Aqueous Zn-ion Batteries Research Articles

Synergistic Regulation of Anode and Cathode Interphases via an Alum Electrolyte Additive for High-Performance Aqueous Zinc-Vanadium Batteries.

A zinc (Zn) metal anode paired with a vanadium oxide (VOx) cathode is a promising system for aqueous Zn-ion batteries (AZIBs); however, side reactions proliferating on the Zn anode surface and the infinite dissolution of the VOx cathode destabilise the battery system. Here, we introduce a multi-functional additive into the ZnSO4 (ZS) electrolyte, KAl(SO4)2 (KASO), to synchronise the in situ construction of the protective layer on the surface of the Zn anode and the VOx cathode. Theoretical calculations and synchrotron radiation have verified that the high-valence Al3+ plays dual roles of competing with Zn2+ for solvation and forming a Zn-Al alloy layer with a homogeneous electric field on the anode surface to mitigate the side reactions and dendrite generation. The Al-containing cathode-electrolyte interface (CEI) considerably alleviates the irreversible dissolution of the VOx cathode and the accumulation of byproducts. Consequently, the Zn||Zn cell with KASO exhibits an ultra-long cycle of 6000 h at 2 mA cm-2. Importantly, the VOx cathodes (VO2, V2O5 and NH4V4O10) in the ZS-KASO electrolyte showed excellent cycling stability, including Zn powder||VO2 cells and Zn||VO2 pouch cells. Even better, the full cell exhibits excellent cycling stability at low negative/positive (N/P) ratio of 2.83 and high mass loading (~16 mg cm-2). This study offers a straightforward and practical reference for concurrently addressing challenges at the anode and cathode of AZIBs.

Exploring the Enhanced Zinc Storage Performance of α-MnSe Polyhedral Microspheres and H+/Zn2+ Co-Insertion Mechanism.

The newly emerged Mn-based selenides as cathodes for aqueous Zn-ion batteries (ZIBs) have drawn researchers' interest because of their lower electronegativity and better electronic conductivity compared with the corresponding Mn-based oxides. Nevertheless, the energy storage mechanism of Mn-based selenides still needs to be further clarified. Herein, the MnSe/Se and MnSe polyhedral microspheres are reported as cathodes for ZIBs, and the MnSe cathode achieves significantly enhanced specific capacity, rate performance, and cycling stability. In-depth kinetic analysis confirms that the MnSe cathode presents better kinetic behavior and density functional theory (DFT) calculations verify the fast diffusion kinetics of the MnSe cathode. More importantly, systematic ex situ characterizations reveal that the microstructured MnSe can exist stably during the charge-discharge process and store energy with H+/Zn2+ co-insertion mechanism, which is greatly different from the phase transformation of the nanostructured α-MnSe reported in the literature. Additionally, it is verified that the different types of separators exhibit remarkably different zinc storage performance of the MnSe cathode. This study not only offers a good guidance for developing high-performance ZIBs Mn-based cathode materials and explores the effect of separators on the zinc storage performance, but also provides new insights into the energy storage mechanism of the MnSe cathode.

Unlocking the stable interface in aqueous zinc-ion battery with multifunctional xylose-based electrolyte additives

The growth of dendrites and the side reactions occurring at the Zn anode pose significant challenges to the commercialization of aqueous Zn-ion batteries (AZIBs). These challenges arise from the inherent conflict between mass transfer and electrochemical kinetics. In this study, we propose the use of a multifunctional electrolyte additive based on the xylose (Xylo) molecule to address these issues by modulating the solvation structure and electrode/electrolyte interface, thereby stabilizing the Zn anode. The introduction of the additive alters the solvation structure, creating steric hindrance that impedes charge transfer and then reduces electrochemical kinetics. Furthermore, in-situ analyses demonstrate that the reconstructed electrode/electrolyte interface facilitates stable and rapid Zn2+ ion migration and suppresses corrosion and hydrogen evolution reactions. As a result, symmetric cells incorporating the Xylo additive exhibit significantly enhanced reversibility during the Zn plating/stripping process, with an impressively long lifespan of up to 1986 h, compared to cells using pure ZnSO4 electrolyte. When combined with a polyaniline cathode, the full cells demonstrate improved capacity and long-term cyclic stability. This work offers an effective direction for improving the stability of Zn anode via electrolyte design, as well as high-performance AZIBs.

