ON THE ANODIC OVERVOLTAGE IN ALUMINUM ELECTROLYSIS

Jomar Thonstad; Eirik Hove

doi:10.1139/v64-237

ON THE ANODIC OVERVOLTAGE IN ALUMINUM ELECTROLYSIS

Canadian Journal of Chemistry ◽

10.1139/v64-237 ◽

1964 ◽

Vol 42 (7) ◽

pp. 1542-1550 ◽

Cited By ~ 18

Author(s):

Jomar Thonstad ◽

Eirik Hove

Keyword(s):

Chemical Reactivity ◽

Reference Electrode ◽

Aluminum Electrolysis ◽

Carbon Anode ◽

Cell Reaction ◽

Chemisorbed Oxygen ◽

Reversible Potential ◽

Graphite Anodes ◽

Slow Transport ◽

Carbon Anodes

The overvoltage on the carbon anode in aluminum electrolysis has been measured against a CO2/C reference electrode placed in the cryolite melt. The behavior of the reference electrode was first investigated against the aluminum cathode. This galvanic cell showed a stable potential of 1.15 V, which was close to the reversible potential for the cell reaction in aluminum electrolysis. Similar measurements were made with CO/C and CO2,CO/C electrodes. The potential of the CO/C electrode was in fair agreement with the reversible potential for the most probable cell reaction. The potentials obtained with CO2–CO mixtures were intermediate between those for the pure gases, increasing with increasing CO2 content. An explanation for the behavior of the CO2,CO/C electrode is suggested.The anodic overvoltage depended only to a limited extent on the chemical reactivity of carbon with respect to oxygen. Graphite anodes showed higher overvoltage than all other types of carbon anodes. Catalyzing and inhibiting additives to the carbon had small but significant influences on the overvoltage. Straight Tafel plots were obtained with slopes varying between 0.26 and 0.27. On this basis it is shown that the overvoltage may be due either to slow transport of oxygen ions through the double layer or to slow reaction between chemisorbed oxygen and carbon.

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Anodic Bubble Behavior in a Laboratory Scale Transparent Electrolytic Cell for Aluminum Electrolysis

Metals ◽

10.3390/met8100806 ◽

2018 ◽

Vol 8 (10) ◽

pp. 806 ◽

Cited By ~ 3

Author(s):

Yipeng Huang ◽

Zhaowen Wang ◽

Youjian Yang ◽

Bingliang Gao ◽

Zhongning Shi ◽

...

Keyword(s):

Bubble Dynamics ◽

Aluminum Electrolysis ◽

Electrolytic Cell ◽

Laboratory Scale ◽

Carbon Anode ◽

Electrolysis Cell ◽

Bubble Behavior ◽

Electrolysis Process ◽

Graphite Anodes ◽

Carbon Anodes

In the Hall-Héroult process for extracting aluminum, the evolution and dynamics of anodic bubbles have a significant influence on the efficiency of the overall electrolysis process. In this study, the behavior of the bubbles beneath the carbon anode in cryolite-alumina molten salt was studied for the first time using a laboratory-scale transparent electrolysis cell to view the anode from the bottom. The bubble dynamics and the relevant characteristic parameters of bubbles were obtained using video cameras and image processing. It was found that the bubbles were observed to preferentially generate at several areas on the underside of the anode and the morphologies of coalesced bubbles show excellent similarity. Moreover, the behavior of gas on carbon and graphite anodes was significantly different, where the carbon anode favored the forming of larger bubbles. These observations confirmed different types of carbon anodes cause different bubble behavior. These findings are expected to be useful in optimizing the aluminum electrolysis process on an industrial scale.

