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Aqueous zinc-ion batteries (AZIBs) have been widely studied due to their high theoretical capacity, green safety, and low production cost. However, passivation, dendrite growth and corrosion of Zn anode are crucial drawbacks that hindering the application of AZIBs. Herein, Zn-based magadiite (Mag) layered nanosheets are developed as a multifunctional protective coating layer on Zn metal surface (Mag-Zn). The Mag-Zn layer can act as a physical isolation for anticorrosion and mitigating hydrogen evolution. More importantly, systematic characterizations and electrochemical analyses indicate the negative-charged enriched interlayer environment as well as the multiple Si–OH bonds not only repel the sulfate anions for restraining the by-product formation but also tailor the Zn ions transport flux with optimized kinetics and reduced the desolvation activation energy for inducing dendrite-free Zn deposition. Therefore, the Mag-Zn exhibits stable plating/stripping performance for 1500 h even at 10 mA cm−2, 1 mAh cm−2. In addition, the NaV 3 O 8 ·1.5H 2 O (NVO)||Mag-Zn battery shows a stable voltage curve and maintained a good capacity for 2000 cycles at 10A g−1, suggesting the practical application of this facile and cost-effective Zn-based Mag coating layer on Zn anode protection. Zn-based magadiite artificial interphase with the negative-charged enriched interlayer environment and multiple Si–OH bonds was developed to tailor the Zn ions transport flux with optimized kinetics and reduced the desolvation activation energy for stable dendrite-free Zn deposition. [Display omitted] • Zn-based magadiite coating layer was designed for stable Zn deposition. • The unique interlayer electronic structure tailors optimized Zn ions kinetics. • The symmetric cells exhibit 1500 h durability even at 10 mA cm−2, 1 mAh cm−2. [ABSTRACT FROM AUTHOR]

[Display omitted] • Lamellar-structured CNT/MXene/SnO 2 host based on lithiophilic gradient is prepared. • Li deposition is guided in a bottom-up manner to inhibit dendrite growth. • The host accommodates metallic Li up to 8 mAh cm−2 with 4.6% volume expansion. • The anodes can be cycled at 40 mA cm−2 (symmetric cell) and 10C (full cell). Lithium (Li) metal batteries have attracted much attention due to extremely high energy density. However, safety concerns and limited lifetime associated with dendrite growth of Li anodes, especially at high capacity loadings and high rates, hamper their practical application. Here, we report the construction of lamellar-structured lithium host containing carbon nanotubes (CNTs), MXene nanosheets, and SnO 2 nanoparticles via a simple step-by-step vacuum filtration method. The architecture is based on the lithiophilic gradient of each component, in which highly-lithiophilic SnO 2 nanoparticles uniformly anchor on the lithiophilic MXene current collector, and lithiophobic CNTs act as the top protective layer. In this way, Li electrodeposition is spatially guided in a bottom-up mode free from dendrite growth. Consequently, the CNT/MXene/SnO 2 scaffold accommodates a high capacity loading of 8 mAh cm−2 with only 4.6 % volume expansion. Furthermore, the Li@CNT/MXene/SnO 2 electrode achieves fast-charging capability and long-term cycling stability in both symmetric cells (40 mA cm−2) and full cells (10C). This work demonstrates an efficient approach to construct dendrite-free anodes for durable and high-power lithium metal batteries. [ABSTRACT FROM AUTHOR]

Aqueous zinc-ion batteries are considered as an ideal substitute for lithium-ion batteries due to their abundant resource storage, high safety, and low price. However, zinc anodes exhibit poor reversibility and cyclic stability in most conventional aqueous electrolytes. Herein, an environmentally friendly Zn(CH 3 SO 3 ) 2 electrolyte is proposed to solve the problems of common aqueous electrolytes. The bulky CH 3 SO 3 - anions can regulate the solvation structure of Zn 2+ by replacing some water molecules in the primary solvation sheath of Zn 2+ , thus slowing the hydrogen evolution side reactions and formation of zinc dendrite. Additionally, the changing solvation structure weakens the bonding between Zn 2+ and the surrounding water molecules, which is conducive to the transport and charge transfer of Zn 2+ , thus improving the battery capacity. In the Zn(CH 3 SO 3 ) 2 electrolyte, Zn plating/stripping exhibits a high Coulombic efficiency of >98% and long-term cyclic stability over 800 h. The specific capacity of the assembled Zn//V 2 O 5 cell in 3 mol L -1 Zn(CH 3 SO 3 ) 2 reaches 350 mA h g -1 at 0.1 A g -1 , much higher than that in the ZnSO 4 electrolyte (213 mA h g -1 ). In conclusion, this work offers insights into the exploration of advanced green electrolyte systems for zinc-ion batteries.

