Metal Dissolution Reaction Research Articles

Azoles as corrosion inhibitors in alkaline medium for ruthenium chemical mechanical planarization applications:Electrochemical and theoretical analysis

The adsorption performance and inhibition mechanism of azoles; Imidazole (IMD), 1, 2, 4-Triazole (TAZ), and 1, 2, 3-Benzotriazole (BTAH) inhibitors on ruthenium (Ru) at 9 pH, were investigated in this study using electrochemical techniques and density functional theory (DFT) simulations. The electrochemical data demonstrate that the three azole compounds being investigated are mixed type corrosion inhibitors with anodic predominance, and the order of corrosion inhibition efficiency for Ru is BTAH > TAZ > IMD. The azole compounds suppress the metal dissolution reaction rate by adhering on to the Ru surface and nature of adsorption (combined physisorption and chemisorption) is explained via Langmuir adsorption isotherm model. The increase in contact angle on the Ru surface verified the successful adsorption of the three organic inhibitors on the Ru surface. Furthermore, the suppression of corrosion reaction kinetics is validated with field emission scanning electron microscopy (FESEM) images. The results of quantum chemistry calculations indicate that the corrosion inhibition effect of BTAH is superior to that of IMD and TAZ. Further, using molecular dynamics modelling, the reliable configuration of the organic inhibitor molecules on the Ru (001) surface in aqueous medium was investigated and the total adsorption energy was computed.

Quantitative study on the metal dissolution reaction with multivalent cations by a modified SECM mode: Pure Ti as a case

Metal corrosion exhibits coupled multi-reaction features, making it challenging to quantitatively study the dissolution reaction with variable-valent cations, particularly in valence quantification. This work develops a novel scanning electrochemical microscopy mode and applies it to Ti dissolution study in acidic fluorides. This mode identifies the potential-dependent corrosion reactions and quantifies the valence evolution of Ti from HER to transpassive regions. Results provide direct electrochemical evidence for soluble Ti(z≤3), for the first time, and revise the reported dissolution equation. The proposed mode overcomes the drawbacks of macro-electrochemical analysis based on coupling information and provides an effective quantitation method for anodic reactions.

Transpassive Metal Dissolution vs. Oxygen Evolution Reaction: Implication for Alloy Stability and Electrocatalysis.

Multi-principal element alloys (MPEAs) are gaining interest in corrosion and electrocatalysis research due to their electrochemical stability across a broad pH range and the design flexibility they offer. Using the equimolar CrCoNi alloy, we observe significant metal dissolution in a corrosive electrolyte (0.1 M NaCl, pH 2) concurrently with the oxygen evolution reaction (OER) in the transpassive region, despite the absence of hysteresis in polarization curves or other obvious corrosion indicators. We present a characterization scheme to delineate the contribution of OER and alloy dissolution, using scanning electrochemical microscopy (SECM) for OER-onset detection, and quantitative chemical analysis with inductively coupled-mass spectrometry (ICP-MS) and ultraviolet visible light (UV/Vis) spectrometry to elucidate metal dissolution processes. In situ electrochemical atomic force microscopy (EC-AFM) revealed that the transpassive metal dissolution on CrCoNi is dominated by intergranular corrosion. These results have significant implications for the stability of MPEAs in corrosion systems, emphasizing the necessity of analytically determining metal ions released from MPEA electrodes into the electrolyte when evaluating Faradaic efficiencies of OER catalysts. The release of transition metal ions not only reduces the Faradaic efficiency of electrolyzers but may also cause poisoning and degradation of membranes in electrochemical reactors.

