Zn Dendrites Research Articles

Janus interface enables reversible Zn-ion battery by regulating interfacial water structure and crystal-orientation.

To tackle the shortcomings of traditional battery systems, there has been much focus on aqueous Zn-ion batteries due to various advantages. However, they still suffer from poor stability of Zn anodes. Here, a methionine additive with unique Janus properties is proposed to regulate the behavior of the interface between Zn anodes and the electrolyte environment. Systematic characterizations as well as calculations elucidate that the Janus additive is adsorbed on the Zn anode via zincophilic -NH2, changing the structure of the electric double layer and breaking the hydrogen bonding network among H2O molecules through hydrophobic S-CH3. At the same time, it can induce preferential formation of Zn(101) with high reversibility. The above two functions contribute to the dendrite inhibiting ability of Zn anodes. As validated, fabricated Zn//Zn symmetric cells achieve stable cycles of 4500 h, 1165 h, and 318 h at 1, 5 and 10 mA cm-2/mA h cm-2, respectively. Furthermore, Zn//Cu asymmetric cells with an average coulombic efficiency of 98.9% for 2200 stable cycles can be realized. Finally, Zn//MnO2 full cells exhibit 79.9% capacity retention with an ultra-high coulombic efficiency of 99.9% for 1000 cycles, much better than that of the pure Zn(ClO4)2 system, indicating the great potential of this useful strategy in aqueous batteries.

A dendrite-free Zn anode enabled by PEDOT:PSS/MoS2 electrokinetic channels for aqueous Zn-ion batteries.

Notorious Zn dendrites and severe parasitic side reactions severely disrupt the anode-electrolyte interface during Zn plating/stripping, resulting in uncontrollable Zn deposition and limiting the application of aqueous zinc-ion batteries (AZIBs). Although the construction of an artificial interface is a highly desirable strategy, it is often limited by slow Zn2+ transport kinetics. To address these issues, we present a bifunctional polymer coating (PEPM) constructed from highly conductive PEDOT:PSS and monolayer MoS2, where the introduced PEDOT plays an important role in driving the fast Zn ion transfer kinetics as a zincophilic site and 2D MoS2 acts as a buffer layer to induce uniform Zn nucleation. With this corrosion inhibition and nucleation-oriented coating, the mobility of Zn2+ flux and the uniformity of Zn deposition were significantly improved, resulting in a stable plating/stripping performance at an ultra-low overpotential (<50 mV) of 2000 h and a high average coulombic efficiency (>99.4%) of 1000 cycles without significant dendrite formation. The proposed strategy provides a cost-efficient remedy and opens a new avenue for the development of dendrite-free zinc anodes.

An ionically cross-linked composite hydrogel electrolyte based on natural biomacromolecules for sustainable zinc-ion batteries.

Zinc-ion batteries (ZIBs) are regarded as promising power sources for flexible and biocompatible devices due to their good sustainability and high intrinsic safety. However, their applications have been hindered by the issues of uncontrolled Zn dendrite growth and severe water-induced side reactions in conventional liquid electrolytes. Herein, an ionically cross-linked composite hydrogel electrolyte based on natural biomacromolecules, including iota-carrageenan and sodium alginate, is designed to promote highly efficient and reversible Zn plating/stripping. The abundant functional groups of macromolecules effectively suppress the reactivity of water molecules and facilitate uniform Zn deposition. Moreover, the composite hydrogel electrolyte exhibits a high ionic conductivity of 5.89 × 10-2 S cm-1 and a Zn2+ transference number of 0.58. Consequently, the Zn‖Zn symmetric cell with the composite hydrogel electrolyte shows a stable cycle life of more than 500 h. Meanwhile, the Zn‖NH4V4O10 coin cell with the composite hydrogel electrolyte retains a high specific capacity of approximately 200 mA h g-1 after 600 cycles at 2 A g-1. The Zn‖NVO pouch cell based on the composite hydrogel electrolyte also shows a high specific capacity of 246.1 mA h g-1 at 0.5 A g-1 and retains 70.7% of its initial capacity after 150 cycles. The pouch cell performs well at different bending angles and exhibits a capacity retention rate of 98% after returning to its initial state from 180° folding. This work aims to construct high-performance hydrogel electrolytes using low-cost natural materials, which may provide a solution for the application of ZIBs in flexible biocompatible devices.

