Anodic Corrosion Research Articles

Using tetramethylammonium hydroxide electrolyte to inhibit corrosion of Mg-based amorphous alloy anodes: A route for promotion energy density of Ni-MH battery

• Ni-MH battery can be assembled with amorphous Mg-Ni anode by using the concentrated TMAH electrolyte. • Concentrated TMAH electrolyte shows an ionic-liquid-like hydrate structure. • Concentrated TMAH electrolyte enables excellent cycle life for Mg-based anodes. • In-situ forming Cu coating can suppress the corrosion of Mg-based anodes and increase rate capability. Concentrated tetramethylammonium hydroxide (TMAH) aqueous electrolyte with a special hydrate structure has been explored and enables excellent cycle stability and high capacity for Mg-based alloy anodes. Mg-based alloy anodes suffer from severe corrosion in conventional electrolytes (KOH solution) and this substantially obstructs the cycle life, which is a great challenge for using them in the Ni-MH battery. Herein, a high concentration tetramethylammonium hydroxide (TMAH) aqueous electrolyte with a special hydrate structure is explored and enables excellent cycle stability and high capacity for Mg-based alloy anodes. In this electrolyte, the Mg 0.4 Ti 0.1 Ni 0.5 alloy anode delivers a maximum discharge capacity of 466 mAh g −1 , and maintains 210 mAh g −1 after 100 cycles owing to the reduced corrosion rate, which are much better than that in 6 M KOH electrolyte, being 425 mAh g −1 and 69 mAh g −1 , respectively. Furthermore, by in-situ forming Cu coating on the Mg 0.4 Ti 0.1 Ni 0.5 electrode surface during charging process with the adding 0.01 M of Cu(OH) 2 in TMAH electrolyte, the corrosion of the electrode is further suppressed and the reversible capacity can reach 313 mAh g −1 after 100 cycles. The high conducting Cu coating can also increase the rate capability of the electrode by promoting the charge transfer. Thus, using TMAH electrolytes provides a new approach to promote the electrochemical performances of Ni-MH batteries with Mg-based alloy anodes.

Anodic corrosion of heteroatom doped graphene oxide supports and its influence on the electrocatalytic oxygen evolution reaction

Transition metal-based electrocatalysts supported on carbon substrates face the challenges of anodic corrosion of carbon during oxygen evolution reaction at high oxidation potential. The role of electrophilic functional groups (carbonyl, pyridinic, thiol, etc.) incorporated in graphene oxide has been studied towards the anodic corrosion resistance. Heteroatom functionalized carbon supports possess modified electronic properties, surface oxygen content, and hydrophilicity, which are crucial in governing electrochemical corrosion in the alkaline oxidative environment. Evidently, electron-withdrawing groups in NGO support (pyridinic, cyano, nitro, etc) and its lower oxygen content impart maximum corrosion resistance and anodic stability in comparison to the other sulfur-doped and co-doped graphene oxide support. In this report, we establish the baseline evaluation of carbon-supported OER electrocatalysts by a systematic analysis of activity and substrate corrosion resistance. The result of this study establishes the role of surface composition of the doped supports while for designing a stable, corrosion-resistant OER electrocatalyst.

Development and Evaluation of Lamella Settlers Combined with Electrocoagulation for Treating Suspended Sediment