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Investigating Effects of Different Flue-Wall Deformation Modes on the Performance of Anode Baking Furnaces for Aluminum Electrolysis

Volume 8: Heat Transfer and Thermal Engineering ◽

10.1115/imece2019-10507 ◽

2019 ◽

Author(s):

Abdul Raouf Tajik ◽

Mouna Zaidani ◽

Tariq Shamim ◽

Rashid K. Abu Al-Rub

Keyword(s):

Gas Flow ◽

Aluminum Electrolysis ◽

Deformation Mode ◽

Carbon Anode ◽

Operational Parameters ◽

Aluminum Reduction ◽

Wall Deformation ◽

Anode Temperature ◽

Carbon Anodes ◽

Deformation Modes

Abstract In carbon anode baking furnaces, temperature and quality of carbon anodes are significantly affected by the deformation of the flue-walls, where the flue-gases flow and combustion occur. Flue-walls aging gives rise to non-homogeneous baking of the carbon anodes and results in deterioration of the anode quality, which eventually causes instabilities in aluminum reduction cells and overconsumption of anodes and energy. It is imperative to develop a fully coupled 3D multi-physics computational model which takes into account a large number of physical phenomena that play vital roles in the baking process and are affected by the flue-wall deformation mode. In the present study, the effects of flue-wall deformation modes on flue-wall cavity gas flow and anode temperature distribution are investigated. The pressure and flow distributions for different levels of flue-wall deformation are demonstrated. It is perceived that a 100 mm convex mode of flue-wall deformation leads to under-baking of anodes by almost 20 degC. For the concave mode of deformation, since the packing coke thickness reduces, overbaking of anode occurs. The methodology and results presented in the present research can be employed effectively by the aluminum industry in modifying the furnace geometrical and operational parameters to enhance baking uniformity after flue-wall is deformed.

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Effect of carbon anode production parameters on anode cracking

SN Applied Sciences ◽

10.1007/s42452-020-04133-8 ◽

2021 ◽

Vol 3 (2) ◽

Author(s):

Salah Amrani ◽

Duygu Kocaefe ◽

Yasar Kocaefe ◽

Dipankar Bhattacharyay ◽

Mohamed Bouazara ◽

...

Keyword(s):

Electrical Resistivity ◽

Crack Density ◽

Raw Material ◽

Carbon Anode ◽

Know How ◽

Production Parameters ◽

Environmental Emissions ◽

Carbon Anodes ◽

Tomographic Analysis

AbstractCarbon anodes are used in the electrolytic production of aluminum. The quality of anodes is directly related to the production cost, carbon and energy consumption, and environmental emissions. It is desired that the anodes have high density, low porosity/cracks, low electrical resistivity as well as low air and CO2 reactivities. Low resistivity of anodes reduces energy required to produce aluminum during electrolysis. The presence of cracks and pores increases the anode electrical resistivity. Therefore, it is important to know how and when the pores and cracks form during the anode production so that the necessary actions could be taken to prevent their formation. A study was carried out to investigate the effect of different anode production parameters such as anode composition, type of raw material used, time and top-former bellow pressure of vibro-compactor, green anode cooling medium, and heating rate used during baking on the crack formation. The anodes are fabricated at the carbon laboratory of University of Quebec at Chicoutimi (UQAC) and characterized by measuring their properties (density, electrical resistivity, and surface crack density). The anode properties, hence the anode quality, were correlated with the anode production parameters. Also, their tomographic analysis was carried out to visualize and quantify the internal cracks. Graphical abstract

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A New Method of Producing Carbon Anode by High-Temperature Mould Pressing

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.415-417.611 ◽

2011 ◽

Vol 415-417 ◽

pp. 611-616

Author(s):

Yao Wu Wang ◽

Nai Xiang Feng ◽

Jing You

Keyword(s):

High Temperature ◽

Bulk Density ◽

Electrical Resistance ◽

Chemical Properties ◽

New Method ◽

Carbon Anode ◽

Crushing Strength ◽

Industrial Carbon ◽

Physico Chemical ◽

Carbon Anodes

Laboratory-scale carbon anodes were produced by a new method of high-temperature mould pressing, and their physico-chemical properties were studied in laboratory. The results showed that the bulk density of carbon anodes produced by high-temperature mould pressing are 1.61-1.63g/cm3, they are higher than industrial carbon anode by 0.06 g/cm3, but the specific electrical resistance is higher and crushing strength is lower.

