Zn Diffusion Research Articles

Advancing Zn-ion Battery Electrodes: Exploring the Potential of Graphene-Polythiophene Nanocomposites through First-Principles Analysis

AbstractThis research investigates the electronic and electrochemical properties of graphene-polythiophene (G/Pth) nanocomposites, as potential anode materials for Zn-ion batteries. By capitalizing on the distinctive attributes of these constituent materials, the research aims to unravel critical aspects, such as: interaction studies, electronic structure, charge transfer, charge density difference, the density of states (DOS), theoretical specific capacity, open circuit voltage, Zn-ion diffusion, and the structural stability of G/Pth. The findings present compelling insights into the adsorption process, revealing an exothermic adsorption energy of -2.79 eV and an adsorption height of 3.51 Å for the polythiophene onto the graphene nanosheets. The loading of Zn atoms onto the G/Pth nanocomposite, yields a noteworthy maximum specific capacity of 585 mAh/g. The nanocomposite exhibits an exceptionally low Zn diffusion barrier of 6 meV, thereby, facilitating a swift Zn diffusion across its surface. These results suggest the promising potential of G/Pth nanocomposites as anode materials for Zn-ion batteries, and hence, providing valuable insights into their electronic and structural properties. It is believed that this study, has significantly, contributed to the advancement of the comprehension of polymer substrate-based energy storage materials. Also, it establishes a foundation for further research to develop more effective and efficient solutions for energy storage in Zn-ion batteries. Graphical Abstract

Poly(3,4-ethylenedioxythiophene)-Coated Vanadium-Doped MnO2 Nanorods for High-Performance Flexible Aqueous Zinc-Ion Battery Cathode.

Manganese-based aqueous zinc-ion batteries (AZIBs) are considered promising cathode materials for large-scale energy storage applications due to their low cost and high safety. However, the primary constraints on achieving high specific capacity and cycling stability are the inherent low conductivity and suboptimal structural stability of the AZIB cathodes. Herein, we report a high-performance poly(3,4-ethylenedioxythiophene) (PEDOT)-coated vanadium-doped MnO2 nanorod (NR) electrode for AZIBs. First, vanadium-doped MnO2 (V-MnO2) NRs were synthesized by a simple hydrothermal synthesis method. The V-MnO2 NRs were further encapsulated with a nanolayer of PEDOT through an in situ polymerization process, which was subsequently treated with sulfuric acid to achieve a smooth surface. The V doping creates oxygen vacancies within the MnO2, allowing for the rapid embedding and diffusion of Zn2+. The PEDOT nanolayer greatly enhances the conductivity and structural stability of the V-MnO2. Benefiting from the unique features, an optimal composite NRs electrode exhibits a high specific capacity of 250 mAh g-1 at 0.4 A g-1, a high energy density (388 Wh kg-1 at 151 W kg-1), and excellent stability over 5000 cycles at 3 A g-1. In addition, the flexible pouch cell assembled with the electrode shows good stability under bending. Given the positive outcomes, the material holds great potential for use as a cathode in next-generation flexible energy storage systems.

Revealing the coarsening behavior of precipitates and its effect on the thermal stability in Tʹ and ηʹ dual-phase strengthened Al-Zn-Mg-Cu alloys

High-strength Al-Zn-Mg-Cu alloys are widely utilized, but their strength deteriorates as strengthening precipitates coarsen rapidly at elevated temperatures, limiting their applications above 150°C. This study systematically investigates the microstructure evolution and its impact on the properties of peak-aged Al-Zn-Mg-Cu alloys with varying Zn/Mg ratios during thermal exposure at a series of temperatures from 150 to 300°C for 500 h. The results reveal that alloys A1 and A2 with an optimal Zn/Mg ratio (1.50−2.14) and relatively lower (Zn + Mg) content (7.0−8.8 wt.%), exhibit superior heat resistance properties compared to the other three alloys. Despite having lower strength relative to alloys with higher solute content, peak-aged alloys A1 and A2 retain the highest strength after thermal exposure. This performance is attributed to the high proportion (over 80%) of T′/T phases in the precipitates for alloys A1 and A2, which demonstrate better thermal stability in comparison to η′/η phases. Additionally, the lower solute content reduces the driving force for diffusion of Zn and Mg atoms, thus inhibiting the coarsening of precipitates. Moreover, the study elucidates that the coarsening mechanism of precipitates transitions from interfacial diffusion control at 150°C to matrix diffusion control at 200−300°C. These insights into the composition-dependent coarsening behavior of precipitates in dual-phase strengthened Al-Zn-Mg-Cu alloys offer valuable guidance for designing heat-resistant aluminum alloys with enhanced performance at elevated temperatures.