Electrolyte Additive l-Lysine Stabilizes the Zinc Electrode in Aqueous Zinc Batteries for Long Cycling Performance.

Rechargeable aqueous Zn-ion batteries (AZIBs) have been recognized as competitive devices for large-scale energy storage due to their characteristics of low cost, safe operation, and environmental friendliness. Nevertheless, their practical applications are greatly limited by zinc dendrite growth and side reactions occurring at the anode/electrolyte interface. Herein, we propose an effective and simple electrolyte engineering strategy, which is the introduction of l-lysine additive containing two amino groups and one carboxyl group into a ZnSO4 electrolyte to achieve stable and reversible Zn depositions. Theoretical calculations and experimental results reveal that the l-lysine can adsorb on the Zn anode surface due to the strong coordination effects between amino groups and Zn metal (Zn-N binding) and induce the reduction of ZnSO4 into inorganic ZnS, which can not only prevent interfacial side reactions but also regulate interfacial electric field on the zinc electrode surface to guide uniform Zn2+ electrodeposition to inhibit zinc dendrites. Consequently, the l-lysine additive in the electrolyte enables Zn||Zn symmetric cells to achieve an ultralong stable cycling up to 2400 h at 1 mA cm-2 with a low polarization of only about 16 mV and Zn||Cu asymmetric cells to obtain a high average Coulombic efficiency of 99.80% after stably cycling for more than 2000 h at 2 mA cm-2 (1 mAh cm-2). In addition, the Zn||MnO2@CNT full cell in an l-lysine-containing electrolyte also exhibits good cycling performance. This study offers a new perspective on multifunctional electrolyte additive for achieving highly reversible Zn metal anodes in AZIBs.

Heterostructure VO2@VS2 tailored by one-step hydrothermal synthesis for stable and highly efficient Zn-ion storage

Abstract The increasing demand for advanced energy storage solutions has driven extensive research into Zn-ion batteries due to their safety, cost-effectiveness, and environmental compatibility. This study presents a synthesis and evaluation of VO2@VS2 hollow nanospheres as a novel cathode material for Zn-ion batteries. The VO2@VS2 composite, synthesized via a one-step hydrothermal method, demonstrates a significant improvement in electrochemical performance. The material exhibits a reversible capacity of 468 mAh g−1 at 0.1 A g−1 and maintains a high capacity of 237 mAh g−1 at 1.0 A g−1 over 1000 cycles with a retention rate of 85%. Electrochemical analyses reveal enhanced charge transfer and Zn-ion storage, attributed to the synergistic effect and built-in electric field of the VO2 and VS2 heterostructure. Additionally, the composite shows superior electrochemical kinetics, facilitating rapid ion transport and charge transfer. In-situ Raman analysis confirms the reversible Zn-ion storage mechanism, further validating the composite’s structural stability during cycling. Density functional theory calculations further support these findings, indicating the composite’s potential for high-rate capability and long-term cycling stability. This research highlights the promise of VO2@VS2 hollow nanospheres in advancing the performance of aqueous Zn-ion batteries.

Rational design of epoxy functionalized ionic liquids electrolyte additive for hydrogen-free and dendrite-free aqueous zinc batteries