Transpassive Metallauflösung vs. Sauerstoffentwicklung: Auswirkungen auf Legierungsstabilität und Elektrokatalyse

AbstractMulti‐Hauptelement‐Legierungen (MPEAs) gewinnen in der Korrosions‐ und Elektrokatalyseforschung aufgrund ihrer elektrochemischen Stabilität über einen breiten pH‐Bereich und der Vielfalt der möglichen chemischen Zusammensetzungen zunehmend an Interesse. In unseren Untersuchungen mit der äquimolaren CrCoNi‐Legierung in einem sauren Elektrolyten (0.1 M NaCl, pH 2) beobachteten wir eine signifikante Metallauflösung, die mit der Sauerstoffentwicklungsreaktion (OER) im transpassiven Bereich einhergeht, obwohl in zyklischen Polarisationskurven keine Hysterese auftrat oder andere offensichtliche Korrosionsindikatoren vorlagen. In diesem Artikel wird ein Charakterisierungskonzept eingeführt, dass die Beiträge der OER und der Legierungsauflösung differenziert. Hierfür kommt die elektrochemische Rastermikroskopie (SECM) zum Nachweis des Beginns der OER und die quantitative chemische Analyse mit induktiv gekoppelter Massenspektrometrie (ICP‐MS) und UV/Vis‐Spektrometrie zur Aufklärung der Metallauflösungsprozesse zum Einsatz. Die elektrochemische In situ‐Atomkraftmikroskopie (EC‐AFM) zeigte, dass die intergranulare Korrosion der dominierende Mechanismus der transpassive Metallauflösung von CrCoNi ist. Diese Ergebnisse besitzen erhebliche Auswirkungen für die Beurteilung der Stabilität von MPEAs in Korrosionssystemen und der Stromausbeute von OER‐Katalysatoren auf der Basis von MPEAs. Die Daten unterstreichen die Notwendigkeit der analytischen Bestimmung von Metallionen, die von MPEA‐Elektroden freigesetzt werden. Die Freisetzung von Übergangsmetallionen verringert nicht nur die Stromausbeute von Elektrolyseuren, sondern kann zu einer Schädigung von Membranen in elektrochemischen Reaktoren führen.

Nanoelectrochemistry of Metal Dissolution and Deposition Reactions

Electrochemical metal dissolution and depositions reactions are reversible processes involving phase transition, which are fundamentally important in battery and corrosion. The electrode kinetics of these reactions are highly sensitive to the surface structures. In this talk, I will present the study on the initiation of metal dissolution reactions on Ag and Ni, representing model systems for oxide-free and oxide-covered metals, respectively. The local dissolution kinetics is voltammetrically mapped via scanning electrochemical cell microscopy (SECCM). Co-localized characterization of crystal orientation reveals slower dissolution on {111} close-packed planes. Direct measurement of local dissolution kinetics on grain boundaries shows a faster dissolution rate on some but not all grain boundaries. We demonstrate that correlative electrochemical and structural imaging are powerful tools for studying heterogeneity at complex electrochemical interfaces, which can also be used to study metal deposition reactions at the nanoscale.

Electrochemical, surface analysis, computational and anticorrosive studies of novel di-imine Schiff base on X65 steel surface

The inhibitory effect of di-imine-SB namely ((N1Z, N4E)-N1, N4-bis (4 (dimethylamino) benzylidene) butane 1,4-diamine) on X65-steel in 1 M HCl has been investigated experimentally and theoretically. The electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), and weight loss outcomes display the anticorrosion properties of “di-imine- SB”. The inhibitory efficiency exceeds 90% at the optimal concentration of 1 × 10–3 M “di-imine- SB”. The metal surface was examined further using scanning electron microscope (SEM) and energy dispersive X-ray (EDX). The effectiveness of the di-imine-SB is returned into its adsorption on X65-steel surface and found in agreement with Langmuir adsorption isotherm. According to the standard Gibbs free energy of adsorption ({Delta G}_{ads}^{^circ }), di-imine-SB adsorption tends to be chemical rather than physical, it increases the activation energy ({mathrm{E}}_{a}) of metal dissolution reaction and makes it hard to occur. The PDP data suggested anodic and cathodic type of the di-imine-SB inhibitor. Meanwhile, increasing the resistance of X65-steel to 301 Ω cm2 after adding 1 mM of di-imine-SB confirms its protective effect. Whereas, the positive value of the fraction of electron transference (ΔN, 0.746), confirms the affinity of di-imine-SB to share electrons to the partially filed 3d-orbital of Fe forming strong protective film over X65-steel surface. Aided by Monte Carlo (MC) simulation, the calculated adsorption energy (Eads) suggests excessive adsorption affinity of di-imine-SB on metal surface over the corrosive chlorides and hydronium ions. A good correlation between the theoretical hypothesis and the experimental inhibition efficiency has been achieved. The comparative study showed the superior of the di-imine-SB as potential corrosion inhibitor compared with those reported before. Finally, global reactivity descriptors; electron affinity (A), ionization potential (I), electronegativity (χ), dipole moment (µ), global hardness (eta), electrophilicity index and, Fukui indices were also calculated and found well correlated to the reactivity of di-imine-SB.