Integrated Interfacial Modulation Strategy: Trace Sodium Hydroxyethyl Sulfonate Additive for Extended-Life Zn Anode Based on Anion Adsorption and Electrostatic Shield.

Aqueous zinc-ion batteries (AZIBs) are poised to play a pivotal part in meeting the growing demands for energy storage and powering portable electronics for their superior security, affordability, and environmentally friendly characteristics. However, the detrimental side reactions occurring at the zinc anode and the dendrite caused by uneven zinc plating/stripping have greatly compromised the cycling life of AZIBs, thereby impeding their practical prospects. In this study, the interfacial comodulation strategy was employed by combining the "electrostatic shielding" effect of cations with the characteristic adsorption of anions. Two molar ZnSO4 served as the matrix, and sodium hydroxyethyl sulfonate (SHES) was selected as a low-cost, nontoxic additive. Experimental results confirm that SHES and zinc anode exhibit robust interactions that lead to the formation of an electrostatic shield and a dynamic adsorption layer at the interface, thereby suppressing hydrogen evolution and corrosion. The combined "electrostatic shielding" effect of sodium ions and the robust characteristic adsorption of hydroxyethyl sulfonate anions serve to guide the directed three-dimensional (3D) diffusion of Zn2+, facilitating rapid, stable, and uniform deposition of zinc. Due to these effects, incorporating 0.2 M SHES as an additive extends the cycle life beyond 3600 h and enables a highly reversible process of deposition and stripping in symmetric cells. Additionally, the Zn-Cu half-cell exhibits reliable cycling for over 1400 cycles, achieving an average Coulombic efficiency of 99.6%. Moreover, the introduction of this additive substantially enhances the performance of Zn-MnO2 and Zn-NH4V4O10 full cells. This study demonstrates the practical feasibility of achieving anodes with high reversibility in AZIBs through the implementation of a strategy that involves anion adsorption at the interface, which holds paramount significance for the practical application of AZIBs.

Effect of MgO/ZnO ratio on the formation process of MgxZn1-xO ceramics

The structural characteristics, chemical composition, and element spatial distribution in MgxZn1-xO ceramics were investigated using X-ray diffraction, scanning electron microscopy, Auger electron spectroscopy, energy-dispersive X-ray spectroscopy, and cathodoluminescence techniques. The study revealed that the morphology of the ceramic samples, as well as the mechanism of solid solution formation, depend on the relative contribution of both oxides in the charge. It was discovered that hexagonal and cubic phases of the solid solution were found to form simultaneously. An increase in the MgO content in the charge results in the magnesium content rise in the hexagonal grains continuously, reaching approximately 13 at.%. It was discovered an enrichment of grain boundaries with zinc and magnesium playing a significant role in doping ZnO and MgO grains. Obtained results allowed to propose two mechanisms involved in the formation of solid solution ceramics: i) diffusion of Mg and Zn along grain boundaries, followed by their incorporation into ZnO or MgO grains, respectively, and ii) interdiffusion of Mg into ZnO and Zn into MgO due to direct contact of ZnO and MgO grains. The second mechanism appears to dominate when both ZnO and MgO contribute comparably, increasing the probability of their direct contact. This study significantly advances the understanding of the process of the formation of MgxZn1-xO ceramics under thermodynamic conditions. These insights are crucial for optimizing the doping process and improving the material properties, thereby promoting innovations in the ceramics industry.

