Aqueous Zn-ion Batteries Research Articles

Nickel Vanadate Cathode Induced In Situ Phase Transition for Improved Zinc Storage by Low Migration Barrier and Zn2+/H+ Co-Insertion Mechanism.

Designing cathode materials that exhibit excellent rate performance and extended cycle life is crucial for the commercial viability of aqueous zinc (Zn)-ion batteries (ZIBs). This report presents a hydrothermal synthesis of stable Ni0.22V2O5·1.22H2O (NVOH) cathode material, demonstrating high-rate performance and extended cycle life. A successful in situ phase transformation yields Zn3(OH)2V2O7·nH2O (ZVO), which undergoes an irreversible phase transition and exhibits exceptional energy storage properties. The procedure maintains the lattice structure of ZVO and ensures high structural stability throughout the phase transformation. The NVOH cathode material exhibits the discharge capacities of 399mA h g-1 at a rate of 1 A g-1 after 400 cycles and 303mA h g-1 at 10 A g-1 after 2000 cycles. Density functional theory calculations indicate that the material is protected by electrostatic forces and exhibits structural stability, with a Zn-ion migration barrier of 0.32eV across the host lattice and the electrode-electrolyte interface. Due to these properties, NVOH also exhibits high energy/power densities of 395Wh kg-1/406W kg-1 at 0.5 A g-1 and 288Wh kg-1/8830W kg-1 at 10 A g-1. Ex situ characterizations indicate structural modifications and irreversible phase changes of NVOH, highlighting the potential of H+ intercalation and in situ phase transitions for high-performance aqueous ZIBs.

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

AbstractA 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.

Nickel-mediated V4O7 as high-performance cathode material for aqueous Zn-ion batteries

Vanadium-based materials are currently favored by researchers due to their multi-structure, which can enhance the steric resistance and electrostatic repulsion during the (de)intercalation process of zinc ions. However, their low conductivity remains an inherent hindrance to their practical application. Therefore, finding a way to adjust the electronic structure of vanadium-based compounds is considered an effective strategy. Presently, we have designed a porous Ni-mediated V4O7, wherein the presence of oxygen defects and heterostructures in V4O7/NiO (Od-NVO-4) substantially improves the diffusion kinetics of ions/electrons and boosts the electrochemical performance. As anticipated, the Zn//V4O7/NiO battery exhibits a high specific capacity (348.6 mAh g−1 at 0.1 A g−1), favorable rate capability (323.8 mAh g−1 at 4 A g−1), and remarkable cycle stability (206.3 mAh g−1 at 2 A g−1 after 2000 cycles). Additionally, the underlying mechanism of electrochemical zinc storage is comprehensively described through electrochemical kinetic analysis and theoretical calculations. These results unambiguously reveal the intrinsic link between the surface/interface structure and electrochemical performance of the cathode, offering a valuable reference for designing high-performance electrode materials.

Combined Effect of Dissolved Oxygen and pH in Aqueous Electrolytes on Zn-Anode Corrosion Behavior in Aqueous Zn-Ion Batteries

Combined Effect of Dissolved Oxygen and pH in Aqueous Electrolytes on Zn-Anode Corrosion Behavior in Aqueous Zn-Ion Batteries

Achieving the dendrite-free zinc anode by constructing a Sn-C interfacial layer with zincophilic and conductive network

Under the basic national policy of sustainable green development, high-performance and low-cost energy storage devices are urgently needed for intermittent generation of clean energy and storage of electrical energy. Zn metal with high capacity, abundant reserves and excellent plasticity, but the inevitable side reactions (hydrogen precipitation and corrosion, etc.) of the Zn metal anode itself have severely limited the development of aqueous Zn ion batteries (AZIBs) in the market. In this study, an artificial protective layer of polymer-derived carbon material combined with Sn is prepared to inhibit hydrogen precipitation and corrosion and prolong the lifetime of AZIBs. With these advantages, the Zn@Sn@N doped carbon (Zn@CNS) symmetric cell could achieve a stable cycle life of 1000 h at 2 mA cm-2 and low overpotential. The excellent stripping life of over 400 h is achieved in half-cells assembled with Cu foils. Furthermore, the α-MnO2//Zn@CNS full battery shows superior stability in rate capability and long-term capacity retention compared to the α-MnO2//Zn battery, indicating that the CNS coating provides excellent performance and practical value.