A comprehensive study on the adsorption, corrosion inhibition efficiency and stability of acriflavine on mild steel in 1 M HCl solution

A comprehensive study was conducted on the adsorption, corrosion inhibition efficiency and stability of acriflavine (ACF) on mild steel (MS) in 1 M HCl solution. Electrochemical studies were conducted to determine the corrosion protection ability of the inhibitor after short and long immersion times. The MS surface after exposing to the uninhibited and inhibited solutions were characterized by SEM, EDX, AFM and contact angle measurements. The excess surface charge of the metal and some thermodynamic parameters were derived after 1 h and 6 h exposure times and a possible adsorption and inhibition mechanism was discussed. The electrochemical stability of the inhibitor film formed on the metal surface was studied using potentiodynamic and potentiostatic techniques. It was found that ACF adsorbs on the MS surface via dominantly chemical and weakly physical interactions and forms a protective surface film. The film was adherent, uniform, protective and electrochemically stable. The inhibitor film provides maximum inhibition efficiencies of 92.8% and 97.1% at 1 mM after 1 h and 6 h immersion times. ACF mitigates the rates of both anodic metal dissolution and cathodic hydrogen evolution reactions. The excess surface charge of the steel in the inhibited solution was negative, which becomes more evident after longer exposure time.

Investigation of oxygen evolution reaction with 316 and 304 stainless-steel mesh electrodes in natural seawater electrolysis

Two commercially available stainless steel mesh substrates (316 SS and 304 SS) were evaluated as electrodes for oxygen evolution reaction (OER) in natural seawater electrolysis. The results show the 304 SS is less stable against corrosion under neutral (pH of 8.5) and low alkaline (0.1 M NaOH, pH of 12.8) seawater electrolytes because of the direct metal dissolution and chlorine evolution reaction (CER), and the 316 SS is superior to 304 SS in terms of electrocatalytic activity and resistance to corrosion under the same media. The performance of 304 SS is comparable to 316 SS under the high alkaline (1 M NaOH, pH of 13.7) seawater electrolyte, where the CER and metal dissolution are suppressed by OER. The overpotential for 304 and 316 SS is around 430 mV at 10 mA cm−2, and the Tafel slopes are below 50 mV dec−1 under the high alkaline (1 M NaOH) seawater electrolyte, showing promising performance. The poor resistance to corrosion of 304 SS is attributed to the low Mo content, and it is supposed that the stability of both 304 and 316 SS can be improved further with the addition of Mo content. This work expands on promising substrates for natural seawater electrolysis, with cost and performance advantages.

Facile Formulation of New Innovative Eco-Friendly Hybrid Protective Coating for Mild Steel in Acidic Media

