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Dendrite defects and loss are early cellular alterations observed across neurodegenerative diseases that play a role in early disease pathogenesis. Dendrite degeneration can be modeled by expressing pathogenic polyglutamine disease transgenes in Drosophila neurons in vivo. Here, we show that we can protect against dendrite loss in neurons modeling neurodegenerative polyglutamine diseases through injury to a single primary dendrite branch. We find that this neuroprotection is specific to injury-induced activation of dendrite regeneration: neither injury to the axon nor injury just to surrounding tissues induces this response. We show that the mechanism of this regenerative response is stabilization of the actin (but not microtubule) cytoskeleton. We also demonstrate that this regenerative response may extend to other neurodegenerative diseases. Together, we provide evidence that activating dendrite regeneration pathways has the potential to slow-or even reverse-dendrite loss in neurodegenerative disease.

During animal development, the spatiotemporal properties of molecular events largely determine the biological outcomes. Conventional gene analysis methods lack the spatiotemporal resolution for precise dissection of developmental mechanisms. Although optogenetic tools exist for manipulating designer proteins in cultured cells, few have been successfully applied to endogenous proteins in live animals. Here, we report OptoTrap, a light-inducible clustering system for manipulating endogenous proteins of diverse sizes, subcellular locations, and functions in Drosophila. This system turns on fast, is reversible in minutes or hours, and contains variants optimized for neurons and epithelial cells. By using OptoTrap to disrupt microtubules and inhibit kinesin-1 in neurons, we show that microtubules support the growth of highly dynamic dendrites and that kinesin-1 is required for patterning of low- and high-order dendritic branches in differential spatiotemporal domains. OptoTrap allows for precise manipulation of endogenous proteins in a spatiotemporal manner and thus holds promise for studying developmental mechanisms in a wide range of cell types and developmental stages.

Dendrites are injured in a variety of clinical conditions such as traumatic brain and spinal cord injuries and stroke. How neurons detect injury directly to their dendrites to initiate a pro-regenerative response has not yet been thoroughly investigated. Calcium plays a critical role in the early stages of axonal injury detection and is also indispensable for regeneration of the severed axon. Here, we report cell and neurite type-specific differences in laser injury-induced elevations of intracellular calcium levels. Using a human KCNJ2 transgene, we demonstrate that hyperpolarizing neurons only at the time of injury dampens dendrite regeneration, suggesting that inhibition of injury-induced membrane depolarization (and thus early calcium influx) plays a role in detecting and responding to dendrite injury. In exploring potential downstream calcium-regulated effectors, we identify L-type voltage-gated calcium channels, inositol triphosphate signaling, and protein kinase D activity as drivers of dendrite regeneration. In conclusion, we demonstrate that dendrite injury-induced calcium elevations play a key role in the regenerative response of dendrites and begin to delineate the molecular mechanisms governing dendrite repair.

SIGNIFICANCE: Advances in genetically encoded sensors and two-photon imaging have unlocked functional imaging at the level of single dendritic spines. Synaptic activity can be measured in real time in awake animals. However, tools are needed to facilitate the analysis of the large datasets acquired by the approach. Commonly available software suites for imaging calcium transients in cell bodies are ill-suited for spine imaging as dendritic spines have structural characteristics distinct from those of the cell bodies. We present an automated tuning analysis tool (AUTOTUNE), which provides analysis routines specifically developed for the extraction and analysis of signals from subcellular compartments, including dendritic subregions and spines. AIM: Although the acquisition of in vivo functional synaptic imaging data is increasingly accessible, a hurdle remains in the computation-heavy analyses of the acquired data. The aim of this study is to overcome this barrier by offering a comprehensive software suite with a user-friendly interface for easy access to nonprogrammers. APPROACH: We demonstrate the utility and effectiveness of our software with demo analyses of dendritic imaging data acquired from layer 2/3 pyramidal neurons in mouse V1 in vivo. A user manual and demo datasets are also provided. RESULTS: AUTOTUNE provides a robust workflow for analyzing functional imaging data from neuronal dendrites. Features include source image registration, segmentation of regions-of-interest and detection of structural turnover, fluorescence transient extraction and smoothing, subtraction of signals from putative backpropagating action potentials, and stimulus and behavioral parameter response tuning analyses. CONCLUSIONS: AUTOTUNE is open-source and extendable for diverse functional synaptic imaging experiments. The ease of functional characterization of dendritic spine activity provided by our software can accelerate new functional studies that complement decades of morphological studies of dendrites, and further expand our understanding of neural circuits in health and in disease.

During learning, synaptic connections between excitatory neurons in the brain display considerable dynamism, with new connections being added and old connections eliminated. Synapse elimination offers an opportunity to understand the features of synapses that the brain deems dispensable. However, with limited observations of synaptic activity and plasticity in vivo, the features of synapses subjected to elimination remain poorly understood. Here, we examined the functional basis of synapse elimination in the apical dendrites of L2/3 neurons in the primary motor cortex throughout motor learning. We found no evidence that synapse elimination is facilitated by a lack of activity or other local forms of plasticity. Instead, eliminated synapses display asynchronous activity with nearby synapses, suggesting that functional synaptic clustering is a critical component of synapse survival. In addition, eliminated synapses show delayed activity timing with respect to postsynaptic output. Thus, synaptic inputs that fail to be co-active with their neighboring synapses or are mistimed with neuronal output are targeted for elimination.

Maintaining precise synaptic contacts between neuronal partners is critical to ensure the proper functioning of the mammalian central nervous system (CNS). Diverse cell recognition molecules, such as classic cadherins (Cdhs), are part of the molecular machinery mediating synaptic choices during development and synaptic maintenance. Yet, the principles governing neuron-neuron wiring across diverse CNS neuron types remain largely unknown. The retinotectal synapses, connections from the retinal ganglion cells (RGCs) to the superior collicular (SC) neurons, offer an ideal experimental system to reveal molecular logic underlying synaptic choices and formation. This is due to the retina's unidirectional and laminar-restricted projections to the SC and the large databases of presynaptic RGC subtypes and postsynaptic SC neuronal types. Here, we focused on determining the role of Type II Cdhs in wiring the retinotectal synapses. We surveyed Cdhs expression patterns at neuronal resolution and revealed that Cdh13 is enriched in the wide-field neurons in the superficial SC (sSC). In either the Cdh13 null mutant or selective adult deletion within the wide-field neurons, there is a significant reduction of spine densities in the distal dendrites of these neurons in both sexes. Additionally, Cdh13 removal from presynaptic RGCs reduced dendritic spines in the postsynaptic wide-field neurons. Cdh13-expressing RGCs use differential mechanisms than αRGCs and On-Off Direction-Selective Ganglion Cells (ooDSGCs) to form specific retinotectal synapses. The results revealed a selective transneuronal interaction mediated by Cdh13 to maintain proper retinotectal synapses in vivo.

Dendritic arborization is a critical determinant of neuronal connectivity. The structure of a neuron's dendritic arbor determines the number of synaptic inputs a neuron can receive and how it processes synaptic input from other neurons. Here, we describe methods for visualizing and quantifying the dendritic arbor in primary cell cultures and in the intact rodent brain. These techniques can be used to answer significant scientific questions, such as the effects of disease processes, drugs, growth factors, and diverse environmental stressors on dendritogenesis in both in vitro and in vivo rodent models.