Stormwater quality has become an increasingly important issue in agricultural, urban, and construction sectors. Soil, nutrient, and pollutant discharge caused during rainfall events is one of the greatest sources of stormwater quality degradation. Enhanced stormwater treatment mechanisms are needed to economically and efficiently remove suspended pollutants in runoff. In this research, the performance of electrocoagulation (EC) combined with lamella settlers (LS) was investigated. EC is a highly effective and proven water-treatment technology that uses an electrochemical anode corrosion process to destabilize and remove contaminants and that has been shown to have widespread applications for treating a variety of wastes. LSs have been shown to enhance soil-particle capture by increasing the surface area and reducing the settling distance. This research demonstrated that the combination of EC and LS can enhance the sedimentation process while simultaneously decreasing the required detention time and size of traditional sediment control practices (i.e., detention basins, sediment basins). Combining EC with a LS is a novel approach for treating suspended particles in stormwater. In this project, bench-scale experiments were conducted using EC as pretreatment upstream of a LS reactor. Synthetic silica filler at concentrations of 500 mg/L, 1,000 mg/L, and 5,000 mg/L were used to evaluate treatment efficiency at 0.5-h, 1.0-h, and 1.5-h residence times. Collected data, including turbidity, total suspended solids, and particle size distribution, were used to statistically characterize the system’s sediment removal performance. Through a series of experiments and statistical analyses of the results, an optimized EC+LS reactor with 1.27-cm (0.5-in.) LS plate spacing and 1.5-h residence time reduced turbidity by up to 98% and total suspended solids by 99% in effluent when compared with a base case reactor with a 31.8 cm (12.5 in.) settling distance (no LS plates installed) and 0.5-h residence time without EC pretreatment. In addition, particle size distribution analyses resulted in a decrease in the D90 value by 84%, indicating that the optimized reactor was effective in capturing larger-diameter soil particles. To validate the laboratory results with synthetic sediment-laden influent, stormwater samples were collected from a construction site and treated through the optimized system, resulting in a turbidity reduction of 50% and TSS reduction of 69%.

Kinetics and mechanism of gold anode corrosion in a weakly basic aqueous solution of triethylenetetramine

Kinetics and mechanism of gold anode corrosion in a weakly basic aqueous solution of triethylenetetramine

Investigation of high current density on zinc electrodeposition and anodic corrosion in zinc electrowinning

Investigation of high current density on zinc electrodeposition and anodic corrosion in zinc electrowinning

Reversible passivation in primary aluminum-air batteries via composite anodes

Despite the fact that primary aluminum-air have extraordinary theoretical energy densities, their shelf life is irreversibly restricted by anodic hydrogen evolution corrosion. However, current corrosion-suppression solutions usually make significant sacrifices in terms of energy and power density. We prepared carbonaceous nanomaterial-reinforced aluminum matrix composites as anodes for reversible passivation, preventing self-corrosion in an open-circuit state. Homogeneous microstructures of the composites induced by severe plastic deformation allow for the formation of passivation films against hydrogen evolution reactions. The strong bonds between magnesium-containing aluminum hydroxides and fluorinated graphene nanoplatelet enhance the stability of the nanosphere-structured passivation layer. The fluorinated nano-reinforcements enable reversible adsorption and exfoliation induced by the discharge process to realize reversible passivation mechanisms. This composite anode in aluminum-air cells achieves a 424% increase in effective energy density during intermittent discharge, which possesses a considerable anode energy utilization of 37.5% and an intermittent discharge efficiency of 95.3 ± 3.1%.

Advanced perfluorinated electrolyte with synergistic effect of fluorinated solvents for high-voltage LiNi0.5Mn1.5O4/Li cell

A series of designed fluorinated electrolytes with single or multiple fluorinated solvents were developed for the application of high-voltage lithium second batteries. The synergistic effect of various fluorinated solvents evidently enhance the reversible capacity, cycle and rate performance of the LiNi0.5Mn1.5O4 (LNMO)/Li cell, profitted from superior durability of the electrolyte to resist oxidation (despite weakened ionic conductivity), successful surface modification on the LNMO cathode to suppress parasitic reaction, and improved Li metal compatibility to aviod anode corrosion. Theoretical calculation results reveal that the competitive coordination among different solvents inevitably regulates the solvation structure of Li ion, redox capability of the electrolyte and then interfacial chemistry on both electrodes.