Liquid cell transmission electron microscopy has become a powerful and increasingly accessible technique for in situ studies of nanoscale processes in liquid and solution phase. Exploring reaction mechanisms in electrochemical or crystal growth processes requires precise control over experimental conditions, with temperature being one of the most critical factors. Here we carry out a series of crystal growth experiments and simulations at different temperatures in the well-studied system of Ag nanocrystal growth driven by the changes in redox environment caused by the electron beam. Liquid cell experiments show strong changes in both morphology and growth rate with temperature. We develop a kinetic model to predict the temperature-dependent solution composition, and we discuss how the combined effect of temperature-dependent chemistry, diffusion, and the balance between nucleation and growth rates affect the morphology. We discuss how this work may provide guidance in interpreting liquid cell TEM and potentially larger-scale synthesis experiments for systems controlled by temperature.

Lithium-sulfur chemistry has greatly expanded the boundaries of lithium batteries, but the persistent parasitic reaction of soluble sulfur intermediates with lithium anode remains a primary challenge. Understanding and regulating the solvation structures of lithium ions (Li + ) and polysulfides (LiPSs) are critical to addressing the above issues. Herein, inspired by the natural superhydrophilic resistance to contamination, we developed a zwitterionic nanoparticles (ZWP) separator capable of modulating the solvated of Li + and LiPSs. The dense solvated layer induced by ZWP effectively prevents the movement of LiPSs without compromising Li + transport. Moreover, the high electrolyte affinity of the ZWP effectively results in minimizing the deposition of LiPSs on the separator. Furthermore, the structure of the solvated Li + and LiPSs is also unveiled by molecular simulation and nuclear magnetic resonance (NMR). In addition, in situ UV setup proved the ZWP separator can effectively suppress the shuttle of LiPSs. The restricted space formed by the tightly packed ZWP stabilizes the lithium deposition and regulates dendrite growth. Consequently, the performance of lithium-sulfur batteries is significantly improved and good cycle stability is maintained even at high sulfur loadings (5 mg cm -2 ). This contribution provides a new insight into the rational design of lithium-sulfur battery separators.

Aqueous zinc-ion batteries hold attractive potential for large-scale energy storage devices owing to their prominent electrochemical performance and high security. Nevertheless, the applications of aqueous electrolytes have generated various challenges, including uncontrolled dendrite growth and parasitic reactions, thereby deteriorating the Zn anode's stability. Herein, inspired by the superior affinity between Zn 2+ and amino acid chains in the zinc finger protein, a cost-effective and green glycine additive is incorporated into aqueous electrolytes to stabilize the Zn anode. As confirmed by experimental characterizations and theoretical calculations, the glycine additives can not only reorganize the solvation sheaths of hydrated Zn 2+ via partial substitution of coordinated H 2 O but also preferentially adsorb onto the Zn anode, thereby significantly restraining dendrite growth and interfacial side reactions. Accordingly, the Zn anode could realize a long lifespan of over 2000 h and enhanced reversibility (98.8%) in the glycine-containing electrolyte. Furthermore, the assembled Zn||α-MnO 2 full cells with glycine-modified electrolyte also delivers substantial capacity retention (82.3% after 1000 cycles at 2 A g -1 ), showing promising application prospects. This innovative bio-inspired design concept would inject new vitality into the development of aqueous electrolytes., (© 2023 Wiley-VCH GmbH.)