• Snf7-3 KO mice reveal its role in synaptic function and cognitive processing. • Snf7-3 KO mice show age-dependent social recognition deficits and higher mEPSCs. • Conditional Snf7-3 KO causes early cognitive deficits and synaptic hyperactivity. • Snf7-3 deficiency increases pre- and postsynaptic puncta in hippocampal neurons. • Snf7-3 is crucial for synaptic maintenance and may contribute to neurodegeneration. Snf7-3 is a crucial component of the endosomal sorting complexes required for transport (ESCRT) pathway, playing a vital role in endolysosomal functions. To elucidate the role of Snf7-3 in vivo, we developed conventional-like and conditional Snf7-3 knockout (KO) mouse models using a "Knockout-first" strategy. Conventional-like Snf7-3 KO mice showed significantly reduced Snf7-3 mRNA expression, and older mice (25–40 weeks) exhibited impaired social recognition and increased miniature excitatory postsynaptic currents (mEPSCs). Similarly, conditional KO mice aged 8–24 weeks, with Snf7-3 specifically deleted in forebrain excitatory neurons, displayed impaired object location memory and elevated mEPSC frequency. Consistently, Snf7-3 knockdown in cultured mouse hippocampal neurons led to increased densities of pre- and postsynaptic puncta, supporting the observed increase in mEPSC frequency. In addition, enhanced dendritic complexity was observed in the medial prefrontal cortex of these mice, indicating early synaptic disturbances. Our findings underscore the critical role of Snf7-3 in maintaining normal cognitive functions and social behaviors. The observed synaptic and behavioral deficits in both conventional-like and conditional KO mice highlight the importance of Snf7-3 in specific neuronal populations, suggesting that early synaptic changes could precede more pronounced cognitive impairments. [ABSTRACT FROM AUTHOR]

The zinc metal anodes are liable to experience detrimental dendrite growth and side reactions, thereby limiting the lifespan of aqueous Zn‐ion batteries. Here, a readily available supramolecule, dimethoxypillar[5]arene (DP[5]), is utilized as a shielding layer to stabilize the Zn anode by exploiting its zincophilicity derived from the ─OCH3 functional groups and its hydrophobicity from the hydrophobic backbone. The DP[5] shielding layer regulates the solvation sheath of Zn2+ and facilitates uniform zinc deposition. Swelling and dendrite formation are obviously suppressed in both the symmetric and full cells. The DP[5]‐Zn symmetrical cell cycles stably for 5500 h, and achieves a coulombic efficiency of 99.76% in a DP[5]‐Zn||Cu half‐cell after 2200 cycles. The DP[5]‐Zn||V2O5 full cell maintains 92.03% of initial capacity after 6000 cycles. Given the cost‐effective fabrication and environmental friendliness of DP[5] films, this material may pave the way for practical applications of zinc anodes. [ABSTRACT FROM AUTHOR]

Neurons become more vulnerable to stress factors with age, which leads to increased oxidative DNA damage, decreased activity of mitochondria and lysosomes, increased levels of p16, decreased LaminB1 proteins, and the depletion of the dendritic tree. These changes are exacerbated in vulnerable neuronal populations during the development of neurodegenerative diseases. Glu-Asp-Arg (EDR) and Lys-Glu-Asp (KED), and Ala-Glu-Asp-Gly (AEDG) peptides have previously demonstrated neuroprotective effects in various models of Alzheimer's disease. In this study, we investigated the influence of EDR, KED, and AEDG peptides on the aging of fibroblast-derived induced neurons. We used a new in vitro cellular model of human neuronal aging based on the transdifferentiation of aged dermal fibroblasts from elderly donors into induced cortical neurons. All peptides promote the arborization of the dendritic tree, increasing both the number of primary processes and the total length of dendrites. Tripeptides have no effect on the activity of mitochondria and lysosomes and the level of p16 protein in induced neurons. EDR peptide reduces oxidative DNA damage in induced neurons derived from elderly donor fibroblasts. Short peptides partially protect induced neurons from age-related changes and stimulate dendritogenesis in neurons. They can be recommended for use as neuroprotective agents. [ABSTRACT FROM AUTHOR]

Li metal batteries based on solid polymer electrolytes offer the benefits of high energy density and safety, as well as extended cycling life, making them an excellent candidate for the next‐generation battery system. However, current solid polymer electrolytes still suffer from low ion conductivity and Li+ transfer number, which seriously restricts its practical application. Herein, a self‐supporting composite solid polymer electrolyte was prepared, where phenolic resin rich in hydroxyl groups (BR) and polyethylene oxide (PEO) are mixed evenly and poured onto a cellulose membrane in one step. In such an electrolyte, PEO and BR combine to form intermolecular hydrogen bonds, lowering the crystallinity of PEO and increasing the Li+ transfer number. Lastly, the obtained solid electrolytes exhibited a high ion conductivity (1.1×10−4 S cm−1) and Li+ transfer number (0.53), as well as improved electrochemical window. Consequently, Li || Li symmetrical cells can run stably for more than 700 h at 0.1 mA cm−2/0.25 mAh cm−2. And full cells with LiFePO4 cathode can also demonstrate high discharge capacity of 152.12 mAh g−1 and rate performance. We believe that such a design based on supramolecular interaction offer a new avenue to advanced solid polymer electrolytes. [ABSTRACT FROM AUTHOR]

The microstructure of electronic solder joints is generated by the solidification of a small volume of bulk undercooled liquid. Here, we study β-Sn dendrite growth in Sn–3Ag–0.5Cu in the specific geometry and nucleation conditions of ball grid array (BGA) solder joints by combining electron backscatter diffraction and imaging of microstructures. It is shown that, while ⟨ 110 ⟩ is the preferred dendrite growth direction, out-of-plane branching and growth with ⟨ 11 W ⟩ directions are important for allowing dendrites to fan out into the spheroidal volume of BGA joints due to the low symmetry of β-Sn. We find that the crystallographic orientation of β-Sn at the nucleation point plays a strong role in subsequent dendrite growth. In single-grain joints, dendrites are often unfavorably oriented for growth, resulting in different types of zig-zag dendrite growth. In cyclic-twinned joints, it is shown how competitive out-of-plane trunk growth between three dendrite orientations produces {101} boundaries and the characteristic beachball microstructure. [ABSTRACT FROM AUTHOR]

A review of different models of spike neural networks has been conducted. A spike type neural network is developed in the article. The mathematical model of exchange of neurotransmitters between neurons is proposed. An algorithm for network operation and neuron interaction is proposed, as well as an approach to training the network based on the formation of new connections from dendrites and increasing the signal transmission coefficient. The model of neural network was created in Python using the developed algorithm and mathematical model. To speed up the calculations, they were paralleled using the Numba library. The library Matplotlib was used for visual modelling and plotting the number of neurotransmitters on neurons. Experimental studies of the developed model of biological type network were carried out. It was shown that the developed network after training responds faster to the signals that were applied to it in the process of training. [ABSTRACT FROM AUTHOR]

