Formation Of Zinc Dendrites Research Articles

Recent progress in structural modification of polymer gel electrolytes for use in solid-state zinc-ion batteries.

Zinc-ion batteries are one of the promising energy storage devices, which have the advantages of environmental friendliness, high safety and low price and are expected to be used in large-scale battery application fields. However, four prominent water-induced adverse reactions, including zinc dendrite formation, zinc corrosion, passivation and the hydrogen evolution reaction in aqueous systems, seriously shorten the cycling life of zinc-ion batteries and greatly hinder their development. Based on this, polymer gel electrolytes have been developed to alleviate these issues due to their unique network structure, which can reduce water activity and suppress water-induced side reactions. Based on the challenges of polymer gel electrolytes, this review systematically summarizes the latest research progress in the use of additives in them and explores new perspectives in response to the existing problems with polymer electrolytes. In order to expand the performance of polymer gel electrolytes in zinc-ion batteries, a range of different types of additives are added via physical/chemical crosslinking, such as organic or inorganic substances, natural plants, etc. In addition, different types of additives and polymerization crosslinking from different angles essentially improve the ionic conductivity of the gel electrolyte, inhibit the growth of zinc dendrites, and reduce hydrogen evolution and oxygen-absorbed corrosion. After these modifications of polymer gel electrolytes, a more stable and superior electrochemical performance of zinc-ion batteries can be obtained, which provides some strategies for solid-state zinc-ion batteries.

An advanced Ca/Zn hybrid battery enabled by the dendrite-free zinc anode and a reversible calcification/decalcification NASICON cathode

The proposal of hybrid ion batteries, which can integrate the advantages of the single ion battery, opens up a new route for developing high-performance secondary batteries. Herein, we successfully constructed an aqueous hybrid battery comprised of polyanionic-type cathode material (Na3V2(PO4)3, NVP), Zn metal anode, and aqueous Ca2+/Zn2+ hybrid electrolyte. This exciting combination gives full play to not only the excellent diffusion dynamics of Ca2+ in the NASICON (sodium super ion conductors) structure but also the electrostatic shielding effect of Ca2+ with low reduction potential that inhibits the formation of zinc dendrites. As results, the NVP//Zn Zn/Ca hybrid battery delivers favorable specific capacity with outstanding rate performance (85.3 mAh g−1 capacity at 1 C, 60.5 mAh g−1 capacity at 20 C), and excellent cycle stability (74 % capacity retention after 1300 cycles).

Functionalized Nanocomposite Gel Polymer Electrolyte with Strong Alkaline-Tolerance and High Zinc Anode Stability for Ultralong-Life Flexible Zinc-Air Batteries.

Increasing pursuit of next-generation wearable electronics has put forward the demand of reliable energy devices with high flexibility, durability, and enhanced electrochemical performances. Flexible aqueous zinc-air batteries (FAZABs) have attracted great interests owing to the high energy density, safety, and environmental benignity, for which quasi-solid-state gel polymer electrolytes (QSGPEs) are state-of-the-art electrolytes with high ionic conductivity, flexibility, and resistance to leakage problems of traditional liquid electrolytes. Compared to commonly used PVA-KOH electrolyte with poor electrolyte retention capability and cycling stability, a new type of sulfonate functionalized nanocomposite QSGPE is applied in FAZABs with high ionic conductivity, strong alkaline tolerance, and high zinc anode stability. Notably, the existence of (1) strong anionic sulfonate groups of QSGPEs, contributing to the exposure of preferred Zn (002) plane that is more resistant to zinc dendrite formation, and (2) nano-attapulgite electrolyte additives, beneficial for the enhancement of ionic conductivity, electrolyte uptake, and retention capability, endows a ultralong cycling life of 450h for the fabricated FAZAB. Furthermore, flexible energy belts and knittable energy wires fabricated with a series/parallel unit of several FAZABs can be used to power various wearable electronics.