A Separator Modified with Rutile Titania and Three‐Dimensional Interconnected Graphene‐Like Carbon for Advanced Li−S Batteries

AbstractAs an advanced energy‐storage system, Li−S batteries have attracted much attention, but there is still a series of problems hindering their commercialization, such as the ‘shuttle effect’ and corrosion of lithium anodes. To alleviate these two important problems simultaneously, we modified the separators with spherical rutile TiO2 with oxygen vacancies (abbreviated OT) and three‐dimensional interconnected graphene‐like carbon (abbreviated GC) for advanced Li−S batteries to improve the electrochemical performance. The modified separators (abbreviation OTCD) have low charge transfer impedance, a catalytic effect on polysulfides, and a barrier effect on polysulfides, which can suppress the ‘shuttle effect’ and prevents the corrosion of lithium anodes in Li−S batteries. The as‐prepared Li−S batteries show good cycling stability for 250 cycles with 0.048 % capacity decay per cycle at 1 C. Moreover, the SEM images of lithium anodes after 50 cycles showed that the lithium anodes were uncorroded. This work provides a practical and effective reference for the advanced Li−S batteries.

Monitoring Corrosion in Sacrificial Anodes With Pulsed Eddy Current and Electromechanical Impedance: A Comparative Analysis

Measuring the extent of corrosion of sacrificial anodes used in cathodic protection systems would enable real-time monitoring of the efficacy and remaining useful life of the cathodic protection system. This article presents a comparison of the sensing capabilities of pulsed eddy current (PEC) and electromechanical impedance (EMI) based techniques for measuring extent of corrosion of zinc sacrificial anodes. Experiments were conducted with a lead zirconate titanate (PZT) transducer attached to the sacrificial anode as well as with a PEC probe placed in the vicinity of the sacrificial anode. Accelerated corrosion tests were performed on the anode and the corrosion was quantified by the root mean square deviation (RMSD) of the conductance spectra for the EMI based measurement and area under the curve (AUC) method for the pulsed eddy current based measurement. The experimental results show good agreement with finite element method (FEM) simulations. We report that the EMI method has large sensitivity to onset of corrosion in the anode, with sensitivity reducing nonlinearly over time due to delamination of corrosion by-products. In contrast, the PEC method shows excellent linearity over the entire duration of the accelerated corrosion experiment. A key insight from this work is that an effective monitoring strategy could combine the merits of both sensing mechanisms, with EMI used for identifying incipient corrosion and PEC used for tracking the extent of corrosion over the life of the sacrificial anode.

Corrosion behaviour improvement from the ultrafine-grained Al–Zn–In​ alloys in Al–air battery

Corrosion of aluminium anode in alkaline solution is a challenging matter for the development of a long-life aluminium anode in Al–air battery. This research focuses on grain size reduction by equal channel angular pressing (ECAP) of Al, Al–Zn, and Al–Zn–In samples. The average grain size of all samples after ECAP is lower than 1μm. Open circuit potential, potentiodynamic polarisation, electrochemical impedance spectroscopy, and self-corrosion test were carried out to study the effects of alloying elements (Zn, In) and grain size reduction by ECAP on the electrochemical behaviours of aluminium alloy anodes. The results show that alloying element, zinc, can improve the stability of ion dissolution by porous Al2ZnO4 film formation. Indium can activate ion dissolution that causes enhanced electrochemical activities for Al–Zn–In sample. Moreover, increasing grain boundaries through grain size reduction can enhance more negative potential and cause a uniformly corroded surface of Al–Zn–In sample, leading to a longer anode life in alkaline solution.

Layer-by-Layer Assembly of CeO2-x@C-rGO Nanocomposites and CNTs as a Multifunctional Separator Coating for Highly Stable Lithium-Sulfur Batteries.

