Primary aluminum is produced by the Hall-Heroult process which is based on electrolysis in molten fluoride electrolyte, Na3AlF6-AlF3, at ∼960 °C in which the raw material alumina is dissolved and ...decomposed into pure aluminum and CO2 gas due to the use of carbon anodes. Direct CO2 emissions are due to the anode process including perfluoro carbon (PFC) formation during anode effect. An inert anode to produce oxygen may eliminate direct CO2 emissions including PFC gases and give possibilities to improve the cell design. CO2 emissions from generation of electricity are the most important issue globally. Also the use of pure metals to produce alloys may significantly increase the carbon footprint due to the primary production of alloying elements. A new approach to produce alloys directly during electrolysis is proposed, and results from lab experiments show that this method may give significant reduction of carbon footprint for the production of aluminum alloys. Other sources of CO2 emissions are production and manufacture of alumina and carbon anodes as well as loss in current efficiency for aluminum. A new process based on aluminum chloride electrolysis and recycling of CO2 may eliminate CO2 emissions from the production process.
Iron alloys were produced by suspension electrolysis in a 50
wt
% NaOH–H
2
O electrolyte at 383 K, and Fe–Cr and Fe–Ni alloys were obtained using a suspension of Fe
2
O
3
+Cr
2
O
3
and Fe
2
O
3
...+Ni(OH)
2
particles, respectively. Highly ordered columnar deposits comprising cubic Fe–Cr particles with approximately 5-micrometer-long sides were obtained on a disk cathode with a current efficiency higher than 90% at 100–300 mA･cm
−2
. In contrast, disordered columnar deposits of Fe–Ni particles with diameters of approximately 1.0
μ
m were obtained on a disk cathode with a current efficiency of approximately 50% at 200 mA･cm
−2
. The proposed method affords iron alloys with compositions in the stainless-steel region that depend on the electrolysis conditions, namely, the current density and Fe
2
O
3
/Cr
2
O
3
or Fe
2
O
3
/Ni(OH)
2
content ratio.
This paper demonstrates the availability of electro‐codeposition (i.e., the simultaneous occurrence of electrophoretic deposition of nanoparticles and electrochemical deposition of metal ions) in ...molten salts without the assistance of stirring of the bath. In molten NaCl–KCl–AlCl3–MoO3 system containing TiB2 nanoparticles at 710°C, the electro‐codeposition of TiB2 nanoparticles and Mo(VI) ions has been achieved, and a (Ti, Mo)B2 coating has been prepared.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
•Electrodeposition of Aluminium-Titanium alloys during aluminium electrolysis in laboratory experiments.•Effect of alloy deposition on the current efficiency for aluminium.•Current efficiency for ...Aluminium-Titanium alloys as an indication of process feasibility.•Current distribution and cell voltage behavior.
This study reports the direct production of an aluminium-titanium alloy during aluminium electrolysis in fluoride-based melts. Experiments were conducted in a laboratory cell dedicated to current efficiency measurements. The temperature was varied from 960 to 980 °C at a cathodic current density (CCD) of 0.9 A/cm2 and a cryolite ratio (CR) of 2.2. The titanium content was up to 1.0 wt%. Titanium was added in the form of a TiO2 precursor. Bath samples were collected regularly and analyzed with ICP-MS to observe the decay of titanium during electrolysis. The current efficiency for electrodeposition of Al–Ti alloys was estimated to be at least around 90%. The surface of the solidified metal deposits was mostly flat, but some deposits were partially deformed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Electrodeposition of aluminium–manganese alloys during aluminium electrolysis in laboratory experiments.•Effect of alloy deposition on the current efficiency for aluminium.•Current efficiency for ...aluminium–manganese alloys as an indication of process feasibility.•Solidified metallic deposits shape and cell voltage behavior.
This study reports the direct production of an aluminium–manganese alloy during aluminium electrolysis in fluoride-based melts. Experiments were conducted in a laboratory cell dedicated for current efficiency measurements. The temperature was varied from 965–980 °C at a cathodic current density (CCD) of 0.9 A/cm2 and a cryolite ratio (CR) of 2.2. The manganese content was up to 3.0 wt%. Manganese was added in the form of Mn2O3. Bath samples were collected regularly and analyzed with ICP-MS to observe the decay of manganese during electrolysis. It was possible to produce Al-Mn alloys of up to 21 wt. % Mn. Current efficiency for the electrodeposition of Al–Mn alloy was estimated to be in the range of 93%. Current efficiencies with respect to aluminium were estimated. The solidified surfaces of the metal deposits were mostly flat, but some were deformed.
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Supercapacitor performances are influenced by binder types and contents in the electrodes. The electrochemical performances of activated carbon (AC) with Nafion, poly(tetrafluoroethylene) (PTFE) and ...poly(vinylidenedifluoride) (PVDF) and different contents of each binder were investigated by cyclic voltammetry (CV), galvanostatic charge discharge (GCD) and electrochemical impedance spectroscopy (EIS). The optimal content of binder in the electrode is 10 wt% for Nafion and PTFE, but only 5 wt% for PVDF. The specific capacitances of the AC electrodes with optimal content of Nafion, PTFE and PVDF are respectively 131.3, 156.6 and 160.6 F g-1; their corresponding specific capacitances retain 87%, 91% and 79.6% after 2000 CV cycles with a scan rate of 200 mV s-1. Therefore, PTFE is the best suitable binder for supercapacitors and its optimal content is 10 wt%.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Electrochemical studies, mainly cyclic voltammetry, square wave voltammetry and chronoamperometry, were carried out to study the behavior of dissolved silicon species in molten LiF-KF with additions ...of K2SiF6 at temperatures from 550 to 800°C. Electrolysis experiments were run at constant current to deposit pure silicon. Working electrodes of silver, tungsten and glassy carbon and cathodes of silver and silicon were used.
The cathodic reduction of dissolved Si (IV) species to silicon was found to be diffusion controlled. Some influence of nucleation phenomena was observed on silver cathode substrates. High purity and good quality silicon deposits were obtained during galvanostatic electrolysis. One challenge is to reduce the inclusions of solidified electrolyte. Current efficiencies for silicon deposition were found to be in the range from 85 to 95%.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Written to record and report on recent research progresses in the field of molten salts, Molten Salts Chemistry and Technology focuses on molten salts and ionic liquids for sustainable supply and ...application of materials. Including coverage of molten salt reactors, electrodeposition, aluminium electrolysis, electrochemistry, and electrowinning, the text provides researchers and postgraduate students with applications include energy conversion (solar cells and fuel cells), heat storage, green solvents, metallurgy, nuclear industry, pharmaceutics and biotechnology.
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