High Zinc Utilization Aqueous Zinc Ion Batteries Enabled by 3D Printed Graphene Arrays

The commercialization of aqueous zinc ion batteries requires good reversibility and high zinc utilization of zinc anode. For commonly applied 2D zinc anodes (zinc foils), their electrochemical performance and reversibility are often negatively correlated with the zinc utilization owing to the formation of zinc dendrites at the electrode-separator interphase. To overcome the disadvantages of 2D geometric design of zinc anode, this work fabricated two types of 3D printing graphene arrays (3DGs), tube arrays and pilar arrays, to simultaneously improve the reversibility and utilization of zinc anodes. The highly ordered 3D printed tubes/pillars array structures can accommodate the significant volume change during the zinc reversibly deposition/dissolution process and modify the zinc deposition on 3DGs. The array structures can also buffer the interaction between the metallic zinc and separator to protect AZIBs from short circuits. Consequently, the 3DGs showed considerable columbic efficiencies at current densities of 10–80 mA cm−2. The 3DGs@Zn anode delivered a lifespan of 1100 h in zinc symmetric cell at 2 mA cm−2 (1 mAh cm−2). The pouch cells fabricated with 3DGs@Zn anodes and V2O5 cathode delivered areal capacity (3.76 mAh cm−2) and zinc utilization (47.12%) under a practical N/P ratio (1.74:1). This work will overcome the limitations of the 2D geometric design of anodes for next-generation battery technologies.

Multifunctional hybrid interface enables controllable zinc deposition for aqueous Zn-ion batteries

Aqueous Zn-ion batteries have gradually become a suitable choice for large-scale energy storage systems owing to their safety and lower cost. However, Zn metal anodes typically suffer from uneven electrodeposition and zinc dendrite formation, which restricts Zn-ion batteries from being used in further applications. To mitigate this problem, a simple and quick chemical surface modification is employed to construct a multifunctional hybrid interface consisting of ZnF2 and Sn on the surface of the Zn metal anode. ZnF2 show a low diffusion energy barrier for Zn2+, effectively shield the direct corrosive reaction from the aqueous electrolyte, and simultaneously increase the hydrogen evolution potential of the Zn electrode. Furthermore, the Sn particles provide a large number of nucleation sites and charge centers, avoiding the direct growth of dendrites. The interface-modified Zn anode achieve stable cycles of 700 h and 500 h at high current densities of 5 and 10 mA/cm2, respectively, while the assembled Zn@ZnF2–Sn||V2O5 full battery achieve over 400 stable cycles at 1 A/g. This work uncover the internal mechanism of inhibiting Zn dendrites by the multifunctional interface, providing a means for stabilizing the Zn anode under practical conditions.

Toward Dendrite-Free Deposition in Zinc-Based Flow Batteries: Status and Prospects

Safe and low-cost zinc-based flow batteries offer great promise for grid-scale energy storage, which is the key to the widespread adoption of renewable energies. However, advancement in this technology is considerably hindered by the notorious zinc dendrite formation that results in low Coulombic efficiencies, fast capacity decay, and even short circuits. In this review, we first discuss the fundamental mechanisms of zinc dendrite formation and identify the key factors affecting zinc deposition. Then, strategies to regulate zinc deposition are clarified and discussed based on electrode, electrolyte, and membrane. The underlying mechanisms, advantages, and shortcomings of each strategy are elaborated. Finally, the remaining challenges and perspectives of zinc-based flow batteries are presented. The review may provide promising directions for the development of dendrite-free zinc-based flow batteries.

Bi-functional inhibitors of zinc corrosion and dendrite formation in aqueous electrolyte: Insights from experiments and theoretical calculations

An organic compound 1-butyl-3-methylimidazolium phosphate dibutyl ester salt (BD) is studied for the first time to effectively inhibit zinc corrosion and the formation of zinc dendrites. Through SEM, AFM, XPS, FTIR, XRD, theoretical calculation, and electrochemical corrosion measurements, the inhibition mechanism of BD on zinc is investigated in 2 M ZnSO4. The maximum anti-corrosion efficiency is over 91% in 2.5 mM BD. Besides, BD can also inhibit the formation of zinc dendrites during galvanostatic cycling tests. The corrosion inhibitor BD endows the symmetric zinc-ion battery with a service life of 1000 h at 8 mA cm−2 for 5 mAh cm−2.