Despite the high safety and low cost associated with aqueous Zn-ion batteries (ZIBs), uncontrolled Zn dendrite growth and parasitic reactions induced by water significantly diminish their stability. Herein, a new epoxy functionalized ionic liquid, 4-methyl-4-glycidylmorpholin bis[(trifluoromethyl)sulfonyl]imide (MGM[TFSI]), has been developed to mitigate water reactivity for stable ZIBs. It was found that the MGM+ cation disrupts the hydrogen bond network of water, hindering its adsorption on Zn anodes, thereby suppressing water decomposition and enhancing anode stability. Additionally, preferential adsorption of MGM+ cations on the Zn anode surface mitigates tip effects, suppresses dendrite growth, and promotes the formation of a ZnF2 solid electrolyte interphase layer, effectively isolating the anode from the bulk electrolyte. As a result, benefiting from the well-designed MGM+-based electrolyte, Zn//Zn cells achieve significantly enhanced cycling stability, lasting over 2000 h at 1 mA cm−2 with 1 mAh cm−2. Furthermore, Zn//MnO2 full cells deliver remarkable stability, retaining approximately 89 % of their initial capacity after 3000 cycles at 5 A/g. This work proposes that the MGM[TFSI] additive can effectively regulate the interfacial chemistry of the Zn anode, providing an opportunity to design advanced electrolytes for highly reversible ZIBs and beyond.

Overcoming Ion Trapping in Chevrel Phase Compounds via Tailored Anion Substitution: An Integrated Study of Theory, Synthesis, and In Operando Techniques for Reversible Aqueous Zn-Ion Batteries.

Sustainable batteries are key for powering electronic devices of the future, with aqueous zinc-ion batteries (AZIBs) standing out for their use of abundant, readily available elements, and safer production processes. Among the various electrode materials studied for AZIBs, the Chevrel Phase, Mo6S8 has shown promise due to its open framework, but issues with zinc ion trapping have limited its practical application. In this work, we employed computational methods to investigate the insertion-deinsertion mechanism in a series of isostructural Mo6S8-xSex (x = 0-8) solid solutions as materials that could balance the gravimetric capacity and reversible cycling for AZIBs. Density functional theory (DFT) calculations revealed that increasing the Se content would reduce the binding energy of Zn within the structures, enabling Zn deinsertion compared to the Mo6S8 structure. Experiments confirmed the formation of Mo6S8-xSex (x = 0-8) solid solutions, and electrochemical testing showed improved reversibility of Zn insertion/deinsertion as the amount of Se increased, consistent with the computational predictions. Furthermore, combined in operando X-ray diffraction and electrochemical studies revealed a continuous, gradual Zn-insertion process into Mo6S4Se4, in stark contrast to the abrupt phase changes observed upon Zn insertion in Mo6S8 and Mo6Se8. DFT calculations attributed the stabilization of Zn0.5Mo6S4Se4 as a prime reason for preventing phase separation, making Se-substituted compounds promising materials for high-performance AZIBs. Overall, this interdisciplinary approach, integrating computational modeling, materials synthesis, and advanced characterization techniques, offers a pathway for fine-tuning anion chemistry that can help create high-performance electrode materials for sustainable energy storage technologies.

Sustainable Fabrication of Graphene Oxide Cathodes from Graphite of Failed Commercial Li-Ion Batteries for High-Performance Aqueous Zn-Ion Batteries.

The need for revamping spent graphite (SG) from battery waste of commercial lithium-ion batteries and employing it as a source for the synthesis of graphene oxide (GO) is focused. Thus, this work emphasizes the study of GO sheets, synthesized via modified Hummer's method from spent graphite (SG-GO) as cathodes for an aqueous zinc ion battery (AZIB) system, for the first time in literature. For comparison, graphene oxide is also synthesized using commercial graphite powder, its structural and morphological properties are analyzed with SG-GO. The coin cell AZIB device is fabricated for both the GOs and the electrochemical performances revealed that SG-GO portrayed an enhanced charge capacity of 270 mAh g-1 at 0.1 A g-1 in 3m ZnSO4 in comparison to GO which delivered ≈198 mAh g-1 at the same current density of 0.1 A g-1. The long-run cycling analysis of SG-GO elucidated the capacity retention of 77.3% at 1 A g-1 even after 1000 cycles. Moreover, the performance of SG-GO is inspected in different electrolyte systems and the suitable electrolyte underwent concentration variation studies to figure out the capability of the system in storing Zn2+ ions which is found to be more in 3M ZnSO4 electrolyte.