In DED melt pools, high solidification rates and temperature gradients complicate characterizing competitive dendrite growth. To address this, the WBM phase-field method simulates dendrite growth in the RCF103 alloy, revealing correlations between tilted dendrites and solidification parameters. It explores the competitive mechanism between different dendrite morphologies (columnar and seaweed) and the role of surface energy anisotropy and tip undercooling in determining dendrite shape. These findings enhance our understanding of DED melt pool dendrite growth, facilitating the establishment of a relationship between solidification structure, conditions, and process parameters. [ABSTRACT FROM AUTHOR]

The document titled "Appendix F: Means and SDs of frequency of prompts per group" provides data on the frequency of prompts in different tasks for two groups, Inq and Inq+ SE. It includes trivia questions related to neuroscience topics, such as brain lobes, neurons, and reflexes, which were used in an online competition. The document also features questions on somatosensation and memory formation, aimed at assessing students' understanding of these concepts. [Extracted from the article]

Computing‐in‐memory (CIM) architecture inspired by the hierarchy of human brain is proposed to resolve the von Neumann bottleneck and boost acceleration of artificial intelligence. Whereas remarkable progress has been achieved for CIM, making further improvements in CIM performance is becoming increasingly challenging, which is mainly caused by the disparity between rapid evolution of synaptic arrays and relatively slow progress in building efficient neuronal devices. Specifically, dedicated efforts are required toward developments of more advanced activation units in terms of both optimized algorithms and innovative hardware implementations. Here a novel bio‐inspired dendrite function‐like neuron based on negative‐differential‐resistance (NDR) behavior is reported and experimentally demonstrates this design as a more efficient neuron. By integrating electrochemical random‐access memory (ECRAM) with ionic regulation, the tunable NDR neuron can be trained to enhance neural network performances. Furthermore, based on a high‐density RRAM chip, fully hardware implementation of CIM is experimentally demonstrated by integrating NDR neuron devices with only a 1.03% accuracy loss. This work provides 516 × and 1.3 × 105 × improvements on LAE (Latency‐Area‐Energy) property, compared to the digital and analog CMOS activation circuits, respectively. With device‐algorithm co‐optimization, this work proposes a compact and energy‐efficient solution that pushes CIM‐based neuromorphic computing into a new paradigm. [ABSTRACT FROM AUTHOR]

The heterotrimeric G‐protein αo subunit is ubiquitously expressed in the CNS as two splice variants Gαo1 and Gαo2, regulating various brain functions. Here, we investigated the effect of single Gαo1, Gαo2, and double Gαo1/2 knockout on the postnatal development of the murine mossy fiber tract, a central pathway of the hippocampal connectivity circuit. The size of the hippocampal synaptic termination fields covered by mossy fiber boutons together with various fiber length parameters of the tract was analyzed by immunohistochemical staining of the vesicular Zinc transporter 3 (ZnT3) or Synaptoporin at postnatal days 2, 4, 8, 12, 16, and in the adult. Ultimately, Gαo1 knockout resulted in a reduced developmental growth of synaptic mossy fiber terminal fields by 37% in the adult Stratum lucidum and by 30% in the total mossy fiber tract size. Other morphological parameters such as projection length of the infrapyramidal bundle of the tract were increased (+52% in Gαo1−/− mice). In contrast, Gαo2 knockout had no effects on the mossy fiber tract. Moreover, by using primary heterozygous and homozygous Gαo1 knockout hippocampal cultures, we detected a strongly pronounced reduction in axon and dendrite length (−50% and −38%, respectively) as well as axon and dendrite arborization complexity (−75% and −72% branch nodes, respectively) in the homozygous knockout. Deletion of both splice variants Gαo1 and Gαo2 partially rescued the in vivo and completely reconstituted the in vitro effects, indicating an opposing functional relevance of the two Gαo splice variants for neuronal development and synaptic connectivity. [ABSTRACT FROM AUTHOR]

Potassium (K) metal anodes are the most competitive candidates for low‐cost and high‐energy density rechargeable batteries. However, uncontrolled K dendrite growth strictly impedes the practical application of K metal anodes. Herein, a potassiophilic and conductive dual‐gradient free‐standing host (named TS‐PKS) composed of the bottom layer with Ti3CN and F doped SnO2 (F‐SnO2) and the top layer with perfluorinated sulfonic acid K (PFSA‐K) and ordered mesoporous silica (SBA15) is constructed to achieve dendrite‐free K deposition. The potassiophilicity and conductivity of the TS‐PKS host increase along with the depth direction to generate a bottom‐up dual‐gradient of K+ affinity and electroconductivity. Such bottom‐up dual‐gradient of K+ affinity and electroconductivity can synergistically manipulate uniform K metal deposition following the bottom‐up manner, preventing the notorious K dendrite growth. As a result, the TS‐PKS@K symmetric cell can stably cycle over 2800 h at 0.5 mA cm−2/0.5 mAh cm−2. Meanwhile, the TS‐PKS@K//PTCDA full battery also exhibits an initial specific capacity of 118.3 mAh g−1 at a high current density of 500 mA g−1 and maintains up to 81.1 mAh g−1 after 1000 cycles. This novel dual‐gradient strategy design offers a straightforward approach to effectively manipulate K metal deposition manner for achieving dendrite‐free K metal anodes. [ABSTRACT FROM AUTHOR]

High-energy-density alkali metal batteries (AMBs) offer a potentially promising and sustainable option for energy storage. However, notorious dendrite growth and uncontrollable plating behaviors resulting from random spatial ion/atom distribution and related high barriers restrict the development of AMBs. Different from interphase engineering and architecture construction, the emerging catalysis modulation is proposed to overcome above-related barriers, achieving uniform alkali metal nucleation and atom diffusion. Among the various catalysts, single atom catalysts (SACs) exhibit an atomic exposure of nearly 100%, displaying high atomic catalytic capability and efficiency. Although it is still at an early stage, the adoption of SACs for modulating alkali metal ion/atom desolvation or diffusion has shown great promise in both fundamental research and practical applications. In this review, the fabrications and characterizations of SACs are briefly summarized, and the principal mechanisms of SAC-incorporated alkali metal anode systems are highlighted in terms of electrochemical analysis, microscopic/spectroscopic characterizations, and theoretical simulations. In addition, sustainable paths for future critical battery chemistry and material selections based on SACs are highlighted. The associated opportunities and challenges are further prospected to achieve a high-performance alkali metal anode. [ABSTRACT FROM AUTHOR]