This research deals with the formulation, characterization, and evaluation of new anticorrosive protective coatings. The study objective is to protect mild carbon steel in acidic media by adherent nonporous polymeric coatings formulated from polystyrene and shrimp shells. Solid wastes of shrimp shells are dried into a fine powder and sonicated in toluene. The obtained suspension is refluxed with polystyrene. The hot-melt coatings are applied to the metal surface by the hot dipping technique. The shrimp shells improve the performance of polystyrene. These eco-friendly, low-cost anticorrosive coatings are formulated from solid waste (SW) of shrimp shells and polystyrene (PS) with no aiding additives. Intense vibrational bands in the infrared spectra and the high thermal stability of the coating samples confirm the compatibility of the coating constituents. The results of the evaluation of coating performance by electrochemical impedance spectroscopy and potentiodynamic polarization techniques show that the coating is protective for mild steel in the aggressive acidic media of 1.0 M HCl. The coating protects the metal surface without affecting the corrosion mechanism. Polarization curves show that the coating film retards both the anodic metal dissolution reaction and the cathodic hydrogen evolution reaction, acting as mixed-type inhibitors. The percent protection (%P) increases with the increasing weight percent (wt.%) of PS and the SW of shrimp shells. A %P up to 99% is achieved for the coating composition of 2.0 g/L PS + 0.02 g/L SW. The %P obtained by impedance and polarization measurements are in good agreement. The prepared multi-functional polymeric coating forms an adherent nonporous coating film on the metal surface. Impedance plots show that the coating samples are insulating dielectric coatings that electrically insulate the metal surface from the aggressive acidic media. The coating protects the metal surface by the adsorption mechanism. Shrimp shells fill the pores and increase the stiffness of the polymeric coating film of polystyrene. The obtained results in this study will be useful for all industrial sectors and academic research in the field of corrosion control of metals and alloys.

Synthesis and evaluation of newly E-octadec-9-enoic acid derivatives as sustainable corrosion inhibitors for mild steel in 1.0 M HCl

Several new amide derivatives having varied aromatic characteristics prepared efficiently via nucleophilic acyl substitution reactions are tested for corrosion inhibition of mild steel in 1 M HCl at 20, 40, and 60 °C range by gravimetric methods. All compounds have shown very good inhibition efficiency (IE%) in acidic solutions. Increasing the temperature (in the presence of the inhibitor in the higher concentration (100–1000 μM) are found to increase the inhibition efficiency of the amide’s derivatives. Results from gravimetric measurements further revealed that Inh. 4 shows excellently at 60 °C giving IE% of 91.88 at 1000 μM. Thermodynamic parameters (ΔG º ads, ΔH º ads, and ΔS º ads) for the adsorption process and kinetic parameters for the metal dissolution (or hydrogen evolution) reaction in the presence of the new derivatives were determined. Experimental results agree with the Temkin adsorption isotherm. The inhibition of corrosion in 1 M HCl, influenced by both physi- and chemisorption, was found to be under mixed control but predominantly under cathodic control as revealed by the potentiodynamic polarization measurements for Inh. 4. Frontier molecular orbital calculations predicted that the newly synthesized inhibitors with aromatic characteristics serve as donor-centers to the empty d-orbital of the metal atoms and would exhibit higher corrosion IE%.

Highly improved structural stability and electrochemical properties of Ni-rich NCM cathode materials

We report a simple, easy way using WO3 to build a conductive protective coating layer on the surface of LiNi0.8Co0.1Mn0.1O2 cathode. The WO3 coating layer can block direct contact between the LiNi0.8Co0.1Mn0.1O2 and electrolyte, resulting in suppress the transition metal dissolution and interfacial unwanted reaction on the particle surface. Moreover, WO3 coating layer allows for the smooth and rapid lithium and electron kinetics. The WO3 coating improves the electrochemical performance, especially, this way significantly enhances the rate capability of 166.2 mAh g−1 at 6.0C and cyclability of 85.8% after 100 cycles. Therefore, WO3 coating provides a new breakthrough to improve the structural stability and suppress the resistance for superior electrochemical performances of lithium ion batteries.

N-[2-(3-indolyl)ethyl]-cinnamamide synthesized from cinnamomum cassia presl and alkaloid tryptamine as green corrosion inhibitor for Q235 steel in acidic medium

