Electrolytic Corrosion Research Articles

Effect of the electrolyte composition on the corrosion resistance of single-layer CVD-graphene

The corrosion resistance of a single-layer graphene film synthetized via chemical vapor deposition (CVD) on a polycrystalline copper substrate is studied. The anticorrosive properties were identified by means of electrochemical tests of potentiodynamic polarization and electrochemical impedance spectroscopy in the following environments: (a) 0.5 M H2SO4, (b) 0.5 M HCl, (c) 3.5wt% NaCl + 0.5 M H2SO4, and (d) Na2S2O3 (10−4 mol / l) + 5% NaCl + (CH3COOH) 0.50%). For the characterization of the graphene and corrosion products, the following techniques were used: Raman spectroscopy, AUGER electron spectroscopy, X-ray energy dispersion probe (EDS), scanning electron microscopy (SEM), and confocal laser scanning microscopy (CLSM). The corrosion mechanism and the degree of degradation of the graphene are discussed as a function of the corrosive electrolyte.

Corrosion inhibition of carbon steel in hydrochloric acid solution by self-formation of a Malpighia glabra leaf extract-based organic film

A forming organic film applied onto a metallic surface to resist electrochemical corrosion is demonstrated as a potentially new low-cost, low toxicity solution. In this work, the inhibitory effect of Malpighia glabra leaf extract (MGLE) on the corrosion of mild steel in 0.01, 0.10, and 1.00 M hydrochloric acid (HCl) media and the changes in its inhibitory efficiency were investigated. The analyses indicate that the inhibition performance increases up to 94.87% with an increase in MGLE concentration in the range of 0–2500 ppm when MGLE is added to 0.1 M HCl solution. However, it slightly decreased with MGLE concentrations greater than 3000 ppm owing to a reduction in the mobility and activity of the MGLE species under the investigated conditions. Notably, the inhibition occurs at a higher level (97.07%) when the steel is immersed in a more aggressive solution (1 M HCl). The results also show good inhibition effectiveness as a mixed corrosion inhibitor with more anodic predomination in a less acidic environment (0.01 M HCl). Furthermore, the surface analysis results show that the uninhibited steel surface is severely corroded, while less corrosion is observed on the inhibited surfaces covered by a protective film. The corrosion mitigation of carbon steel could be attributed to the bonding of the MGLE species on the surface to form a protective layer with densely packed organic compounds involving the MGLE species. Therefore, this work could deliver a new inhibitor with high resistance to steel corrosion in an acidic medium through controlled corrosive electrolytes.

The Stabilizing Effect of Li4Ti5O12 Coating on Li1.1Ni0.35Mn0.55O2 Cathode for Liquid and Solid–State Lithium-Metal Batteries

Li–rich layered cathode materials with high energy density suffer from severe capacity decay during cycling, which is associated with volume change and electrolyte corrosion during (de)lithiation. A Li+ ionic conducting Li4Ti5O12 coating with high structural integrity is developed on Li1.1Ni0.35Mn0.55O2 cathodes via a dry powder coating method. The electrochemical performances of Li4Ti5O12–coated Li1.1Ni0.35Mn0.55O2 cathodes in liquid and solid–state lithium batteries were investigated. The initial discharge capacity of Li4Ti5O12–coated Li1.1Ni0.35Mn0.55O2 in the liquid electrolyte has been improved from 116.5 mA h g−1 to 123.7 mA h g−1 at 0.1°C. An impressive cyclability with a high capacity retention of 89.3% was achieved in solid–state lithium batteries. These results demonstrate that the Li4Ti5O12 coating plays an essential role in enhancing the specific capacity and better performance for Li1.1Ni0.35Mn0.55O2 cathode.

