Properties Of Cathode Research Articles

Assessment of pyrazole Schiff base's corrosion inhibition effectiveness incorporating oxadiazole moiety on mild steel in 1 M HCl: A holistic theoretical and experimental analysis

Modern industries place a high value on reasonably priced, eco-friendly products that effectively stop metal breakdown. Hence, our goal was to create an ecologically acceptable pyrazole Schiff base (PSB) that would effectively preserve mild steel (MS) during pickling and descaling procedures. We achieved this by integrating oxadiazole, which demonstrated good anti-corrosion capabilities. A complete investigation was conducted using spectroscopic analysis, electrochemical techniques, and gravimetric measurement in 1 M HCl solution. The PSB inhibitor displayed considerable corrosion inhibition on MS. PSB exhibited both cathodic and anodic properties in its dual adsorption pattern, as shown by the electrochemical investigation. Polarization resistance (Rp) values rose with the PSB concentration from 50 to 300 ppm, peaking at 300 ppm with values ranging from 31.01 to 141.21 Ω.cm². At 300 ppm and 298 K, the inhibitor effectiveness reached 90.12 %. Electrochemical testing validated the protection against mixed-type corrosion, while surface examinations (SEM, EDS, CA, AFM) showed that PSB developed a protective antioxidant layer on the MS surface. According to theoretical DFT calculations, PSB adsorbs onto the steel surface in a flat alignment. The remarkable precision of the adsorption process was validated by the high coefficient of determination (R2 = 1) for both Langmuir and other adsorption isotherms. Computational, chemical, and electrochemical analyses all support PSB's superiority as a corrosion inhibitor. The incorporation of aryl and heterocyclic rings improves the PSB structure's molecular stiffness, which facilitates effective adsorption onto the MS surface. This feature creates novel prospects for material protection and corrosion prevention, presenting PSB as a viable and eco-friendly substitute for conventional corrosion inhibitors in industrial applications.

Superior fast-charging Ni-rich cathode via promoted kinetic-mechanical performance

The sluggish Li-ion kinetics restrict the rapid charging capabilities and contribute to the structural deterioration of Ni-rich cathode materials. Notably, crack propagation during repeated charging cycles deteriorates the electrochemical stability, which hinders the further development of high-energy-density batteries for electric vehicles (EVs). In this paper, we proposed a simple yet effective method to enhance the Li-ion diffusion and mechanical properties of Ni-rich cathodes via straightforward Zr doping. In-situ high-rate XRD reveals that the detrimental uneven delithiation under the fast-charging process has been largely alleviated. Particularly, a robust structure with higher modulus and fracture strength is constructed owing to the higher Zr-O bond. By mitigating the kinetic hindrance and increasing the particle’s stiffness, the proposed Ni-rich cathode shows an impressive 97.6 % capacity retention under a 5 C rate current. This work provides a facile and efficient strategy for large-scale production of fast-charging Ni-rich cathode materials.

Ultrathin Titanium Dioxide Coating Enables High-Rate and Long-Life Lithium Cobalt Oxide.

Lithium cobalt oxide (LCO) has been widely used as a leading cathode material for lithium-ion batteries in consumer electronics. However, unstable cathode electrolyte interphase (CEI) and undesired phase transitions during fast Li+ diffusivity always incur an inferior stability of the high-voltage LCO (HV-LCO). Here, an ultra-thin amorphous titanium dioxide (TiO2) coating layer engineered on LCO by an atomic layer deposition (ALD) strategy is demonstrated to improve the high-rate and long-cycling properties of the HV-LCO cathode. Benefitting from the uniform TiO2 protective layer, the Li+ storage properties of the modified LCO obtained after 50 ALD cycles (LCO-ALD50) are significantly improved. The results show that the average Li+ diffusion coefficient is nearly tripled with a high-rate capability of 125 mAh g-1 at 5C. An improved cycling stability with a high-capacity retention (86.7%) after 300 cycles at 1C is also achieved, far outperforming the bare LCO (37.9%). The in situ XRD and ex situ XPS results demonstrate that the dense and stable CEI induced by the surface TiO2 coating layer buffers heterogenous lithium flux insertion during cycling and prevents electrolyte, which contributes to the excellent cycling stability of LCO-ALD50. This work reveals the mechanism of surface protection by transition metal oxides coating and facilitates the development of long-life HV-LCO electrodes.