Sodium (Na) metal battery is regarded as one of the most promising candidates for large‐scale energy storage devices, benefiting from the abundant sodium reserves and low cost. However, its practical application is hindered by the dendrite growth and unstable electrode‐electrolyte interface. Herein, a 3D sodiophilic structure composed of a carbon matrix overlaid with g‐C3N4 coating layers (g‐C3N4/3D‐C) is designed to stabilize the Na plating/stripping behavior. The sodiophilicity is endowed by a highly reversible adsorption‐intercalation process at the hetero‐interface, which can guide conformal Na deposition and induce the formation of inorganic‐rich solid‐electrolyte interphases with high structural stability and fast Na‐ion transport. Meanwhile, the 3D scaffold can effectively accommodate Na deposition during Na plating/stripping and depress the dendrite formation. As a result, the half cell assembled with g‐C3N4/3D‐C electrode delivers long‐term cycling performance at 1.0 mA cm−2 with a high Coulombic efficiency of 99.92% for over 2000 cycles and of 99.94% even at 5 mA cm−2, 10 mAh cm−2. The practical feasibility of the g‐C3N4/3D‐C is verified with full cells, which shows favorable rate capability and long‐cycle performance. The sodiophilic hetero‐interface construction strategy proposed in this work sparks new insights for designing high‐performance Na metal anodes. [ABSTRACT FROM AUTHOR]

Reelin, a secreted glycoprotein, plays a crucial role in guiding neocortical neuronal migration, dendritic outgrowth and arborization, and synaptic plasticity in the adult brain. Reelin primarily operates through the canonical lipoprotein receptors apolipoprotein E receptor 2 (Apoer2) and very low-density lipoprotein receptor (Vldlr). Reelin also engages with noncanonical receptors and unidentified coreceptors; however, the effects of which are less understood. Using high-throughput tandem mass tag (TMT) liquid chromatography tandem mass spectrometry (LC-MS/MS)-based proteomics and gene set enrichment analysis (GSEA), we identified both shared and unique intracellular pathways activated by Reelin through its canonical and noncanonical signaling in primary murine neurons of either sex during dendritic growth and arborization. We observed pathway cross talk related to regulation of cytoskeleton, neuron projection development, protein transport, and actin filament-based process. We also found enriched gene sets exclusively by the noncanonical Reelin pathway including protein translation, mRNA metabolic process, and ribonucleoprotein complex biogenesis suggesting Reelin fine-tunes neuronal structure through distinct signaling pathways. A key discovery is the identification of aldolase A, a glycolytic enzyme and actin-binding protein, as a novel effector of Reelin signaling. Reelin induced de novo translation and mobilization of aldolase A from the actin cytoskeleton. We demonstrated that aldolase A is necessary for Reelin-mediated dendrite growth and arborization in primary murine neurons and mouse brain cortical neurons. Interestingly, the function of aldolase A in dendrite development is independent of its known role in glycolysis. Altogether, our findings provide new insights into the Reelin-dependent signaling pathways and effector proteins that are crucial for dendritic development. [ABSTRACT FROM AUTHOR]

Aqueous batteries employing Zinc metal anodes (ZMAs) are considered to be promising next‐generation energy storage systems. However, the severe interfacial side reactions and dendrite growth restrict the practical application of ZMAs in aqueous electrolytes. Herein, a water‐insoluble dual‐ionic electrolyte additive of yttrium 2,4,5‐trifluorophenylacetate (YTFPAA) is developed to stabilize the aqueous ZMAs. Notably, the ethanol‐solvated TFPAA− can capture H+ and thus buffer the decreased electrolyte pH caused by the hydrolysis of Y3+. Furthermore, the ethanol‐solvated TFPAA− can dynamically adsorb onto the surface of ZMAs through a reversible oxidation‐reduction reaction, effectively suppressing the interfacial side reactions by forming a water‐poor interface, and enhancing the reversibility of Zn2+ deposition/stripping by redistributing the Zn2+ flux. These favorable effects of TFPAA− combined with the dynamic electrostatic shielding effect of Y3+ ultimately enable uniform and dense Zn2+ deposition. As a result, the Zn/Zn cells assembled with 0.25YTFPAA electrolyte exhibit an impressive cycle life of 2100 h at 0.5 mA cm−2–0.25 mAh cm−2. More importantly, the assembled V2O5/Zn full cell shows an ultra‐long cycle life of up to 18000 cycles at 5.0 A g−1. This work highlights the rational design of multifunctional ionic additives for stabilizing aqueous ZMAs. [ABSTRACT FROM AUTHOR]

The suboptimal ionic conductivity of commercial polyolefin separators exacerbates uncontrolled lithium dendrite formation, deteriorating lithium metal battery performance and posing safety hazards. To address this challenge, a novel organic‐inorganic composite separator designed is prepared to enhance ion transport and effectively suppress dendrite growth. This separator features a thermally stable, highly porous poly(m‐phenylene isophthalamide) (PMIA) electrospun membrane, coated with ultralong hydroxyapatite (HAP) nanowires that promote “ion flow redistribution.” The synergistic effects of the nitrogen atoms in PMIA and the hydroxyl groups in HAP hinder anion transport while facilitating efficient Li+ conduction. Meanwhile, the optimized unilateral pore structure ensures uniform ion transport. These results show that the 19 µm‐thick HAP/PMIA composite separator achieves remarkable ionic conductivity (0.68 mS cm−1) and a high lithium‐ion transference number (0.51). Lithium symmetric cells using HAP/PMIA separators exhibit a lifespan exceeding 1000 h with low polarization, significantly outperforming commercial polypropylene separators. Furthermore, this separator enables LiFePO4||Li cells to achieve an enhanced retention of 97.3% after 200 cycles at 1 C and demonstrates impressive rate capability with a discharge capacity of 72.7 mAh g−1 at 15 C. [ABSTRACT FROM AUTHOR]

Corrosion, hydrogen evolution, and dendrite formation seriously affect the Zn anode, significantly limiting the practical application of aqueous zinc ion batteries. Herein, the Zn anode surface is innovatively reconstructed by decorating a zincophilic tellurium layer (Te@Zn) to enhance the Zn deposition kinetics. Theoretical calculations and experimental characterizations demonstrate that the zincophilic Te provides an abundance of anchoring sites for Zn nucleation and homogenizes the interface electric field to suppress dendrite growth. The Te@Zn anode exhibits an ultralow overpotential of 14.8 mV at 1.0 mA cm−2 and 1.0 mAh cm−2 with high Coulombic efficiency, and maintains ultra‐stable operation for over 3600 h at 0.2 mA cm−2 and 0.2 mAh cm−2. The Te@Zn||KVOH full cells and soft–pack batteries also deliver a brilliant rate capability and long cycling stability. The interfacial manipulation strategy using the Te layer on Zn anode surface paves the way for large‐scale energy storage applications. [ABSTRACT FROM AUTHOR]

