Deposition Behavior Research Articles

Leveraging Ion Pairing and Transport in Localized High-Concentration Electrolytes for Reversible Lithium Metal Anodes at Low Temperatures.

Coulombic efficiency of over 99% is rarely achieved for Li metal anode below -40°C, hindering the practical application of high-energy-density Li metal batteries under extreme conditions. Herein, limiting factors for Li metal reversibility are investigated utilizing ether-based localized high-concentration electrolytes of different solvent-diluent combinations. We find that along with the desolvation barrier, bulk ion transport properties including ionic conductivity, transference number, and diffusivity are also crucial factors for low-temperature Li deposition behavior. Superior Li metal reversibility was observed within the combination of the solvent with moderately weak solvating power and the diluent with minimal viscosity, highlighting the role of ion transport and the necessity for a trade-off with desolvation. The optimized electrolyte composed of lithium bis(fluorosulfonyl)imide, methyl n-propyl ether, and 1,1,2,2-tetrafluoroethyl methyl ether delivers exceptional Coulombic efficiency of 99.34% at -40°C and 98.96% at -60°C under a current density of 0.5 mA cm-2. Furthermore, Li||LiCoO2 (2.7 mAh cm-2) cells demonstrate impressive reversible capacity and cycling stability at these temperatures. This work sheds light on the less-recognized relevance of bulk ion transport to low-temperature performance and provides guidelines for the electrolyte design of Li metal batteries operating in cold environments.

Numerical model of asphaltene deposition in vertical wellbores: Considerations of particle shape and drag force

Asphaltene deposition and plugging are common phenomena during crude oil production, significantly reducing production efficiency. Understanding the deposition behavior of asphaltene particles in vertical wellbores, particularly in relation to drag force interactions and settlement velocity, is imperative to mitigate these issues. Existing empirical models often fail due to their inherent inaccuracies and neglect of asphaltene particles' irregular shapes. This work established a quantitative method to describe irregular geometries of asphaltene particles. Shape coefficient, ∅, and shape coefficient influence factor, θ, are used to assess the impact of particle shape on the drag force coefficient and settling velocity. Experimental results from sedimentation experiments reveal particles with smaller shape coefficients encounter greater flow resistance and higher drag force coefficients. Moreover, the impact of shape coefficient on the drag coefficient gradually decreases as the Reynolds number increases. Based on these experimental findings, distinct models for the drag force coefficient and settling velocity of asphaltene particles are established, achieving a reduction in average error ranging between 2 % ∼ 25 % compared to existing models.

Unraveling the Deposition and Dissolution Behavior of the Ag-Modified Li Surface Based on Electrochemical Atomic Force Microscopy.

Lithium is a promising anode material for advanced batteries because of its high capacity and low redox potential. However, its practical use is hindered by nonuniform Li deposition and dendrite formation, leading to safety concerns in Li metal batteries. Our study shows that Ag-based materials enhance the uniformity of Li deposition on Ag-modified Li (AgLi) surfaces, thereby addressing these key challenges. This improvement is due to the strong affinity of Ag for Li, which promotes uniform deposition and dissolution. Additionally, the AgLi surface demonstrated an improved cycling stability, which is crucial for long-term battery reliability. Emphasizing our analytical approach, we utilized comprehensive techniques such as Kelvin probe force microscopy (KPFM) and electrochemical atomic force microscopy (EC-AFM) to locally analyze the electrical properties and unravel the Li deposition/dissolution mechanisms. KPFM analysis provided crucial insights into surface potential variations, while EC-AFM highlighted topographical changes during the Li deposition and dissolution processes, contributing significantly to the development of safer and more efficient Li metal batteries.