Strong Lewis Electron-Pair Bonding in Vanadium Oxide for Ultra-fast and Long-term Stable Zn-ion Storage

Vanadium-based oxides typically show low electrical conductivity, high repulsion for Zn2+, and severe structure collapse problems, resulting in unsatisfied cathode performance for aqueous Zn-ion batteries (AZIBs). Herein, we propose an advanced structural optimization strategy to address the above issues by constructing strong Lewis electron-pair bonding in vanadium oxide through initial doping Ca and a subsequent in-situ electrochemical activation process. We prepared the precursor of Ca-doped and amorphous carbon-encapsulated V2O3 material (Ca0.17V2O3-x@C) and verified a phase transition into a layered V2O5-typed cathode during the activation process. Importantly, we find the initial-doped Ca and generated abundant oxygen vacancy defects are well restored in the phase-transformed crystal lattice. We reveal that band and bond structures of the phase-transformed cathode are optimized, exhibiting an improved electrical conductivity, optimal Zn2+ binding energy, ultra-low Zn-ion transport barrier, and considerably strong bonds of Ca-O and V-O, thereby realizing enhanced reaction kinetics and stability. The Ca0.17V2O3-x@C exhibits surprisingly high-rate performance (233 mAh g–1 at 40 A g–1) and excellent cycling stability (10,000 cycles with 82% retention at 20 A g–1). This work offers a novel and simple band and bond structure engineering strategy for preparing high-performance phase transformation typed vanadium oxide cathodes for AZIBs.

Regulating the space charge at interface by negative polar biomolecule enabling ultrastable Zn anode chemistry

The irreversibility of Zn metal anode arising from uncontrollable dendrite growth and hydrogen evolution reaction, especially at high current densities, has challenged the commercialization application of aqueous Zn-ion batteries. Here we report biomolecule additive, named xanthan gum, to solve these issues through making use of dissociated electronegative groups to reduce space charge near the anode-electrolyte interface, tuning solvation structure and form H2O-poor electrical double layer to regulate the Zn deposition behaviors. Meanwhile, the dissolved xanthan gum with multiple polar groups can break the association between H2O and Zn2+ to reconstruct solvated structures of Zn ions to suppress hydrogen evolution reaction (HER). Therefore, the Zn//Zn symmetric cells in ZnSO4 electrolyte with xanthan gum deliver an ultra-long cycle life (>4700 h), and also present excellent cycling performances in other electrolytes (Zn(OAc)2 and Zn(OTf)2). More importantly, a high coulombic efficiency of 99.7 % is achieved using Zn//Cu half cells tested and excellent cycling life for KVO//Zn full cells. This work provides a guidance to design the electrolyte additive for highly reversible Zn metal batteries.

Ternary Eutectic Electrolyte for Flexible Wide-Temperature Zinc-Ion Batteries from -20 °C to 70 °C.

Aqueous Zn-ion batteries (ZIBs) have attracted attention for grid applications due to their cost-effectiveness and high security. However, their lifespan decreases at high temperatures due to declining interfacial stability and increased side reactions. To address these challenges, a ternary deep eutectic solvent-based flexible electrolyte, comprised of Zn(ClO4)2 ⋅ 6H2O, butanedinitrile (BD), and LiCl in an amphoteric polymer matrix, was developed to enable wide-temperature ZIBs working from -20 °C to 70 °C. The interactions among BD, Li+, and zinc hydrate alongside the amphoteric groups on the polyelectrolyte matrix could effectively suppress the interfacial side reactions and Zn dendrites formation. Consequently, the symmetric Zn cell demonstrates exceptional stability across a wide-temperature range, with the ability to survive up to 2780 hours (1 mA cm-2) at 50 °C. Furthermore, the flexible Zn||PANI battery can operate stably over 1000 cycles at 50 °C, boasting an initial specific capacity of 124.8 mAh g-1 and capacity retention rate of 87.9 % (3 A g-1). This work presents an effective strategy for designing high-stability energy storage devices with excellent security features that can function reliably across diverse temperature conditions.

Functionalized Quasi-Solid-State Electrolytes in Aqueous Zn-Ion Batteries for Flexible Devices: Challenges and Strategies.

The rapid development of wearable and intelligent flexible devices has posed strict requirements for power sources, including excellent mechanical strength, inherent safety, high energy density, and eco-friendliness. Zn-ion batteries with aqueous quasi-solid-state electrolytes (AQSSEs) with various functional groups that contain electronegative atoms (O/N/F) with tunable electron accumulation states are considered as a promising candidate to power the flexible devices and tremendous progress has been achieved in this prospering area. Herein, this review proposes a comprehensive summary of the recent achievements using the AQSSE in flexible devices by focusing on the significance of different functional groups. The fundamentals and challenges of the ZIBs are introduced from a chemical view in the first place. Then, the mechanism behind the stabilization of the flexible ZIBs with the functionalized AQSSE is summarized and explained in detail. Then the recent progress regarding the enhanced electrochemical stability of the ZIBs with the AQSSE is summarized and classified based on the functional groups on the polymer chain. The advanced characterization methods for the AQSSE are briefly introduced in the following sections. Last but not least, current challenges and future perspectives for this promising area are provided from the authors' point of view.