Performance improvement of 1.3 μm InAlGaAs MQW modulators grown by MOVPE using C-doped InAl(Ga)As cladding layers

We propose a novel epitaxial layer structure to prevent Zn from diffusing into a multiple quantum well (MQW) layer of an electro-absorption modulator (EAM). Zn is practically employed as a p-type dopant in an InP material system, but there is a technical issue of unintentional Zn diffusion. In this work, we introduce a novel C-doped p-type layer between a Zn-doped p-cladding layer of InP and MQW to both reduce Zn diffusion and accurately define a p-i-n junction interface. The Zn concentrations in the MQW for each device are compared by measuring secondary ion mass spectrometry (SIMS). To clarify how the reduction of diffused Zn affects the EAM characteristics, we fabricate the EAMs with each epitaxial structure and compare their extinction ratio characteristics. The evaluation of extinction ratio per EAM capacitance successfully demonstrates that employing the C-doped layer effectively improves the EAM characteristics.

Optimizing Crystal Orientation and Defect Mitigation in Antimony Selenide Thin-Film Solar Cells through Buffer Layer Energy Band Adjustment.

Antimony selenide (Sb2Se3) has sparked significant interest in high-efficiency photovoltaic applications due to its advantageous material and optoelectronic properties. In recent years, there has been considerable development in this area. Nonetheless, defects and suboptimal [hk0] crystal orientation expressively limit further device efficiency enhancement. This study used Zinc (Zn) to adjust the interfacial energy band and strengthen carrier transport. For the first time, it is discovered that the diffusion of Zn in the cadmium sulfide (CdS) buffer layer can affect the crystalline orientation of the Sb2Se3 thin films in the superstrate structure. The effect of Zn diffusion on the morphology of Sb2Se3 thin films with CdxZn1-xS buffer layer has been investigated in detail. Additionally, Zn doping promotes forming Sb2Se3 thin films with the desired [hk1] orientation, resulting in denser and larger grain sizes which will eventually regulate the defect density. Finally, based on the energy band structure and high-quality Sb2Se3 thin films, this study achieves a champion power conversion efficiency (PCE) of 8.76%, with a VOC of 458mV, a JSC of 28.13mA cm-2, and an FF of 67.85%. Overall, this study explores the growth mechanism of Sb2Se3 thin films, which can lead to further improvements in the efficiency of Sb2Se3 solar cells.

Harnessing eco-friendly additives to manipulate zinc-ion solvation structures towards stable zinc metal batteries

Considerable research efforts have been dedicated to investigating the side reactions and the growth of Zn dendritic in aqueous zinc-ion batteries (AZIBs). The incorporation of organic solvents as additives in electrolytes has yielded highly promising results. Nevertheless, their pervasive use has been hindered by concerns regarding their toxicity, flammability, and economic viability. Herein, we propose the utilization of γ-valerolactone (γ-V), a novel eco-friendly solvent, as an alternative for conventional organic additives to improve the performance of Zn anode. Experimental investigations and theoretical analyses have verified that γ-V additives can diminish the Zn2+-desolvation energy and enhance Zn2+ transport kinetics. The adsorbed γ-V molecules modulate the nucleation and diffusion of Zn2+, facilitating Zn growth along the (002) crystal plane, thus inhibiting dendrite formation and side reactions. Consequently, the modified electrolyte with 3% γ-V exhibit highly reversible cycling for 2800 h at 1 mA cm−2 and 1 mA h cm−2 in Zn//Zn symmetric cell. The Zn//KVOH coin cells deliver a capacity retention of 74.7% after 1000 cycles at 5 A g−1. The Zn//KVOH pouch cells maintain a capacity retention of 78.7% over 90 cycles at 3 A g−1. Notably, the γ-V additives also effectively alleviate the self-discharge phenomenon. This work provides valuable insights on the development of aqueous zinc-ion batteries with superior safety through the modulation of electrolytes using eco-friendly additives.