Cellulose-Acetate Coating by Integrating Ester Group with Zinc Salt for Dendrite-Free Zn Metal Anodes.

Zinc (Zn) metal is considered a potential anode owing to its high theoretical capacity, safety, and low cost. However, the dendrites and corresponding side reactions in aqueous electrolytes hinder their further development in environmentally-friendly energy storage. Herein, ion-affiliative cellulose acetate (CA) coating with Zn(CF3 SO3 )2 is constructed on Zn anode (CAZ@Zn). Owing to the complexation effect between the polar ester group (CO) and Zn salt (Zn2+ ), the CAZ polymer coating enhances the hydrophilicity of the Zn anode and reduces the interfacial resistance, allowing the rapid Zn2+ diffusion and homogenizing the Zn deposition in an aqueous electrolyte to suppress zinc dendrite formation and growth. Therefore, the symmetric CAZ@Zn//CAZ@Zn battery achieves reversible plating/stripping over 2800 h at 1mA cm-2 with 1 mAh cm-2 , about sevenfold higher than bare Zn. The full cell fabricated with an optimized Zn anode and the NH4 V4 O10 cathode achieves substantially stable performance, superior to that of bare Zn. This work provides a straightforward, effective, and scalable method to suppress the zinc dendrites and corresponding side reactions for aqueous Zn-ions batteries.

Rechargeable Manganese Dioxide−Zinc Batteries: A Review Focusing on Challenges and Optimization Strategies under Alkaline and Mild Acidic Electrolyte Media

AbstractHerein, we have reviewed the recent developments of rechargeable manganese dioxide−zinc (MnO2−Zn) batteries under both alkaline and mild acidic electrolyte systems. The evolution pathway of MnO2−Zn system from Leclanché cell to alkaline primary batteries and from primary to secondary batteries is chronologically depicted. Several adverse phenomena are associated with the reversibility of metallic zinc negative electrode under alkaline (pH 14) electrolyte mediums, and these may include zinc dendrite formation, passivation of electrode surface, shape change of the electrode, zincate crossover through separator and hydrogen evolution upon charging. The MnO2positive electrode also experiences few performance degrading issues under alkaline mediums; like generation of electrochemically inert phases (Mn3O4and ZnMn2O4) in the electrode upon deep‐discharge and Mn‐dissolution in the electrolyte. The mitigation measures of these challenges are well documented and systematically analysed. On the invention of zinc‐ion batteries, the MnO2−Zn secondary batteries are assembled under mild acidic (pH 4–6) electrolytes, and eventually, several adverse effects of alkaline systems are drastically nullified. However, recent scientific and technical efforts are coined to address the challenges of large‐scale MnO2−Zn batteries in mild acidic mediums, and formulate the optimization strategies. This review culminates with a few smart designs of MnO2−Zn batteries, whereas, truly path‐breaking concepts are associated with. To the best of our knowledge, it is the first review that covers the entire spectrum of MnO2−Zn system in both alkaline and mild acidic mediums, along with evolution pathways.

Three-dimensional ordered macroporous patterned structure for dendrite-free and stable zinc anodes

The irregular formation of zinc dendrites and side reactions on Zn anodes severely restrict the stability and cycling life of aqueous Zn-ion batteries. Herein, we report a dendrite-free zinc anode with three-dimensional ordered macroporous patterned structure (3D Zn). The 3D Zn anode can provide enlarged electrochemically active surface areas towards uniform electric field distribution with reduced local current densities and a regulated ion distribution for oriented zinc plating/stripping. The 3D structure with homogeneous Zn can also facilitate charge transfer and lower polarizations, to boost the electrochemical reaction kinetics. Consequently, a lowered nucleation overpotential of 19.2 mV and an extended lifespan of 1000 h are achieved in the 3D Zn-based symmetric cells. Moreover, 3D Zn//MnO2 full cells retain 80.9% of the initial capacity at 1 A/g after 1500 cycles with outstanding reversibility. Our work presents a feasible approach to develop dendrite-free and stable metal anodes for safe energy storage systems.