Constructing Quasi-Single Ion Conductors by a β-Cyclodextrin Polymer to Stabilize Zn Anode.

Aqueous Zn-ion batteries (AZIBs) are promising for the next-generation large-scale energy storage. However, the Zn anode remains facing challenges. Here, we report a cyclodextrin polymer (P-CD) to construct quasi-single ion conductor for coating and protecting Zn anodes. The P-CD coating layer inhibited the corrosion of Zn anode and prevented the side reaction of metal anodes. More important is that the cyclodextrin units enabled the trapping of anions through host-guest interactions and hydrogen bonds, forming a quasi-single ion conductor that elevated the Zn ion transference number (from 0.31 to 0.68), suppressed the formation of space charge regions and hence stabilized the plating/striping of Zn ions. As a result, the Zn//Zn symmetric cells coated with P-CD achieved a 70.6 times improvement in cycle life at high current densities of 10 mA cm-2 with 10 mAh cm-2. Importantly, the Zn//K1.1V3O8 (KVO) full-cells with high mass loading of cathode materials and low N/P ratio of 1.46 reached the capacity retention of 94.5 % after 1000 cycles at 10 A g-1; while the cell without coating failed only after 230 cycles. These results provide novel perspective into the control of solid-electrolyte interfaces for stabilizing Zn anode and offer a practical strategy to improve AZIBs.

Dual zinco-phobic/-philic ferroelectric nanorods coated mesh for stable Zn anode

Aqueous Zn-ion batteries are emerging as a promising option for energy storage systems due to their safety and environmental benefits. However, their stability and reversibility are often hindered by dendrite growth and interfacial side reactions. In this study, we introduce an innovative strategy to address these issues by engineering an artificial interfacial layer (AIL) on Zn anode surface. This AIL is composed of a dual zinco-phobic/-philic ferroelectric nanorods (FE NRs) mesh, which contrasts with the traditional BaTiO3 nanoparticles. The BTO NRs, particularly those with exposed P4/mmm (100) and (211) facets enriched with oxygen vacancy, facilitate a partial phase transition from the FE tetragonal P4mm phase to the paraelectric tetragonal P4/mmm phase, thereby creating dual zinco-phobic/-philic sites. Additionally, the integration of microchannels within the FE BTO NRs mesh can efficiently modulate the electric field distribution and Zn2+ concentration, leading to a more uniform Zn deposition, as conformed by electrochemical simulations. The Zn anode coated with the FE BTO NRs mesh exhibits impressive performance, achieving an ultralong cycle life of 3050 h at 1 mA cm−2 and 1mAh cm−2. It sustains a Coulombic efficiency exceeding 99.8 % over 2000 cycles, highlighting its exceptional reversibility. These findings underscore the potential of the dual zinco-phobic/-philic FE NRs mesh in overcoming the challenges faced in aqueous metal-ion batteries, showcasing its versatility and the significant performance enhancements it can offer.

AI-Driven Electrolyte Additive Selection to Boost Aqueous Zn-Ion Batteries Stability.

In tackling the stability challenge of aqueous Zn-ion batteries (AZIBs) for large-scale energy storage, the adoption of electrolyte additive emerges as a practical solution. Unlike current trial-and-error methods for selecting electrolyte additives, a data-driven strategy is proposed using theoretically computed surface free energy as a stability descriptor, benchmarked against experimental results. Numerous additives are calculated from existing literature, forming a database for machine learning (ML) training. Importantly, this ML model relies solely on experimental values, effectively addressing the challenge of large solvent molecule models that are difficult to handle with quantum chemistry computation. The interpretable linear regression algorithm identifies the number of heavy atoms in the additive molecule and the liquid surface tension as key factors. Artificial intelligence (AI) clustering categorizes additive molecules, identifying regions with the most significant impact on enhancing battery stability. Experimental verification successfully confirms the exceptional performance of 1,2,3-butanetriol and acetone in the optimal region. This integrated methodology, combining theoretical models, data-driven ML, and experimental validation, provides insights into the rational design of battery electrolyte additives.

Highly Reversible Zn Anode Design Through Oriented ZnO(002) Facets.