Exploring the corrosion inhibition mechanism of 8-hydroxyquinoline for a PEO-coated magnesium alloy

In this study, the corrosion inhibition effect of 8-hydroxyquinoline (8HQ) on a PEO-coated AZ21 magnesium alloy is explored. The interaction of 8HQ molecules with both bare AZ21 and PEO layer was thoroughly scrutinized during the exposure to a corrosive NaCl electrolyte using different characterization methods, including EIS, SEM, Raman spectroscopy, and XRD. The corrosion inhibition mechanism stems from the extensive precipitation of the insoluble complex between 8HQ molecules and Mg2+ on top of the PEO layer, which leads to subsequently inhibition-enhancing phenomena, including modification of the corrosion products and re-precipitation of the PEO amorphous phase.

Suppressing oxygen vacancies on the surface of Li-rich material as a high-energy cathode via high oxygen affinity Ca0.95Bi0.05MnO3 coating

Because of high energy density and work voltage, the Li-rich materials are considered to be one of the most promising next-generation lithium-ion batteries. However, the commercial applications are limited by the capacity loss, poor rate capability, and voltage decay during cycling. Herein, functionalizing the surface of Li1.2Mn0.54Ni0.13Co0.13O2 by Ca0.95Bi0.05MnO3 is proposed, which suppresses the formation of the oxygen vacancies and maintains structural stability by high oxygen affinity and alleviative electrolyte corrosion. Electrochemical tests demonstrate that this admirable electrode delivers excellent cycling stability. The Li-rich electrode decorated with 5 wt.% Ca0.95Bi0.05MnO3 exhibits a stable capacity retention of 86.5% at 0.1C after 200 cycles and an excellent full cell performance with the energy retention of 95.4% at 0.1C after 100 cycles. Moreover, the voltage decay of the modified material is restrained from 5.02 to 3.07 mV per cycle over 200 cycles. The finding here sheds new light on the development of the better Li-rich cathodes for improving electrochemical performance of electrode materials.

Microgroove-patterned Zn metal anode enables ultra-stable and low-overpotential Zn deposition for long-cycling aqueous batteries

The application of zinc (Zn) metal in aqueous Zn metal batteries (ZMBs) has been hindered by the susceptibility of Zn anodes to dendritic electrodeposition due to its inhomogeneous surface structures. Herein, we design uniform microgroove patterns on practically accessible Zn foil anodes using a simple and scalable acid etching strategy. The unique surface structure guides homogeneous Zn deposition, accelerates interfacial reaction kinetics, and inhibits electrolyte corrosion. The resulting Zn anodes afford an excellent plating/stripping stability of 2920 h at an ultralow overpotential of 19.5 mV under 1 mA cm−2/1 mAh cm−2 cycling, with both the cycle life and overpotential ranking among the best records reported thus far. Moreover, the synergetic mechanisms for morphology-induced enhancement were rigorously elucidated. The present strategy contributes a reliable performance baseline for future studies, and can be readily combined with other emerging tactics such as surface coating to accelerate further performance upgrades towards practical ZMBs.

Significant Enhancement of the Capacity and Cycling Stability of Lithium-Rich Manganese-Based Layered Cathode Materials via Molybdenum Surface Modification.

Lithium-rich manganese-based layered cathode materials are considered to be one of the best options for next-generation lithium-ion batteries, owing to their ultra-high specific capacity (>250 mAh·g−1) and platform voltage. However, their poor cycling stability, caused by the release of lattice oxygen as well as the electrode/electrolyte side reactions accompanying complex phase transformation, makes it difficult to use this material in practical applications. In this work, we suggest a molybdenum surface modification strategy to improve the electrochemical performance of Li1.2Mn0.54Ni0.13Co0.13O2. The Mo-modified Li1.2Mn0.54Ni0.13Co0.13O2 material exhibits an enhanced discharge specific capacity of up to 290.5 mAh·g−1 (20 mA·g−1) and a capacity retention rate of 82% (300 cycles at 200 mA·g−1), compared with 261.2 mAh·g−1 and a 70% retention rate for the material without Mo modification. The significantly enhanced performance of the modified material can be ascribed to the formation of a Mo-compound-involved nanolayer on the surface of the materials, which effectively lessens the electrolyte corrosion of the cathode, as well as the activation of Mo6+ towards Ni2+/Ni4+ redox couples and the pre-activation of a Mo compound. This study offers a facile and effective strategy to address the poor cyclability of lithium-rich manganese-based layered cathode materials.