• The Ti 3 C 2 /CPNC heterostructure is designed by intercalating Ti 3 C 2 nanosheets with CoP nanocages, in which Ti 3 C 2 prevent the aggregation of CoP and CoP also restrain the recombination of Ti 3 C 2. • The Ti 3 C 2 /CPNC provides abundant actives sites for effective adsorption-diffusion-conversion of LiPSs. • The Ti 3 C 2 /CPNC with remarkable lithiophilicity and high conductivity can accomplish uniform Li deposition to inhibit the growth of dendrites. • The Li–S full cell harvests excellent electrochemical performance even at a high sulfur loading of 5.3 mg cm−2 and a negative to positive electrode capacity ratio of 1.7:1. The practical application of lithium–sulfur (Li-S) batteries has been hampered by the shuttle effect of lithium polysulfides (LiPSs) and seriously uncontrollable Li dendrite growth. Herein, we report an elaborate heterostructure (Ti 3 C 2 /CPNC), composed of Ti 3 C 2 nanosheets-encapsulated CoP nanocages with abundant lithiophilic/sulfiphilic sites for suppressing polysulfide shuttling and dendritic growth in Li-S batteries. Functioning as a separator mediator, the Ti 3 C 2 /CPNC heterostructure affords a synergistic effect of strong chemical interactions and fast conversion kinetics toward LiPSs. A half cell with the Ti 3 C 2 /CPNC interlayer exhibits a remarkable cycling stability with a capacity decay of only 0.039 % per cycle at 1C after 1150 cycles. As a Li host, the Ti 3 C 2 /CPNC heterostructure with remarkable lithiophilicity and high conductivity regulates the uniform plating/stripping of Li. The integrated Li–S full cell harvests an excellent electrochemical performance, even at a high sulfur loading of 5.3 mg cm−2 with a negative to positive (N/P) electrode capacity ratio of 1.7:1. This work demonstrates the potential application of bifunctional mediators for fabricating Li–S full batteries with outstanding electrochemical performance. [ABSTRACT FROM AUTHOR]

Rechargeable aqueous zinc-metal batteries have attracted soaring attention as alternative to conventional lithium-ion batteries for energy storage systems due to the high safety, low cost, and environmental benignancy. However, the spontaneous side reaction and dendrite growth lead to the poor electrochemical performance as well as serious safety issues. Herein, a multifunctional layer composed of zinc alginate (ZA) and vermiculite sheets (VS) is coating on zinc foil surface to simultaneously suppress the side reaction and dendrite growth. Unique Zn2+ channels built by ZA polymer and VS endow the ZAVS film with high zinc-ion transference number (t Zn 2+ = 0.81), which can both improve the migration of Zn2+ and redistribute the Zn2+ flux on the electrode surface. Consequently, dendrite growth is obviously inhibited. In addition, ZAVS film can serves as a buffer layer to isolate zinc anode from aqueous electrolyte, alleviating the zinc corrosion and hydrogen generation. Benefiting from the inhibition of dendrite growth and side reaction, superior electrochemical performance can be achieved as evidenced by the high Coulombic efficiency of 99.18% for 520 cycles, and ultra-long cycling stability over 1000 h with small voltage hysteresis. The construction of ZAVS artificial layer could be a promising strategy for advanced RAZMBs. • The well combination of flexibility and rigidity is achieved for hybrid layer. • The design of oriented conduction pathways enable fast transport of zinc ions. • Physical isolation weakens the corrosion of zinc anode from electrolyte. • Hybrid layer simultaneously inhibits the dendrite growth and side reaction. [ABSTRACT FROM AUTHOR]

[Display omitted] • Data assimilation system for dendrite growth with liquid flow and solid motion. • Phase-field lattice Boltzmann method is used as a simulation model. • Twin experiments of an isolated equiaxed dendrite grows with sedimentation. • Validation of the developed data assimilation system via the twin experiments. • Kinematic viscosity is inferred in the twin experiments. Integrating phase-field simulations and in situ observation experiments is a promising approach to better understand dendrite growth during alloy solidification. To integrate simulations and experiments, we developed a data assimilation system using an ensemble Kalman filter for dendrite growth with liquid flow and solid motion. In this system, we used the phase-field lattice Boltzmann (PF–LB) model as the simulation model. Through twin experiments in which an isolated equiaxed dendrite grows with sedimentation owing to the density difference between the solid and liquid phases, we validated that the developed data assimilation system can effectively incorporate the observation data into the PF–LB simulation. In addition, we discuss the accuracy of data assimilation in different conditions by comparing the results of columnar dendrite growth with natural convection. [ABSTRACT FROM AUTHOR]

A quantitative phase-field model for directional solidification is applied to study dendrite growth under forced flow conditions in an Al-Cu Gas Tungsten Arc (GTA) welding molten pool. Evolution of the dendrite morphology and the solute field under forced flow conditions is simulated. Growth of columnar grains goes through three periods, including the initial instability period, the competitive growth period and the relatively stable period. The solute segregation, the solute redistribution and the solute concentration in the liquid side of the interface are investigated, respectively. For the given conditions, simulation results are in good agreement with experimental findings. [ABSTRACT FROM AUTHOR]