The practical implementation of aqueous Zn-ion batteries presents formidable hurdles, including uncontrolled dendrite growth, water-induced side reactions, suboptimal Zn metal utilization, and intricate Zn anode manufacturing. Here, large-scale construction of a highly oriented ZnO(002) lattice plane on Zn anode (ZnO(002)@Zn) with thermodynamic inertia and kinetic zincophilicity is designed to address such problems. Both theoretical calculations and experiment results elucidate that the ZnO(002)@Zn possesses high Zn chemical affinity, hydrogen evolution reaction suppression, and dendrite-free deposition ability due to the abundant lattice oxygen species in ZnO(002) and its low lattice mismatch with Zn(002). These features synergistically promote ion transport and enable homogeneous Zn deposition. Consequently, the ZnO(002)@Zn anode displays a stable and prolonged cycling lifespan exceeding 500h even under a larger depth of discharge (85.6%) and realizes an impressive average Coulombic efficiency of 99.7%. Moreover, its efficacy is also evident in V2O5-cathode coin cells and pouch cells with not only high discharge capacity but also exceptional cycling stability. This integrated approach presents a promising avenue for addressing the challenges associated with Zn metal anodes, thereby advancing the prospects of aqueous Zn-ion battery technologies.

Regulating Zn Deposition Manner by Confining the Reactivity of Free Water in the Electric Double Layer.

Aqueous Zn ion batteries (AZIBs) are promising candidates of next-generation energy storage devices with high safety and theoretical capacity. However, the irreversibility of metallic Zn anode, attributed to dendrite growth and water decomposition, severely limits the cycling durability of AZIBs and restricts their further development. Herein, a facile surface engineering strategy is put forward to tackle the issue of poor reversibility of the Zn anode. Benzotriazole (BTA) is employed as a functional additive of ZnSO4 electrolyte to confine the reactivity of free water situated in the electric double layer (EDL). Experimental results and theoretical simulation reveal that BTA can preferiencially adsorb onto the Zn surface to uniform Zn2+ ion distribution and alleviate H2O-involved side reactions like hydrogen evolution, and surface passivation. Consequently, in BTA-modulated aqueous electrolyte, the lifespan of the Zn anode is extended from 170 h to 1092 h at 1 mA cm-2/1 mAh cm-2. The reversibility improvement of Zn anode also benefits the cycling durability of full devices including supercapacitors and batteries. Zn||I₂ batteries assembled in as-designed electrolyte witness only 11.3% capacity decay over 17000 cycles at 1 A g-1, far outstripping that observed in ZnSO4 counterpart (~ 4675 cycles).

Multifunctional Self-Assembled Bio-Interfacial Layers for High-Performance Zinc Metal Anodes.

Rechargeable aqueous zinc-ion (Zn-ion) batteries are widely regarded as important candidates for next-generation energy storage systems for low-cost renewable energy storage. However, the development of Zn-ion batteries is currently facing significant challenges due to uncontrollable Zn dendrite growth and severe parasitic reactions on Zn metal anodes. Herein, we report an effective strategy to improve the performance of aqueous Zn-ion batteries by leveraging the self-assembly of bovine serum albumin (BSA) into a bilayer configuration on Zn metal anodes. BSA's hydrophilic and hydrophobic fragments form unique and intelligent ion channels, which regulate the migration of Zn ions and facilitate their desolvation process, significantly diminishing parasitic reactions on Zn anodes and leading to a uniform Zn deposition along the Zn (002) plane. Notably, the Zn||Zn symmetric cell with BSA as the electrolyte additive demonstrated a stable cycling performance for up to 2400 hours at a high current density of 10 mA cm-2. This work demonstrates the pivotal role of self-assembled protein bilayer structures in improving the durability of Zn anodes in aqueous Zn-ion batteries.

Thermal conversion engineering of vanadium nitride-oxide cathode for high-rate aqueous Zn-ion battery

Vanadium-based materials are promising cathodes for high electrochemical performance aqueous Zn-ion batteries (AZIBs) due to their high specific capacity and multielectron redox reactions. However, vanadium-based materials suffer from low intrinsic conductivities and slow reaction kinetics, leading to poor rate performance. Here, we introduce vanadium nitride-oxide (VOVN) composites fabricated through a thermal conversion strategy, which exhibit high capacity and superior rate performance. The interface regulation of V2O3 and VN composite promotes charge carrier transport and enhances cathode reaction kinetics. Additionally, the dual energy storage mechanism in VOVN composites facilitates highly reversible Zn2+ storage processes. Consequently, the VOVN cathode demonstrates high discharge capacity (445.3 mAh g−1 at 0.1 A g−1), excellent rate performance (151.4 mAh g−1 at 30 A g−1), and fast diffusion coefficient (10−9–10−10 cm2 s−1). This study provides a straightforward and effective approach to developing high-performance cathodes for AZIBs.