Selective control of sharp-edge zinc electrodes with (002) plane for high-performance aqueous zinc-ion batteries

This study introduces a novel ZnSE electrode fabrication method, stabilizing the (002) crystal plane to reduce Zn dendrite growth, lower HER, and enhance corrosion resistance.

Elucidating synergistic mechanisms of an anion–cation electrolyte additive for ultra-stable zinc metal anodes

The present work presents a multi-functional 0.2 M NaI electrolyte additive to suppress Zn dendrites and water-induced parasitic reactions in aqueous Zn metal batteries, featuring an astonishing Zn deposition/stripping cyclability of 8632 h.

Guiding uniform Zn deposition with a multifunctional additive for highly utilized Zn anodes.

The practical applications of aqueous zinc-ion batteries (AZIBs) have been restricted by the fast growth of Zn dendrites and severe side reactions at the Zn/electrolyte interface. Herein, a multifunctional additive, L-leucine (Leu), is incorporated into a mild acidic electrolyte to stabilize the Zn anode. The Leu molecule, featuring both carboxyl and amino groups, exhibits strong interactions with Zn2+, which can reshape the solvation structure of Zn2+ and facilitate the uniform electrodeposition of Zn. Simultaneously, the Leu molecule exhibits preferential adsorption onto the Zn surface, effectively isolating it from direct contact with water, thus suppressing unwanted side reactions. Consequently, the Zn∥Cu asymmetric cell exhibits a high and stable coulombic efficiency of 99.5% at a current density of 5 mA cm-2 for 1100 h. Importantly, the capacity retention of the Zn∥NH4V4O10 full cell based on the Leu electrolyte reaches 80% after 1200 cycles at a current density of 2 A g-1. The successful application of the low-cost Leu effectively enhances the cycling stability of the AZIBs and accelerates their applications.

Phytic acid cross-linked and Hofmeister effect strengthened polyvinyl alcohol hydrogels for zinc ion storage.

It is a big challenge to retain the water and thus reduce the charge impedance for solid electrolytes used in flexible and wearable zinc ion batteries. Here, we propose novel phytic acid (PA) cross-linked polyvinyl alcohol (PVA) hydrogels as high-performanced solid electrolytes strengthened by the Hofmeister effect. In this approach, freeze-thawing followed by a salting-out procedure via anions to induce the Hofmeister effect can greatly improve the tensile strain and flexibility of the hydrogels. The PA addition dramatically enhances the ionic conductivity and increases the affinity between the electrolyte and zinc plate. Consequently, the PVA/PA hydrogels exhibit remarkable electrochemical performances with stable full-cell cycling in zinc ion storage and capability in inhibiting Zn dendrite growth.

Inducing preferential growth of the Zn (002) plane by using a multifunctional chelator for achieving highly reversible Zn anodes.

Aqueous zinc-ion batteries (AZIBs) have demonstrated great potential for large-scale energy storage. However, their practical applications have been restricted by fast Zn dendrite growth and severe side reactions at the Zn/electrolyte interface. Herein, sodium gluconate is incorporated into a mild acidic electrolyte as a multifunctional additive to stabilize the Zn anode. Experiments and theoretical calculations reveal that the SG additive can induce planar growth of Zn along its (002) direction, thereby inhibiting Zn dendrite growth. This dendrite inhibition effect is attributed to the preferential adsorption of Zn2+ on the Zn (002) plane, while the Zn (100) and (101) planes are shielded by gluconate ions. Consequently, Zn||Zn symmetric cells with the electrolyte additive exhibit significantly prolonged cycle lives of 2000 h at 1 mA cm-2, 1 mA h cm-2 and 900 h at 5 mA cm-2, 2.5 mA h cm-2. Futhermore, the Zn||NH4V4O10 full cell retains 95% of its initial capacity after 2000 cycles at a current density of 5 A g-1 with an average CE of nearly 100%. This work offers a cost-effective strategy to enhance the electrochemical performance of AZIBs.

Rational design of a dual-gradient zincophilic–conductive interphase for dendrite-free zinc batteries

A dual-gradient carbon-fiber/argentiferous interphase with longitudinally strengthened zincophilicity-conductivity is devised on a Zn anode, which guides bottom-preferential homogeneous Zn deposition for mitigating Zn dendrites and side reactions.