Commercialization of high-energy Li-S batteries is greatly restricted by their unsatisfactory cycle retention and poor cycling life originated from the notorious "shuttling effect" of lithium polysulfides. Modification of a commercial separator with a functional coating layer is a facile and efficient strategy beyond nanostructured composite cathodes for suppressing polysulfide shuttling. Herein, a multilayered functional CeO2-x@C-rGO/CNT separator was successfully achieved by alternately depositing conductive carbon nanotubes (CNTs) and synthetic CeO2-x@C-rGO onto the surface of the commercial separator. The cooperation of multiple components including Ce-MOF-derived CeO2-x@C, rGO, and CNTs enables the as-built CeO2-x@C-rGO/CNT separator to perform multifunctions from the separator surface: (i) to hinder the diffusion of polysulfide species through physical blocking or chemical adsorption, (ii) to accelerate the sluggish redox reactions of sulfur species, and (iii) to enhance the conductivity for sulfur re-activation and efficient utilization. Serving as a multilayer and powerful barrier, the CeO2-x@C-rGO/CNT separator greatly constrains and reutilizes the polysulfide species. Thus, the Li-S battery assembled with the CeO2-x@C-rGO/CNT separator demonstrates an excellent combination of capacity, rate capability, and cycling performances (an initial capacity of 1107 mA h g-1 with a low decay rate of 0.060% per cycle over 500 cycles at 1 C, 651 mA h g-1 at 5 C) together with remarkably mitigated self-discharge and anode corrosion. This work provides guidelines for functional separator design as well as rare-earth material applications for Li-S batteries and other energy storage systems.

Long-Life and Highly Utilized Zinc Anode for Aqueous Batteries Enabled by Electrolyte Additives with Synergistic Effects.

After decades of development, zinc-based batteries with the advantages of high energy density, low cost, and environmental benignity have been considered as a promising battery system in the application of energy storage. However, the poor cycle performance of zinc anode strongly restricts the cycle life of zinc-based batteries and thus limits its large-scale application. Electrolyte additives have been proven to be one of the most straightforward strategies in improving the stability of zinc anode during cycles, while the options of additives are still limited. This work is based on the in-depth investigation of the electrochemical behavior of both the organic additives and the zinc species in the electrolyte. The modification effects of poly(vinyl alcohol) (PVA) and vanillin as two typical additives from the electroplating industry in both the zinc plating and zinc anode are systematically studied. It is revealed that PVA could increase the utilization and rate performance of the anode, while greatly promoting the corrosion and shape change of the zinc anode. On the contrary, the existence of vanillin could maintain the structure of the anode during cycles, while the rate performance of the battery is hindered. With the coaddition of the PVA and vanillin, the zinc anode shows superior performance in cycle life, rate performance, active material utilization, and discharge energy retention. These findings provide insight for the enrichment of electrolyte additives in zinc-based batteries.

Electrochemical CO2 reduction to ethylene by ultrathin CuO nanoplate arrays

Electrochemical reduction of CO2 to multi-carbon fuels and chemical feedstocks is an appealing approach to mitigate excessive CO2 emissions. However, the reported catalysts always show either a low Faradaic efficiency of the C2+ product or poor long-term stability. Herein, we report a facile and scalable anodic corrosion method to synthesize oxygen-rich ultrathin CuO nanoplate arrays, which form Cu/Cu2O heterogeneous interfaces through self-evolution during electrocatalysis. The catalyst exhibits a high C2H4 Faradaic efficiency of 84.5%, stable electrolysis for ~55 h in a flow cell using a neutral KCl electrolyte, and a full-cell ethylene energy efficiency of 27.6% at 200 mA cm−2 in a membrane electrode assembly electrolyzer. Mechanism analyses reveal that the stable nanostructures, stable Cu/Cu2O interfaces, and enhanced adsorption of the *OCCOH intermediate preserve selective and prolonged C2H4 production. The robust and scalable produced catalyst coupled with mild electrolytic conditions facilitates the practical application of electrochemical CO2 reduction.

