the phase boundaries of the corresponding three‐phase equilibria.

Reaction of chloride ions in low-temperature molten salts and application to the study of complex ion stoichiometry

Etudes, en presence d'une electrode tournante de Pt, de l'oxydation des ions chlorure, ajoutes en exces au melange fondu de chlorure d'aluminium, et de chlorure N-n-butylpyridinium ou de chlorure de methyl-1 ethyl-3 imidazolium. Donnees sur les complexes chloro formes

Rechargeable high voltage low temperature molten, salt cell Na/β''-alumina/SCl 3+ in AlCl 3-NaCl

This paper deals with the rechargeable molten salt cell: Na/β''-alumina/SCl 3 + in AlCl 3-NaCl, and its underlying chemistry. This cell is operated at 180–250°C, and is characterized by two discharge plateaus: 4Na + SC1 3AlCl 4 + 3AlCl 3 = S + 4NaAlCl 4 2Na + S + AlCl 3 = AlSCl + 2NaCl The AlCl 3-NaCl melt is important in stabilizing several sulfur species formed in charge/discharge processes and in maintaining a conducting liquid positive mixture. The cell voltage in the fully charged state is ⪢ =4.30 V for the first step and 2.75 V for the second step. The theoretical capacity is in excess of 190 Ah kg −1 , corresponding to a theoretical energy density in excess of 700 Wh kg −1. High energy and power densities have been achieved. Hundreds of deep charge/discharge cycles have been obtained for several cells using Reticulated Vitreous Carbon or tungsten positive current-collectors.

Buried Single-Mode Waveguides in Glass

Buried planar single-mode waveguides can be fabricated in glass by electromigration of ions from a low temperature molten mixture of nitrates. Surface scattering is reduced and high efficiency planar catadioptric elements are demonstrated to be feasible.

Electrochemical studies in low temperature molten salt systems containing aluminum chloride

Purified aluminium chloride undergoes a series of lewis acid-base reactions with other chlorides. The sequence of reactions with both the alkali-chloride (e.g. NaCl) and the alkyl-pyridinium chlorides (e.g.butyl pyridinium chloride) are similar, forming low melting chloroaluminates. The most important equilibria in these melts can be represented by the equation 2AlCl4−=Al2Cl7−+Cl− For sodium chloride containing melts at 175°C the equilibrium constant is 1.06×10−7, while for butyl pyridinium systems at 30°C the constant is 2.2×10−13. The stabilising effect resulting from the formation of the complexes enables a wide range of solutes to be studied. some metal chlorides that dissolve nn the melt enable co-deposition of alloys with aluminium or direct electroplating of the metal. However, depending on whether the melt is neutral or acidic according to the above equilibria, marked changes in the solubility of certain metal ions, and their deposition reaction mechanism can occur. The reversibility of the aluminium electrode in the pure solvent makes these melts attractive electrolytes for both battery systems, and plating of the pure metal.

Electrochemical studies in low temperature molten salt systems containing alumnium chloride

Purified aluminium chloride undergoes a series of lewis acid-base reactions with other chlorides. The sequence of reactions with both the alkali-chloride (e.g. NaCl) and the alkyl-pyridinium chlorides (e.g.butyl pyridinium chloride) are similar, forming low melting chloroaluminates. The most important equilibria in these melts can be represented by the equation 2AlCl 4 −=Al 2Cl 7 −+Cl − For sodium chloride containing melts at 175°C the equilibrium constant is 1.06×10 −7, while for butyl pyridinium systems at 30°C the constant is 2.2×10 −13. The stabilising effect resulting from the formation of the complexes enables a wide range of solutes to be studied. some metal chlorides that dissolve nn the melt enable co-deposition of alloys with aluminium or direct electroplating of the metal. However, depending on whether the melt is neutral or acidic according to the above equilibria, marked changes in the solubility of certain metal ions, and their deposition reaction mechanism can occur. The reversibility of the aluminium electrode in the pure solvent makes these melts attractive electrolytes for both battery systems, and plating of the pure metal.

The Electrochemical Behavior of Aluminum in the Low Temperature Molten Salt System n Butyl Pyridinium Chloride: Aluminum Chloride and Mixtures of This Molten Salt with Benzene

The aluminum deposition and stripping processes at tungsten, platinum, and glassy carbon electrodes in the low temperature molten salt system, n butyl pyridinium chloride: aluminum chloride, and the 50 volume percent (v/o) mixture of this molten salt with benzene have been investigated, using a variety of electrochemical techniques. At all three electrodes, and in both solvent systems, the deposition reaction in slightly acidic melts, the reduction of ions, was found to involve a nucleation process while at the tungsten and platinum electrodes underpotential deposition was also observed. Reduction of the n butyl pyridinium cation was found to occur at −1.1V vs. Al(2:1 melt) which is positive of the reduction potential of ions and therefore aluminum deposition in basic melts was not observable. Studies of the stripping of aluminum from inert substrates showed that aluminum is very slowly corroded in acidic melts, and melt‐benzene mixtures, by traces of oxidizing impurities while in basic systems aluminum reduces the n butyl pyridinium cation. Potentiometric titration of the 50 v/o melt‐benzene mixture showed that the acid‐base properties of this system are defined, as in the pure melt, by the equilibrium with an equilibrium constant of at 30°C.

Evaluation and optimization of pelletized LiAl/NaAlCl 4/ MoCl 5 electrochemical cells

A proposed, low temperature molten salt thermally activated reserve battery (thermal battery) was investigated using single cell testing techniques. Th