Selective Recycling of Spent Lithium‐Ion Batteries Enables Toward Aqueous Zn‐Ion Batteries Cathode

AbstractEffective selective recycling of spent lithium‐ion batteries (S‐LIBs) and giving recycled products a “second life” are crucial for advancing energy supply circularity, environmental and economic sustainability development. However, separating metal compounds with similar charge differences requires substantial energy, water, and chemical inputs. Herein, an innovative strategy is present for selective recycling S‐LIBs by photoexcitation inspired by the Hard Soft Acid Base (HSAB) principle. Theoretical calculations and experimental results show that photoexcitation drives charge transfer and modulates subtle charge density differences among metal components, thereby enhancing their solubility disparity and facilitating metal separation. Remarkably, the photoexcitation‐induced metal separation factor reaches 46900 and the metal recovery efficiency approaches 100%, representing a significant improvement over non‐photoexcitation separation with a separation factor of non‐photoexcitation of merely 2.7. Through techno‐economic analysis, the viability of photoexcitation selective recycling technology has been confirmed as an eco‐friendly and economical approach for battery recycling. Furthermore, high‐value reuse of recovered Mn components is implemented. The Recycled Mn components are treated by calcination to obtain porous, defect‐rich Mn2O3, which showed a specific capacity of 613 mAh g−1 at 0.1 A g−1) in aqueous Zn‐ion batteries (AZIBs). This work provides fresh insight into recycling S‐LIBs and moving toward more sustainable storage technologies.

Prominent cycling reversibility and kinetics enabled by CaTiO3 protective layer on Zn metal for aqueous Zn-ion batteries

Aqueous Zn-ion batteries (AZIBs) have received considerable attention owing to their various advantages such as safety, low cost, simple battery assembly conditions, and high ionic conductivity. However, they still suffer from serious problems, including uncontrollable dendrite growth, corrosion, hydrogen evolution reaction (HER) from water decomposition, electrode passivation, and unexpected by-products. The creation of a uniform artificial nanocrystal layer on the Zn anode surface is a promising strategy for resolving these issues. Herein, we propose the use of a perovskite CaTiO3 (CTO) protective layer on Zn (CTO@Zn) as a promising approach for improving the performance of AZIBs. The CTO artificial layer provides an efficient pathway for Zn ion diffusion towards the Zn metal because of the high dielectric constant (εr = 180) and ferroelectric characteristics that enable the alignment of dipole moments and redistribute the Zn2+ ions in the CTO layer. By avoiding the direct contact of the Zn anode with the electrolyte solution, the uneven dendrite growth, corrosion, parasitic side reactions, and HER are mitigated, while CTO retains its mechanical and chemical robustness during cycling. Consequently, CTO@Zn demonstrates an improved lifespan in a symmetric cell configuration compared with bare Zn. CTO@Zn shows steady overpotential (∼68 mV) for 1500 h at 1 mA cm−2/0.5 mA h cm−2, excelling bare Zn. Moreover, when paired with the V2O5-C cathode, the CTO@Zn//V2O5-C full battery delivers 148.4 mA h g−1 (based on the mass of the cathode) after 300 cycles. This study provides new insights into Zn metal anodes and the development of high-performance AZIBs.

Modulating Interfacial Zn2+ Desolvation and Transport Kinetics through Coordination Interaction toward Stable Anodes in Aqueous Zn-Ion Batteries.

Aqueous Zn-ion batteries (AZIBs) are promising candidates for grid-scale energy-storage applications, but uneven Zn2+ flux distribution and undesirable water-related interfacial side reactions seriously hinder their practical application. Herein, a strategy of regulating the coordination interaction between Zn2+ and artificial interphase layers (AILs) to modulate the interfacial Zn2+ desolvation/transport behaviors and relieve side reactions for building stable Zn anodes is proposed. By selectively choosing appropriate polymers with different functional groups, it is shown that compared with the strong interaction offered by aryl groups in polystyrene-based AILs, cyano groups in polyacrylonitrile (PAN)-based AILs provide a moderate coordination interaction with Zn2+, which not only accelerates interfacial Zn2+desolvation kinetics but also enables efficient Zn2+ transport within AILs. Moreover, the Zn2+ transport kinetics of PAN-based AILs can be further enhanced with the incorporation of an ionic conductor, zinc phosphate (ZP). Because of these advantages, the Zn anodes decorated with the hybrid AILs composed of PAN and ZP can steadily operate for >2000h at 0.2mA cm-2 and >350h at a high current density of 10mA cm-2. This work provides a valuable guideline for selective design of AILs at the molecular level for durable AZIBs.