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Solutions for the problems of silicon–carbon anode materials for lithium-ion batteries

Royal Society Open Science ◽

10.1098/rsos.172370 ◽

2018 ◽

Vol 5 (6) ◽

pp. 172370 ◽

Cited By ~ 16

Author(s):

Xuyan Liu ◽

Xinjie Zhu ◽

Deng Pan

Keyword(s):

Lithium Ion Batteries ◽

Anode Materials ◽

High Capacity ◽

Lithium Ion ◽

Cycling Performance ◽

Carbon Anode ◽

Environmental Friendliness ◽

Silicon Carbon ◽

New Energy ◽

Carbon Anodes

Lithium-ion batteries are widely used in various industries, such as portable electronic devices, mobile phones, new energy car batteries, etc., and show great potential for more demanding applications like electric vehicles. Among advanced anode materials applied to lithium-ion batteries, silicon–carbon anodes have been explored extensively due to their high capacity, good operation potential, environmental friendliness and high abundance. Silicon–carbon anodes have demonstrated great potential as an anode material for lithium-ion batteries because they have perfectly improved the problems that existed in silicon anodes, such as the particle pulverization, shedding and failures of electrochemical performance during lithiation and delithiation. However, there are still some problems, such as low first discharge efficiency, poor conductivity and poor cycling performance, which need to be improved. This paper mainly presents some methods for solving the existing problems of silicon–carbon anode materials through different perspectives.

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Environmental impact, life cycle analysis and battery performance of upcycled carbon anodes

Environmental Science Nano ◽

10.1039/c8en00196k ◽

2018 ◽

Vol 5 (5) ◽

pp. 1237-1250 ◽

Cited By ~ 6

Author(s):

Andrea L. Hicks ◽

Arthur D. Dysart ◽

Vilas G. Pol

Keyword(s):

Life Cycle ◽

Environmental Impact ◽

Lithium Ion Batteries ◽

Life Cycle Analysis ◽

Lithium Ion ◽

Environmental Costs ◽

Graphite Anodes ◽

Synthetic Graphite ◽

Carbon Anodes ◽

Natural And Synthetic

For rechargeable lithium ion batteries, natural and synthetic graphite anodes come with great economic and environmental costs.

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Improved Carbon Anode Materials for Lithium-Ion Cells

MRS Proceedings ◽

10.1557/proc-496-613 ◽

1997 ◽

Vol 496 ◽

Author(s):

J. Flynn ◽

C. Marsh

Keyword(s):

Anode Materials ◽

Reference Electrode ◽

Lithium Ion ◽

Discharge Voltage ◽

Carbon Anode ◽

Test Results ◽

Half Cell ◽

Cell Discharge ◽

Lithium Ion Cells ◽

Cell Data

ABSTRACTSeveral carbon materials have been studied for suitability as anode materials in lithium-ion cells. Carbons that have been included in this evaluation are three grades of commercially available mesophase carbon microbeads (MCMB) 6–28, 10–28 and 25–28, two specially prepared mesophase fibers (Amoco), a foreign mesophase fiber and KS-15 graphite (Lonza). Differences in cycling behavior between the three types of MCMB material are shown. Data of full lithium-ion cells demonstrate the effect that the choice of carbon material has on the cell discharge voltage and capacity. Lithium reference electrode experiments in full cells (3.0–4.0Ah capacity), elucidate the dynamics under several charge/discharge regimes and provide a comparison between the performance of carbon fiber and graphite anode materials. These test results indicate that the fibers can be charged at significantly higher rates than graphite without showing polarization at the anode. Full and half cell data also demonstrates the high coulombic efficiencies of the mesophase materials and first cycle efficiencies as compared to graphite. A comparison of two mesophase materials with different textures in full cells under strenuous cycling conditions shows significant differences in capacity retention. SEM photos of fibers showing the different textures are also presented.

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