Interfacial Zn2+-solvation regulator towards reversible and stable Zn anode

Aqueous zinc-ion batteries (AZIBs) are fundamentally challenged by the instability of the electrode/electrolyte interface, predominantly due to irreversible zinc (Zn) deposition and hydrogen evolution. Particularly, the intricate mechanisms behind the electrochemical discrepancies induced by interfacial Zn2+-solvation and deposition behavior demand comprehensive investigation. Organic molecules endowed with special functional groups (such as hydroxyl, carboxyl, etc.) have the potential to significantly optimize the solvation structure of Zn2+ and regulate the interfacial electric double layer (EDL). By increasing nucleation overpotential and decreasing interfacial free energy, these functional groups facilitate a lower critical nucleation radius, thereby forming an asymptotic nucleation model to promote uniform Zn deposition. Herein, this study presents a pioneering approach by introducing trace amounts of n-butanol as solvation regulators to engineer the homogenized Zn (H-Zn) anode with a uniform and dense structure. The interfacial reaction and structure evolution are explored by in/ex-situ experimental techniques, indicating that the H-Zn anode exhibits dendrite-free growth, no by-products, and weak hydrogen evolution, in sharp contrast to the bare Zn. Consequently, the H-Zn anode achieves a remarkable Zn utilization rate of approximately 20% and simultaneously sustains a prolonged cycle life exceeding 500 h. Moreover, the H-Zn//NH4V4O10 (NVO) full battery showcases exceptional cycle stability, retaining 95.04% capacity retention after 400 cycles at a large current density of 5 A g−1. This study enlightens solvation-regulated additives to develop Zn anode with superior utilization efficiency and extended operational lifespan.

Fluorine-Rich Electrolyte Additive for Achieving Dendrite-Free Lithium Anodes at Low Temperatures.

The practical application of lithium metal anodes is significantly impeded by poor interfacial stability and uncontrolled dendrite growth. Herein, we introduce methyl trifluoroacetate (MTFA), a low-melting-point small molecule, as an electrolyte additive in an ether-based electrolyte. This additive facilitates the formation of an in situ composite solid electrolyte interphase (SEI) layer that is rich in LiF and features an ester-based flexible matrix. The resulting composite layer exhibits high ionic conductivity and mechanical stability, effectively regulating the lithium deposition behavior over a broad temperature range and inhibiting dendrite formation. Based on MTFA, the Li||Li symmetrical cell achieves a lifespan exceeding 5000 h at room temperature and 800 h at -20 °C, both with ultralow overpotential and exceptional cycling stability. In Li||LiFePO4 full cells with a high-area loading (10.52 mg cm-2) and an N/P ratio of 1.68, an average capacity decay of merely 0.096% per cycle is observed over 200 cycles. Even at -20 °C, the Li||LiFePO4 cell shows a CE of over 99% and maintains stable cycling performance. This work provides an innovative approach for optimizing lithium metal anode interfaces and enhancing low-temperature operation capabilities through the use of electrolyte additives.

Influence of the inner roughness of powder channels on the powder propagation behavior in laser metal deposition

The powder propagation behavior of powder nozzles for the laser metal deposition process has a significant influence on powder utilization rate and track geometry. A well-focused powder stream will lead to a higher process efficiency and lower material loss. Powder channels with different roughness and a constant diameter of 1.5 mm were placed by wire electrical discharge machining into a copper alloy printed by powder bed fusion. Nickel base powder with a size of −106 to +45 μm was delivered through the powder channels with varied carrier gas flow rates and varied powder mass flow rates. High-speed imaging was used to analyze the powder flow. From these recordings, the dispersion angle of the powder stream from single channels could be measured as well as the velocity of particles. Moreover, the relationship between individual particle velocity and individual particle flight angle was investigated. It was found that the inner roughness of powder channels has a major impact on powder propagation behavior. It could be shown that with a decrease in Ra from 2.16 to 0.27 μm the divergence angle decreased by around 61% while the particle velocity was increased by at least 28% for all varied parameters. Particles with a high velocity tend to have a lower particle flight angle.

Atomistic simulation on the deposition behavior of cold spray

Cold spray is an effective method for surface coating, which has been applied in various engineering areas. However, it is difficult to directly observe the dynamic deformation process in experiments. This paper applies the molecular dynamics simulation to model the deposition of a monocrystalline Cu particle onto a Cu substrate and, subsequently, carries out a systematic study on the deposition mechanism and microstructure evolution. The results indicate that the deposition process consists of an impact stage and a relaxation stage. It is mainly the high speed collision and the friction following the collision that lead to particle deposition, which, under different circumstances, can be defined as surface deposition or penetration deposition. Two methods, namely, drastic shear deformation and cooling in the relaxation stage, can help form nanocrystallines. Jetting and melting are not the necessary factors for the deposition of nano-sized particles. The formation of dislocation lines is influenced by impact velocities. At lower impact velocities, the dislocation lines are mainly distributed near the contact surface. However, when the impact velocity is higher, dislocation lines are almost uniformly distributed in the particle.