Lithium metal is a promising anode material for Li-ion batteries due to its high theoretical specific capacity and low potential. The growth of dendrites is a major barrier to the development of high capacity, rechargeable Li batteries with lithium metal anodes, and hence, significant efforts have been undertaken to develop new electrolytes and separator materials that can prevent this process or promote smooth deposits at the anode. Central to these goals, and to the task of understanding the conditions that initiate and propagate dendrite growth, is the development of analytical and nondestructive techniques that can be applied in situ to functioning batteries. MRI has recently been demonstrated to provide noninvasive imaging methodology that can detect and localize microstructure buildup. However, until now, monitoring dendrite growth by MRI has been limited to observing the relatively insensitive metal nucleus directly, thus restricting the temporal and spatial resolution and requiring special hardware and acquisition modes. Here, we present an alternative approach to detect a broad class of metallic dendrite growth via the dendrites' indirect effects on the surrounding electrolyte, allowing for the application of fast 3D ¹H MRI experiments with high resolution. We use these experiments to reconstruct 3D images of growing Li dendrites from MRI, revealing details about the growth rate and fractal behavior. Radiofrequency and static magnetic field calculations are used alongside the images to quantify the amount of the growing structures. [ABSTRACT FROM AUTHOR]

Dendrite formation on the anode surface of a battery is closely related to the safety and capacity of high energy density batteries, thus suppressing dendrite growth will significantly improve the performance of batteries. Many experimental reports reveal that convection near the dendrite nucleation site can change the local mass transport, and ultimately affect dendrite growth. Investigation of the convection effect in batteries will guide the development of strategies to suppress dendrite growth in a convective electrolyte. Most of the existing electro-convection computational models for dendrite growth studies are based on Eulerian frameworks. These methods have difficulty modeling the moving boundaries associated with dendrite growth and are less computationally efficient in simulating convective fluid motion. In this paper we adopt a mesh-free particle based Lagrangian method to address the challenges of previous grid based Eulerian electro-convection models. The developed model is verified by comparison to analytical solutions, including verification of ion migration and the electric potential. Simulation results show that the predicted dendrite growth and electro-convective flow patterns compare well with experimental results during early dendrite growth stages. Parametric studies reveal that low viscosity electrolytes suppress the dendrite growth by increasing the mass transport of ions near the anode/electrolyte interface. [ABSTRACT FROM AUTHOR]

A three-dimensional (3D) cellular automata (CA) model has been developed for simulation of dendrite growth during non-equilibrium solidification. The heat and mass transports are calculated using 3D finite element (FE) method. The migration of solid/liquid (SL) interface is associated with effective free energy difference incorporating solute trapping and relaxation effects. The non-equilibrium solute partition coefficient involving solute trapping and relaxation effects is used to calculate solute redistribution at SL interface. The interface curvature and anisotropy of surface energy are introduced to represent the characteristics of dendrite tip. The CA model has been applied to simulate the microstructure evolution of Fe-1.5 wt.% C alloy. The grain morphology, solute and temperature distributions, and velocity of dendrite tip are characterized during both isothermal and non-isothermal conditions. The velocity of dendrite tip and secondary dendrite arm spacing during directional solidification are validated and are in good agreements with previous experimental and mathematical results. [ABSTRACT FROM AUTHOR]

Based on DFT calculations, we have revealed some conditions for the Li dendrite-free, dendrite-formation, and dendrite-suppression processes. [Display omitted] • Three types of competitive intrinsic kinetics processes have been identified. • The dendrite-free, -forming, and -suppressing conditions are revealed. • Adjusting the intrinsic kinetics to suppress the dendrite growth was demonstrated. Although many works have been devoted to designing the dendrite-suppression lithium anodes through modifying the growth environments or electrode configurations, studies on their related intrinsic kinetics processes are still lacking. Using DFT calculations, the intrinsic kinetics processes to control the dendrite growth in different environments are investigated herein. Under different coverage concentrations and distributions of lithium, three types of competitive kinetics processes have been identified and defined as the two-dimensional (2D) accumulation, 2D dispersion, and 3D accumulation kinetics processes based on the near-neighboring interactions in the same layer. It was found that the dendrite-free condition can be realized under the natural growth processes based on the dominant 2D accumulation processes, but the dominant kinetics processes can be replaced by the 3D accumulation processes during the nonuniform deposition processes under the condition of moderate coverage concentration, leading to the formation of dendrites. Correspondingly, the suppression condition for the dendrite growth requires that the 2D dispersion kinetics processes can triumph over the 3D accumulation kinetics processes. Therefore, we employed the lithium-affinity molecules to illustrate how to adjust the 2D dispersion kinetics processes to suppress dendrite growth. These results provide microscopic guidance suppressing dendrite growth. [ABSTRACT FROM AUTHOR]