Parallel zinc deposition enabled by diethylene triaminepentaacetic acid induced interfacial complex for dendrite-free zinc metal anode

Given the high safety, cost-effectiveness, and volumetric capacity, aqueous zinc-ion batteries (ZIBs) constitute a promising energy system, but the severe side reactions and dendrite growth at the anode/electrolyte interface limited ZIBs from large-scale utilization. Here, we proposed a facile strategy to stabilize the anode/electrolyte interface and enhance the reversibility of the zinc plating/stripping via additive engineering. A trace amount of the diethylene triaminepentaacetic acid (DTPA, 3 mM) was employed as an additive, which spontaneously adsorbed onto the Zn anode, and in-situ formed a complex interlayer. This interlayer effectively shielded the water molecules, leading to a superior anti-corrosion property, facilitating the desolvation and diffusion of Zn2+, and inducing the Zn (002) oriented deposition. As a result, outstanding durability was achieved at ultrahigh current density (3000 cycles at 100 mA·cm−2) and relatively high depth of discharge (140 h at 5 mA·cm−2, 85 % DOD) in the Zn||Zn symmetric cell. Superior cyclability was also observed in the coin cell (1000 cycles at 5 A·g−1) and pouch cell (500 cycles at 1 A·g−1) with an NH4V4O10 cathode. Furthermore, the formation of complex molecule clusters was elucidated via in-situ Raman and the “bowl” morphologies are firstly visualized by SEM and AFM. These morphologies enable the rapid trapping of Zn2+oriented Zn deposition in the hollow area. We believe this work provides a novel strategy for long-term ZIB designs and offers new insights into the mechanisms for regulating zinc-oriented-deposition behavior at the molecular scale.

Effects of Ag/Sc microadditions on the precipitation of over-aged Al–Zn–Mg–Cu alloys

Microalloying addition plays a significant role in controlling the characteristics of precipitates in Al alloys. This study investigates the effects of Ag and Sc microalloying addition on the thermal stability of Al–Zn–Mg–Cu alloys, via differential scanning calorimetry, transmission electron microscopy, and atom-probe tomography. The results demonstrate that Ag and Sc additions increase the number density of η-MgZn2 type nano-precipitates (formed during heat treatment) by forming direct (Mg–Ag phase, prototype of precipitate) or indirect precursors (Al2Sc phase, constituent of precipitate) for the precipitate. In addition, the Ag and Sc elements can effectively prevent the coarsening of η precipitates and facilitate the high-density distribution of fine η precipitates, during the over-aging period, improving the thermal stability of the Al–Zn–Mg–Cu alloys. The thermal stability is particularly improved by Ag addition because Ag atoms directly prevent the coarsening of η precipitates by hindering Zn diffusion into the precipitate. On the contrary, Sc addition indirectly prevents the coarsening of η precipitates by depleting the solute species from the Al matrix, enabling abundant precipitates limited growth. Thus Ag addition improves precipitation strengthening by preventing the coarsening of precipitates during over-aging.

Formation of High Hardness ZnO/Cu Nanocomposite by Thermal Oxidation from Cu-Zn Alloy Strips

Due to their superior thermal, electrical, and mechanical properties, brass and Cu-Zn alloys are widely used in a broad range of applications. In applications requiring greater durability, corrosion resistance, and wear resistance, however, the ZnO/Cu composite is preferable. Typically, ZnO/Cu composites are manufactured through powder metallurgy. In this article, brass strips are thermally oxidized in an oxygen atmosphere to produce ZnO/Cu composite strips. The optimal temperature and oxygen pressure are 600–650 °C and less than one atmosphere, respectively. The homogeneous distribution of nanoscale ZnO clusters in the Cu matrix can be attributed to the diffusion of both Zn and O in the matrix. In addition, the composite is substantially harder than brass, increasing from 70–90 HV to 200–240 HV. Therefore, thermal oxidation has been shown to be a simple and cost-effective process for producing ZnO/Cu composites with high hardness.