Insight into layer formation during friction surfacing: Relationship between deposition behavior and microstructure

Friction surfacing (FS) is a solid state layer deposition technique with a simple setup, presenting advantages compared to fusion-based approaches. Previous investigations showed microstructural gradients along layer width and thickness. The current study provides new insight into the FS layer formation for aluminum and its relation with the microstructure evolution. Special consumable studs containing two different aluminum alloys were used to visualize the different materials in the resulting deposit. The investigation was performed at different process parameters, revealing some fundamental material flow characteristics. The layer center presents inner stud material, where advancing side and top are formed by outer stud material. The bottom and retreating side present a mixture of inner and outer stud material. The part of the layer that is formed by the outer material, presumably undergoes higher strain rates during deposition, presenting finer grains. The top of FS layers shows a pronounced texture, i.e. shear texture components, compared to the other parts with random texture. This phenomenon can be related to the shearing of the stud material between already deposited material below and the stud at its rear edge. Overall, the FS layer formation characteristics revealed in this study are directly related to local microstructural properties.

Covalent Triazine Based Frameworks with Donor‐Donor‐π‐Acceptor Structures for Dendrite‐Free Lithium Metal Batteries

AbstractThe appearance of disordered lithium dendrites and fragile solid electrolyte interfaces (SEI) significantly hinder the serviceability of lithium metal batteries. Herein, guided by theoretical predictions, a multi‐component covalent triazine framework with partially electronegative channels (4C‐TA0.5TF0.5‐CTF) is incorporated as a protective layer to modulate the interface stability of the lithium metal batteries. Notably, the 4C‐TA0.5TF0.5‐CTF with optimized electronic structure at the molecular level by fine‐tuning the local acceptor‐donor functionalities not only enhances the intermolecular interaction thereby providing larger dipole moment and improved crystallinity and mechanical stress, but also facilitates the beneficial effect of lithiophilic sites (C−F bonds, triazine cores, C=N linkages and aromatic rings) to further regulate the migration of Li+ and achieve a uniform lithium deposition behavior as determined by various in‐depth in/ex situ characterizations. Due to the synergistic effect of multi‐component organic functionalities, the 4C‐TA0.5TF0.5‐CTF modified full cells perform significantly better than the common two/three‐component 2C‐TA‐CTF and 3C‐TF‐CTF electrodes, delivering an excellent capacity of 116.3 mAh g−1 (capacity retention ratio: 86.8 %) after 1000 cycles at 5 C and improved rate capability. This work lays a platform for the prospective molecular design of improved organic framework relative artificial SEI for highly stable lithium metal batteries.

Molecular key tuned steric-hindrance effect toward Zn (100) facet texture anode

Electrolyte additive is one of the most effective strategies to optimize Zn anode in aqueous zinc ion batteries. Few reports are available on the influence of spatial-hindrance effect on Zn2+ deposition behavior. Herein, the environmentally safe aspartame and neotame are selected to finely tune the molecular structure, thereby affecting molecular adsorption behavior as well as Zn2+ diffusion and deposition behavior, and the molecular structure regulation strategy is proposed to achieve the optimization of Zn anode. According to theoretical calculations and experimental conclusions, aspartame, as the molecular robot, uniformly adsorbs on Zn anode surface via oxygen-containing functional groups, captures Zn2+ via −NH2, homogenizes Zn2+ flux, and catalyzes Zn2+ desolvation, resulting in Zn2+ oriented deposition to form Zn (100) facet texture. Benefited from the molecular structure regulation strategy, Zn anode exhibits an ultra-long lifespan of more than 4600 h and an extremely high cumulative plated capacity of 11.7 Ah cm−2. Furthermore, Zn anode operates stably for more than 270 h under 80 % depth of discharge and possesses a high coulombic efficiency of 99.8 % in Zn||Cu half cells. This strategy provides a new perspective on selecting additives.