Corrosion crack failure analysis of 316L hydraulic control pipeline in high temperature aerobic steam environment of heavy oil thermal recovery well

The 316L hydraulic control pipeline (HCP) easily caused corrosion failure in the process of heavy oil recovery. In this study, the corrosion failure of 316L HCP in the 260–350 °C high temperature aerobic steam environment was investigated by using autoclave. Based on SEM, EDS, cracks morphology and XPS analysis, the failure mechanism of 316L HCP exposure in different high temperature steam environments was concluded. The results indicate that the corrosion fracture occurs at 260 °C. The SCC cracking was transgranular propagation, and the corrosion failure was attributed to anodic dissolution stress corrosion cracking. With the increase of temperature, the formation of absorbed water film on the surface contributes to improving the compactness of corrosion products which could prevent the crack propagating under corrosion medium. Moreover, the high temperature significantly affected the content of Cr(OH)3 and Ni(OH)2 in the oxide film which improved the corrosion resistance of stainless steel.

Ultrathin and super-tough membrane for anti-dendrite separator in aqueous zinc-ion batteries

Rechargeable aqueous zinc-ion batteries have emerged as potential alternatives to lithium-ion batteries in grid energy storage due to their intrinsic safety, economy, and high capacity of zinc anode. Unfortunately, dendrite growth, limited reversibility, and corrosion of metal zinc anodes in aqueous systems seriously hamper the application of zinc-ion batteries. Herein, ultrathin and high-toughness membranes composed of eco-friendly biomass nanofibers are constructed for substituting glass-fiber separators in rechargeable zinc-ion batteries. The presence of this robust biomass membrane lowers separator thickness to 9 μm, which can prevent the pierce of zinc dendrite, manipulate crystallographic orientation during zinc deposition, and improve the anti-corrosion property of zinc. Thus, this robust biomass membrane enables excellent electrochemical performance and sheds light on a multifunctional design for improving metal zinc anode performance from separators beyond zinc itself.

Defect Engineering in a Multiple Confined Geometry for Robust Lithium–Sulfur Batteries

AbstractThe decay of lithium–sulfur (Li–S) batteries is mainly due to the shuttle effect caused by intermediate polysulfides (LiPSs). Herein, a multiple confined cathode architecture is prepared by filling graphitized Pinus sylvestris with carbon nanotubes and defective LaNiO3−x (LNO‐V) nanoparticles. The composite electrode with high areal sulfur loading of 11.6 mg cm−2 shows a high areal specific capacity of 8.5 mAh cm−2 at 1 mA cm−2 (0.05 C). Both experimental results and theoretical calculations reveal that this unique structure not only provides physical restriction on LiPSs within microchannels but also offers strong chemical immobilization and catalytic conversion of LiPSs attributed to the spin density around oxygen vacancies of LaNiO3−x. These oxygen vacancies elongate the SS and LiS bonds and make them easy to break. Furthermore, the lengthwise channels derived from cytoderm restrict the transverse diffusion of polysulfides, leading to a uniform areal current and thus homogeneous lithium infiltration. This suppresses the corrosion of the lithium anode due to polysulfides confinement. The discovery of the multiple confined structure that provides chemical adsorption, fast diffusion, and catalytic conversion for polysulfides can broaden the application of biomass materials and offer a new strategy to achieve robust Li–S batteries.

Constructing robust zincophilic–channels on Zn anode for long-life Zn-ion batteries

Zn-metal anodes are promising candidates for aqueous Zn-ion batteries (ZIBs) owing to their high theoretical capacity, good electrochemical reversibility, and the natural abundance of zinc. However, dendrite growth and corrosion of Zn anodes during cycling hinder the practical application of ZIBs. In this study, we built robust zincophilic channels based on carboxylated hollow ceria (CHC) nanostructures on a Zn anode. With a robust three-dimensional nanostructure, the zincophilic–channel interfaces on the Zn anode present highly stable Zn plating/stripping cycling stability for up to 2000 h at a high current density of 3 mA cm−2. The resulting CHC@Zn//MnO2 full cell exhibits enhanced electrochemical performance.

Energy-Saving Hydrogen Production by Seawater Electrolysis Coupling Sulfion Degradation.