A self-assembled 2-hydroxyphosphonoacetic acid protective layer enables dendrite-free Zn anodes.

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.

A multifunctional protective layer filled with 2D anionic nanosheets enabling a dendrite-free zinc anode

Metallic zinc (Zn) has been considered as an ideal anode material for aqueous batteries, but its development is hampered by the growth of Zn dendrites and side reactions with aqueous electrolytes.

Triflate anion chemistry for enhanced four-electron zinc-iodine aqueous batteries.

I+ hydrolysis, sluggish iodine redox kinetics and the instability of Zn anodes are the primary challenges for aqueous four-electron zinc-iodine batteries (4eZIBs). Herein, the OTf- anion chemistry in aqueous electrolyte is essential for developing advanced 4eZIBs. It is elucidated that OTf- anions establish weak hydrogen bonds (H bonds) with water to stabilize I+ species while optimizing a water-lean Zn2+ coordination structure to mitigate Zn dendrites and corrosion. Moreover, the interaction of the OTf- anions with the iodine species results in an increased equilibrium average intermolecular bond length of the iodine species, facilitating the 4e redox kinetics of iodine with improved reversibility.

Unveiling The Mechanism of The Dendrite Nucleation and Growth in Aqueous Zinc Ion Batteries

AbstractAqueous zinc ion batteries (ZIBs) exhibit great potential for next‐generation energy storage devices. However, significant challenges exist, including the uncontrollable formation of Zn dendrite and side reactions during zinc stripping and plating. The mechanism of Zn dendrite nucleation has yet to be fully understood. In this work, the first principles simulations are used to investigate the Zn dendrite formation process. The unintentionally adsorbed O2− and OH− ions are the inducing factors for Zn dendrite nucleation and growth on the Zn (0001) plane due to significantly increased Zn diffusion barriers. A top‐down method is demonstrated to suppress the dendrite using delaminated V2CTx to capture O2− and OH− ions thanks to reduced Zn diffusion barriers. The experimental results revealed significantly suppressed Zn dendrite nucleation and growth, resulting in a layer‐by‐layer deposit/stripping of Zn. Based on the electrochemical evaluations, the V2CTx‐coated Zn composite delivers a high coulombic efficiency of 99.3% at 1.0 mAh cm−2. Furthermore, the full cell achieves excellent cyclic performance of 93.6% capacity retention after 2000 cycles at 1 A g−1. This strategy has broad scalability and can be widely applied in designing metallic anodes for rechargeable batteries.

Temperature inversion enables superior stability for low-temperature Zn-ion batteries

It is challenging for aqueous Zn-ion batteries (ZIBs) to achieve comparable low-temperature (low-T) performance due to the easy-frozen electrolyte and severe Zn dendrites. Herein, an aqueous electrolyte with a low freezing point and high ionic conductivity is proposed. Combined with molecular dynamics simulation and multi-scale interface analysis (time of flight secondary ion mass spectrometry three-dimensional mapping and in-situ electrochemical impedance spectroscopy method), the temperature independence of the V2O5 cathode and Zn anode is observed to be opposite. Surprisingly, dominated by the solvent structure of the designed electrolyte at low temperatures, vanadium dissolution/shuttle is significantly inhibited, and the zinc dendrites caused by this electrochemical crosstalk are greatly relieved, thus showing an abnormal temperature inversion effect. Through the disclosure and improvement of the above phenomena, the designed Zn||V2O5 full cell delivers superior low-T performance, maintaining almost 99% capacity retention after 9500 cycles (working more than 2500 h) at −20 °C. This work proposes a kind of electrolyte suitable for low-T ZIBs and reveals the inverse temperature dependence of the Zn anode, which might offer a novel perspective for the investigation of low-T aqueous battery systems.