Effects of different Ti concentrations doping on Li2MnO3 cathode material for lithium-ion batteries via density functional theory

Li2MnO3 is extensively studied for a cathode material in lithium-ion batteries because of its high voltage and specific capacity. Nevertheless, it has the disadvantages due to low conductivity and Li-ion diffusion. To modify its performance, we determine the structure stability and electronic properties of Li2MnO3 cathodes doped with different Ti-ion concentrations using the spin-polarized density functional theory including the Hubbard term (DFT + U). For the calculations, cell parameters, formation energies, band gaps, total density of states, partial density of states and stability voltages are determined. The results highlight that the expansion of the cell volumes by Ti-ion impurities has a positive effect on the diffusion of Li ions in these cathodes. Because of the minor voltage changes, Li2MnO3 cathode doped with a Ti-ion concentration of 0.250 exhibits the highest voltage stability. Overall, these results are effective for the lithium-ion battery application based on Ti-doped Li2MnO3 cathodes.

Chalcogen effects and cathodic properties of scandium-based materials for sodium-ion batteries

Chalcogen effects and cathodic properties of scandium-based materials for sodium-ion batteries

Enhancing the cycling stability of full-concentration-gradient Ni-rich layered cathodes via in-situ Zr doping

Full-concentration-gradient (FCG) Ni-rich layered cathodes suffers from severe structural deterioration caused by the high-Ni content in the cores of the particles. Herein, an in-situ doping strategy is proposed to remove the structural deterioration in the cores of the particles, and a Zr-doped FCG LiNi0.80-xZrxCo0.05Mn0.15O2 (FNCMZ) cathode is successfully prepared. In-situ doping achieved a gradient distribution of Zr inside the particles, and induced the Li+/Ni2+mixing into an order structure. The order structure and Zr–O strong bonds reduced the degree of lattice contraction in the cores of the particles during the H2–H3 phase transition. Density functional theory calculations further proved that Zr doping and the order structure improved the electronic conductivity and structural stability of the cathodes. The improvement of structural stability and ion/electron migration environment enhanced the cycling stability and thermal stability of the FCG cathodes. Therefore, The FNCMZ0.2 cathode (doped with 0.2 mol% Zr) exhibited a high initial discharge specific capacity (181.7 mAh/g) with excellent capacity retention (91.9 %) after 200 cycles (1 C, 2.7–4.3 V). Even at a high cutoff voltage (4.5 V) and high temperature (50 °C), the capacity retention remained high at 83.7 % and 85.2 %, respectively, after 200 cycles. Overall, in-situ Zr doping effectively resolves structural deterioration in the cores of the particles and improves the electrochemical properties of FCG Ni-rich layered cathodes.

WITHDRAWN: Hybrid morphology of fine nanowires encapsulated with nanoparticles in VO2/CuWO4 nanocomposite as Zn-ion battery cathode

Energy crisis due to decaying fossil fuels can be tackled by using electrochemical energy storage devices specially Zn-ion battery for their non-flammability, cost-effectiveness and promising energy density. However, its feasibility requires excellent cathode materials with high Zn2+ intercalation activity. In this regard, vanadium-based compounds at nanoscale regime are very effective. This work presents a profound synthesis of VO2 nanowires and a novel approach to improve its cathodic property by blending it with a multifunctional CuWO4 compound. For the first time VO2/CuWO4 nanocomposite is developed as a cathode material of Zn-ion battery to showcase a promising specific capacity of 479.9 mAh/g at 0.3 A/g. A stable capacity retention of 85% is achieved after 1000 cycles. SEM and TEM analyses confirms a considerable size reduction of VO2 and CuWO4 constituent in the nanocomposite against their pristine counterparts. This size reduction phenomenon could establish a synergistic effect between VO2 and CuWO4 for a favourable pseudo behaviour combining diffusion and capacitive controlled activities.