• Dendrite growth of electrodeposited zinc is inhibited by an applied capacitor. • Zinc Morphologies can be controlled in the magnetic/flow fields. • Acting mechanism of capacitor on the depositing morphology is analyzed. Rapid growth of dendrites at high current densities is ubiquitous in the field of zinc electrodeposition, zinc ion batteries and zinc-air batteries, seriously affecting surface quality of depositing layer, electrode capacity and battery lifetime. Here, we propose a strategy of regulating ion transfer to inhibit the growth of zinc dendrites by means of an applied capacitor, investigating the effect of capacitance on morphologies of electrodeposited zinc in comparison to shape change in the magnetic field and flowing field. The results show that external physical fields can suppress the growth of zinc dendrites by reducing mass impedance of zinc ions, among which the capacitor can partially counteract the impact of internal electric field on zinc ions, magnetic field would change moving trajectory of the ions and the flowing field may increase transporting journey of the ions. [ABSTRACT FROM AUTHOR]

Aqueous zinc-ion batteries have drawn increasing attention due to the intrinsic safety, cost-effectiveness and high energy density. However, parasitic reactions and non-uniform dendrite growth on the Zn anode side impede their application. Herein, a multifunctional additive, ammonium dihydrogen phosphate (NHP), is introduced to regulate uniform zinc deposition and to suppress side reactions. The results show that the NH 4 + tends to be preferably absorbed on the Zn surface to form a "shielding effect" and blocks the direct contact of water with Zn. Moreover, NH 4 + and (H 2 PO 4 ) - jointly maintain pH values of the electrode-electrolyte interface. Consequently, the NHP additive enables highly reversible Zn plating/stripping behaviors in Zn//Zn and Zn//Cu cells. Furthermore, the electrochemical performances of Zn//MnO 2 full cells and Zn//active carbon (AC) capacitors are improved. This work provides an efficient and general strategy for modifying Zn plating/stripping behaviors and suppressing side reactions in mild aqueous electrolyte., (© 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Aqueous Zn batteries (AZBs) are a promising energy storage technology, due to their high theoretical capacity, low redox potential, and safety. However, dendrite growth and parasitic reactions occurring at the surface of metallic Zn result in severe instability. Here we report a new method to achieve ultrafine Zn nanograin anodes by using ethylene glycol monomethyl ether (EGME) molecules to manipulate zinc nucleation and growth processes. It is demonstrated that EGME complexes with Zn 2+ to moderately increase the driving force for nucleation, as well as adsorbs on the Zn surface to prevent H-corrosion and dendritic protuberances by refining the grains. As a result, the nanoscale anode delivers high Coulombic efficiency (ca. 99.5%), long-term cycle life (over 366 days and 8800 cycles), and outstanding compatibility with state-of-the-art cathodes (ZnVO and AC) in full cells. This work offers a new route for interfacial engineering in aqueous metal-ion batteries, with significant implications for the commercial future of AZBs.

Due to the extensive applications in the automotive and aerospace industries of Al–7Si–Mg casting alloys, an understanding of their dendrite microstructural formation in three dimensions is of great importance in order to control the desirable microstructure, so as to modify the performance of castings. For this reason, a three-dimensional cellular automaton model (3-D CA) allowing for the prediction of dendrite growth of ternary alloys is presented. The growth kinetics of the solid/liquid (S/L) interface is calculated based on the solutal equilibrium approach. This proposed model introduces a modified decentered octahedron algorithm for neighborhood tracking, in order to eliminate the effects of mesh dependency on dendrite growth. The thermodynamic and kinetic data needed in the simulations are obtained through coupling with the Pandat software package in combination with thermodynamic/kinetic/equilibrium phase diagram calculation databases. The solute interactions between alloying elements are considered in the model. The model was first used to simulate the Al–7Si dendrite, followed by a validation using theoretical predictions. The influence of Mg content on the dendrite growth dynamics and dendrite morphologies was investigated. Also, the model was applied to Al–7Si–0.5Mg dendrite simulation both with and without a consideration of solute interactions between the Si and Mg alloying elements and the effects on dendrite growth process was analyzed using the simulation results. This model was finally used in order to simulate the dendrite growth in different crystallographic orientations in an Al–7Si–0.36Mg ternary alloy during polycrystalline solidification, resulting in a predicted secondary dendrite arm spacing (SDAS) and dendrite volume fraction data that show a reasonable agreement with experimental results. The single dendrite and polycrystalline growth simulations effectively demonstrate the capability of this model in predicting the three-dimensional dendrite microstructure of ternary alloys. [ABSTRACT FROM AUTHOR]