Suppressing interface recombination via element diffusion regulation towards high-efficiency Cd-free Cu(In,Ga)Se2 solar cells

Magnetron-sputtered Zn1-xMgxO (ZMO) films suffer from severe elemental diffusion to Cu(In,Ga)Se2 (CIGS), which limits the further improvement of device performance. Herein, we introduced Zn(O,S) (ZOS) as a barrier layer, and we controlled the diffusion of Zn within an appropriate range by adjusting the annealing temperature of ZOS. The results indicate that Zn can occupy copper vacancies (VCu) in CIGS and easily diffuse through VCu. A moderate amount of Zn at the interface acts as a charge compensator, reducing the band tailing effect and promoting the carrier collection efficiency of photovoltaic (PV) devices. However, excessive Zn doping induces additional defects dominated by ZnCu, ZnGa and ZnIn, leading to severe nonradiative recombination. Consequently, the Cd-free CIGS solar cell produced based on these insights exhibited a 49.4-mV reduction in the Voc deficit (Voc,def) as well as a notable increase in the power conversion efficiency (PCE) to 18.0 %. This study is the first to reveal the mechanism of defects caused by Zn diffusion, and these findings provide theoretical support for the study of Cd-free thin-film solar cells.

Volatilization Kinetics of Zinc from the Flotation Products of Low-Grade Lead–Zinc Oxide Ore during Carbothermic Reduction

Zinc extraction from oxide ore has been paid more and more attention to due to the exhaustion of zinc sulfide ore resources. In this work, the volatilization kinetics of Zn from the flotation products of low-grade lead–zinc oxide ore during carbothermal reduction in the temperature range of 900–1300 °C were investigated. The phase transformation in briquettes during the reduction process was investigated by XRD and EPMA. The results showed that the transformation of ZnS by CaO may begin within the temperature range of 900–1050 °C, with the main occurrence observed in the range of 1050–1250 °C. The kinetics behavior of Zn volatilization was associated with the phase transformation. The volatilization of Zn was controlled by the interfacial chemical reaction within 900–1150 °C. As the reaction proceeded, the generation of the product layers (CaS, FeS and new slag phase) impeded the internal diffusion of Zn, CO and CO2. At this time, internal diffusion served as the rate-controlling step for Zn volatilization in the range of 1150–1300 °C. Hence, a staged kinetics model of Zn volatilization during carbothermal reduction in the form of carbon-bearing briquettes was established, and the apparent rate constants (k(T)) and activation energies (Ea) were obtained. This work provides a scientific basis for the flotation products treatment by carbothermal reduction and is of great significance in improving the sustainability of resources in the zinc smelting industry.

Modulating the solvation structure and electrode interface through phosphate additive for highly reversible zinc metal anode

Aqueous zinc-ion batteries (ZIBs) are considered one of the ideal battery systems for large-scale energy storage. However, ZIBs usually show a limited cycle life due to side reactions and dendrite growth at Zn anode. In this study, an ultra-trace amount of β-glycerophosphate sodium (β-GADS) was employed as an additive in aqueous electrolyte to enable highly reversible Zn plating/stripping. For the first time, we show that the phosphate groups in β-GADS could participate in the cation solvation structure, which is more favorable for the de-solvation and diffusion of Zn2+. Moreover, phosphate can absorb on the surface of Zn, and Na+ tend to accumulate at the surface protrusions to form an electrostatic shield that prevent formation of dendrites. Benefitting from the triply synergistic effects of the β-GADS additive, the Zn anode shows the inhibition of dendrites, hydrogen evolution reaction, corrosion reactions, and the formation of by-products. Operated based on 2 M ZnSO4 electrolyte with β-GADS additive, Zn||Zn symmetric cells demonstrated stable cycling for over 1,900 h at 0.5 mA cm−2 and over 1,200 h at a high current density of 5 mA cm−2. The Zn||(NH4)2V7O16·3.2H2O full cell with the above electrolyte also delivered a high capacity and excellent stability for over 1,000 cycles.