Zn metal as a promising anode for aqueous batteries suffers from severe zinc dendrites, anion‐related side reactions, hydrogen evolution reaction (HER) and narrow electrochemical stable window (ESW). Herein, an "anions‐in‐colloid" hydrated deep eutectic electrolyte consisting of Zn(ClO4)2 ⋅ 6H2O, β‐cyclodextrin (β‐CD), and H2O with mass ratio of 7 : 4.5 : 3 (ACDE‐3) is designed to improve the stability of zinc anode. The ACDE‐3 reconfigures the hydrogen‐bond (HB) network and regulates the solvation shell. More importantly, the hydroxyl‐rich β‐cyclodextrins (β‐CDs) in ACDE‐3 self‐assemble into micelles, in which the steric effect between adjacent β‐CDs in micelles restricts the movement of anions. This unique "anions‐in‐colloid" structure enables the eutectic system with a high Zn2+ transference number (tZn2+) of 0.84. Thus, ACDE‐3 inhibits the formation of dendrite, prevents the anion‐involved side reactions, suppresses the HER, and enlarges the ESW to 2.32 V. The Zn//Zn symmetric cell delivers a long lifespan of 900 hours at 0.5 mA cm−2, and the Zn//Cu half cells have a high average columbic efficiency (ACE) of 97.9 % at 0.5 mA cm−2 from cycle 15 to 200 with a uniform and compact zinc deposition. When matched with a poly(1,5‐naphthalenediamine) (poly(1, 5‐NAPD)) cathode, the full battery with a low negative/positive capacity (N/P) ratio of 2 can still cycle steadily for 200 cycles at a current density of 1.0 A g−1. Additionally, this electrolyte has been proven to be operative over a wide temperature range from −40 °C to 40 °C. [ABSTRACT FROM AUTHOR]

Solid‐electrolyte interphase (SEI) plays a decisive role in building reliable Li metal batteries. However, the scarcity of anions in Helmholtz layer (HL) caused by electrostatic repulsion usually leads to the inferior SEI derived from solvents, resulting in dendrites and ‘dead’ Li. Therefore, regulating the distribution of anions in electric double layer (EDL) and continuously introducing more anions into HL to tailor anions‐derived SEI is crucial for achieving stable Li plating/stripping. Herein, by jointly utilizing the controlled defects of reduced graphene oxide (rGO) and the oriented dipoles of ferroelectric BaTiO3 (BTO), the rGO‐BTO composite layer sustainedly brings more TFSI− and NO3− into anion‐defecient HL, promoting favorable decomposition of anions and guiding the generation of robust and fast‐Li+‐transport SEI containing more inorganics LiF and Li3N species. Thus, the resulting Li deposit shows smooth and dense morphologies without dendrites, leading to high average Coulombic efficiency. The Li//Cu@rGO‐BTO (10 mAh cm−2 plated Li) cell exhibits an enhanced Li plating/stripping stability (2700 h) and a higher rate capability. The LiFePO4 full cell (N/P≈6.3) using rGO‐BTO displays an enhanced capacity retention (82.0 % @ 430 cycles). This work provides a new insight on the construction of robust SEI by regulating the distribution of anions within EDL. [ABSTRACT FROM AUTHOR]

Homogeneous Li‐ion flux is a significant precondition of uniform Li‐ion deposition in Li metal batteries (LMBs). Numerous methodologies have been presented for homogenizing Li‐ion flux before Li deposition based on the features of Li‐ion deposition. Separators that provide Li‐ion transfer channels and are directly exposed to Li metal anodes have attracted rising attention for their role in guiding regular Li‐ion distribution. More novel functional separators have been proposed aiming to achieve dendrite‐free deposition. Herein, the factors and strategies that regulate Li‐ion distribution through functional separators toward LMBs are concentrated on. The current mechanisms of Li‐ion flux regulation by functional separators are first highlighted, including physical properties, interactions with the electrolyte, and modification of the solid‐state electrolyte interphase. According to these mechanisms, functional separator strategies for regulating Li‐ion flux are divided into three methodologies, and typical examples are introduced. Finally, current limitations and suggestions for future functional separator studies are presented, aiming to inspire engaged researchers and newcomers to trigger more exciting works in this area. [ABSTRACT FROM AUTHOR]

A stable self-assembled 2-hydroxyphosphonoacetic acid (HPAA) layer was constructed on the Zn surface via chelation. This HPAA protective layer significantly inhibits the water-related side reactions and suppresses Zn dendrite growth. Consequently, the Zn-HPAA-1h anode shows a long cycling lifetime of 650 h in a symmetric cell at 30.0 mA cm−2. Also, the Zn-HPAA-1h//V2O5 full cell demonstrates a high capacity of 154.1 mA h g−1 after 1000 cycles at 2 A g−1. This study provides a new strategy for developing dendrite-free Zn anodes. [ABSTRACT FROM AUTHOR]

Aqueous zinc‐ion batteries (ZIBs) have generated extensive research attention for stationary energy storage, due to their advantaged superiority in terms of inherent safety, low cost, and eco‐friendliness. However, uncontrollable dendrite growth and side reactions of the Zn anode affect the cycle life of ZIBs. Conventional separators are almost ineffective in inhibiting these issues. Herein, a chitin nanofiber membrane separator is developed to tackle these issues via a simple, low‐cost, and scalable strategy. The obtained separator exhibits abundant zincophilic functional groups, homogeneous nanopores, and excellent mechanical properties, which facilitate the desolvation of hydrated Zn2+ ions, improve the Zn2+ transference number, and homogenize the ion flux, simultaneously. Moreover, the separator can also reduce the deposition barrier, and accelerate Zn2+ deposition kinetics. Therefore, Zn dendrites and harmful side reactions are effectively and synchronously suppressed, enabling the assembled ZIBs with an ultralong cycle life and good rate capability. Impressively, the assembled Zn‐MnO2 pouch cell exhibits excellent stability and safety under various external damages. The above highlights mark a significant step toward the practical application of ZIBs. [ABSTRACT FROM AUTHOR]

The effect of strand (S‐) and final (F‐) electromagnetic stirring (EMS) on solidification structure characteristic of a φ690 mm continuously cast round bloom has been investigated industrially and theoretically. The newly designed S1‐EMS equipped just below the foot zone takes great effect on both equiaxed ratio and distribution alignment, as well as central porosity. Larger current S1‐EMS leads to higher equiaxed ratio, more symmetrical equiaxed zone, and smaller diameter of central porosity, and the effect is much more obvious than conventional S2‐EMS and F‐EMS. It is also noticed that there should be a saturation effect of S1‐EMS on the promotion of equiaxed dendrite nucleation. The S2‐EMS is beneficial for the expanding of equiaxed zone and improving of central porosity. When S1‐EMS is weak, strong S2‐EMS results in more asymmetrical equiaxed zone. However, when S‐EMS is strong, strong S2‐EMS results in more symmetrical distribution of equiaxed zone. The F‐EMS takes a little impact on the expanding of equiaxed zone in the large‐sized round bloom, and almost no effect on the alignment. The central porosity, however, is improved by F‐EMS with the help of decrease in temperature gradient and compensation of solidification contraction. [ABSTRACT FROM AUTHOR]

The practical applications of zinc metal anode are restricted by detrimental dendrite growth and hydrogen evolution reaction (HER), especially at high current densities. Previous works have demonstrated that constructing Zn(002) texture could effectively suppress dendrite growth and HER. However, the surface grain distribution of commercial zinc metal remains indistinct. Herein, a simple mechanical grinding approach is demonstrated to construct (002)‐textured zinc metal anodes. After grinding, the (002) relative texture coefficient of commercial zinc metal increases from 10.58 to 42.28, indicating a significant more (002) planes exposure. As prepared (002)‐textured zinc anode exhibits a high critical current density of 141 mA cm−2 and stably cycles for over 1500 cycles at 50 mA cm−2 and 1 mAh cm−2. Benefiting from the stability and fast kinetics of this (002)‐textured zinc anode, the zinc‐ion capacitor achieves a power density of 8500 W kg−1 and long cycle over 10 000 cycles with Coulombic efficiency (CE) exceeding 99.9%. This work provides both fundamental and practical insights for dendrite‐free and HER‐suppressed zinc metal anodes and inspiring guidance for other metal batteries. [ABSTRACT FROM AUTHOR]

