Homogeneous Deposition Research Articles

Interfacial Engineering with a Conjugated Conductive Polymer for a Highly Reversible Zn Anode.

For Zn metal batteries, the Zn anode faces several challenges, including Zn dendrites, hydrogen evolution, and corrosion. These issues are closely related to the Zn deposition process at the electrode/electrolyte interface. Herein, we propose interfacial engineering to protect the Zn anode and induce homogeneous deposition using conjugated cyclized polyacrylonitrile (cPAN) polymer nanofibers. It works as a hydrophobic protective layer that inhibits contact with H2O molecules, thus reducing side reactions and enhancing the anticorrosion property. Also, with abundant zincophilic sites on cPAN nanofibers via coordination chemistry, Zn2+ ion transport is promoted and homogeneous dendrite-free Zn deposition is obtained. As a result, the cPAN-coated Zn (cPAN@Zn) anode demonstrates high coulombic efficiency of over 99.9%, high cycling stability of over 2000 h at 1 mA cm-2, long cycling of over 16 000 cycles at 10 mA cm-2, and excellent kinetics with a low overpotential below 0.15 V at 50 mA cm-2. This work provides novel insights into organic interfacial engineering via conjugated polymers in aqueous rechargeable Zn energy storage systems.

High Specific Activity during Electrochemical CO2 Reduction through Homogeneous Deposition of Gold Nanoparticles on Gas Diffusion Electrodes

High Specific Activity during Electrochemical CO₂ Reduction through Homogeneous Deposition of Gold Nanoparticles on Gas Diffusion Electrodes

Hydrogel Electrolyte-Mediated In Situ Zn-Anode Modification and the Ru-RuO2/NGr-Coated Cathode for High-Performance Solid-State Rechargeable Zn-Air Batteries.

This work aims to deal with the challenges associated with designing complementary bifunctional electrocatalysts and a separator/membrane that enables rechargeable zinc-air batteries (RZABs) with nearly solid-state operability. This solid-state RZAB was accomplished by integrating a bifunctional electrocatalyst based on Ru-RuO2 interface nanoparticles supported on nitrogen-doped (N-doped) graphene (Ru-RuO2/NGr) and a dual-doped poly(acrylic acid) hydrogel (d-PAA) electrolyte soaked in KOH with sodium stannate additive. The catalyst shows enhanced activity and stability toward the two oxygen reactions, i.e., oxygen reduction and evolution reactions (ORR and OER), with a very low potential difference (ΔE) of 0.64 V. The computational insights bring out the electronic factors contributing to the enhanced catalytic activity of Ru-RuO2/NGr based on the charge density difference (CDD) between the interfaces. The disadvantages of the existing solid-state RZABs, such as their limited lifespan brought on by passivation, dendritic growth, corrosion, and shape change, have also been taken into account. The introduction of the stannate additive to the electrolyte induced an in situ Zn-anode modification, which subsequently improved the interfacial stability of the ZABs and, hence, the battery life cycles. The experimental observations reveal that, during the charging process, the Sn nanoparticles enable the homogeneous Zn deposition on the surface of the anode. Thus, the in situ Zn-anode surface modification assisted in achieving a high-rate cycle capability, viz., the homemade catalyst-based system exhibited continuous charge-discharge cycles for 20 h at a current density of 2.0 mA cm-2, with each cycle lasting for 5 min.

Lithium directed growth triggered by vertical interface activity gradient framework enabling long-life Li metal anode