Long-Life flexible mild Ag-Zn fibrous battery with bifunctional gel electrolyte

Silver-zinc (Ag-Zn) fibrous batteries are considered as a promising power source for next-generation flexible/wearable electronics because of their superior safety, high energy density, and stable output voltage. Nevertheless, the widespread application of Ag-Zn batteries is hindered by their limited cycle life, primarily caused by Zn dendrite growth and Ag migration. Herein, we develop a flexible mild Ag-Zn fibrous battery with outstanding cycle performance via designing a bifunctional gel electrolyte. The graphene oxide (GO) introduced into the electrolyte provides dual enhancement in suppressing the growth of Zn dendrite and migration of Ag, leading to improved structural integrity and long cycle life. The designed fibrous battery demonstrates a high capacity of 0.85 mAh cm−1 and it can retain 90% (77.4%) of the initial capacity after 250 cycles under current density of 0.5 (5) mA cm−1. Additionally, the battery can maintain its performance under various deformations and a four-battery set is employed as the power source for LED patterns and wearable sensors. This work provides a rational way to design advanced gel electrolytes for high-performance flexible batteries.

Spatially restricted deposition of Zn metal in localized-activation 3D electrode enables long-term stable zinc ion batteries

3D structures with organized channels have attracted extensive interest in constructing weak-dendrite anode for Zinc ion batteries (ZIBs). However, the uncontrolled “top-growth” dendrites caused by the unrestricted zinc deposition at all locations of the 3D electrode may eventually trigger a separator failure. Herein, a novel design principle of localized-activation 3D electrodes for spatially restricted deposition of metals is proposed. Based on the principle, a 3D Zn@CuSnAg/SiOC anode with spatially restricted feature (P-G Zn@CuSnAg/SiOC-SR), whose top surface (near separator) is an insulating SiOC and other surfaces are highly reactive Zn@CuSnAg, is fabricated by coupling polymer-derived ceramics (PDCs) 3D printing and surface modified method. Uniquely, the insulated SiOC of the top surface bestows a spatially restricted Zn deposition within the anode and ultimately prevents the upper surface from Zn plating and stripping, eliminating “top-growth” Zn dendrites in the 3D electrode. As expected, the P-G Zn@CuSnAg/SiOC-SR symmetrical battery affords spatially restricted Zn plating/stripping with a superior lifespan over 2100 h at 1.0 mA cm−2 for 0.82 mAh cm−2. Meanwhile, the VO2/C//P-G Zn@CuSnAg/SiOC-SR full battery demonstrates remarkable cyclic stability over 800 cycles (capacity retention: 80.5 %). This work sheds light on the 3D anode design and fabrication for the next-generation long-term stable ZIBs.

Peptide Gel Electrolytes for Stabilized Zn Metal Anodes.

The rechargeable aqueous Zn ion battery (AZIB) is considered a promising candidate for future energy storage applications due to its intrinsic safety features and low cost. However, Zn dendrites and side reactions (e.g., corrosion, hydrogen evolution reaction, and inactive side product (Zn hydroxide sulfate) formation) at the Zn metal anode have been serious obstacles to realizing a satisfactory AZIB performance. The application of gel electrolytes is a common strategy for suppressing these problems, but the normally used highly cross-linked polymer matrix (e.g., polyacrylamide (PAM)) brings additional difficulties for battery assembly and recycling. Herein, we have developed a gel electrolyte for Zn metal anode stabilization, where a peptide matrix, a highly biocompatible material, is used for gel construction. Various experiments and simulations elucidate the sulfate anion-assisted self-assembly gel formation and its effect in stabilizing Zn metal anodes. Unlike polymer gel electrolytes, the peptide gel electrolyte can reversibly transform between gel and liquid states, thus facilitating the gel-involved battery assembly and recycling. Furthermore, the peptide gel electrolyte provides fast Zn ion diffusion (comparable to conventional liquid electrolyte) while suppressing side reactions and dendrite growth, thus achieving highly stable Zn metal anodes as validated in various cell configurations. We believe that our concept of gel electrolyte design will inspire more future directions for Zn metal anode protection based on gel electrolyte design.

(Invited) A Sustainable and Reliable Electrolyte Toward Safe Zn-MnO2 Alkaline Rechargeable Batteries