In this work, N-[2-(3-indolyl)ethyl]-cinnamamide (IA) synthesized from tryptamine (TA) and cinnamic acid was evaluated as green corrosion inhibitor for Q235 steel in 0.5 M HCl solution by weight loss tests, potentiodynamic polarization (PDP) curve and electrochemical impedance spectroscopy (EIS). Gravimetric measurements displayed the maximum inhibition efficiencies of TA and IA at 1.0 mM were up to 92.8% and 97.6%, respectively. PDP and EIS studies revealed they could hinder both hydrogen evolution and metal dissolution reactions and that the inhibiting effect was temperature and concentration dependent. The surface analysis of sample was presented through scanning electron microscope (SEM), energy dispersive spectroscopy (EDX) and atomic force microscope (AFM), which indicated the anti-corrosion ability of Q235 steel in hydrochloric acid was enhanced by the inhibitor. The adsorptive behavior of inhibitors including physisorption and chemisorption obeyed Langmuir isotherm. The inhibition mechanism was elucidated by determining the potential of zero charge (Epzc) at solid/liquid interface. Quantum chemistry calculation provided a theoretical estimate of the reactivities of TA and IA as corrosion inhibitors to ascertain the correlation between the inhibition efficiency and molecular structures. Results of molecular dynamics (MD) simulations confirm that IA shows better inhibitive performance due to higher interaction energy (– 79.1 kJ mol−1 for TA and – 144.16 kJ mol−1 for IA).

Optimization of Loading Content of Li4Ti5O12-Hard Carbon Composite Anode for the Fast Charging Li-Ion Battery

Fast charge of lithium-ion batteries (LIBs) needs anode and cathode materials operating at high current densities. Li4Ti5O12 (LTO) can enable fast lithium ion (Li+) transport due to its 3D crystal structure. Nonetheless, this material suffers from low specific capacity and high operating voltage. In contrast, Hard Carbon (H.C) with high specific capacity and low practical voltage is one of the promising anode materials for high-energy lithium-ion batteries. However, practical application of this material is compromised with its slow kinetic, and reduced cycling performance associated with irreversibly trapped ions in its structure [1]. In this report, effect of loading ratio of H.C and LTO composite anode on the electrochemical behavior of fast charging lithium ion battery is studied. Electrochemical characterization results show that a certain loading of H.C plays a critical role in improving the electrochemical performance of LTO-H.C composite electrodes. Specifically, superior cycling stability and specific capacity achieved for the composite electrode with 20 wt.% H.C. It is believed that composite electrodes with an optimized ratio can effectively contribute to Li-ion storage and form a robust protective solid electrolyte interface (SEI) on the electrode surface. The latter might minimize further electrolyte decomposition and continuous growth of the SEI layer upon cycling, then improves the cycling stability of the electrode. In addition, the cycling performance and rate capability of LiNiMnCoO2 (NMC) with different nickel (Ni) and manganese (Mn) contents were evaluated and compared. The results clearly suggest that higher Ni content can improve specific capacity (115 mAhg-1for NMC333 vs 149 mAhg-1 for NMC811 at 1C). However, cycling stability deteriorates with increasing the Ni content (77% capacity retention for NMC333 vs 45% for NMC811 after 300 cycles). It is postulated that electrodes with higher Ni content are susceptible to transition metal dissolution and side reactions at electrode-electrolyte interface, which could lead to performance degradation by impeding Li+ diffusion across the electrode, and irreversible consumption of Li+ [2]. Finally, the possibility of use of the optimized anode for fabricating full cell with the selected NMC cathode is investigated.

Nanoscale Colocalized Electrochemical and Structural Mapping of Metal Dissolution Reaction.

Understanding the structure-activity relationship in electrochemical metal dissolution reactions is fundamentally important, from designing higher density batteries to mitigating corrosions. The kinetics of metal dissolution reaction is highly dependent on surface structures, including grain boundaries and local defects. However, directly probing the electrochemical activity at these sites is difficult because the conventional bulk electrochemistry measures an averaged kinetics, obscuring the structure-activity correlation. Herein, we report the colocalized mapping of an electrochemical metal dissolution reaction using Ag as a model system. The local dissolution kinetics is voltammetrically mapped via scanning electrochemical cell microscopy (SECCM), which is correlated with local structures obtained via colocalized electron backscattering diffraction (EBSD). Individual pits of ∼200 nm are formed, and their geometries suggest dissolution is fastest in the direction parallel to the {111} planes. Enhanced dissolution kinetics is observed at the high-angle grain boundaries but not at twin boundaries, which are attributed to the different binding energy of Ag atoms. Furthermore, the faster local dissolution correlates with the geometrically necessary dislocation density. The work demonstrates the importance of nanoscale local electrochemical mapping and colocalized microscopic measurement in obtaining the structure-activity relationship for electrochemical reactions at complex interfaces.