Three-dimension (3D) current collector with interior porous structure and large specific surface area can suppress the volume change of lithium (Li) metal anode and reduce the local current density, which is beneficial for uniform deposition of Li. However, the low Li affinity and instability of Li+ transport allow Li metal to easily deposit on the top of the 3D current collector, accelerating the growth of Li dendrites. Herein, a 3D current collector with a stable Li+ transport channel and a vertical interfacial activity gradient is proposed, realizing a long-life Li metal battery. The density functional theory (DFT) and experimental results demonstrate that the vertically Cu nanoarray has a low Li+ migration barrier, while the ZnO nanocrystalline at the bottom of the 3D current collector has a high Li affinity. The synergistic action of the vertically Cu nanoarray and ZnO nanocrystalline results in the directed Li metal homogeneous deposition. Furthermore, the Li2O artificial protective layer formed by the interaction of ZnO with Li metal also promotes the transport of Li+ into the inner current collector. Hence, the Li directed homogeneous deposition realizes a long cycle life Li metal anode for more than 4000 h of the symmetrical cell at 2.0 mA cm−2 current density and 1.0 mA h cm−2 plating/stripping capacity, as well as more than 500 cycles with 98.8 % coulombic efficiency of the half cell at 1.0 mA cm−2 current density and 1.0 mA h cm−2 capacity. This work provides a feasible vertical activity gradient directionally guided Li deposition strategy for realizing long cycle life Li metal batteries.

A lithiophilic interphase enabled by thiophenol additive for stable lithium metal anode

Lithium metal is regarded as a highly promising anode material owing to its ultrahigh theoretical capacity and low electrode potential. Unfortunately, significant concerns including poor Coulombic efficiency (CE) and uncontrolled Li dendritic growth severely hinder its development. Constructing a stable solid electrolyte interphase (SEI) on the electrode surface has been considered a practical and effective approach to settle the previous issues. In this study, 4-(trifluoromethyl)thiophenol (TFTP), an organic thiophenol, is introduced as an electrolyte additive to generate a lithiophilic organosulfur interphase with lithiophilic S sites through in situ reaction, guiding uniform Li nucleation and Li plating. Additionally, the generation of LiF/Li3N-rich layer during the cycling further facilitates homogeneous Li deposition. Therefore, the reliable SEI results in a uniform Li morphology and rapid kinetic of Li deposition. Benefiting from the TFTP electrolyte, the Li–Li symmetric cell exhibits a long-lasting lifespan of 1200 hours, and the full cell coupling with sulfur cathode shows a remarkable discharge capacity of 733.6 mAh g−1 after 200 cycles.

Constructing a Li2O/LiZn Mixed Ionic Electron Conductive Layer by Ultrasonic Spraying to Enhance Li/Garnet Solid Electrolyte Interface Stability for Solid-State Batteries.

Garnet-type Li6.25Ga0.25La3Zr2O12(LGLZO) is believed to be a promising solid electrolyte for solid-state batteries due to its high ionic conductivity, safety, and good stability toward Li. However, one of the most challenges in practical application of LGLZO is the poor contact between Li and LGLZO. Herein, a ZnO layer is prepared on the surface of LGLZO pellet by ultrasonic spraying. Then, a Li2O/LiZn mixed ionic and electron conductive (MIEC) layer is formed at the Li/LGLZO interface via the conversion reaction between ZnO and molten Li. Experiments and theoretical calculations reveal that this MIEC layer can simultaneously improve interface contact, optimize interfacial kinetics, and guide homogeneous Li deposition. As a result, the interface impedance decreases significantly to 36 Ω cm2, the critical current density (CCD) can reach as high as 2.15 mA cm-2, and the Li/ZnO@LGLZO/LiFePO4 all-solid-state cells stably cycle 100 times at 0.5 C. This simple and effective approach may provide a viable strategy for improving the cycle performance of solid lithium metal batteries.

Alkaline etching assisted polydopamine coating for enhanced cell–material interactions on 3D printed polylactic acid scaffolds