A Comprehensive Study of Nonuniformity Properties of the LiCoO2 Thin-Film Cathode Fabricated by RF Sputtering

A Comprehensive Study of Nonuniformity Properties of the LiCoO2 Thin-Film Cathode Fabricated by RF Sputtering

Impact of ball milling on the energy storage properties of LiFePO4 cathodes for lithium-ion batteries

Impact of ball milling on the energy storage properties of LiFePO4 cathodes for lithium-ion batteries

Investigation of cathode properties of two-dimensional NbS2Cl2 for Li and Na-ion batteries using density functional theory

Exploring novel two-dimensional materials (2D) for electrode and electrochemical storage applications stands as a pivotal pursuit in advancing renewable energy technologies. While recent research has predominantly focused on anode materials, cathode materials have received comparatively lesser attention. This study delves into the potential cathode applications of the novel two-dimensional material NbS2Cl2 using density functional theory. Fundamental properties, encompassing electronic and thermodynamic attributes, were scrutinized to comprehend the material’s characteristics. Our investigation extended to examining the adsorption and diffusion properties of these electrode materials. Comprehensive calculations of mechanical and thermodynamic properties reaffirmed the stability of this system. Upon adsorption of Li/Na atoms, the conducting nature emerged, evident through charge density difference and projected density of states. Our findings notably reveal minimal diffusion barriers of 1.5 eV and 0.35 eV for Li and Na atoms. Moreover, the observed open circuit voltages for adsorbed Li and Na ions were 4.69 V and 2.62 V, respectively. The calculated theoretical capacity for adsorbed Li-ion on 2D-NbS2Cl2 is 400 mAh g−1, while for Na-ion adsorption, it is 353 mAh g−1, awaiting validation through future experimental verifications.

Pre-introducing Li4NiWO6 defect phase by tungsten modification enables highly stabilized Ni-rich cathode

Tungsten (W) has attracted considerable attention as a promising dopant capable of enhancing the structural stability of Ni-rich cathode materials. However, investigations into W modification remain highly debated due to the elusive mechanisms involved, particularly in determining whether W is doped into the lattice structure or exists as a distinct phase on the surface of the particles. In this work, we systematically observe the effects induced by the introduction of W into LiNi0.9Co0.05Mn0.05O2 (NCM). We discovered that during high-temperature solid-state reactions, W-containing substances tend to react preferentially with surface Li, creating a lithium-deficient state on the NCM surface, resulting in the generation of Li4NiWO6. Molecular dynamics simulations tracking Li, W, and Ni elemental changes at the interface confirm the initial creation of Li6WO6, succeeded by diffusion of Ni to replace Li, forming Li4NiWO6. The pre-introducing Li4NiWO6 defect phase can effectively absorb anisotropic lattice strain, preserving the mechanical integrity of the secondary particles. Furthermore, the Li4NiWO6 phase, combined with the amorphous LixWyOz coating layer, effectively acts as a guard against undesirable interfacial side reactions, ultimately imparting excellent electrochemical performance to NCM. Understanding the dynamic processes of interfacial reactions is crucial for tailoring surface properties of Ni-rich cathodes towards long-life lithium-ion batteries.

Impact of the Surface Microenvironment on the Redox Properties of a Co-Based Molecular Cathode for Selective Aqueous Electrochemical CO2-to-CO Reduction.

Electrode-confined molecular catalysts are promising systems to enable the efficient conversion of CO2 to useful products. Here, we describe the development of an original molecular cathode for CO2 reduction to CO based on the noncovalent integration of a tetraazamacrocyclic Co complex to a carbon nanotube-based matrix. Aqueous electrochemical characterization of the modified electrode allowed for clear observation of a change of redox behavior of the Co center as surface concentration was tuned, highlighting the impact of the catalyst microenvironment on its redox properties. The molecular cathode enabled efficient CO2-to-CO conversion in fully aqueous conditions, giving rise to a turnover number (TONCO) of up to 20 × 103 after 2 h of constant electrolysis at a mild overpotential (η = 450 mV) and with a faradaic efficiency for CO of about 95%. Post operando measurements using electrochemical techniques, inductively coupled plasma, X-ray photoelectron spectroscopy and X-ray absorption spectroscopy characterization of the films demonstrated that the catalysis remained of molecular nature, making this Co-based electrode a new promising alternative for molecular electrocatalytic conversion of CO2-to-CO in fully aqueous media.