In spite of the strong relevance of electrochemical energy conversion and storage, the atomistic modeling of structures and processes in electrochemical systems from first principles is hampered by severe problems. Among others, these problems are associated with the theoretical description of the electrode potential, the characterization of interfaces, the proper treatment of liquid electrolytes, changes in the bulk structure of battery electrodes, and limitations of the functionals used in first-principles electronic structure calculations. We will illustrate these obstacles, but also indicate strategies to overcome them. [ABSTRACT FROM AUTHOR]

Developing a poly(ethylene oxide) (PEO)-based polymer electrolyte with high ionic conductivity and robust mechanical property is beneficial for real applications of all-solid-state lithium metal batteries (ASSLMBs). Herein, an excellent organic/inorganic interface compatibility of all-solid-state composite polymer electrolytes (CPEs) is achieved using a novel imidazolium-type poly(ionic liquid) with strong electrostatic interactions, providing insights into the achievement of highly stable CPEs. The key properties such as micromorphologies, thermal behavior, crystallinity, t Li + , mechanical property, lithium anode surficial morphology, and electrochemical performance are systematically investigated. The combined experimental and density functional theory (DFT) simulation results exhibit that the strong electrostatic interaction and ion-dipole interaction cooperated to improve the compatibility of the CPE, with a high ionic conductivity of 1.46 × 10 -4 S cm -1 at 40 °C and an incredible mechanical strain of 2000% for dendrite-free and highly stable all-solid-state LMBs. This work affords a promising strategy to accelerate the development of PEO-based polymer electrolytes for real applications in ASSLMBs.

Enabling highly stable alkali metal anodes in gas atmospheres, such as oxygen and carbon dioxide, is critical for the implementation of emerging metal-gas batteries with high energy density and improved safety. Herein, we demonstrate a three-salt electrolyte system to tackle the problems of gas crossover and uncontrolled metallic dendrite growth for all-climate sodium-gas batteries by the formation of an electrochemically/chemically stable solid electrolyte interphase that is rich in fluoride and sulfate compounds. Consequently, the sodium metal anodes present high reversible capacity (10 mAh cm -2 at 1.5 mA cm -2 ) and long cycle life (2000 h) in gas atmospheres across a wide operating temperature range. Using the three-salt electrolyte, all-climate sodium-oxygen and sodium-carbon dioxide batteries are demonstrated with a reversible capacity of 1000 mAh g -1 over 100 cycles at ambient temperature and good adaptability to temperatures from -60 to 60 °C.

Rechargeable multivalent metal (e.g., zinc (Zn) and aluminum (Al)) batteries are ideal choices for large-scale energy storage owing to their intrinsic low cost and safety. However, the poor compatibility between metallic anodes and electrolytes strongly hampers their practical applications. Herein, it is demonstrated that confining multivalent metals in a biomimetic scaffold (Bio-scaffold) can achieve highly efficient multivalent metal plating/stripping. This Bio-scaffold is well-tailored through the synergy of a parallel-aligned array of fractal copper branches and a CaTiO 3 (CTO)-based coating layer. By virtue of this design strategy, the as-developed Bio-scaffold-based Zn- and Al-metal anodes exhibited dendrite-free morphologies with high reversibility and long lifespan, as well as excellent performance for Zn and Al full batteries. Theoretical modeling and experimental investigations reveal that the fractal copper array not only facilitates multivalent ion diffusion and electrolyte wetting but also effectively reduces the local current densities during cycling; Meanwhile, the CTO-based coating layer effectively blocks interfacial side reactions and enables a homogeneous ionic flux. This work opens a new avenue for developing multivalent metal batteries., (© 2022 The Authors. Advanced Materials published by Wiley-VCH GmbH.)

Development of high-performance rechargeable batteries is hinged on a clear mechanistic understanding of the fundamental electrochemical processes. In operando transmission electron microscopy (TEM) provides a nanoscale insight into the dynamic microstructural evolution of battery components. The open-cell and closed-cell are the main configurations for in situ/operando TEM battery studies. While the open-cell configuration uses an ionic liquid or a solid electrolyte, the closed-cell configuration adopts a dynamic flow of a liquid electrolyte. As such, the processes observed in the closed-cell configuration more reliably reflect the electrochemical setup in most ion batteries under development. This also permits the observation of processes such as dendritic growth and solid electrolyte interphase formation, which cannot be observed in the open-cell configuration. However, the benefits of the closed-cell configuration come at the cost of imaging resolution. In this review, the opportunities and obstacles for current closed-cell in operando TEM systems is explored. This is done by highlighting and comparing the key findings between closed-cell and open-cell configurations where possible. These include Li-ion (LIBs) and the state-of-the-art Li-O 2 , Na-ion (NIBs), Na-O 2 and Ca-ion batteries. Furthermore, the closed-cell in operando testing conditions are systematically consolidated including information on electrodes, electrolyte and flow parameters, TEM beam conditions and cell membrane thickness. This information is critical in ensuring the reliability and reproducibility of the experimental work. Finally, we address the challenges still faced with closed-cells and deliver future perspectives of in situ/operando TEM in rechargeable battery characterization. [Display omitted] [ABSTRACT FROM AUTHOR]