Integrated Structural Modulation Inducing Fast Charge Transfer in Aqueous Zinc-Ion Batteries.

Aqueous Zn-ion batteries (AZIBs) are promising energy-storage devices owing to their exceptional safety, long cycle life, simple production, and high storage capacity. Manganese oxides are considered potential cathode materials for AZIBs, primarily because of their safety, low cost, simple synthesis, and high storage capacity. However, MnO2-based cathodes tend to deteriorate structurally during long-term cycling, which reduces their reversible capacity. In this study, an advanced α-MnO2@SnO2 nanocomposite via facile hydrothermal synthesis is developed. The synergistic effects of lattice disorder and increased electron conductivity in the α-MnO2@SnO2 nanocomposite mitigate structural degradation and enhance the overall electrochemical performance. The nanocomposite exhibits a high reversible capacity of 347 mAh g-1 at a current density of 100mA g-1 after 50 cycles. Furthermore, it exhibits excellent rate performance and stable capacity even after 1000 cycles, maintaining a capacity of 78 mAh g-1 at a high current density of 5 A g-1. This excellent electrochemical performance is attributed to the reversible Zn intercalation in α-MnO2@SnO2 nanocomposites due to the increased structural stability and fast ion/electron exchange caused by the distortion of the tunnel structure, on the basis of various ex situ experiments, density functional theory calculations, and electrochemical characterizations.

Construction of hydrophilic and hydrophobic hybrid interface to achieve controlled zinc deposition for aqueous Zn-ion batteries

Aqueous Zn-ion batteries show superior development prospects and competitiveness with high theoretical capacity, abundant reserves and low potential. However, the inhomogeneous electrodeposition of zinc anodes and zinc dendrite growth highly limit their commercialization. To address these issues, multifunctional hybridized interfaces consisting of layered double hydroxide (LDH) and graphene quantum dots (GQDs) are constructed on the surface of zinc metal anodes. LDH with hydrophobicity will effectively shield the corrosion of aqueous electrolyte on the zinc anode, and simultaneously serve as a mechanical skeleton for zinc deposition. The hydrophilic GQDs will control the coordination environment of solvated Zn2+, reduce the reactivity of water and promote the uniform deposition of zinc ions along the (002) crystal surface. The interfacially modified Zn anode achieves more than 1000 h and 1200 h of stable cycling at 1 and 2 mA cm−2, respectively. Moreover, the assembled Zn@LDH@GQDs//NH4V4O10 full cells achieve 2000 stable cycles at a high current density of 10 A g−1. The present work reveals the intrinsic mechanism of inhibiting zinc dendrites by the protective layer of multifunctional hybrid materials, which provides an important idea for stabilizing zinc anodes.

Highly reversible Zn anodes enabled by in-situ construction of zincophilic zinc polyacrylate interphase for aqueous Zn-ion batteries

The irreversibility and low utilization of Zn anode stemming from the corrosion and dendrite growth have largely limited the commercialization of aqueous zinc batteries. Here, a carbonyl-rich polymer interphase of zinc polyacrylate (ZPAA) is spontaneously in-situ constructed on Zn anode to address the above-mentioned dilemmas. The ZPAA interlayer enables fast transport kinetics of Zn2+ and tailors the interfacial electric field for realizing the uniform Zn deposition due to superior zincophilicity, high Zn2+ transference number and inherent ion-diffusion channel. Importantly, acting as a buffer interphase with strong adhesion and isolation of electrolytes, this functional layer effectively protects the Zn electrode against the water-induced erosion and passivation. Remarkably, the ZPAA@Zn electrode realizes an enhanced Coulombic efficiency of 99.71 % within 2200 cycles, delivers an ultra-long cycling stability over 7660 h (>319 days, 1 mA cm−2) and 2460 h (5 mA cm−2) with lower voltage hysteresis. Also, the ZPAA@Zn/MnO2 full cell maintains a high capacity of 114 mAh/g after 2000 cycles, much better that of untreated Zn/MnO2 cell (25 mAh/g). This concept of in-situ fabricating ion-sieve-like polymer interphase provides a facile approach to stabilize Zn anode and further paves a way for high-performance aqueous batteries.