Boosting Zn2+ intercalation in manganese oxides for aqueous zinc ion batteries via delocalizing the d-electrons spin states of Mn site

Rechargeable aqueous zinc-ion batteries (AZIBs) have received increasing attention on account of their eco-friendliness and low cost. However, the limited capacity and poor rate properties of cathodes remain a major challenge due to the low electrochemical reactivity of cathode materials and sluggish Zn2+ transport kinetics. Herein, we design a 1,5-naphthalenediamine (NAPD) pre-intercalate potassium manganese dioxide (KMO-NAPD) with high capacity and rate capability for AZIBs. The introduction of NAPD can delocalize the d-electrons spin states of the Mn site and activate the reactivity of KMO-NAPD for Zn2+ intercalation. Moreover, the interaction between intercalated Zn2+ and KMO-NAPD is weakened due to the decreased electrostatic interaction force, which promotes the diffusion of Zn2+. Consequently, the KMO-NAPD cathode exhibits high specific capacity (237 mAh g−1 at 1 A g−1) satisfying rate capability (129 mAh g−1 at 4 A g−1), and excellent cycling stability (85 % capacity retention after 1000 cycles). Furthermore, the fabricated AZIBs based on the KMO-NAPD exhibit a high energy density of 294.3 Wh kg−1 and a peak power density of 8.6 kW kg−1. This study opens up a new path for the development of high-energy organic-inorganic hybrid cathode materials with modulated electronic structures for advanced AZIBs.

Exploring Li-Ion Transport Properties of Li3TiCl6: A Machine Learning Molecular Dynamics Study

We performed large-scale molecular dynamics simulations based on a machine-learning force field (MLFF) to investigate the Li-ion transport mechanism in cation-disordered Li3TiCl6 cathode at six different temperatures, ranging from 25°C to 100°C. In this work, deep neural network method and data generated by ab − initio molecular dynamics (AIMD) simulations were deployed to build a high-fidelity MLFF. Radial distribution functions, Li-ion mean square displacements (MSD), diffusion coefficients, ionic conductivity, activation energy, and crystallographic direction-dependent migration barriers were calculated and compared with corresponding AIMD and experimental data to benchmark the accuracy of the MLFF. From MSD analysis, we captured both the self and distinct parts of Li-ion dynamics. The latter reveals that the Li-ions are involved in anti-correlation motion that was rarely reported for solid-state materials. Similarly, the self and distinct parts of Li-ion dynamics were used to determine Haven’s ratio to describe the Li-ion transport mechanism in Li3TiCl6. Obtained trajectory from molecular dynamics infers that the Li-ion transportation is mainly through interstitial hopping which was confirmed by intra- and inter-layer Li-ion displacement with respect to simulation time. Ionic conductivity (1.06 mS/cm) and activation energy (0.29eV) calculated by our simulation are highly comparable with that of experimental values. Overall, the combination of machine-learning methods and AIMD simulations explains the intricate electrochemical properties of the Li3TiCl6 cathode with remarkably reduced computational time. Thus, our work strongly suggests that the deep neural network-based MLFF could be a promising method for large-scale complex materials.