The liquid–metal-cooling (LMC) directional-solidification process offers refinement of dendritic structure due to the increased cooling rate from enhanced heat extraction. However, under some conditions in the LMC process substantial lateral heat extraction occurs that leads to a change in dendrite morphology, resulting in grain nucleation or lateral growth – the formation of long secondary dendrite arms overgrowing favorably aligned primary dendrites. The conditions under which lateral growth occurs during solidification of alloys CMSX-486 and René-N4 have been studied experimentally and via solidification modeling. Solidification experiments have been conducted in a LMC furnace that utilizes liquid tin as the cooling medium and a floating ceramic baffle. A mold geometry was designed to evaluate a range of thermal conditions during solidification and assess the tendency for lateral growth. Correlations between dendritic structure, solidification-front curvature, solidification rate and thermal gradients have been analyzed. A criterion for predicting the onset of lateral growth based on the inclination of the solidification front at the casting surface is demonstrated. [ABSTRACT FROM AUTHOR]

In a previous paper (Castle et al., 2014) [17], we employed a melt fluxing technique to study the velocity-undercooling relationship and microstructural development of a Cu-8.9wt.% Ni alloy in order to investigate the fundamental mechanism behind the rapid solidification phenomenon of "spontaneous grain refinement". A number of growth transitions were identified with increasing undercooling, including an extended dendrite orientation transition through: fully 〈100〉-oriented→multiply twinned, mixed 〈100〉/〈111〉-oriented→fully 〈111〉-oriented. Here, we present the results of an identical study of a Cu-Ni alloy of lower Ni content and observe a similar set of growth transitions, with some notable differences. In particular, three distinct grain refinement mechanisms have been observed between the two alloys, including: recrystallization, dendrite fragmentation and dendritic seaweed fragmentation. It appears that the mechanism selected depends strongly upon the original growth structure present, which we suggest is dictated by the balance between the capillary and kinetic anisotropies; with the addition of Ni to Cu either increasing the strength of the kinetic anisotropy, decreasing the strength of the capillary anisotropy, or a combination of both. The unambiguous identification of three different spontaneous grain refinement mechanisms in two closely related alloys is significant as it may help to resolve some of the debate surrounding the "true" grain refinement mechanism. [ABSTRACT FROM AUTHOR]

The growth velocity during solidification of an undercooled melt of a Co-Cu alloy processed by electromagnetic levitation was measured using a high speed video camera. Applying a model of local non-equilibrium solidification, theoretical predictions of dendrite growth velocity and dendritic growth radii are compared with high-accuracy measurements of the growth kinetics. As the undercooling ΔT reaches a critical value consistent with the dendrite growth velocity being equal to the atomic diffusion speed VD in bulk liquid, ΔT = ΔT(VD), the velocity-undercooling relationship exhibits a break-point. A distinct change in the dendritic growth mechanism exists with the onset of complete solute trapping and chemically partitionless solidification of the core of the main stems of the dendrites occurs. A complete transition to the thermally controlled growth of dendrites occurs at ΔT = ΔT(VD) that leads to essential changes in the microstructure of dendritic patterns The phenomenon of dendritic fragmentation in Co-Cu melts, solidifying at ΔT < ΔT(VD), is discussed. [ABSTRACT FROM AUTHOR]

Most theoretical work on solidification focuses on dilute binary alloys, while those commonly used in industry are multi-component with high solute concentrations. In concentrated alloys, the diffusion of one component will be inevitably influenced by the others, which will further affect the rapid solidification kinetics. Assuming local non-equilibrium at the solid/liquid (S/L) interface and in the bulk liquid, the kinetics of planar interface migration and dendrite growth in strongly non-equilibrium solidification of Ni-Cu-Co alloys is comparatively studied. It is found that, for planar interface kinetics, the thermodynamic interactions lead to a non-monotonic tendency of the partition coefficient of Co with a slightly lowered interface temperature. Meanwhile, for dendrite growth (i.e. curved interface), the curvature effect and the thermodynamic interactions together result in the non-monotonic variation of partition coefficients. Due to the lowered dendrite tip temperature as a result of the thermodynamic interactions, larger undercooling is needed for interface migration and the dendrite growth is slowed down. [ABSTRACT FROM AUTHOR]