Organic Small Molecules of Hydroxy-Rich Vitamins as Electrolyte Additives for Inducing Dendrite-Free and High-Performance Aqueous Zn-Ion Batteries

Organic Small Molecules of Hydroxy-Rich Vitamins as Electrolyte Additives for Inducing Dendrite-Free and High-Performance Aqueous Zn-Ion Batteries

Customizing H2O-Poor Electric Double Layer and Boosting Texture Exposure of Zn (101) Plane towards Super-High Areal Capacity Zinc Metal Batteries.

The catastrophic dendrite hyperplasia and parasitic reactions severely impede the future deployment of aqueous Zn-ion batteries. Controlling zinc orientation growth is considered to be an effective method to overcome the aforementioned concerns, especially for regulating the (002) plane of deposited Zn. Unfortunately, Zn (002) texture is difficult to obtain stable cycling under high deposition capacity resulting from its large lattice distortion and nonuniform distribution in electric field. Herein, different from traditional cognition, a crystallization orientation regulation tactic is proposed to boost Zn (101) texture exposure and inhibit zinc dendrite proliferation during plating/stripping. Experimental results and theoretical calculations demonstrate the malate molecules preferentially adsorb on the Zn (002) facet, leading to the texture exposure of distinctive Zn (101) plane. Meanwhile, the -COOH and -OH groups of malate molecules exhibit strong adsorption on the Zn anode surface and chelate with Zn2+, achievingH2O-poorelectrical double layer. Very impressively, the multifunctional malate additive enlists zinc anode to survive for 600 h under a harsh condition of 15 mAh cm-2/15 mAh cm-2. Moreover, the symmetric cell harvests highly-reversible cycling life of 6600 h at 5 mA cm-2/1.25 mAh cm-2, remarkably outperforming the ZnSO4 electrolyte. The assembled Zn//MnO2 full cells also demonstrate prominent electrochemical reversibility.

Long-duration aqueous Zn-ion batteries achieved by dual-salt highly-concentrated electrolyte with low water activity

Aqueous Zn-ion batteries have attracted much attention due to their unique high safety and low-cost merits. However, their practical applications are at a slow pace due to their short cycle life, which fundamentally results from the instability of the positive/negative electrode interface in the traditional dilute aqueous electrolytes with high water activity. Developing highly concentrated electrolyte (HCE) has been considered as an effective solution. Unlike previous studies of single salt-based HCE (SS-HCE), herein, a new dual-salt HCE (15 m ZnCl2 + 10 m NH4NH2SO3 DS-HCE) was proposed for the first time. DS-HCE was proven to simultaneously possess higher conductivity than traditional dilute electrolytes and ultralow water activity of SS-HCE by the regulation of dual high-concentration salts on the solvation structure, which renders the Zn||Zn symmetric cell the record-long cycling life of 2200 h compared with those with SS-HCE (30 m ZnCl2, 300 h) and other reported HCEs. Additionally, the Zn||NH4V4O10 full cell with DS-HCE demonstrated impressed rate capability within a wide-range current densities from 0.1 to 10 A g−1. Moreover, at the high current density of 5 A g−1, the full cell shows almost 100% capacity retention after 4000 cycles, which indicates the promising future of the DS-HCE system for long-duration aqueous Zn-ion batteries.

Zincophilic Nanospheres Assembled as Solid-Electrolyte Interphase on Zn Metal Anodes for Reversible High-rate Zn-Ion Storage.

Aqueous Zn-ion batteries (ZIBs) are considered to be one of the most promising energy storage devices in the post-lithium-ion era with fast ionic conductivity, safety, and low cost. However, excessive accumulation of zinc dendrites will fracture and produce dead zinc, resulting in the unsatisfied utilization rate of Zn anodes, which greatly restricts the lifespan of the battery and reduces the reversibility. In this paper, by constructing a protective layer of ZnSnO3 hollow nanospheres in situ growth on the surface of the Zn anode, more zincophilic sites are established on the electrode surface. It demonstrates that uniform deposition of Zn ions by deepening the binding energy with Zn ion and its unique hollow structure shortens the diffusion distance of Zn ions and enhances the reaction kinetics. The assembled Zn-ion hybrid supercapacitor (ZHSC) of ZnSnO3@Zn//AC achieved a long-term lifespan with 4000 cycles at a current density of 10mAcm-2 with a Coulombic efficiency of 99.31% and capacity retention of 79.6%. This work offers a new path for advanced Zn anodes interphase supporting the long cycle life with large capacities and improving electrochemical reversibility.