Improving the electrochemical performance of Ni-rich cathode materials using a fast ion conductor coating of Li2O–B2O3–LiBr

The high-Ni layered metal oxide, LiNi 0.8 Co 0.1 Mn 0.1 O 2 (LNCM811), has received widespread attention in the energy field because of its high specific capacity, but its large-scale applications are hindered due to severe capacity fading. Herein, a uniform and thin Li 2 O–B 2 O 3 –LiBr-glass (LBBrO-glass) coating was deposited on LNCM811 by a liquid-phase coating and thermal treatment method. The experimental results suggested that the LBBrO-glass coating acted as a protective layer that inhibited transition metal dissolution and side reactions, which helped improve the electrochemical properties of LNCM811. Remarkably, after 200 cycles, the 2 wt% coating (LBBrO@LNCM-2) delivered a superior capacity retention of 88.9%, while only 71.8% was obtained for the pristine material (LNCM811). The discharge capacity of LBBrO@LNCM-2 was 163.5 mAh g −1 at 5C, while it was only 139 mAh g −1 for the pristine material.

Hydrazinecarbothioamide Derivative as an Effective Inhibitor for Corrosion Control: Electrochemical, Surface and Theoretical Studies

Aluminium has played a significant role in the advancement of metal matrix composites (MMC) and has drawn the attention of researchers since Al composites find extensive application in aerospace, military and automobile industries. This paper describes the corrosion property of 6061 Al-15 vol%. SiC(p) composites in hydrochloric acid medium. This composite with high strength-to-weight ratio and other alluring properties undergoes corrosion in acid media and a study has been made in 0.5 M hydrochloric acid using (2Z)-2-(2-hydroxy-3methoxybenzylidene) hydrazinecarbothioamide (HCT) as an inhibitor. Results of the electrochemical studies and surface morphology are presented. With the increase in HCT concentration, inhibition efficiency increased. But efficiency decreased with an increase in temperature. The maximum efficiency was found to be 56.8% for the addition of 10 × 10–5 M HCT concentration at 303 K. The inhibitor was found to behave as a mixed inhibitor affecting both anodic metal dissolution reaction and cathodic hydrogen evolution to the same extent. The HCT molecules were found to physisorb over the Al-composite surface and adsorption followed Langmuir’s adsorption isotherm. Adsorption of HCT was confirmed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Computational studies using density functional theory (DFT) supported experimental findings. Density functional theory calculations gave a clear insight into the mechanistic aspects of corrosion inhibition.Graphic

HEPES-Assisted Co-Precipitation Synthesis of LiNi0.5Mn1.5O4: Tuning the Mn3+ Content and Electrochemical Properties by pH Values

Spinel LiNi0.5Mn1.5O4 material (LNMO) is now actively developed as a promising cathode for next generation lithium-ion batteries due to its high specific energy, high rate capability, high operating potential, and low cost. However, its performance degradation originating from transition metal dissolution and severe side reactions remains a critical challenge. Herein, a new solution system 2-[4-(2-hydroxyethyl)-1-piperazinyl]ethanesulfonic acid (HEPES) buffer solution for the synthesis of the spinel LiNi0.5Mn1.5O4 material is reported, which is not only the pH stabilizer, but also the chelating agent. The obtained LNMO exhibits excellent electrochemical performance, and its capacity retention is kept as 95.8%, and 88.9% after cycled at 5 C and 10 C for 1000 times, respectively. These can be attributed to homogenous distributions of elements in the as-prepared carbonate precursors, stable pH value of reaction base solution and suitable Mn3+ content in pure LNMO.