Comparative evaluation of the oxidation resistance of untreated, annealed and quenched 434 ferritic stainless steels in corrosive electrolytes

Comparative evaluation of the oxidation resistance of untreated, annealed and quenched 434 ferritic stainless steels in corrosive electrolytes

Experimental and theoretical examinations of two quinolin-8-ol-piperazine derivatives as organic corrosion inhibitors for C35E steel in hydrochloric acid

The mitigation impacts of two quinolin-8-ol-piperazine analogs 7-((4-(benzo[d][1,3]dioxol-5-ylmethyl)piperazin-1-yl)methyl)quinolin-8-ol (OPMQ) and 7-((4-benzylpiperazin-1-yl)methyl)quinolin-8-ol (BPMQ) on the C35E steel corrosion in 1 M HCl environment were examined by gravimetric, electrochemical, surface analysis, electrolyte analysis, as well as molecular modeling techniques. The examined OPMQ and BPMQ exhibited obvious anticorrosion performances within the scope of concentrations and temperature considered, maximum reached of 95.1% and 88.7% at 10−3 M, respectively. Polarization examinations demonstrated that the OPMQ and BPMQ being as mixed-type inhibitors. Moreover, the quinolin-8-ol-piperazine analogs adsorption obeyed the Langmuir adsorption isotherm, presenting chemical interactions. Thermodynamic and kinetic quantities were estimated and discussed. Uv/Visible spectra proved the occurrence of chemical interaction among the C35E steel and quinolin-8-ol-piperazine analogs molecules, while no damages have been observed in the SEM images after the addition of quinolin-8-ol-piperazine analogs adsorption to the corrosive electrolyte. The computational correlations (DFT and Molecular Dynamic simulations) justify the experimental observations.

Enhanced structure and electrochemical stability of single crystal nickel-rich cathode material by La2Li0.5Co0.5O4 surface coating

The emergence of single crystal nickel-rich cathode materials preparation offsets the poor cycle performance of traditional ternary cathode materials, with an efficient enhancement of the energy density. Despite all this, the stability of single crystal Ni-rich materials is still hard to fully meet the commercial requirements. We select La and Co elements for co-coating single crystal cathode materials by an efficient method, La2Li0.5Co0.5O4 coating layer with a thickness of about 5 nm is successfully formed on the single crystal nickel-rich samples. The coating layer effectively protect nickel-rich materials from the corrosion of electrolyte and retain a high Li-ion conductivity during charge/discharge processes. Besides, the part of residual lithium reacts with La and Co, forming La2Li0.5Co0.5O4 coating layer, and decorates the materials surface. Eventually, the single crystal NCM811 with 2 wt% La2Li0.5Co0.5O4 coating affords a terrific cyclic stability after 200 cycles. The capacity retention is 81.15% at 1 C with voltage range of 2.8–4.3 V, obtaining an 18% performance improvement compare with that of pristine material. Moreover, the rate performance and first charge/discharge efficiency are improved to a certain extent. The co-coating process with La and Co is a competitive approach to modify the performance of single crystal nickel-rich cathode materials and contribute to the commercial application of the NCM811 materials.

Interfacial Reviving of the Degraded LiNi0.8 Co0.1 Mn0.1 O2 Cathode by LiPO3 Repair Strategy.

Nickel-rich cathode materials, owing to their high energy density and low cost, are considered to be one of the cathodes with the most potential in next-generation lithium-ion batteries. Unfortunately, this kind of cathode with highly active surface is easy to react with H2 O and CO2 when exposed to ambient air, resulting in the formation of lithium impurities and interfacial phase transition as well as deterioration of the electrochemical properties. In this work, the evolution mechanism of the structure and interface of LiNi0.8 Co0.1 Mn0.1 O2 during air-exposure is systematically investigated. Furthermore, a facile reviving strategy is proposed to restore the degraded LiNi0.8 Co0.1 Mn0.1 O2 by using LiPO3 as the repair agent. The lithium impurities on the surface of the degraded sample can transform into the repair/coating layer, and part of the rock salt phase on the subsurface can revive to layered phase after repair heat treatment. As a result, the optimized cathode delivers an initial discharge capacity of 198.3 mAh g-1 at 0.1C and a capacity retention of 85.5% after 50 cycles. Although slightly lower than the bare sample (201 mAh g-1 and 88%), they are obviously higher than the exposed samples (166.5 mAh g-1 and 40.4%). The regenerated electrochemical properties should be attributed to the multifunctional repair layer that can efficiently reduce the surface lithium impurities, prevent the corrosion of electrolyte, and improve the interfacial Li+ diffusion kinetics. This work can effectively reduce the waste of the degraded Ni-rich ternary materials and realize the transformation of "waste" into wealth.