Unravelling the ion transport and the interphase properties of a mixed olivine cathode for Na-ion battery

The replacement of Li by Na in an analogue battery to the commercial Li-ion one appears a sustainable strategy to overcome the several concerns triggered by the increased demand for the electrochemical energy storage. However, the apparently simple change of the alkali metal represents a challenging step which requires notable and dedicated studies. Therefore, we investigate herein the features of a NaFe0.6Mn0.4PO4 (NFMP) cathode with triphylite structure achieved from the conversion of a LiFe0.6Mn0.4PO4 (LFMP) olivine for application in Na-ion battery. The work initially characterizes the structure, morphology and performances in sodium cell of NFMP, achieving a maximum capacity exceeding 100 mAh g−1 at a temperature of 55 °C, adequate rate capability, and suitable retention confirmed by ex-situ measurements. Subsequently, the study compares in parallel key parameters of the NFMP and LFMP such as Na+/Li+ ions diffusion, interfacial characteristics, and reaction mechanism in Na/Li cells using various electrochemical techniques. The data reveal that relatively limited modifications of NFMP chemistry, structure and morphology compared to LFMP greatly impact the reaction mechanism, kinetics and electrochemical features. These changes are ascribed to the different physical and chemical features of the two compounds, the slower mobility of Na+ with respect to Li+, and a more resistive electrode/electrolyte interphase of sodium compared with lithium. Relevantly, the study reveals analogue trends of the charge transfer resistance and the ion diffusion coefficient in NFMP and LFMP during the electrochemical process in half-cell. Hence, the NFMP achieved herein is suggested as a possible candidate for application in a low-cost, efficient, and environmentally friendly Na-ion battery.

MoS2/ReS2 Hollow Heterojunction for Enhanced Aqueous Zinc-Ion Storage Performance.

The research of cathode materials for water-based zinc ion batteries (ZIBs) is very hot because the current mainstream electrode makes it difficult to meet the requirements of high specific discharge capacity and maintain a stable structure in the electrochemical process. In this work, the cathode properties are adjusted by the modification idea of morphology regulation and heterojunction construction. The simple hydrothermal method is used to prepare the hollow bimetallic heterojunction nanospheres, and their electrochemical properties as cathode materials for ZIBs are studied for the first time. Herein, the optimized cathode delivers high-rate performance and long-term cycling stability (∼98.9% Coulombic efficiency at 0.1 A g-1 after 200 cycles). The results indicate that the hollow bimetallic heterojunction nanospheres can support the material structure and provide a wide Zn2+ migration channel. The excellent performance is because hollow heterojunction bimetallic sulfides can provide abundant catalytic active sites, improve the mobility of electrons, and enhance the battery performance fundamentally. Therefore, we firmly believe that the combination of the different modification ideas can coordinate to adjust the electrode performance of ZIBs, enriching the electrode types and expanding the energy system application range.

Synergistic Strain Suppressing and Interface Engineering in Na4MnV(PO4)3/C for Wide-Temperature and Long-Calendar-Life Sodium-Ion Storage.

A Na4MnV(PO4)3 (NMVP) cathode is regarded as a promising cathode candidate for sodium-ion batteries (SIBs). However, issues such as low electronic conductivity and partial cation dissolution contribute to high polarization and structure distortion. Herein, we engineered the local electron density and reaction kinetic properties of NMVP cathodes with varying oxygen vacancies by introducing varying amounts of Zr doping and carbon coating. The optimized sample exhibited a high-rate capacity of 71.8 mAh g-1 at 30 C (83.1% capacity retention after 1000 cycles) and excellent performance over a wide temperature range (84.1 mAh g-1 at 60 °C and 61.4 mAh g-1 at -30 °C). In situ X-ray diffraction technology confirmed a redox solid solution and a two-phase reaction mechanism, revealing minor changes in cell volume and slight strain variations after Zr doping, effectively suppressing the structural distortion. Theoretical calculations illustrated that Zr doping largely shrinks the band gap of NMVP, enriches local electron density, and slightly alters the local element distribution and bond lengths. Moreover, full-cells have shown high energy density (259.9 Wh kg-1) and outstanding cycling stability (200 cycles). The work provides fresh insights into the synergistic effect of strain suppressing and interface engineering in promoting the development of wide temperature range and long-calendar-life SIBs.