In situ construction of solid electrolyte interfaces (SEI) is an effective strategy to enhance the reversibility of zinc (Zn) anodes. However, in situ SEI to afford high reversibility under high current density conditions (≥20 mA cm−2) is highly desired yet extremely challenging. Herein, we propose a dual reaction strategy of spontaneous electrostatic reaction and electrochemical decomposition for the in situ construction of SEI, which is composed of organic‐rich upper layer and inorganic‐rich inner layer. Particularly, in situ SEI performs as "growth binder" at small current density and "orientation regulator" at high current density, which significantly suppresses side reactions and dendrite growth. The in situ SEI affords the record‐breaking reversibility of Zn anode under practical conditions, Zn//Zn symmetric cells can stably cycle for over 1300 h and 400 h at current densities of 50 mA cm−2 and 100 mA cm−2, respectively, showcasing an exceptional cumulative capacity of 67.5 Ah cm−2. Furthermore, the practicality of this in situ SEI is verified in Zn//PANI pouch cells with high mass loading of 25.48 mg cm−2. This work provides a universal strategy to design advanced SEI for practical Zn‐ion batteries. [ABSTRACT FROM AUTHOR]

As a modern method of contact free fusion, laser beam welding has gained importance in recent years. This is due to both the possibiliy of a high advance speed of the laser and low thermal distortion of the components compared to other welding processes, see Dal and Fabbro. These beneficial process properties follow from a focused laser, which thus results in a precise energy input. In addition, laser beam welding processes can be automated which makes the process attractive for a wide range of applications, cf. Dilthey. Nevertheless, various influences, like the temperature gradient, the chemical composition or process parameters, may have an effect on the occurrence of so‐called solidification cracks. Solidification cracks arise during solidification and occur in the area of the mushy zone, which is located behind the melt pool. The material behavior in the mushy zone is governed by a dendritic morphology. Due to this, liquid phase inclusions may occur in some parts of the mushy zone, see Hills et al. When these trapped areas solidify, no further liquid phase can follow and a negative pressure is created. The resulting stresses can then lead to solidification cracks. In further studies, the geometry of the dendritic morphology will be generated on the basis of previous phase field simulations. These describe the dendrite growth controlled by the chemical concentration. The resulting geometry will then be simulated using the possibilities of a thermo‐elastoplastic material model, which will enable temperature‐driven imitation of growth. This contribution addresses the evolving state of the dendritic microstructure in a simplified manner. Therefore, for the first study, a simplified morphology is used, that is, no secondary arms and an elliptical geometry of the dendrites is assumed. Thermal as well as elastoplastic effects are already taken into account, in order to represent the inherent stress and strain states in the microstructure. These may be related to critical states leading to failure in the future. [ABSTRACT FROM AUTHOR]

This study investigates the impact of the cooling rates, from 18 to 1.5 °C/s, on the as-cast microstructure of the CMSX-4 Ni-based superalloy, especially on morphological changes in primary γ′ precipitates in the dendrite core and border. Microstructural characterization along the height of directionally solidified samples included the measurement of grain density, secondary dendrite arm spacing, γ–γ′ eutectic morphology and volume fraction, solute segregation, and primary γ′ precipitate morphology & size in both dendrite core and border. A simple thermodynamic model was employed to investigate the morphological transitions observed during coarsening of primary γ′ precipitates, from sphere to cube, concave cube, octocube and solid-state dendrite. The γ–γ′ lattice misfit, the γ/γ′ elastic strain energy values within the γ matrix, and the critical precipitation sizes for morphological changes were extrapolated for the dendrite core and border. The thermodynamic model, which considers the balance between elastic and interfacial energies, does not completely explain the differences in size and shape of the primary γ′ particles between the dendrite border and core. The more varied γ′ particle morphologies in the dendrite border are due to faster precipitate coarsening, driven by lower Re and W contents, higher atomic diffusivity, increased solvus temperature, and reduced supercooling for the precipitation reaction. [ABSTRACT FROM AUTHOR]

In previous studies, the mushy zone constant was assigned a fixed value or a value associated with dendrite characteristics at room temperature. However, elucidating the constitutive behaviors of mushy dendrites at high temperatures using solid dendrite characteristics at room temperature poses challenges. In this study, a numerical model was constructed to investigate the effects of variable mushy zone constants on fluid flow and heat transfer in the mold. The results revealed that "Zone Z‐1/2" exhibited a thinner solidified shell compared with the other zones, indicating a close correlation between heat transfer and thickness differences. Under default simulation conditions, the liquid steel cooled rapidly, leading to the dissipation of superheat. The mushy zone exhibited a wide range, with almost no pure liquid phase present in the mold. In cases 2, 3, and 4 within "Zone Z‐1/2", the average thickness of the solidified shell gradually increased during solidification, indicating the absence of evident remelting phenomena in the mold. As the variable mushy zone constants increased, the local temperature gradient increased, while the local cooling rate decreased. The accuracy of the numerical model was validated through actual measurements and empirical formulas. The simulation results for case 4 exhibited a high degree of fitting. [ABSTRACT FROM AUTHOR]

Gradual disability of Zn anode and high negative/positive electrode (N/P) ratio usually depreciate calendar life and energy density of aqueous Zn batteries (AZBs). Herein, within original Zn2+‐free hydrated electrolytes, a steric hindrance/electric field shielding‐driven "hydrophobic ion barrier" is engineered towards ultradurable (002) plane‐exposed Zn stripping/plating to solve this issue. Guided by theoretical simulations, hydrophobic adiponitrile (ADN) is employed as a steric hindrance agent to ally with inert electric field shielding additive (Mn2+) for plane adsorption priority manipulation, thereby constructing the "hydrophobic ion barrier". This design robustly suppresses the (002) plane/dendrite growth, enabling ultradurable (002) plane‐exposed dendrite‐free Zn stripping/plating. Even being cycled in Zn‖Zn symmetric cell over 2150 h at 0.5 mA cm−2, the efficacy remains well‐kept. Additionally, Zn‖Zn symmetric cells can be also stably cycled over 918 h at 1 mA cm−2, verifying uncompromised Zn stripping/plating kinetics. As‐assembled anode‐less Zn‖VOPO4 ⋅ 2H2O full cells with a low N/P ratio (2 : 1) show a high energy density of 75.2 Wh kg−1full electrode after 842 cycles at 1 A g−1, far surpassing counterparts with thick Zn anode and low cathode loading mass, featuring excellent practicality. This study opens a new avenue by robust "hydrophobic ion barrier" design to develop long‐life anode‐less Zn batteries. [ABSTRACT FROM AUTHOR]