Corrosion behavior of marine structural steel in tidal zone based on wire beam electrode technology and partitioned cellular automata model

The initial corrosion evolution of marine structural steel in tidal zone is studied using wire beam electrode (WBE). The electrochemical experiment results show that the WBE in the high and middle tidal zones are in the anodic dissolution state for less time than that in the low tidal and immersion zones. The fitting results of WBE experiment provide the boundary conditions for the partitioned cellular automata (PCA) model, which is adopted to simulate the initial corrosion evolutions of steel in the tidal zone. The proposed independent variable of the electrolyte concentration (ρ), corrosion probability (Pc), passivation probability (Pp), and movement direction probability (Pm) on the corrosion behavior of steel are studied. The calculated results demonstrate that ρ and Pm can well characterize the corrosion evolutions of the steel in ocean tidal zones. This model is effective in predicting the corrosion evolution of marine structural steel in tidal zone. It provides a new method for predicting the corrosion evolution of marine structural steel in tidal zone.

Hybrid interlayer enables dendrite-free and deposition-modulated zinc anodes

Metal zinc is regarded as one of ideal anode choices for aqueous batteries owing to the high-safety and low-cost energy storage property. Nevertheless, the poor reversibility and short cycle life of metal Zn anodes caused by notorious dendrites and chemical corrosion have compromised the practical application. In this direction, a new-formed ZnO/C hybrid serving as a multifunctional artificial protection layer is designed via simple complex calcination method and coated on zinc surface to mitigate degradation. The as-synthesized inorganic-carbon hybrid interlayer is utilized as a robust physical barrier to remit corrosion of electrolyte and avoid drastic evolution of dendrite, which can contribute to uniform interfacial Zn ion flux, even charge distribution, and increased stripping/plating reversibility. The electrochemical results indicate deposition stability is greatly improved with an extended cycle life of 2000 h at 0.25 mA cm−2 and 600 h at 5 mA cm−2. Even under high current density of 10 mA cm−2, the coated electrode can still stably maintain for over 300 h. Moreover, the feasibility of artificial layer is also investigated by full cells with MnO2- and V2O5-based cathodes. All of the full battery devices exhibit long operation life with higher specific capacity, revealing the prospect of ZnO/C hybrid interlayer in aqueous rechargeable zinc-ion batteries.

In Situ Atomic Force Microscopy Analysis of the Corrosion Processes at the Buried Interface of an Epoxy‐like Model Organic Film and AA2024‐T3 Aluminum Alloy

The application of characterization methods with high spatial resolution to the analysis of buried coating/metal interfaces requires the design and use of model systems. Herein, an epoxy‐like thin film is used as a model coating resembling the epoxy‐based coatings and adhesives widely used in technical applications. Spin coating is used for the deposition of a 30 nm‐thin bilayer (BL) composed of poly‐(ethylenimine) (PEI) and poly[(o‐cresyl glycidyl ether)‐co‐formaldehyde] (CNER). Fourier‐transform infrared spectroscopy (FTIR) results confirm that the exposure of coated AA2024‐T3 (AA) samples to the corrosive electrolyte solution does not cause the degradation of the polymer layer. In situ atomic force microscopy (AFM) studies are performed to monitor local corrosion processes at the buried interface of the epoxy‐like film and the AA2024‐T3 aluminum alloy surface in an aqueous electrolyte solution. Hydrogen evolution due to the reduction of water as the cathodic corrosion reaction leads to local blister formation. Based on the results of the complementary energy‐dispersive X‐ray spectroscopy (EDX) analysis performed at the same region of interest, most of the hydrogen evolved originates at the vicinity of Mg‐containing intermetallic particles.