Polyaniline/graphene oxide nanocomposite as an innovative cathode for high energy density aqueous zinc-ion batteries

In order to resolve hard processability, poor conductive and lower capacity of polyaniline(PANI), We design and obtain a nanofiber network polyaniline/graphene oxide(PGO) and polyaniline/graphene oxide/manganese dioxide(PMGO) composite cathode. They are synthesized by electrochemical in-situ intercalative polymerization on oxidized graphite paper and assembled with the zinc anode into aqueous Zn-ion batteries(AZIBs). The initial discharged specific capacity of the PGO cathode is 224 mAh·g-1, and it is lower than that of the PMGO electrode when it discharges at 200mA·g-1. However, the capacity can reach 345 mAh·g-1 with better stability and reversibility compared to the PMGO under the same discharge/charge conditions. Characterization analysis and electrochemical studies show that the PGO composite cathode provides a large specific surface and charge/discharge channel, which optimizes the electrochemical performance of the battery. We also propose a new energy storage mechanism for intercalating PANI into graphene oxide(GO) layers to construct a nano-three-dimensional(3D) network for AZIBs and a proton pool with a hydrogen bond network of the PGO electrode. It is profitable for hindering the polarization, facilitating the electrode reaction, and enhancing the capacity and stability. For these reasons, the storage performance of the PGO electrode is superior to the polyaniline cathode reported at present.

Phosphate ions functionalized metal-organic framework-derived cobalt oxide with improved redox reactivity for high-performance alkaline aqueous Zn-ion batteries

Alkaline aqueous Zn/Co3O4 batteries (AZCBs) have captured significant attention within the field of scalable grid energy storage due to their high output voltage (>1.8 V), superior safety profile, and low manufacturing cost. Nevertheless, the intrinsic Co3O4 material experiences limitations in terms of low electronic conductivity and insufficient active sites, consequently constraining its electrochemical performance in AZCBs. To address this challenge, this investigation focuses on the use of phosphate ions functionalized Co3O4 (referred to as PCO) material derived from cobalt-based metal-organic frameworks (Co-MOFs) as a cathode electrode in AZCBs. Both theory calculations and experimental verification illustrate that the functionalization with phosphate ion enhances the active sites for electrochemical redox reactions and increases the electrical conductivity of intrinsic Co3O4. Consequently, a pouch cell configuration of PCO-2||Zn with the optimized PCO-2 sample as cathode exhibits a high capacity of 162.0 mAh g−1, a maximum energy density of 265.7 Wh kg−1, a maximum power density of 16.39 kW kg−1. Furthermore, excellent long-term stability is observed, with the capacity retention rate reaching 92.3 % over 5000 cycles at a high current density of 5 A g−1. Additionally, the constructed fibrous flexible solid-state device also demonstrates notable long-term stability, with a capacity retention of 96 % after 2000 cycles under a high current density of 10 mA cm−2, and performs well under different deformation statuses. This successful approach may hold potential for the exploration of other cathode materials, such as Mn or V-based compounds, which may exhibit high performance in aqueous zinc-based batteries.