Electrolysis of costless and infinite seawater is a promising way toward grid-scale hydrogen production without causing freshwater stress. Practical potential of this technology, however, is hindered by low energy efficiency and anode corrosion by the detrimental chlorine chemistry in seawater in addition to unaffordable electricity expense. Herein, energy-saving hydrogen production is reported by chlorine-free seawater splitting coupling sulfion oxidation. It yields hydrogen at a low cell voltage of 0.97V, cutting the electricity consumption to 2.32kWh per m3 H2 at 300mA cm-2 . Compared to alkaline water electrolysis, the energy expense is primarily saved by 60% with 50% lower energy equivalent input. Benefiting from the ultralow cell voltage, the hazardous chlorine chemistry is fully avoided without anode corrosion regardless of Cl- crossover. Meanwhile, it also allows fast degradation of S2- pollutant from the water body to value-added sulfur with 80% efficiency, for further reducing hydrogen cost and protection of the ecosystem. Connecting such a hybrid seawater electrolyzer to a commercial solar cell can harvest the hydrogen from seawater with better sustainability. This work may offer new opportunities for low-cost hydrogen production from the unlimited ocean resources with environmental protection.

Local Basicity Dependent Gas-Liquid Interfacial Corrosion of Nickel Anode and Its Protection in Molten Li2CO3-Na2CO3-K2CO3

Revealing the gas-liquid interfacial corrosion mechanism of metals under anodic polarization in molten salts is crucial for the development of metallic anodes for molten carbonate electrolysis. Herein, the effects of operating temperature, gas atmosphere, applied current density and electrolysis time on the gas-liquid interfacial corrosion behaviors of nickel anodes in molten Li2CO3-Na2CO3-K2CO3 were systematically investigated. It was found that the gas-liquid interfacial corrosion of nickel anodes was accelerated with decreasing temperature and increasing CO2 content of gas atmosphere. Three distinct corrosion regions of nickel anodes can be identified: (I) the thin salt film region, (II) the meniscus region, and (III) the full immersion region. It was revealed that the formation of negative basicity gradient in the meniscus induced the dissolution/re-precipitation of NiO scale, thereby accelerating the gas-liquid interfacial corrosion of nickel anodes. Furthermore, an Al2O3 sheath was applied to shield the gas-liquid part of nickel electrodes to prevent gas-liquid interfacial corrosion, thus making Ni a stable oxygen-evolution inert anode.

A robust and eco-friendly waterborne anti-corrosion composite coating with multiple synergistic corrosion protections

Environmentally friendly waterborne coatings have received significant attention recently due to their lower volatile organic compounds (VOCs) emission than solvent-based coatings, but their practical applications are severely limited by poor barrier properties. Herein, a novel and robust waterborne OBN-PA-Zn-D/WEP anti-corrosion composite coating was successfully fabricated by utilizing hydroxyl-functionalized h-BN (OBN) nanosheets , phytic acid (PA), Zn 2+ and dicyandiamide. Due to the π-π interactions between OBN and organic-inorganic PA-Zn-D complex, the dispersibility of OBN-PA-Zn-D nanosheets was improved, which was beneficial for enhancing the physical barrier properties of OBN-PA-Zn-D/WEP composite coating. After adding dicyandiamide, the interface compatibility between OBN-PA-Zn-D nanosheets and the waterborne resin matrix was significantly improved, greatly reducing the defects inside the OBN-PA-Zn-D/WEP composite coating. In addition, PA and Zn 2+ formed protective layer in the defect area to inhibit the corrosion of anode and cathode . Therefore, under the effect of multiple synergistic corrosion protections , the eco-friendly waterborne OBN-PA-Zn-D/WEP composite coating exhibited unique anti-corrosion performance that was greatly improved compared with the conventional waterborne epoxy coatings . • A robust and eco-friendly waterborne anti-corrosion composite coating was prepared. • OBN-PA-Zn-D/WEP composite coating provided strong corrosion protection. • Physical barrier, corrosion inhibition and interface enhancement synergistically enhance anti-corrosion ability.