AC corrosion behavior and the effect of stone-hard-soil on corrosion process in the earth alkaline rich environment

Many oil and gas pipelines are parallel with high voltage transmission lines in a long distance. Corrosion failures in such situation have been reported and typical corrosion morphology (stone-hard-soil) have found in these failures. In this paper, AC corrosion behavior and the effects on corrosion process after the formation of typical corrosion morphology are investigated in earth alkaline rich environment through laboratory simulated tests. This study produce a corrosion rate map where high CP AC corrosion and local corrosion are observed. In domain of high CP AC corrosion, local environment, including typical morphology of stone-hard-soil and corrosive electrolyte at interface, are analyzed. After the formation of stone-hard-soil, the electric field and its effects on migration of Cl-, are discussed. These results, combining the changes in instantaneous potential and pH at local regions, provide a guide to understand the occurrence and development of local corrosion under high CP level and AC interference.

Property evaluation of TixZrNbTaFeBy high entropy alloy coatings: Effect of Ti and B contents

High entropy alloy (HEA) coatings have been widely explored due to their unique properties as compared with conventional alloy coatings. In this work, an equimolar TiZrNbTaFe HEA target and a TiB2 target were used to fabricate six TixZrNbTaFeBy HEA alloys with different Ti and B contents. The Ti and B contents were increased by adjusting the input power ratios of TiZrNbTaFe HEA and TiB2 targets. The (Ti + B)/(Zr + Ta + Nb + Fe) ratio of the coatings increased from 0.91 to 11.61 as the TiB2 to ZrTiNbTaFe HEA target input power ratio increased from 1.43 to 20. The TixZrNbTaFeBy coating kept its amorphous structure while the (Ti + B)/(Zr + Ta + Nb + Fe) ratio was less than 11.61. A nanocomposite microstructure consisting of TiB2 nanocrystallites embedded in an amorphous TiZrNbTaFe matrix was obtained for the Ti15.2Zr0.9Nb1Ta1.2Fe1.1B33.8 coating. The hardness of TixZrNbTaFeBy coatings increased with increasing Ti and B contents. Good adhesion properties were found for coatings with higher (Ti + B)/(Zr + Ta + Nb + Fe) ratios. Each amorphous TixZrNbTaFeBy coating enhanced the corrosion resistance of bare 304 stainless steel substrate because of the dense microstructures to block the attack of corrosive electrolytes. The nanocrystalline TiB2 structure found in the Ti15.2Zr0.9Nb1Ta1.2Fe1.1B33.8 coating exhibited a potential application as a protective coating in harsh environments due to its high hardness of 21 GPa, excellent adhesion, good wear resistance, and adequate anticorrosion property.

A Valence Gradient Protective Layer for Dendrite‐Free and Highly Stable Lithium Metal Anodes

AbstractLi metal is the next‐generation anode material for high‐energy‐density Li‐ion batteries. Unfortunately, its practical application is hampered by drawbacks such as an unstable solid electrolyte interphase and undesirable Li dendrites. Herein, an Fe‐based protective layer with a valence gradient is constructed on Li anodes, which consists of an Fe3+/Fe2+‐rich outer layer and an Fe0‐containing inner layer. The protective layer not only isolates the underlying Li metal from the corrosive carbonate electrolyte, but also uniformly stores Li during plating and inhibits the growth of Li dendrites. The Li anode with the Fe‐based protective layer shows dendrite‐free Li plating/stripping behaviors; therefore, Li symmetric cells stably run for 1000 h at 1 mA cm‐2 and 1 mA h cm‐2 and even survive for 380 h at an ultra‐high capacity of 30 mA h cm‐2. With such a highly stable Li anode, LiFePO4 cells operate steadily for 1600 and 1000 cycles at 1 and 5 C, respectively. High‐loading LiCoO2 cells also present excellent cycling stability and rate capability, proving the advantages of the protective layer in Li anode protection.