Laser-directed energy deposition (L-DED) is an additive manufacturing technique that, in addition to fabricating new parts, is especially adept at creating and repairing thin wall structures. This study explores the effects of the number of infill passes on the microstructure and mechanical properties of Inconel 718 thin walls fabricated by L-DED. The effects of spatially varying cooling rates across both heights above the substrate and through the thickness of the thin wall samples, quantified through a combination of dendrite arm spacing measurements and finite element simulations, revealed that the most rapid cooling occurred at the walls' base under all conditions. The number of infill passes had a significant effect on this behavior, with the no infill pass (P2 sample) condition showing the most uniform cooling rate through its height. Moreover, the microstructure variation resulted in spatially varying hardness ranging from 170 HV in the stainless steel substrate, to ~ 220 HV towards the skin and top of the samples, and finally up to ~ 270 HV in the center of the samples where the cooling rate was the highest. More infill passes (P3 sample with one infill pass and P4 sample with two infill passes) led to higher cooling rates, finer grain structures, and increased hardness, particularly in the central regions of the thin wall samples. Conversely, fewer passes resulted in a more uniform but generally lower hardness throughout the sample. It is concluded that the infill pass strategy is a critical parameter in the L-DED process that directly influences the thermal history and, thus, the resultant microstructure and properties of Inconel 718 thin walls. [ABSTRACT FROM AUTHOR]

To prevent zinc (Zn) dendrite formation and improve electrochemical stability, it is essential to understand Zn dendrite growth, particularly in terms of morphology and relation with the solid electrolyte interface (SEI) film. In this study, we employ in-situ scanning transmission X-ray microscopy (STXM) and spectro-ptychography to monitor the morphology evolution of Zn dendrites and to identify their chemical composition and distribution on the Zn surface during the stripping/plating progress. Our findings reveal that in 50 mM ZnSO4, the initiation of moss/whisker dendrites is chemically controlled, while their continued growth over extended cycles is kinetically governed. The presence of a dense and stable SEI film is critical for inhibiting the formation and growth of Zn dendrites. By adding 50 mM lithium chloride (LiCl) as an electrolyte additive, we successfully construct a dense and stable SEI film composed of Li2S2O7 and Li2CO3, which significantly improves cycling performance. Moreover, the symmetric cell achieves a prolonged cycle life of up to 3900 h with the incorporation of 5% 12-crown-4 additives. This work offers a strategy for in-situ observation and analysis of Zn dendrite formation mechanisms and provides an effective approach for designing high-performance Zn-ion batteries. Understanding the evolution of Zn dendrites during cycling is crucial for development of Zn batteries. Here, authors employ in situ scanning transmission X-ray microscopy to identify the chemical origins of Zn dendrite formation and propose an electrolyte additive strategy to prolong cycle life. [ABSTRACT FROM AUTHOR]

To enhance the quality of vacuum arc remelting (VAR) ingots in enterprises, a remelting model and cracking criterion was developed based on simulation and a series of designed experiments to predict the segregation behavior, shrinkage cavity, thermal stress, and cracking tendency of VAR ingot. The remelting model was established by MeltFlow-VAR and Abaqus software. As MeltFlow-VAR cannot calculate the stress, through the secondary development program, the thermal stress of VAR ingot was calculated by introducing the temperature field of VAR process into Abaqus. This model was verified by longitudinal dissection of a 406 kg IN718 alloy VAR ingot. The simulated evolution of molten pool, shrinkage cavity, freckle formation probability and secondary dendrite arm spacing (SDAS) align consistently with the ingot microstructure and experimental results. Combined with thermal stress, the alloy strength at different temperature during cooling and solidification, and failure criterion, a crack criterion was constructed to predict the cracking tendency. Calculating the complete solidification time and cracking tendency of the VAR ingot after melting allows for the determination of the safe demolding time without cracks. This method can be used to explore the effect of different melting parameters, optimize VAR process and improve the quality of VAR production. [ABSTRACT FROM AUTHOR]

To enhance the performance of H13 steel, the effects of the cooling rate on the inclusions, primary carbides, and microstructure in rare-earth H13 steel were investigated. Various remelting experiments on rare-earth H13 steel were conducted. The evolution of inclusions was demonstrated to be Ce–O–S, Ce–O, and Ce–O–As → Ce–O–S → Ce–Al–O, and Al2O3, which could be attributed to the increase in Al elements, decomposition, and flotation of inclusions. The type of primary carbides remained unchanged, but their number increased considerably and their size decreased as the cooling rate increased. The secondary dendrite arm spacing was reduced with a faster cooling rate and was shown to be 7.35 ±2.04 μm; the size of austenite was also reduced. The relationship between secondary dendrite arm spacing and cooling rate was λ= 238.62 × Rc–0.438. The segregation ratio of the alloying elements was estimated based on the Clyne–Kurz model, which indicated that Mo had the highest segregation ratio, followed by V, C, and Cr. The cooling rate increased the segregation ratios of Mo, V, and Cr but had a minimal effect on that of C. The equilibrium phase diagram of rare-earth H13 steel was obtained based on Thermo-Calc software, which was consistent with the experimental results. The study provides theoretical insights for controlling the inclusions, primary carbides, and microstructure in steel. [ABSTRACT FROM AUTHOR]

Hot tears are typically classified as intergranular fractures, but recently we have found evidence of dendritic main stem fracture during the hot tearing in steel. This study conducted mechanical property tests on the mushy zone of the steel with stress directions parallel or perpendicular to the primary dendritic arms. The fracture strength and brittle toughness under the two conditions were clearly contrasted. Hot tearing prediction should consider the effects of dendrite morphology and stress direction. [ABSTRACT FROM AUTHOR]

The influence of magnesium treatment on cleanliness and microstructure characteristics of as-cast high-nitrogen stainless bearing steel (HNSBS) was systematically investigated. Results manifested that as the magnesium content increased from 0.0003 to 0.0054 wt pct, the oxygen and sulfur contents in steel, along with the number density and average size of inclusions significantly decreased due to the strong thermodynamic affinity and the removal of inclusions. Meanwhile, the inclusion evolution processes were Al2O3 → MgO·Al2O3 → MgO and MnS → MgS + Mg3N2, and the magnesium content in HNSBS should not exceed 0.0047 wt pct to prevent the formation of deleterious Mg3N2 inclusion. Additionally, the secondary dendrite spacing and the area fraction of precipitates (M23(C, N)6 and M2(C, N)) at the 1/2 radius of ingots decreased form 83 ± 25 μm and 17 pct to 63 ± 16 μm and 12 pct, respectively. The dendrite structure was refined owing to the increase in effective nucleation sites for γ-Fe provided by MgO·Al2O3 and MgS inclusions, as well as the enrichment of magnesium in the liquid phase at solidifying front. The area fraction and size of precipitates were reduced due to the decrease of chromium activity. The finer and more dispersed precipitates was attributed to the reduction of growth space and increase in effective nucleation sites. This work provides theoretical guidance for preventing the formation of deleterious inclusions (especially for nitrides) in high-nitrogen alloy systems and refining the microstructure of alloy systems containing M23(C, N)6 and M2(C, N) precipitates. [ABSTRACT FROM AUTHOR]