Experimental Study of Poly(1‐Acetamide‐3‐vinylimidazolium Bromide) as a Corrosion Inhibitor for N80 Carbon Steel in HCl

AbstractA poly(ionic liquid) (PIL), poly(1‐acetamide‐3‐vinylimidazolium bromide) (PCVIB), was investigated as a potential hydrochloric acid corrosion inhibitor for N80 carbon steel (N80‐CS) at 25 °C. In this work, the corrosion inhibition properties of PCVIB were monitored using weight loss, potential dynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and X‐ray photoelectron spectroscopy (XPS). Results show that the maximum inhibition efficiency (IE, η) of PCVIB can reach up to 95.8 %, whereas its monomer only exhibits a low IE of η=33.6 % under the same conditions. Moreover, PCVIB is characteristic of a mixed type inhibitor, which can effectively impede both cathodic hydrogen evolutions and metal dissolution reactions. Additionally, the adsorption of PCVIB on steel surfaces obeys the Langmuir adsorption isotherm. This finding implies that the polymerization can be a viable and facile method to create the high‐efficiency inhibitor from monomeric units that were found or used with the poor IE previously.

Development of NMC811@ZrO2 Core-Shell By Mechano-Fusion Process and Annealing Process for Next-Generation Lithium-Ion Batteries

The application of advanced Ni-rich cathode materials in commercial lithium-ion batteries is increasing attention due to its high capacity. The Ni-rich lithium nickel manganese cobalt oxide (LiNi0.8Mn0.1Co0.1O2, NMC811) is a cathode material for the state-of-the-art lithium-ion battery due to its high specific energy, long cycle life, safety issue, and cost-effective. However, the challenges of NMC811 such as cation mixing, micro-crack, metal dissolution, and parasitic reaction urgently need to be overcome(1, 2). Both synergistic effects of the surface protection layer of NMC@ZrO2 core–shell structure using a solvent-free mechano-fusion process. Also, the doping concept of Zr4+ into the Li slab of its structure by the annealing process is of interest in this work. These two strategies can enhance the performance and life cycle of NMC811 batteries by addressing all of the issues of NMC811. REFERENCES T. Li, X.-Z. Yuan, L. Zhang, D. Song, K. Shi and C. Bock, Electrochemical Energy Reviews, 3, 43 (2020). W. Li, Journal of The Electrochemical Society, 167, 090514 (2020). Figure 1

Three-Dimensional Simulation of Solution-Contact Electrolytic Dissolution

Electrochemical dissolution is a process where a metal is dissolved via oxidation and can be controlled through electrolyte properties, electrolyte flow, and applied potential. Electrochemical dissolution is employed in many manufacturing applications such as electrochemical machining, electrochemical pickling, metal refining, metal surface finishing, etc. Most of these dissolution applications use a traditional metal-contact method (metal being dissolved is in direct contact with the anode); however, some applications will have phenomena that cause operational issues, safety issues, or damage to the dissolver components. These phenomena include (1) difficulty maintaining contact, (2) arcing/sparking[1] in a flammable environment, which occurs because of a build-up of oxide, or (3) overheating, which can cause melting during dissolution. To avoid unsafe or destructive phenomena, a solution-contact electrolytic dissolution (SCED) method (metal being dissolved is only in contact with electrolyte) can be employed. Here, a three-dimensional model is developed to simulate solution-contact electrolytic dissolution in a small-scale system for the first time.A representation of a small-scale SCED system is shown in Figure 1. This system takes place within a HNO3 solution and includes a Pt anode and cathode where water-splitting and hydrogen formation occur, respectively. The sample coupon (our target for dissolution) acts as a physical barrier, so hydrogen ions gather on the anode-side of the sample coupon, forming a positively charged region, while H+ ions are consumed on the cathode-side of the coupon, leaving a negatively charged region. This imbalance of charge, along with the potential profile that forms within the system when voltage is applied to the anode, drive reactions to occur on the surface of the sample coupon. The reactions include the ejection of a metal ion, Mν+, towards the negatively charged region, while H+ ions combine with the free e-s released from the metal dissolution reaction to form hydrogen gas. The model theory developed here is able to predict stray currents in the solution-phase, a useful design tool to avoid corrosion of other components within an electrochemical system. [2-3] Discussion over important phenomena that must be properly represented to simulate this electrolytic dissolution process will take place, including electrochemical species transport, local surface reaction rates (using Butler-Volmer kinetics), and electrodynamic potential.