Scalable fabrication of NiCoMnO4 yolk-shell microspheres with gradient oxygen vacancies for high-performance aqueous zinc ion batteries

Defect regulation, which enables better charge transfer and capacity retention in manganese-based cathode materials, is the key to the development of rechargeable aqueous zinc-ion batteries. Herein, yolk-shell structured NiCoMnO4-VO with gradient oxygen vacancies are synthesized by spray pyrolysis and ammonia etching. The generation of the yolk-shell structures are regulated by the diffusion rate of ions in the atomized droplets during the nucleation process instead of adding template agent. In addition, the etching effect of ammonia gradually dissolves nickel oxide in the material from the surface to the interior, creating abounding gradient oxygen vacancies and thereby achieving more active sites for zinc storage and faster charge transfer. Therefore, the material exhibits superior electrochemical performances with initial discharge capacities of 277.9 mA h g−1 at 0.2 A g−1, and the long-term capacities retention rate is 89.3% after 2800 cycles at 5 A g−1. Ex-situ XRD demonstrates NiCoMnO4-VO belongs to the embedding-extraction mechanism of H+ and Zn2+. In-situ optical microscopy reveals that the formation of zinc dendrites is suppressed to some extent.

Nanoporous core–shell–structured multi-wall carbon nanotube/graphene oxide nanoribbons as cathodes and protection layer for aqueous zinc-ion capacitors: Mechanism study of zinc dendrite suppression by in-situ transmission X-ray microscopy

Recently, owing to the increasing demand for wearable electronics, it is necessary to investigate flexible and highly safe energy storage devices. Commonly used energy storage devices, such as lithium-ion batteries and supercapacitors with organic electrolytes, may suffer from fire and explosion. Therefore, zinc-ion capacitors (ZICs) with nontoxic and nonflammable aqueous electrolytes have recently attracted considerable attention. In this study, high-surface-area nanoporous core-shell-structured multiwalled carbon nanotube@graphene oxide nanoribbon (NP-MWCNT@GONR) is used as the cathode material in aqueous ZICs for the first time. These ZICs exhibit a high energy density of 90 Wh kg−1 at 95 W kg−1 and a high power density of 19 kW kg−1 at 31 Wh kg−1. The cycling retention is 86.5% after 200 cycles; however, the device fails after 200 cycles owing to the formation of zinc dendrites on the anode. To suppress dendrite formation, NP-MWCNT@GONR-coated zinc anode and freeze-dried gel electrolyte are used, and the cycle life is extended beyond 2000 cycles. In-situ synchrotron transmission X-ray microscopy is performed during charging and discharging, which demonstrates that the gel electrolyte and the NP-MWCNT@GONR-coated zinc anode can effectively inhibit dendrite formation. This study reveals that ZICs with NP-MWCNT@GONR cathodes, NP-MWCNT@GONR-coated zinc anode, and gel electrolytes are highly safe energy storage devices for use in flexible and wearable electronics.

Optimized cyclic and electrochemical performance by organic ion N(CH3)4+ pre-inserted into N(CH3)4V8O20 cathode and hierarchy distributive Zn anode in aqueous zinc ion batteries

Vanadate based cathode materials have been enormously investigated into aqueous zinc-ion batteries (AZIBs) in current research due to high specific capacity and large layer spacing that can accommodate sufficient ions. However, bulk vanadate based cathode materials suffer from a rapid capacity decaying as a result of low electronic conductivity, inferior ion diffusion kinetics and unstable structure during the zinc ion de/intercalation. Meanwhile, the inescapable zinc dendrite formation and reactive irreversibility during long cyclic testing also lead to growing polarization and poor cyclic performance. Herein, we put forward a strategy of structural design by synergistically introducing quaternary ammonium cation within vanadium bronze structure. The desired N(CH3)4V8O20 material, pure monomorph phase, was firstly synthesized by facile one-step hydrothermal method, which owns lattice spacing of 11.5 Å and stable crystalline structure for faster kinetics, higher capacity and better cyclic stability. Combined with the optimized 3D braid architecture of Zn@carbon paper anode, the as-obtained AZIBs exhibit a high capacity of 360 mAh g−1 at 0.5 A g−1. While the current density raises to 100 folds from 0.5 A g−1 to 50 A g−1, appreciable capacity of 105 mAh g−1 and outstanding stability of ultra-long lifespan with capacity retention 97% after 5000 cycles are achieved. Combining the sound investigations of experimental practices and computational research, mechanism of rapid and stable Zn2+ storage was systemically demonstrated. The optimized electrochemical performance could be attributed to highly reversible ion de/intercalation, superior ion diffusion kinetics and no side reactions. This work leads to a new strategy of the design for cathodes in AZIBs and unfolds a new path for the actualization of high-up vanadate based materials.