The as-cast microstructure of 2024 high-strength aluminum alloy has an important effect on its thermal workability and end-use performance. The effects of Cu/Mg ratio and solidification rate on as-cast microstructure were investigated by regulating the Cu and Mg content and solidification rate of 2024 alloy. The results show that with the mass ratio of Cu/Mg increases from 2.1 to 4.1, the type of second phase in the alloy is not changed. However, the content of Al2CuMg gradually decreases, while the content of Al2Cu and Al23Cu(Fe, Mn)4 gradually increases. When the solidification rate increases from 0.2 °C/s to 2.4 °/s, the grain size is obviously refined, the average grain size decreases from 293.0 μm to 77.0 μm. Moreover, the dendrites become developed, and the dendrite arm spacing decreases, and the second phase becomes smaller and distributes more homogeneous in the matrix, and the content of Al23Cu(Fe, Mn)4 insoluble phase obviously reduces. The formation of iron-rich insoluble phase can be reduced by reducing the Cu/Mg ratio and increasing the solidification rate, so as that the machining and mechanical properties of the alloy can be improved. [ABSTRACT FROM AUTHOR]

Cu-W alloys are widely used in high-voltage circuit breaker contacts due to their high resistance to arc ablation, but few studies have analyzed the microstructure of Cu-W alloys under arc ablation. This study applied a phase-field model based on the phase-field model developed by Karma and co-workers to the evolution of dendrite growth in the solidification process of Cu-W alloy under arc ablation. The process of columnar dendrite evolution during solidification was simulated, and the effect of the supercooling degree and anisotropic strength on the morphology of the dendrites during solidification was analyzed. The results show that the solid–liquid interface becomes unstable with the release of latent heat, and competitive growth between dendrites occurs with a large amount of solute discharge. In addition, when the supercooling degree is 289 K, the interface is located at a lower height of only 15 μm, and the growth rate is slow. At high anisotropy, the side branches of the dendrites are more fully developed and tertiary dendritic arms appear, leading to a decrease in the alloy's relative density and poorer ablation resistance. In contrast, the main dendrites are more developed under high supercooling, which improves the density and ablation resistance of the material. The results in this paper may provide a novel way to study the microstructure evolution and material property changes in Cu-W alloys under the high temperature of the arc for high-voltage circuit breaker contacts. [ABSTRACT FROM AUTHOR]

Laser cladding is an emerging environmentally friendly surface-strengthening technology. During the cladding process, the changes in molten pool temperature and velocity directly affect the solidification process and element distribution. The quantitative revelation of the directional solidification mechanism in the molten pool during the cladding process is crucial for enhancing the quality of the cladding layer. In this study, a multi-field coupling numerical model was developed to simulate the coating process of 316L powder on 45 steel matrices using a disk laser. The instantaneous evolution law of the temperature and flow fields was derived, providing input conditions for simulating microstructure evolution in the molten pool's paste zone. The behavior characteristics of the molten pool were predicted through numerical simulation, and the microstructure evolution was simulated using the phase field method. The phase field model reveals that dendrite formation in the molten pool follows a sequence of plane crystal growth, cell crystal growth, and columnar crystal growth. The dendrites can undergo splitting to form algal structures under conditions of higher cooling rates and lower temperature gradients. The scanning speed of laser cladding (6 mm/s) has minimal impact on dendrite growth; instead, convection within the molten pool primarily influences dendrite growth and tilt and solute distribution. [ABSTRACT FROM AUTHOR]

Lithium metal batteries offer high energy density but are challenged by dendrite growth, which can lead to short circuits and battery failure. Multiple models with varying degrees of accuracy and computational cost have been developed to understand and predict dendrite growth. This study presents a simple model to simulate macroscale dendrite growth on lithium metal electrodes. The model uses a 3D single-particle Diffusion-Limited Aggregation (DLA) algorithm with an electric field bias to simulate dendrite growth. The electric field bias was introduced into the model with an important parameter, namely the biasing factor c, which determines the balance between diffusion and electric field effects. Before performing the simulation with the proposed model, the dendrite growth in a lithium symmetric cell during charging was measured by sequential 3D magnetic resonance imaging (MRI). These data were then used to validate the simulation, as the dendrite structure in each measured MRI time frame was used a starting point for a new simulation, the results of which were then validated with the measured dendrite structure of the next time frame. The best agreement between the simulated and measured dendrite structures using the overlap and displacement of deposition sites metrics was obtained at the biasing factor c = 0.7. This agreement was also good in terms with the fractal dimension of the dendrite structures. The proposed method offers a simple, accurate, and scalable framework for predicting dendrite growth over long deposition periods, making it a valuable tool for studying dendrite suppression under real-world battery charging conditions. [ABSTRACT FROM AUTHOR]

Na metal batteries (NMBs) stand at the forefront of advancing energy storage technologies, but are severely hampered by Na dendrite issues, especially when using carbonate electrolytes. Suppressing the growth of Na dendrites through constructing NaF‐rich solid‐electrolyte‐interphase (SEI) is a commonly‐used strategy to prolong the lifespan of NMBs. In contrast, fluorinated organic SEI components are often underutilized. Inspired by unveiling the adsorption configuration of fluorinated organic compounds on the surface of Na metal, an optimized SEI architecture for stabilizing NMBs is proposed by investigating the C4H9SO2F‐/C4F9SO2F‐treated Na metal anodes. It is revealed that the SEI built on a fluorinated inorganic/organic hybrid layer exhibit favorable Na passivation capability, significantly improving Na deposition behavior. As a result, the NMB with a high‐loading cathode (15 mg cm−2) and a negative/positive capacity ratio (N/P) ratio of 4 shows a long‐term life span over 1000 cycles with 92.8% capacity retention at 2 C. This work opens a new pathway for developing robust and high‐energy‐density NMBs. [ABSTRACT FROM AUTHOR]

Li plating is widely known as the key factor leading to degradation and safety issues in lithium‐ion batteries (LIBs). Herein, the feasibility of monitoring the onset and progression of Li plating is proposed and justified in the graphite/LiFePO4 pouch cell by an operando impedance‐thickness combinational technique. First, as a proof‐of‐concept, the real‐time thickness/impedance variations of LIBs during charging at low temperature (≈0 °C) are obtained and dissected. Three distinct stages corresponding to different Li plating patterns are observed with the critical changing points of charge‐transfer resistance, which match well with the counterpoints in the differential thickness/capacity curves. Post‐mortem analysis by Mass Titration and Scanning Microscopy also indicate that these stages are Li intercalation, Li nucleation & nuclei growth, and Li dendrite growth, respectively. Thereafter, different cycling protocols are proposed and carried out to test the as‐mentioned Li plating processes by this novel technique. The results disclose that the extensive deposition of metallic Li significantly intensifies the loss of Li inventory, leading to cell aging or even a "capacity plunge", and depict a safer boundary plot about preventing the occurrence of "Li plating" region. This work provides new insights on Li plating behavior and battery safety control under harsh operational conditions. [ABSTRACT FROM AUTHOR]