Co-Regulating Solvation Structure and Hydrogen Bond Network via Bio-Inspired Additive for Highly Reversible ZincAnode.

The feasibility of aqueous zinc-ion batteries for large-scale energy storage is hindered by the inherent challenges of Zn anode. Drawing inspiration from cellular mechanisms governing metal ion and nutrient transport, erythritol is introduced, a zincophilic additive, into the ZnSO4 electrolyte. This innovation stabilizes the Zn anode via chelation interactions between polysaccharides and Zn2+. Experimental tests in conjunction with theoretical calculation results verified that the erythritol additive can simultaneously regulate the solvation structure of hydrated Zn2+ and reconstruct the hydrogen bond network within the solution environment. Additionally, erythritol molecules preferentially adsorb onto the Zn anode, forming a dynamic protective layer. These modifications significantly mitigate undesirable side reactions, thus enhancing the Zn2+ transport and deposition behavior. Consequently, there is a notable increase in cumulative capacity, reaching 6000mA h cm⁻2 at a current density of 5mA cm-2. Specifically, a high average coulombic efficiency of 99.72% and long cycling stability of >500 cycles are obtained at 2mA cm-2 and 1mA h cm-2. Furthermore, full batteries comprised of MnO2 cathode and Zn anode in an erythritol-containing electrolyte deliver superior capacity retention. This work provides a strategy to promote the performance of Zn anodes toward practical applications.

Uniformly dispersed zinc-tin alloy as high-performance anode for aqueous zinc ion batteries

Uncontrolled dendrite and side reactions of aqueous zinc ion batteries (AZIBs) hinder their commercial application. To overcome these obstacles, a novel zinc alloy anode for multifunctional AZIBs was designed by incorporating metal elements into the zinc anode. The metal elements are intended to improve the overall electrochemical performance of the battery by solving the zinc anode problem in an “incorporation” manner. In this study, the effect of Sn-induced surface structure reconstruction on the diffusion and deposition behavior of Zn2+ was investigated using binary zinc alloy (Zn@Sn) as a zinc anode. The zinc anode with Zn (002) crystal plane as the preferred crystal plane was able to inhibit the disordered growth of zinc dendrites, and the introduction of Sn elements enhanced the anti-hydrogen evolution reaction ability of the zinc anode. At a current density of 1.2 mA cm–2, the Zn@Sn symmetric cell was able to maintain stable operation for 1000 h, demonstrating a more prominent deposition/stripping stability. This work provides a promising strategy and new insights into the design of electrolyte-anode interfacial protection.

Influence of the Acetylene Flow Rate and Process Pressure on the Carbon Deposition Behavior by Thermal Chemical Vapor Deposition Process

We used the chemical vapor deposition process to deposit carbon film at a high temperature (900 °C). The carbon films were deposited on AISI 1006 foils using an acetylene gas. We analyzed the carbon film deposited on the surface using Raman spectroscopy, scanning electron microscopy, and high-resolution transmission electron microscopy to define changes in the bonding structure of the carbon film. The results of Raman spectroscopy and high-resolution transmission electron microscopy revealed that as the acetylene flow rate increased, the shape of the deposited carbon film changed from graphene to graphite. In addition, in order to compare the quality of the carbon film in terms of mechanical and electrical properties, carbon films treated under various conditions were closely analyzed using nano-indenter and a sheet resistance meter. Therefore, the optimal condition (1 Torr-50 sccm) was selected in which graphene was uniformly deposited and had the lowest electrical resistance (500 Ω/sq) and highest hardness (12 GPa).

The dual effects of digital inclusive finance on the urban-rural income gap: An empirical investigation in China's Yangtze River Delta region

The digital development of finance has positive implications for improving income inequality. As one of the mainstream research findings, the view that digital inclusive finance could alleviate the urban-rural income gap has been reaffirmed. Further empirical evidence reveals that digital inclusive finance bridges the urban-rural income gap by enhancing deposit behavior and promoting innovation activities. Compared with large population scale cities, the development of digital inclusive finance in small ones has a more significant reduction effect on the urban-rural income gap.