The implant surface chemistry and topography are primary factors regulating the success and survival of bone scaffold. Surface modification is a promising alternative to enhance the biocompatibility and tissue response to augment the osteogenic functionalities of polyesters like PLA. The study employed the synergistic effect of alkaline hydrolysis and polydopamine (PDA) functionalization to enhance the cell–material interactions on 3D printed polylactic acid (PLA) scaffold. Comprehensive characterization of the modified PLA highlights the improvements in the physical, chemical and cell–material interactions upon two-step surface modification. The X-ray photoelectron spectroscopy (XPS) analysis substantiated enhanced PDA deposition with a ∼8.2% increase in surface N composition after surface etching due to homogeneous PDA deposition compared to the non-etched counterpart. The changes in surface chemistry and morphology upon dual surface modification complemented the human osteoblast (HOS) attachment and proliferation, with distinct cell morphology and spreading on PDA coated etched PLA (Et-PLAPDA) scaffolds. Moreover, substantial improvement in osteogenic differentiation of UMR-106 cells on etched PLA (Et-PLA) and Et-PLAPDA highlights the suitability of alkali etching-mediated PDA deposition to improve mineralization on PLA. Overall, the present work opens insights to modify scaffold surface composition, topography, hydrophilicity and roughness to regulate local cell adhesion to improve the osteogenic potential of PLA.

Ion flux regulating with Au-modified separator to realize a homogenize Zn metal deposition.

Aqueous Zn-ion batteries (AZIBs) have attracted widespread attention owing to the feature of low cost, inherent safety and eco-friendliness. However, the poor reversibility of Zn anode severely hinders the practical applicability of AZIBs. Separator modification is an effective way to functionalize the electrode/electrolyte interface and improve the cycling performance. Here, we propose a modified glass fiber separator with Au coating (Au@GF), which could realize uniform Zn2+ distribution at the electrode/electrolyte interface and regulate the plating/stripping behaviors, achieving a dense and homogenous deposition. Zn||Zn symmetric cells assembled with Au@GF separator demonstrate evidently prolonged cycle life over 1600h at the current density of 5mAcm-2 and the capacity of 1mAhcm-2, while symmetric cells with GF fail in less than 40h. Even at the condition of 15mAcm-2/3mAhcm-2, lifespan of Zn||Zn cells with Au@GF is extended to 750h, which is more than 3 times compared with that of GF. The modified separator with highly conductive coating is capable of a longtime stable Zn plating/stripping. Moreover, an enhanced cycling performance is also detected in a series of full cells with different cathode materials. This work provides an easy and efficient approach to homogenize Zn2+ deposition.

Three-dimensional Zn foam coated with zeolitic imidazolate frameworks as stable zinc-ion battery anode

Zinc-ion batteries (ZIBs) offer several advantages including low cost, safety, and high volumetric capacity. However, the potential of ZIBs is hindered by dendrite Zn growth, by-products, and hydrogen evolution resulting in poor lifespan. Herein, this study adopts three-dimensional Zn foams coated with zeolitic imidazolate framework (ZIF) as an anode for ZIBs for the first time. NaCl is selected as a spacer and mixed with Zn powder to vary the pore and strut size of Zn foams. The optimal condition for ZIF coating is investigated taking into account corrosion and electrical resistance as well as hydrogen evolution. The ZIF layer leads to the homogeneous Zn deposition and suppresses the hydrogen evolution and the by-product formation of zinc hydroxide sulfate. A Zn foam with a spacer size of >300 μm, which shows the most stable behavior during stripping/plating tests in a beaker cell, is also employed in symmetric coin-cell tests. Its excellent lifespan characteristic is demonstrated at 1 and 3 mA/cm2 for 1-h intervals over a duration of 300 h. Furthermore, ZIF-coated Zn foam and MnO2-filled Ti foam are assembled in full cells to evaluate the ZIB performance. The full cells show a capacity retention of 75.7 % over 100 cycles, demonstrating the potential of ZIF-coated Zn foam as a ZIB anode. This work provides a solution to practical anodes for ZIBs by maximizing the inherent structural advantages of Zn foam with the adequate coating of ZIF.