Intercalation of Zinc Monochloride Cations by Deep Eutectic Solvents for High-Performance Rechargeable Non-aqueous Zinc Ion Batteries.

Zinc ion batteries have been extensively studied with an aqueous electrolyte system. However, the batteries suffer from a limited potential window, gas evolution, cathode dissolution, and dendrite formation on the anode. Considering these limitations, we developed an alternative electrolyte system based on deep eutectic solvents (DESs) because of their low cost, high stability, biodegradability, and non-flammability, making them optimal candidates for sustainable batteries. The DES electrolyte enables reversible Zn plating/stripping and effectively suppresses zinc dendrite formation. Furthermore, in-depth characterizations reveal that the energy storage mechanism can be attributed to [ZnCl]+ ion intercalation and the intermediate complex ion plays a pivotal role in electrochemical reactions, which deliver a high reversible capacity of 310 mAh g-1 at 0.1 A g-1and long-term stability (167 mAh g-1 at a current density of 0.3 A g-1 after 300 cycles, Coulombic efficiency: ∼98%). Overall, this work represents our new finding in rechargeable batteries with the DES electrolyte.

Designing Zinc Deposition Substrate with Fully Preferred Orientation to Elude the Interfacial Inhomogeneous Dendrite Growth.

The development of zinc-ion batteries with high energy density remains a great challenge due to the uncontrollable dendrite growth on their zinc metal anodes. Film anodes plated on the substrate have attracted increasing attention to alleviate these dendrite issues. Herein, we first point out that both the random crystal orientation and the low metal affinity of the substrate are important factors of zinc dendrite formation. Accordingly, the (1 0 1) fully preferred tin interface layer with high zinc affinity was fabricated by chemical tin plating on (1 0 0) oriented copper. This tin decorated copper substrate can realize high reversible zinc plating/stripping behavior, and full cell using this zinc plated substrate can be operated for more than 1000 cycles with high capacity retention (85.3%) and low electrochemical impedance. The proposed strategy can be also applied to lithium metal batteries, which demonstrates that the substrate orientation regulation and metal affinity design are the promising approaches to achieve dendrite-free metal anode and overcome the challenges of highly reactive metal anodes.

Aqueous Zn2+/Na+ dual-salt batteries with stable discharge voltage and high columbic efficiency by systematic electrolyte regulation

While aqueous Zn-Na hybrid batteries have garnered widespread attention because of their low cost and high safety, it is still challenging to achieve long cycle-life and stable discharge-voltage due to sluggish reaction kinetics, zinc dendrite formation, and side reactions. Herein, we design a Zn2+/Na+ dual-salt battery, in which sodiation of the NVP cathode favors zinc intercalation under an energy threshold, leading to decoupled redox reactions on the cathode and anode. Systematic investigations of the electrolyte effects show that the ion intercalation mechanism and the kinetics in the mixture of triflate- and acetate-based electrolytes are superior to those in the common acetate-only electrolytes. As a result, we have achieved fast discharging capability, suppressed zinc dendrites, a stable discharge voltage at 1.45 V with small polarization, and nearly 100% Columbic efficiency in the dual-salt mixture electrolyte with optimized concentration of 1 M Zn(OAc)2 + 1 M NaCF3SO3. This work demonstrates the importance of electrolyte regulation in aqueous dual-salt hybrid batteries for the energy storage.