Crystallographically textured zinc nucleation and planar electrodeposition for zinc metal batteries via magnetoelectric and magnetization effects

The premature failure of zinc metal anodes is critically associated with the uncontrollable nucleation and random orientation of hexagonal Zn electrodeposits. Herein, we realize to control the crystallographical texture of zinc crystal nuclei and enable planar electrodeposition by simply applying a magnetic field. We unveil the novel mechanism of magnetoelectric and magnetization effects on the different deposition behavior under magnetic fields. The magnetohydrodynamic effect can flatten the uneven electrode surface during electrodeposition by deflecting the motion of Zn2+ ions. Especially, influences of the Hall effect on electrode polarization and magnetization effect on crystallographical Zn nucleation are first uncovered and validated. We demonstrate the proper use of these magnetic field-related effects is propitious to dense, homogeneous, and highly reversible deposition/dissolution of Zn metal anodes. The cycle lives of Zn anodes are extended 2–4 times at different currents and cycling capacities. Moreover, exceptional reversibility of 99.85 % is achieved. Full cells with a low N/P ratio of 5.4 and ultrahigh cathode mass loading of 19.98 mg cm−2 can release stable capacity up to 3.2 mAh cm−2. Our study provides new paradigms for magnetic field regulation of Zn metal battery electrochemistry, as well as for other external field applications in adjusting battery performance.

Regulating Preferred Crystal Plane with Modification of Exposed Grain Boundary Toward Stable Zn Anode

AbstractAqueous Zn metal batteries (ZMBs) are largely hampered by the poor stability of zinc (Zn) anode in aqueous electrolyte due to uncontrollable deposition behavior and parasitic reactions. Hence, a stable Glu@Zn anode via acid etching is developed that simultaneously exposes (002) plane and modifies exposed grain boundaries. The surface‐preferred (002) plane is achieved by minimizing its surface energy. And the exposed grain boundaries are also modified by decomposition products of acid etching, which can greatly reduce the adverse effects caused by highly active grain boundaries. These features favor Glu@Zn anode by accrediting a long‐term cycle lifespan exceeding 4400 h with a high average coulombic efficiency (CE) of 98.9%. Surprisingly, Glu@Zn anode can run for more than 250 h with 50% Zn utilization. The assembled Glu@Zn//NH4V4O10 full batteries deliver a specific capacity of 291.6 mAh g−1 after 400 cycles even at a low current density of 0.5 A g−1. It can also obtain a stable cycling performance up to 2000 cycles. To further verify its stability, a pouch cell is constructed that can preserve stable 400 cycles with 5 mAh. This study sheds light on surface energy regulation exposing preferred crystal plane to develop highly stable and reversible cycling aqueous ZMBs.

Pulse Charge Suppressing Dendrite Growth at Low Temperature by Rapidly Replenishing Lithium Ion on Anode Surface.

Dendrite growth of lithium (Li) metal anodes is considered as one of the most tough issues for Li metal batteries with a theoretically high energy density. This is attributed to the rapid exhaustion of Li ions at the electrode/electrolyte interface, which is even worse at low temperatures with poor diffusion kinetics of Li ions. Here, pulse charge with intermittent rest time during battery charging is proposed to handle the dendrite growth issue of Li metal anodes at low temperatures. The depleted Li ions near the interfaces can be rapidly replenished during the rest time, thus effectively suppressing the dendrites growth. Further investigation found that the large dendrites can be suppressed at the Li ion nucleation stage. The equivalent lifespan considering the rest time is proposed. At -10 °C, the lifespan of Li||Li batteries cycled under 3 mA cm-2 and 1 mAh cm-2 is increased from 24 h to equivalent 64 h. Li||LiNi0.5Co0.2Mn0.3O2 batteries with 80% capacity retention can be stably operated from 39 cycles to 56 cycles. This design presents an efficient and convenient strategy to regulate the deposition behaviors of Li metal anodes with a dendrite-free morphology.