Ag-doped Cu nanoboxes supported by rGO for ultra-stable Zn anodes in aqueous Zn-ion battery

Ag-doped Cu nanoboxes supported by rGO for ultra-stable Zn anodes in aqueous Zn-ion battery

Unveiled mechanism of prolonged stability of Zn anode coated with two‐dimensional nanomaterial protective layers toward high‐performance aqueous Zn ion batteries

AbstractRechargeable aqueous zinc (Zn) ion batteries (AZIBs) are gaining popularity in large‐scale energy storage due to their low cost, high safety, and environmental friendliness; however, dendrite growth and side reactions in Zn metal anodes limit their practical applications. Additionally, the difficulty of developing successful passivation of Zn anodes, combined with large‐area coating of protective layers, remains a major limitation to the commercialization of AZIBs. Here, we introduce two‐dimensional (2D) nanomaterials including MoS2, h‐BN, and Ti3C2Tx MXene as protective layers for Zn anodes, created on a Zn surface using a scalable, large‐area spray‐coating process. Examinations of electrochemical performance‐related material characterizations revealed that a specific type of 2D material with an optimal thickness prevents vertical growth of Zn dendrites, as well as side reactions including hydrogen evolution and corrosion, resulting in stable device operation with minimal overpotential and extended life, even under harsh measurement conditions. The highly stable MoS2@Zn anode allowed the MoS2@Zn//MnO2 full cell to achieve significantly more stable capacity retention, compared with the bare Zn//MnO2 cell. Our versatile and scalable solution‐based coating technique for easily forming large‐area 2D protective layers on Zn anodes offers new insights concerning improvements to AZIB reliability and performance.image

Tuning Zn-ion de-solvation chemistry with trace amount of additive towards stable Aqueous Zn anodes

Aqueous Zn-ion batteries (AZIBs) have attracted widespread attention due to their intrinsic safety, cost-effectiveness. However, active H2O in the solvated ions [Zn(H2O)6]2+ continuously migrate to the Zn surface to trigger hydrogen evolution reaction (HER) and accelerate Zn corrosion. Herein, Zn dendrites and the related by-products have been successfully inhibited by using trace amounts of Nitrilotriacetic acid (NTA). Theoretical research indicates that two carboxyl groups of NTA molecule strongly anchored on the Zn surface and exposed another carboxyl group outside. Due to the violent interaction of carboxyl groups of NTA with H2O, the de-solvation energy barrier of solvated Zn2+ ([Zn(H2O)6]2+) on the Zn surface was obviously decreased, inhibit the active water splitting. Meanwhile, the preferential adsorption of NTA on the Zn surface increases the thickness of electric double layer EDL and provides a buffer layer to hinder the dendrite growth. Using 0.04 M NTA as additives in 2.0 M ZnSO4 electrolyte, the cycling lifespan of both Zn||Zn symmetric and Zn||MnO2 full cells is markedly prolonged. This study provides certain perspectives for trace amounts of electrolyte additives to satisfy the demand of long-cycle life AZIBs.

Achieving high-durability aqueous Zn-ion batteries enabled by reanimating inactive Zn on Zn anodes

The heavy by-products generated on Zn anode surface decrease the active surface of Zn anodes and thus induce uneven Zn deposition, seriously reducing the service life of aqueous Zn-ion batteries (AZIBs). Herein, we propose an elimination strategy enabled by the coordination chemistry to dissolve the main by-products (Zn4SO4(OH)6·xH2O). Urea as a proof-of-concept has been applied as the reactivator in the electrolyte to catalytically produce highly active NH3 on the surface of the by-products. Then the NH3 can powerfully coordinate with the Zn2+ ion in the by-products to form the soluble complex [Zn(NH3)4]2+. Consequently, the proposed electrolyte can not only lead to the timely decomposition of the by-products to prevent the Zn anode from inactivation during cycling, but also repair the waste Zn anodes for reutilization. The action mechanism has been systematically demonstrated via theoretical simulation and experimental study. As a result, the high durability with ultrahigh cumulative capacity of 10,600 mAh cm−2 for the Zn||Zn symmetric cell has been achieved at 40 mA cm−2. Particularly, the dead Zn||Zn symmetric cells and Zn||LiFePO4 full cells have been successfully reactivated. This study lights a new route to extend the cell lifespan and reuse waste Zn-ion batteries.