Intrinsically zincophobic protective layer for dendrite-free zinc metal anode

Aqueous zinc anodes have attracted the attention of many researchers owing to their high safety, low cost, and high theoretical specific capacity. However, its practical application is severely limited by the dendrite growth on zinc anode. Herein, we develop an intrinsically zincophobic barium-titanate protective layer with a porous structure to suppress the zinc dendrite formation by homogenizing the ion distribution on the anode surface, increasing the nucleation sites, and limiting the irregular zinc growth. Based on these synergistic effects, the coated zinc anode can exhibit long cycle life (840 h at 0.5 mA/cm2 for 0.5 mAh/cm2) and low voltage hysteresis (36 mV). This work can provide a feasible direction for the design of intrinsically zincophobic coating materials to uniformize the zinc stripping and plating.

Current Advances on Zn Anodes for Aqueous Zinc‐Ion Batteries

AbstractAs the representative in rechargeable multivalence ion batteries, aqueous zinc ion battery (ZIB) is a promising safe and green solution in the post‐lithium ion era. Though ZIB is being intensively investigated due to its unique merits, the development of ZIB is facing the fundamental obstacles during Zn stripping/plating, namely, zinc dendrite formation, hydrogen evolution, and solid‐electrolyte interface (SEI) formation, which severely affect the cycling stability of ZIB. In this minireview, we aim to provide current aspects of novel approaches to deal with the above critical issues. The approaches are discussed from the perspectives of regulation of electrolyte, construction of Zn anode, and design of surface coating or SEI layer, where their effects on Zn deposition and surface evolution are focused. Last, the challenges and outlooks on the current approaches towards highly reversible Zn anode are presented for the development of ZIB.

In situ visualization of zinc plating in gel polymer electrolyte

Uniform zinc metal plating has been raised as a critical issue in zinc-based batteries. Randomly localized ions lead to severe zinc dendrite formation in liquid electrolyte due to nonuniform ion flux caused by electroconvective flow. One of the mitigating approaches is to use gel polymer electrolyte to regulate the ion flux for suppressing zinc dendrites by imparting viscoelasticity to the electrolyte and improving the ion transport along charged functional groups of polymer chains. However, to this date, the effectiveness of gel polymer electrolyte has been visualized using ex situ methods (e.g., scanning electron microscopy) that requires cell disassembly. And the underlying mechanism is poorly understood. Herein, we applied in situ optical microscopy with dark-field illumination and a transparent glass slide cell to visualize zinc metal plating in the gel polymer electrolyte. At a given current density, the morphological differences of plated zinc metal between the liquid and gel polymer electrolytes were compared. Our in situ optical microscopy platform successfully showed that the gel polymer electrolyte supported by cross-linked polyacrylic acid (PAA)/N,N’-methylenebisacrylamide (MBA) polymer framework significantly suppressed the dendrite formation in contrast to the liquid electrolyte during plating. In addition, at various current densities, the tendency of dendritic growth was observed and statistically compared in both electrolytes. The findings will be useful for future design of rechargeable zinc-based batteries.

In Situ Carbon Insertion in Laminated Molybdenum Dioxide by Interlayer Engineering Toward Ultrastable “Rocking‐Chair” Zinc‐Ion Batteries

AbstractAqueous zinc‐ion batteries (ZIBs) have attracted significant attention due to their intrinsic safety, cost‐effectiveness, and environmental friendliness. However, the common zinc metal anode suffers from zinc dendrite formation, self‐corrosion, and surface passivation, which impede the further application of aqueous ZIBs. Herein, carbon‐inserted molybdenum dioxide (MoO2) materials with laminated structure are designed as novel intercalation‐type anodes for ZIBs by combination of interlayer engineering and in situ carbonization of aniline guest in molybdenum trioxide interlayers. The uniform dispersion of carbon layers in laminated MoO2 not only provide fast transportation paths for electron but also strengthen the framework of MoO2, leading to high structural integration during high‐rate cycling. Benefiting from the unique structural design, the carbon‐inserted MoO2 electrode exhibits high initial Coulombic efficiency, excellent cycling stability, and outstanding rate capability. Multiple ex situ characterizations reveal its excellent electrochemical stability is derived from reversible intercalation mechanism and ultrastable structural framework. Furthermore, the rocking‐chair zinc‐ion full battery assembled with the zinc pre‐intercalated Na3V2(PO4)2O2F cathode presents excellent stability and ultralong lifespan with a high capacity retention of 91% over 8000 cycles.