Experimental study of flake graphite large-area explosion electron emission cathode performance based on particle size discrepancy

Graphite is the most commonly used large-area cathode material in the high-power vacuum electron device for its long life and good repetitive-frequency performance, but its particle size selection scheme has not been elucidated. Therefore, in the present work, the explosive electron emission properties of flake graphite large area explosive electron emission cathodes with varied particle sizes are studied. The 320 mesh flake graphite has a current delay reduction of 0.2–0.9 ns compared to other samples at the same peak voltage. According to the Murphy–Good equation, the emission performance of each sample during the priming stage was calculated, and the threshold characteristics of 320 mesh flake graphite were significantly better than the other samples. After the space charge limited current is formed, the plasma expansion rate of all samples is 1.2±0.2cm/μs with a difference not exceeding 4% between samples. Our research provides a strong basis for the selection of raw materials for graphite based large area explosive electron emission cathodes and contributes to the development of cross-field high-power vacuum devices.

Stabilizing Layered‐Type K0.4V2O5 Cathode by K Site Substitution with Strontium for K‐Ion Batteries

AbstractDeveloping suitable cathodes with high capacity and high power is challenging for K‐ion batteries. Herein, electrochemical K‐ion storage properties of the layered‐type K0.4V2O5 (KVO) cathode by incorporating divalent strontium ions (Sr2+) into its crystal structure are enhanced. Divalent strontium ions (1.18 Å) are preferentially incorporated into the octahedrally coordinated K (1.38 Å) layers due to the similar ionic size compared to V4+ (0.58 Å). The introduction of 3 mmol of Sr ions in the KVO crystal improves electrical conductivity and reduces K‐ion diffusion energy barriers. In addition, the strong Sr2+ and O2− interaction acts as a structural pillar, suppressing irreversible phase transition during charge–discharge process. Multi‐physics simulations clearly confirm that the K0.34Sr0.03V2O5 (KS3VO) cathode exhibits a more uniform K‐ion distribution and enhanced reactions of K‐ions compared to the KVO cathode at various depths of discharge. As a result, the KS3VO cathode demonstrates improved reversible capacity, cycling stability, and power capability over the KVO cathode in a K‐ion cell. Synchrotron X‐ray analysis reveals how Sr substitution enhances the electrochemical K‐ion storage properties of the KS3VO cathode. In addition, the KS3VO cathode exhibits superior thermal stability and cycling stability in a full cell coupled with a hard carbon anode compared to the KVO cathode.

A systematic analysis and optimization of bicarbonate electrolysis based on a bipolar membrane through multiscale simulation

Bicarbonate electrolysis facilitated by bipolar membrane has emerged as a compelling alternative to gaseous CO2 electrolysis, primarily because of its enhanced product concentration and streamlined processes. However, despite increasing attention, a comprehensive understanding of bicarbonate electrolysis has been eclipsed by the complexity of the intertwined electrode reactions and water dissociation promotion mechanisms of bipolar membranes. A physics-based modeling approach has substantial potential to untangle the impact of intertwined physicochemical processes and expedite the optimization of bicarbonate electrolysis. In this study, a multiscale model coupled with a 1D bipolar membrane and a 2D cathode model is presented to explore the effects of bipolar membranes on cathode reactions and performance optimization using H+ flux as a bridge. For a bipolar membrane, the attenuation mechanism of water dissociation involving ohmic and concentration losses is presented and described using mathematical eqs. A quantification metric, the water dissociation efficiency of a bipolar membrane, is proposed to denote the degree of promoted water dissociation. Two noteworthy parameters related to the fixed functional group concentration are determined and detailed: the onset current density required to stimulate water dissociation and the limited water dissociation efficiency caused by attenuation. For the cathode, a synergistic enhancement mechanism among the operating parameters, membrane properties, and cathode properties is identified. The combined effect of these parameters on the electrolytic performance surpasses the sum of their individual enhancements. Following parameter optimization, there is a notable increase in the current density and Faraday efficiency of bicarbonate electrolysis by 68.6 mA/cm2 and 18.3%, respectively. This study provides a holistic understanding of bicarbonate electrolysis and substantial guidance for its future design.