Ordered and Expanded Li Ion Channels for Dendrite‐Free and Fast Kinetics Lithium–Sulfur Battery

AbstractThe uncontrolled polysulfide shuttling and lithium dendrite growth greatly impede the practical implementation of Li–S batteries. These issues can be alleviated by constructing an artificial layer that immobilizes soluble polysulfides and regulates Li+ flux. Here, a layer‐expanded lithium montmorillonite is fabricated through molecular intercalation to serve as a dual regulator for Li–S batteries. The lithiophilic montmorillonite, with its ordered and expanded Li+ diffusion channels, exhibits a high transference number, and promotes homogeneous Li deposition. Additionally, its moderate adsorption of polysulfides, combined with favorable Li diffusion behavior, enhanced the redox kinetics of sulfur species. This unique structure enables a prolonged lifespan of 1000 cycles at 0.5C with a low capacity decay of 0.04% per cycle for practical Li–S batteries.

Zincophilic SnS2 protective layer for homogeneous deposition towards dendrite-free aqueous Zn metal batteries

As one of the most promising candidates for grid-scale energy storage, aqueous Zn metal batteries (AZMBs) have attracted extensive attention owing to their high theoretical capacity, high safety, low voltage, and environmental benign. However, Zn metal continuously suffers the corrosion and dendrites issue during cycling owing to uneven deposition. Herein, we proposed a facile deposition strategy, achieving a continuous deposition process from moderately heterogeneous phase evolution to smoothly homogeneous deposition, realizing a dendrites-free anode for AZMBs. The flower-like SnS2 structure provides nucleation assistance by enlarging the active area and guiding zinc ion flux through its favorable affinity for zinc. Meanwhile, the SnS2 layer also inhibits the HER and corrosion serving as a protective layer. The symmetrical cell with the modified Zn metal anode realizes a stable and prolonged lifespan of 1,000 h under a current density of 5 mA/cm2. This study presents an innovative approach to zinc ion storage materials, realizing guiding zinc ion flux, assisting nucleation processes, and providing corrosion inhibition.

Verifying the Effect of Organic Additives in Aqueous Zinc Batteries Via Operando Imaging Technology

Aqueous zinc batteries (AZBs) have emerged as an alternative of lithium-ion batteries (LIBs) due to their potential for high energy density, safety, and cost-effectiveness. However, the long-term stability of zinc metal anode has been hindered by hydrogen evolution reaction (HER), dendrite growth, and byproduct formation (Zn4(OH)6SO4·xH2O, zinc basic sulfate). To stabilize the zinc metal anode, various strategies such as surface coating and electrolyte design have been studied. In particular, electrolyte additives are regarded as practical strategies owing to low cost and simple methods.To improve the stability of zinc metal anode, organic additive was introduced. During the plating/stripping process, the enormous dendrites were observed in blank electrolyte via side-view operando X-ray imaging. Furthermore, a number of H2 bubbles were generated at the electrode surface. On the contrary, when the organic additive was added into electrolyte, the smooth surface with homogeneous deposition was confirmed and the formation of hydrogen gas was rarely observed. In addition, the uniform Zn deposition with organic additive was also verified through top-view operando optical imaging, whereas the black spots were formed on the surface without the additive, which represent the Zn dendrite formation. Based on the superior stability, the Zn||Cu half-cell with the organic additive maintained the steady voltage profile over 1600 h at 1 mA cm-2, while the short circuit occurred after 100 h without the additive. Figure 1

Enhanced Durability of Zn-Metal Anodes through in-Situ Bi-Layer Coating with Metal Fluoride and Polymer