Recycling of cathode material from spent lithium-ion batteries: Challenges and future perspectives

The intrinsic advancement of lithium-ion batteries (LIBs) for application in electric vehicles (EVs), portable electronic devices, and energy-storage devices has led to an increase in the number of spent LIBs. Spent LIBs contain hazardous metals (such as Li, Co, Ni, and Mn), toxic and corrosive electrolytes, metal casting, and polymer binders that pose a serious threat to the environment and human health. Additionally, spent LIBs may serve as an economic source for transition metals, which could be applied to redesigning under a closed-circuit recycling process. Thus, the development of environmentally benign, low cost, and efficient processes for recycling of LIBs for a sustainable future has attracted worldwide attention. Therefore, herein, we introduce the concept of LIBs and review state-of-art technologies for metal recycling processes. Moreover, we emphasize on LIB pretreatment approaches, metal extraction, and pyrometallurgical, hydrometallurgical, and biometallurgical approaches. Direct recycling technologies combined with the profitable and sustainable cathode healing technology have significant potential for the recycling of LIBs without decomposition into substituent elements or precipitation; hence, these technologies can be industrially adopted for EV batteries. Finally, commercial technological developments, existing challenges, and suggestions are presented for the development of effective, environmentally friendly recycling technology for the future.

Highly stable operation of LiCoO2 at cut-off ≥ 4.6 V enabled by synergistic structural and interfacial manipulation

Elevating the charge cut-off voltage is the most effective approach for boosting the energy density of LiCoO2 (LCO), which however is hindered by accelerated structural devastation and interfacial degradation at high voltages, e.g. ≥ 4.6 V vs. Li/Li+. In this work, we propose a synergistic strategy by designing a Mg doped and Se coated LCO (LCO-Mg@Se). The strong Mg-O bond greatly stabilizes the layered structure of LCO, to alleviate the lattice parameter variation during deep delithiation. Se surface treatment, acting as an artificial CEI layer, interacts with O2−: 2p during deep stage of charge, effectively weakening the Co: 3d-t2g – O2−: 2p hybridization. Moreover, the Se coating layer could inhibit the parasitic side reactions and refrains the electrolyte corrosion toward the electrolyte-cathode interface, further mitigating the phase transformation to disordered rock salt phase at LCO particle surface and reducing the generation of resistive byproducts. These cooperative efforts enable the substantially enhanced high-voltage electrochemical performance of LCO-Mg@Se, achieving 147 mAh g−1 after 1000 cycles (72.9% retention) at charge cut-off 4.6 V and 148 mAh g−1 after 400 cycles at charge cut-off 4.65 V. The high-temperature cycling performance and thermal stability are greatly enhanced as well. This bifunctional structure/interface engineering approach provides scalable design ideas for developing cathode materials for high energy density batteries.

Zn-Based Deep Eutectic Solvent as the Stabilizing Electrolyte for Zn Metal Anode in Rechargeable Aqueous Batteries.

Owing to its low cost and high safety, metallic zinc has received considerable attention as an anode material for zinc aqueous batteries (ZIBs). However, the Zn metal instability as a result ultrafast of obstinate dendrite formation, free-water-induced parasite reactions, and corrosive electrolytes has detrimental effects on the implementation of ZIBs. We present an alternative stable electrolyte for ZIBs based on a zinc chloride/ethylene glycol deep eutectic solvent (DES). This electrolyte consists of abundant low-cost materials and a utilizable Zn2+ concentration of approximately 1 M. It combines the advantages of the aqueous and DES media to provide safe and reversible Zn plating/stripping with a two-fold increase in the cycling life compared to that of conventional aqueous electrolytes. With these advantages, the Zn symmetric cell operates at 0.2 mA cm−2 for 300 h. Due to its high efficiency and compositional versatility, this electrolyte enables the investigation of a non-aqueous electrolyte family for ZIBs that fulfill grid-scale electrical energy storage requirements.