Atom probe tomography-assisted kinetic assessment of spinodal decomposition in an Al-12.5 at.%Zn alloy

The rates of atomic clustering and precipitation hardening are closely related to the diffusivity of solutes and the concentration of vacancies during the natural aging of aluminum alloys. The measurement of the diffusivity of solutes at room temperature, especially in systems with an equilibrium vacancy concentration, is beneficial to the design of the aging process. However, this measurement has long been challenging because of the extremely low diffusion rates of solutes in aluminum at room temperature and the presence of supersaturated vacancies. In this work, we propose a method to quantify the diffusivity of solutes based on the kinetic evaluation of the spinodal decomposition process. This evaluation involves conducting atom probe tomography experiments, analyzing the radial distribution function, and modeling the phase separation process using the Cahn–Hilliard theory. The aging experiments were conducted on nanoscale samples, where excess vacancies can be eliminated at free surfaces due to a high surface-to-volume ratio. The results yielded a diffusivity of Zn in the Al-12.5 at.% Zn alloy of (1.32±0.46)×10−25 m2/s at 295 K. This work introduces a novel approach to assess the solute diffusivity under conditions of equilibrium vacancy concentration at room temperature and expands the temperature range for measuring the diffusivity in systems with spinodal decomposition, particularly in cases where kinetic data at low temperatures are scarce.

Self-supporting oxygen vacancy-rich α-MnO2 nanowire/few-layer graphite/SWNT bundle composite film for high-performance flexible aqueous zinc-ion battery cathode

The increasing demand for flexible and wearable electronic devices has led to widespread interest in flexible electrochemical energy storage devices. However, the transformation of the battery structure from conventional to flexible presents a great challenge to the battery design. Herein, we developed a facile method for the preparation of a self-supporting composite film consisting of oxygen-vacancy rich MnO2 nanowires (NWs), few-layer graphite nanosheets (FLGs), and single-walled carbon nanotube (SWNT) bundles as the cathode of flexible zinc-ion batteries. This ternary interwoven interconnection 3D structure enhances the electrochemical performance of the battery and realizes fast charge transfer; oxygen vacancies in the MnO2 NWs caused by heat treatment (300 °C in Ar) allow for rapid intercalation and diffusion of Zn2+. The interwoven FLGs and SWNT bundles improve the electrical conductivity, and the robust interactions between the two carbon nanomaterials and the MnO2 NWs effectively make the composite film with excellent mechanical properties. This self-supporting flexible electrode exhibits a high specific capacity of 374 mAh/g at 0.4 A/g, maintains a Coulombic efficiency of ∼ 100 % after 1600 cycles at 2 A/g, and has a high energy density of 651.5 Wh kg−1 at 65.2 W kg−1. Moreover, the flexible zinc ion batteries assembled with the electrode demonstrate good mechanical properties and a high reversible specific capacity of 343 mAh/g after 75 bending cycles. Based on these findings, we believe that this composite film holds great promise as a cathode material in flexible energy storage applications.

Periodically-Poled Lithium Tantalate Ridge Waveguides for Efficient Nonlinear Frequency Conversion in the Near UV

Optical damage resistant ridge waveguides for blue and near UV wavelengths have been fabricated using high-temperature Zr and Zn diffusion doping and vapor transport equilibration (VTE) of congruent LiTaO3 crystals. For both dopants high optical damage thresholds >10 MW/cm2 for 532 nm light were demonstrated at room temperature, which can be increased by a factor ~3 when heating the samples to ~150°C. Ridge waveguides with low optical losses of ~0.4 dB/cm were fabricated using diamond-blade dicing. First-order periodic poling with grating periods of ~3 μm can be used for efficient nonlinear frequency conversion for both SHG (800 nm pump) or SPDC (400 nm pump) processes.