Aqueous Zn metal batteries (AZBs) have garnered considerable attention in the quest for safer, more sustainable energy storage solutions, primarily due to their inherent non-flammability and cost-effectiveness. However, the commercial deployment of AZBs has been hindered by two major challenges: the growth of Zn dendrites and the parasitic hydrogen evolution reaction (HER) at the Zn metal anodes (ZMAs). These phenomena compromise battery safety and efficiency, thereby limiting their practical applications. To address these issues, this study introduces a novel bi-layered Zn protective layer (BSPL@Zn), fabricated through a one-step in-situ coating process. This protection strategy employs a polyvinyl(alcohol), hydrophilic polymeric outer layer coupled with a zincophilic, Ag-decorated inner layer (Ag0/ZnF2), created by an in-situ displacement reaction facilitated by a silver fluoride (AgF) additive.The innovative aspect of BSPL@Zn lies in its dual functionality. The Ag-decorated inner layer is specifically engineered to be zincophilic, promoting homogeneous Zn deposition, while the hydrophilic polymer outer layer effectively suppresses the HER. This configuration not only mitigates the formation of dendritic structures but also significantly reduces the rate of hydrogen gas evolution—a common issue that exacerbates anode degradation and battery failure. Experimental results demonstrate that the BSPL@Zn successfully extends the short-circuiting time of the batteries, achieving a three-fold reduction in H2 gas evolution compared to conventional ZMA systems.Further evaluations in Zn||Zn symmetric cells reveal that BSPL@Zn enables robust cycling performance, sustaining over 1800 hours at a Zn plating capacity of 5 mAh cm−2. When implemented in Zn||NH4V4O10 cells, BSPL@Zn maintains stable battery operation across 1000 cycles with an impressive 80% capacity retention. These findings underscore the effectiveness of the bi-layer approach in enhancing the durability and operational stability of AZBs.This study not only elucidates the mechanisms by which BSPL@Zn enhances the performance and safety of AZBs but also highlights the importance of material selection and strategic design in anode protection. By integrating zincophilic and hydrophilic properties within a single protective structure, this work paves the way for future advancements in battery technology. The development of such tailored protective coatings could significantly propel the commercial viability of AZBs, promoting their wider adoption in various applications demanding high safety and efficiency standards.

Surface Modification Strategies for Improved Electrochemical Performance and Long-Term Cyclability in Aqueous Zinc-Ion Batteries

Although aqueous zinc ion batteries are promising for grid-scale energy storage because of their low cost, safety, and high capacity, they are still limited by poor reversibility and a short cycle lifetime. The main causes of these problems are the spontaneous side reactions and the inhomogeneous deposition/dissolution behavior of the zinc electrode. In this study, we address these limitations by mitigating the inhomogeneous surface reactions of the zinc electrode, a key factor in achieving long-term cycling stability. By employing appropriate surface modification techniques to eliminate the intrinsic passivation layer and reduce surface roughness, we enable uniform electrochemical reactions on the electrode surface, resulting in homogeneous zinc deposition, accelerated electrochemical kinetics, and enhanced cycling performance. Two distinct surface modification strategies were utilized: chemical treatment and mechanical polishing. The chemical treatment entailed the application of acidic, neutral, or alkaline solutions to the zinc electrode, effectively removing the organic passivation layer, improving electrolyte wettability, rate capability, and enabling uniform zinc deposition. Mechanical polishing not only removed the passivation layer but also smoothed the rough surface of the zinc electrode, reducing local charge concentrations and further promoting uniform deposition, which enhanced long-term stability. Our research indicates that simple surface modification methods can significantly improve the electrochemical performance of zinc electrodes. These strategies may be applicable to other types of energy storage systems using metal foil-based electrode, including lithium, magnesium, and aluminum batteries, as well as zinc-ion batteries.

Controlling SnOx Stoichiometry via ALD Deposition on Cu Current Collectors: Investigating Stability and Reversibility Enhancement in Lithium Metal Batteries

Recent advancements in battery technology have led to the emergence of various types of secondary batteries with higher capacities to meet increasing demands. Among these, research on Lithium metal batteries (LMBs) with high capacity potential is actively pursued. However, LMBs face stability issues due to dendrite formation and low reversibility in Li plating-stripping processes. To address these challenges, we have modified the surface of Cu current collectors with lithiatable material, SnOx, to inhibit dendrite formation, enhance the stability and reversibility of LMBs. Furthermore, SnOx films reduce the overpotential of Li and enable stable Solid Electrolyte Interphase (SEI) formation. Therefore, they enhance the reversibility of Li plating/stripping processes. SnOx films were deposited via Thermal Atomic Layer Deposition (ALD) at 200°C with a thickness of 20nm. We have already reported the effectiveness of SnOx in enhancing the efficiency and stability of LMBs.[1] Therefore, in this study, we conducted research on the variation in characteristics of LMBs resulting from the control of stoichiometry in this lithiatable SnOx. Stoichiometry was adjusted through two methods. One method involved post-deposition heat treatment, where treatments were conducted at 400°C for one hour under H2 (H2 4%, Ar 96% gas) and N2 atmospheres. Additionally, we adjusted the injection time of H2O, the reactant in ALD, varying it from 1 to 3sec to create an oxygen deficient environment, and analyzed each characteristic accordingly. We will present our findings on the effect of SnOx stoichiometry on the performance and stability of LMBs.[1] Kim, Junghwan, et al. "Homogeneous Li Deposition guided by Ultra-thin Lithiophilic Layer for Highly Stable Anode-free Batteries." Energy Storage Materials (2023): 102899. Figure 1