Ion‐sieving MXene flakes with quantum dots enable high plating capacity for dendrite‐free Zn anodes

AbstractThe commercial utilization of Zn metal anodes with high plating capacity is significantly hindered by the uncontrolled growth of dendrites and associated side reactions. Herein, a robust artificial ion‐sieving MXene flake (MXF)‐coating layer, with abundant polar terminated groups, is constructed to regulate the interfacial Zn2+ deposition behavior. In particular, the fragmented MXF coupled with in situ generated quantum dots not only has strong Zn affinity to homogenize electric fields but also generates numerous zincophilic sites to reduce nucleation energy, thus securing a uniform dendrite‐free surface. Additionally, the porous coating layer with polar groups allows the downward diffusion of Zn2+ to achieve bottom‐up deposition and repels the excessive free water and anions to prevent parasitic reactions. The ion‐sieving effect of MXF is firmly verified in symmetric cells with high areal capacity of 10–40 mAh cm−2 (1.0 mA cm−2) and depth of discharge of 15%–60%. Therefore, the functional MXF‐coated anode manifests long‐term cycling with 2700 h of stable plating/stripping in Zn||Zn cell. Such rational design of MXF protective layer breaks new ground in developing high plating capacity zinc anodes for practical applications.

A multi-step discharge/charge model of Li[sbnd]O2 batteries coupled with electrolyte decomposition and carbon electrode corrosion reactions

Electrolyte decomposition and electrode corrosion stand as two primary side reactions in lithium‑oxygen (LiO2) batteries during their discharge/charge cycles. In this work, a comprehensive LiO2 battery model combining multi-step lithium peroxide (Li2O2) formation, electrolyte decomposition, and electrode corrosion is proposed. Based on this model, the deposition behaviors and cycling performance of the LiO2 battery under deep discharge/charge cycles are investigated. The stop of discharge is mainly ascribed to the loss of active surface area for the battery using tetraethylene glycol dimethyl ether (TEGDME) electrolyte, while both O2 transport limitation and active surface area loss lead to the discharge termination for battery using dimethyl sulfoxide (DMSO) electrolyte. The incomplete decomposition of Li2O2 and lithium carbonate (Li2CO3) clogs electrode pores, leading to a continuous decline in the discharge capacity of the LiO2 battery. For the TEGDME-based battery, the undecomposed Li2CO3 gradually dominates the deposition with cycles, wherein electrode corrosion becomes the primary source of the undecomposed Li2CO3 after 3 cycles. For the DMSO-based battery, undecomposed Li2O2 is always a dominant trigger for battery discharge capacity degradation, although electrode corrosion remains a key contributor to Li2CO3 generation. Despite the DMSO-based battery exhibiting lower rates of electrolyte decomposition and electrode corrosion, it demonstrates poorer cyclic performance than the TEGDME-based battery due to the generation of more toroidal Li2O2. Moreover, when the charging cut-off voltage is reduced to 4.2 V, discharge capacity diminishes more rapidly due to the increased accumulation of undecomposed Li2O2, despite suppressed Li2CO3 deposition. Finally, the results confirm that thick electrodes lead to deteriorating cycling performance, stemming from increased discharge/charge overpotential and extended discharge/charge times, thus intensifying the side reactions.

Highly reversible Zn anode by guiding uniform Zn deposition through LiF protective layer

Deep-seated issues such as ineluctable dendrite deposition and parasitic reaction of Zn anode pose a major obstacle to the commercialization of aqueous zinc ion batteries (AZIBs). Herein, we proposed LiF as a solid-electrolyte interphase for highly reversible Zn anode. Combining experimental analyses and theoretical simulation calculations, the electronegative fluorine atoms could provide uniform zincophilic nucleation sites to regulate Zn deposition behavior. Additionally, a ZnF2 layer with outstanding Zn2+ conductive can be formed insitu thus further shielding bulk water molecules and expediting the Zn2+ transfer kinetics. Therefore, the LiF@Zn symmetric cells manifest long-cycling stability with 650 h at 1.0 mA/cm2 and 1.0 mAh/cm2 and 1000 h at 2.0 mA/cm2 and 1.0 mAh/cm2. Meanwhile, the rate performance of Zn//MnO2 and Zn//NH4V4O10 full cells are also enhanced by the LiF coating. This work provides a horizon for the design of artificial protective layer and promotes the large-scale practical development of AZIBs.