Hierarchical porous carbon guided by constructing organic-inorganic interpenetrating polymer networks to facilitate performance of zinc hybrid supercapacitors

Customized design of well-defined cathode structures with abundant adsorption sites and rapid diffusion dynamics, holds great promise in filling capacity gap of carbonaceous cathodes towards high-performance Zn-ion hybrid supercapacitors (ZHC). Herein, we fabricate a series of dynamics-oriented hierarchical porous carbons derived from the unique organic-inorganic interpenetrating polymer networks. The interpenetrating polymer networks are obtained through physically knitting polyferric chloride (PFC) network into the highly crosslinked resorcinol-formaldehyde (RF) network. Instead of covalent bonding, physical interpenetrating force in such RF-PFC networks efficiently relieves the RF skeleton shrinkage upon pyrolysis. Meanwhile, the in-situ PFC network sacrifices as a structure-directing agent to suppress the macrophase separation, and correspondingly 3D hierarchical porous structure with plentiful ion-diffusion channels (pore volume of 1.35 cm3/g) is generated in the representative HPC4via nanospace occupation and swelling effect. Further removal of Fe fillers leaves behind a large accessible specific surface area of 1550 m2/g for enhanced Zn-ion adsorption. When used as the cathode for ZHC, HPC4 demonstrates a remarkable electrochemical performance with a specific capacity of 215.1 mAh/g at 0.5 A/g and a high Zn2+ ion diffusion coefficient of 11.1 × 10−18 cm2/s. The ZHC device yields 117.0 Wh/kg energy output at a power density of 272.1 W/kg, coupled with good cycle lifespan (100,000 cycles@10 A/g). This work inspires innovative insights to accelerate Zn diffusion dynamics by structure elaboration towards high-capacity cathode materials.

Unveiling The Mechanism of The Dendrite Nucleation and Growth in Aqueous Zinc Ion Batteries

AbstractAqueous zinc ion batteries (ZIBs) exhibit great potential for next‐generation energy storage devices. However, significant challenges exist, including the uncontrollable formation of Zn dendrite and side reactions during zinc stripping and plating. The mechanism of Zn dendrite nucleation has yet to be fully understood. In this work, the first principles simulations are used to investigate the Zn dendrite formation process. The unintentionally adsorbed O2− and OH− ions are the inducing factors for Zn dendrite nucleation and growth on the Zn (0001) plane due to significantly increased Zn diffusion barriers. A top‐down method is demonstrated to suppress the dendrite using delaminated V2CTx to capture O2− and OH− ions thanks to reduced Zn diffusion barriers. The experimental results revealed significantly suppressed Zn dendrite nucleation and growth, resulting in a layer‐by‐layer deposit/stripping of Zn. Based on the electrochemical evaluations, the V2CTx‐coated Zn composite delivers a high coulombic efficiency of 99.3% at 1.0 mAh cm−2. Furthermore, the full cell achieves excellent cyclic performance of 93.6% capacity retention after 2000 cycles at 1 A g−1. This strategy has broad scalability and can be widely applied in designing metallic anodes for rechargeable batteries.

Insight into grain boundaries with reduced liquid metal embrittlement susceptibility in a boron-added 3rd generation advanced high strength steel

The addition of boron to the advanced high-strength steels (AHSS) enhances grain boundary cohesion and can play a significant role in intergranular degradation phenomena such as Zn-assisted liquid metal embrittlement (LME). The objective of this study is to reveal a thorough understanding of the effect of B on LME behaviour, where the welding test results indicated substantial improvement even at relatively low B concentration. Here, we adopted the strategy of identifying LME-sensitive grain boundaries, followed by characterizing grain boundary chemistry. EBSD measurements and prior austenite grain (PAG) reconstruction provided strong evidence of intergranular LME crack propagation via PAGBs. Further transmission electron microscopy and energy dispersive X-ray spectroscopy investigations demonstrated an asymmetric Mn profile along the PAGB in B-free steel. Therefore, we propose that B addition and consequently, lower grain boundary energy appears to prevent Mn segregation. Based on our observation, we conclude that B seems to have the similar desired effect on Zn diffusion along the PAGBs and eventually mitigates Zn-assisted LME.