Zinc-Manganese Dioxide (Zn-MnO2) rechargeable batteries has spurred interest due to lower cost, high specific capacity, increased safety while using in small electronic devices and wearable technology. Zn-MnO2 alkaline batteries form inactive compounds during charging and discharging that hinder their ability to be utilized in rechargeable settings. Design and development of functional electrolyte to replace traditional electrolyte have become an effective way to inhibit irreversible compound formations and Zn dendrite growth, avoid leakage issues and metallic packaging. However, many challenges such as reliable and reproducible ionic conductivity and ion transference number of free-standing electrolyte films at lower thickness (150 µm), and interfacial contact resistance between electrolyte and electrode layer still exist. Our assumption is producing reliable and consistent ionic conductivity and ion transference number of electrolytes at lower thickness (150 µm) will help in providing the faster redox reaction kinetics at electrolyte-electrode interface. Moreover, by reducing the interfacial contact resistance between electrolyte and electrode interface will help in reducing the charge transfer resistance and zincate ion movements and results in improving the reversible life cycle of batteries. Many electrolytes fabricated utilize two different solutions that are mixed separately, forming either a liquid or a solid electrolyte after curing. Due to separate mixing, both solutions are never fully incorporated into one another, causing discrepancies in the consistency of the electrolyte. Here, we propose to use sustainable chitosan, which utilized 5:1 ratio of naturally occurring Chitosan (Chi) and Polyvinyl Alcohol (PVA) respectively. The Chi and PVA solution were premixed using ultrasonic bath and vacuum suction was used to remove extra bubbles formation due to mixing of Chi and PVA. This new process of electrolyte formation was compared between different thickness (120 µm, 150 µm, and 250µm), and the best electrolyte was then compared to the old process of mixing the solutions separately for electrolyte formation. The different thickness electrolytes were soaked into Potassium Hydroxide (KOH) and compared on their Ionic Conductivity, Ionic Conductance, Ion Transference Number, PH, and Swelling Ratio. To reduce the interfacial contact resistance between electrolyte and electrode, free standing electrolyte layer will be dipped into Chi solution and then put in contact with electrodes. These electrolytes were then used in the fabrication of Zn-MnO2 batteries and measure their performance using cyclic voltammetry and galvanostatic charge-discharge.

Enhanced kinetics and stability for aqueous Zn battery enabled by low-cost additive chemistry

Rechargeable aqueous zinc(Zn) batteries are a sustainable alternative to lithium-based energy storage devices due to their high safety, low cost, and scalability. Unfortunately, the Zn/Zn2+ redox chemistry is significantly plagued by undesirable interface caused by the instability of water, which directly dictates the low Zn reversibility and dendrite growth behavior. Here, we report an aqueous electrolyte in which low-cost ammonium dihydrogen phosphate is utilized as an electrolyte additive to enable the in-situ construction of phosphate-based interphase on the Zn-metal surface. Importantly, such interphase not only effectively eliminates water-related parasitic reactions and enables a highly reversible Zn deposition/dissolution, as demonstrated by its high Coulombic efficiency of 99.3 %, but also contributes a dendrite-free Zn morphology. Apart from the improved stability of the Zn anode, the addition of NH4H2PO4 also grants the enhanced reaction kinetics of Zn2+, bringing a lower Zn2+ de-solvation energy barrier and much-improved rate performance. Benefiting from the synergistic factors, excellent cycling performances of the Zn0.25V2O5·nH2O (ZVO)/Zn batteries are guaranteed. Additionally, a 31.2 mAh ZVO/Zn pouch cell also demonstrates a stable long life of 400 cycles, and capacity retention of 67.8 % is also retained. The low-cost and efficient electrolyte strategy points out a promising direction for practical Zn batteries.

Zn dendrite suppression and solid electrolyte interface control using N-allylthiourea as an electrolyte additive for aqueous Zn-ion batteries

Despite being promising candidates for Li-ion batteries, the development of aqueous Zn-ion batteries is still impeded by inherent unresolved problems such as dendrite growth and side reactions on the anode side. In this study, a stabilized Zn-electrolyte interface is established using N-allylthiourea (ATU) as an additive in mildly acidic electrolytes because of its strong affinity towards Zn2+ ions and the Zn metal. Through this favorable electrostatic adsorption, side reactions owing to water molecules are inhibited, and uniform Zn deposition is achieved, leading to highly reversible stripping/plating performance. Consequently, a stable cycling performance of up to 500 h at a current density of 1 mA cm–2 and an areal capacity of 1 mAh cm–2 is demonstrated for Zn symmetric cells. Furthermore, a Zn|VO2 full cell validates the possible practical use of ATU where it delivers a promising cycling performance of up to 300 cycles at a current rate of 1C (200 mA g–1). This study contributes insights into the role of additives in optimizing battery performance and creates opportunities for further exploration of similar compounds in pursuit of sustainable energy storage systems.