Carbon Nanomaterial Enabled Ultra High Conductivity Cu Composites for Advanced Conductors

Growing demand for electrical energy and increasing need for high power grid systems necessitates development of new conductors for enhanced electrical and thermal conductivity. The power losses associated with the electrical resistance of Cu adversely impact the efficiency and performance of all electric devices. Ballistic electrical transport in carbon nanotubes (CNTs) is expected to improve the conductivity of the Cu matrix with additional CNT-enabled benefits that can enable low-weight, flexibility, and better thermal management. By using scalable, cost-effective, and commercially viable processing methods, we demonstrate a novel technological platform to produce high-performance conductors that incorporates CNTs into the Cu matrix ― ultra-conductive metal composites (UCC), which promise significant technological and economic impact in all energy sectors, ranging from electrical vehicles to power grid. Our approach, which combines materials synthesis, characterization, and first-principles modeling, enables an efficient and systematic exploration of the multidimensional complex materials parameter space of Cu-CNT composites with dopants and identifies the key individual structural and interfacial components that govern the electronic transport properties of the UCC composites. Our experimental technology platform is concentrated on Cu tapes and involves processes from production of stable CNT dispersions, electrospinning techniques to deposit shear induced aligned CNT coatings along the direction of the current flow, post thermal treatment procedures, and homogeneous deposition of metal overlayers onto CNT coated tapes. Here, we demonstrate that the prototype UCC composites exhibit improved electrical conductivity (by > 5%), higher current carrying capacity (> 10%), and higher mechanical strength (> 10%) than the reference pure Cu counterparts.

Microbial mats writing the fossil record of true substrates in clastic rock successions

True substrates are bedding surfaces that represent the original environmental surfaces that existed at the time of burial. In the clastic depositional regime, there are abiotic and biotic causes that may contribute to the formation of such true substrates. This paper focuses on how sediment-stabilizing microbial mats may increase the preservation potential of true substrates. Baffling and trapping enrich fine-grained particles and heavy minerals in mat textures inducing a layer of heterogeneity in the otherwise homogenous deposits. Together with in situ mineral precipitation during the life time of the microbial mat and post-depositional diagenesis, baffling and trapping contributes to processes leading to bedding plane preservation. Microbial mats interact with the hydrological system of a coastal environment causing typical microbially induced sedimentary structures (MISS). The morphologies of MISS can indicate climate seasonality and zone of the respective true substrate. The interaction of animals and plants with microbial mats allow reconstructing events that took place during the exposure of the original environmental surface. Finally, true substrates displaying MISS are well-defined indicators for life exploration of Earth's oldest sedimentary rock successions and equivalent lithologies on other planets.

Influence of flow discharge and minibasin shape on the flow behavior and depositional mechanics of ponded turbidity currents