To address the role of the transforming growth factor beta (TGFβ)-Smad3 signaling pathway in dendrite growth and associated synaptogenesis, we used small inhibitory RNA to knockdown the Smad3 gene in either cultured neurons and or primary astrocytes. We found that TGFβ1 treatment of primary neurons increased dendrite extensions and the number of synapsin-1-positive synapses. When Smad3 was knockdown in primary neurons, dendrite growth was inhibited and the number of synapsin-1-positive synapses reduced even with TGFβ1 treatment. When astrocyte-conditioned medium (ACM), collected from TGFβ1-treated astrocytes (TGFβ1-stimulated ACM), was added to cultured neurons, dendritic growth was inhibited and the number of synapsin-1-positive puncta reduced. When TGFβ1-stimulated ACM was collected from astrocytes with Smad3 knocked down, this conditioned media promoted the growth of dendrites and the number of synapsin-1-positive puncta in cultured neurons. We further found that TGFβ1 signaling through Smad3 increased the expression of chondroitin sulfate proteoglycans, neurocan, and phosphacan in ACM. Application of chondroitinase ABC to the TGFβ1-stimulated ACM reversed its inhibitory effects on the dendrite growth and the number of synapsin-1-positive puncta. On the other hand, we found that TGFβ1 treatment caused a facilitation of Smad3 phosphorylation and translocation to the nucleus induced by status epilepticus (SE) in wild-type (Smad3) mice, and this treatment also caused a promotion of γ-aminobutyric acid-ergic synaptogenesis impaired by SE in Smad3 as well as in Smad3 mice, but more dramatic promotion in Smad3 mice. Thus, we provide evidence for the first time that TGFβ-Smad3 signaling pathways within neuron and astrocyte differentially regulate dendrite growth and synaptogenesis, and this pathway may be involved in the pathogenesis of some central nervous system diseases, such as epilepsy. [ABSTRACT FROM AUTHOR]

If a liquid is undercooled below its equilibrium melting temperature an excess Gibbs free energy is created. This gives access to solidification of metastable solids under non-equilibrium conditions. In the present work, techniques of containerless processing are applied. Electromagnetic and electrostatic levitation enable to freely suspend a liquid drop of a few millimeters in diameter. Heterogeneous nucleation on container walls is completely avoided leading to large undercoolings. The freely suspended drop is accessible for direct observation of rapid solidification under conditions far away from equilibrium by applying proper diagnostic means. Nucleation of metastable crystalline phases is monitored by X-ray diffraction using synchrotron radiation during non-equilibrium solidification. While nucleation preselects the crystallographic phase, subsequent crystal growth controls the microstructure evolution. Metastable microstructures are obtained from deeply undercooled melts as supersaturated solid solutions, disordered superlattice structures of intermetallics. Nucleation and crystal growth take place by heat and mass transport. Comparative experiments in reduced gravity allow for investigations on how forced convection can be used to alter the transport processes and design materials by using undercooling and convection as process parameters. [ABSTRACT FROM AUTHOR]

Abstract: Directional solidification via the liquid metal cooling process results in refined microstructure and reduced defects, thus providing improved mechanical performance of single crystal (SX) materials. However, the enhanced heat extraction inherent to the process results in a curved solidification front that may lead to non-axial growth of dendrites near the casting walls. The mechanism by which the lateral growth occurs has been investigated by microstructure modeling via solute-adjusted, diffusional growth of dendrites. Local thermal profiles derived from continuum solidification models were used as inputs to a dendrite-growth model capable of simulations in both two and three dimensions. A finite difference calculation of the diffusion field and volume of fluid tracking for the growth of the dendrite front was coupled to predict the microstructure evolution during directional solidification. Model predictions were compared to experimentally observed dendritic structures. In addition, a parametric analysis was conducted to evaluate the sensitivity of the dendrite-growth mode to changes in thermal, structural (such as dendrite position and spacing) and model parameters. The inclination angle of the solidification front strongly influenced the evolution of dendritic structure. The degree of misorientation of the 〈001〉 SX orientation from the withdrawal axis significantly contributed to the onset of lateral dendritic growth. [Copyright &y& Elsevier]