The interplay between seafloor sediment-laden density-driven flows, turbidity currents, and topography helps to shape continental margins. However, these interactions are poorly understood, especially those within enclosed depressions termed minibasins. In this study, novel experiments quantify the three-dimensional (3-D) dynamics of turbidity currents interacting with a range of minibasin geometries that, for the first time, scale within the parameter space of natural systems. Controls on flow dynamics are quantified by measuring the evolving velocity and sediment transport fields, in addition to maps of bathymetry. This study focuses on three aspects of turbidity current interactions with minibasins. First, the results suggest that sediment transport and deposition in minibasins is likely dominated by evolving flow conditions. Contrary to earlier studies in two-dimensional (2-D) flumes, this study supports a time-to-flow equilibrium in minibasins that scales with the time to replace ambient fluid with turbid influx, and this replacement time likely takes days to achieve in many field-scale minibasins. Second, in all experiments, horizontal flow circulation is observed, which is critical for distributing sediment throughout minibasins. However, the strength of the horizontal circulation reduces as the ratio of minibasin length to width increases, which leads to stagnant or even upstream-directed flow near the bed, elevated height of the velocity maximum in flows, the lowering of near-bed shear stresses, and more homogeneous deposits through a reduction in bed reworking. Finally, the results indicate that fluid detrainment from minibasins significantly reduces sediment fall velocities, severely lowering the sediment-trapping efficiency for small or light particles. This reduction in effective fall velocities of sediments suggests a mechanism that fractionates fine particulates (e.g., clays), nutrients (e.g., organic carbon), and pollutants (e.g., microplastics) along transport paths down topographically complex margins.

Dendrite‐Free Zinc Anode for Zinc‐Based Batteries by Pre‐Deposition of a Cu–Zn Alloy Layer on Copper Surface via an In Situ Electrochemical Oxidation–Reduction Reaction

ABSTRACTThe prevention of uncontrollable growth of zinc dendrites on the zinc electrodes is one of the key challenges, hindering the widespread commercialization of zinc‐based energy storage technologies. Herein, we report a facile method to mitigate dendrite growth on a copper surface by an initial in situ coating of a Cu–Zn alloy layer, before zinc deposition. During further zinc deposition, the initially formed Cu–Zn alloy layer provides uniform nucleating sites and promotes homogeneous zinc deposition. A symmetrical cell, assembled using a Cu–Zn/Cu electrode could be stably cycled for over 1000 cycles in ZnSO4 solution, at a current density of 30 mA/cm2 and a coulombic efficiency of 99.9%. A zinc–air cell, assembled using Zn@Cu–Zn/Cu as the anode and rGO/Co3O4 composite as the cathode, exhibited a very stable performance at a high current density of 50 mA/cm2 and coulombic efficiency of ~93%, for over 400 cycles. After cycling experiments, the X‐ray photoelectron spectroscopy and the X‐ray diffraction analysis confirmed the formation of the Cu–Zn alloy layer. Hence, the present method provides an easy route for fabricating a dendrite‐free zinc electrode, for a wide range of zinc anode‐based batteries.

High-viscoelasticity alginate-based coatings for reversible zinc metal anodes

High-safety aqueous zinc (Zn) ion batteries are troubled by dendrite growth and hydrogen evolution reaction on Zn anode, which can be well solved via the construction of surface protective layer. The recent researches mainly focus on the bulk property of the protective layer, but its separation from Zn anode is ignored. In this work, high-viscoelasticity alginate-based (HVAA) layer was in-situ constructed on Zn anodes by the cross-linking of sodium alginate with formaldehyde and the plastifying of glycerin. HVAA layer can combine with H2O and coordinate with Zn2+ ions in aqueous electrolyte to achieve viscoelasticity on Zn anode, which can accommodate volume change of Zn anode during plating/stripping processes to continuously protect Zn anodes under the real battery system. Physical block effect of HVAA layer impedes hydrogen evolution corrosion reaction by avoiding the immediate contact of Zn anodes with aqueous electrolyte. Ionic conductive ability of HVAA layer by coordinating oxygen-containing groups with Zn2+ can uniform ion flux to induce the homogeneous deposition of Zn2+ on Zn anode. Zn anode with HVAA endows ZnZn symmetric battery with stably cycle of 4000 h and Zn-iodide full batteries with better electrochemical performance of 8000 cycles comparing with bare Zn anode. This work opens a novel route to continuously protect Zn anode through the high-viscoelasticity films to closely fit with Zn surface and implement the high-value application of renewable sources.