水系锌离子电池正极材料锰基、钒基、钒酸锰盐

Aqueous zinc-ion batteries (AZIBs) have recently attracted worldwide attention due to the natural abundance of Zn, low cost, high safety, and environmental benignity. Up to the present, several kinds of cathode materials have been employed for aqueous zinc-ion batteries, including manganese-based, vanadium-based, organic electrode materials, Prussian Blues, and their analogues, etc. Among all the cathode materials, manganese (Mn)-based oxide cathode materials possess the advantages of low cost, high theoretical specific capacity, and abundance of reserves, making them the most promising cathode materials for commercialization. However, several critical issues, including intrinsically poor conductivity, sluggish diffusion kinetics of Zn2+, Jahn–Teller effect, and Mn dissolution, hinder their practical applications. This Review provides an overview of the development history, research status, and scientific challenges of manganese-based oxide cathode materials for aqueous zinc-ion batteries. In addition, the failure mechanisms of manganese-based oxide materials are also discussed. To address the issues facing manganese-based oxide cathode materials, various strategies, including pre-intercalation, defect engineering, interface modification, morphology regulation, electrolyte optimization, composite construction, and activation of dissolution/deposition mechanism, are summarized. Finally, based on the analysis above, we provide future guidelines for designing Mn-based oxide cathode materials for aqueous zinc-ion batteries.

Aqueous zinc‐ion batteries (AZIBs) are regarded as promising electrochemical energy storage devices owing to its low cost, intrinsic safety, abundant zinc reserves, and ideal specific capacity. Compared with other cathode materials, manganese dioxide with high voltage, environmental protection, and high theoretical specific capacity receives considerable attention. However, the problems of structural instability, manganese dissolution, and poor electrical conductivity make the exploration of high‐performance manganese dioxide still a great challenge and impede its practical applications. Besides, zinc storage mechanisms involved are complex and somewhat controversial. To address these issues, tremendous efforts, such as surface engineering, heteroatoms doping, defect engineering, electrolyte modification, and some advanced characterization technologies, have been devoted to improving its electrochemical performance and illustrating zinc storage mechanism. In this review, we particularly focus on the classification of manganese dioxide based on crystal structures, zinc ions storage mechanisms, the existing challenges, and corresponding optimization strategies as well as structure–performance relationship. In the final section, the application perspectives of manganese oxide cathode materials in AZIBs are prospected.

Layered manganese oxides adopting pre‐accommodated cations have drawn tremendous interest for the application as cathodes in aqueous zinc‐ion batteries (AZIBs) owing to their open 2D channels for fast ion‐diffusion and mild phase transition upon topochemical (de)intercalation processes. However, it is inevitable to see these “pillar” cations leaching from the hosts owing to the loose interaction with negatively charged Helmholtz planes within the hosts and shearing/bulking effects in 2D structures upon guest species (de)intercalation, which implies a limited modulation to prevent them from rapid performance decay. Herein, a new class of layered manganese oxides, Mg0.9Mn3O7·2.7H2O, is proposed for the first time, aims to achieve a robust cathode for high‐performance AZIBs. The cathode can deliver a high capacity of 312 mAh g−1 at 0.2 A g−1 and exceptional cycling stability with 92% capacity retention after 5 000 cycles at 5 A g−1. The comprehensive characterizations elucidate its peculiar motif of pined Mg‐□Mn‐Mg dumbbell configuration along with interstratified hydrogen bond responsible for less Mn migration/dissolution and quasi‐zero‐strain characters. The revealed new structure‐function insights can open up an avenue toward the rational design of superstructural cathodes for reversible AZIBs.

… specific capacity, recently, manganese-based oxides with … as cathode materials for aqueous ZIBs. This review presents research progress of manganese-based cathodes in aqueous …

Rechargeable aqueous zinc‐ion batteries (ZIBs) are promising candidates for advanced electrical energy storage systems owing to low cost, intrinsic safety, environmental benignity, and decent energy densities. Currently, significant research efforts are being made to develop high‐performance positive electrodes for ZIBs. Nevertheless, there are still many obstacles to be overcome in pursuit of the comprehensive performance of cathode materials, including specific capacity, structural stability, rate performance, and so forth. Many manganese‐based compounds have become the hotspots in the study of ZIB cathodes due to their advantages of natural abundance, less toxicity, and high operating voltage. Here, different energy storage mechanisms of various kinds of manganese‐based compounds are summarized. Electrochemical results of manganese‐based cathodes are compared and analyzed. Moreover, optimization strategies for addressing existing issues of these materials and improving ZIBs are discussed in detail.

Manganese (Mn) oxides are promising cathode materials for rechargeable aqueous Zn‐ion batteries. However, the Mn dissolution in weakly acidic electrolytes always hinders the development of better aqueous Zn–Mn batteries. Herein, a hydroxylated manganese oxide cathode material (H‐MnO2) is fabricated using an electrochemical method for stable aqueous Zn–Mn batteries without relying on the Mn2+ electrolyte additives. The partial hydroxylation of the oxides leads to charge redistribution of the material, changing the reaction thermodynamics and kinetics. Theoretical simulation suggests that the hydroxylation of manganese oxide promotes both Zn2+ adsorption thermodynamics and diffusion kinetics on the surface of H‐MnO2 but weakens the interaction between H+ and the electrode. Therefore, Zn2+ ions can be more reactive with the hydroxylated manganese oxide than H+ ions. Experimental results show that the Zn2+ insertion mechanism dominates the charge storage process of H‐MnO2, and the H+‐induced Mn dissolution reaction is effectively alleviated. Importantly, H‐MnO2 exhibits good cycling stability with 95% capacity retention over 5000 cycles at the current density of 3.8 A g−1 in the ZnSO4 electrolyte, outperforming the state‐of‐the‐art aqueous Zn–Mn batteries, even those with Mn2+ electrolyte additives. The findings provide new insights for designing stable manganese oxide cathodes in aqueous Zn–Mn batteries.

The construction of new energy sources and their energy storage systems will be a key part of achieving the goal of green and sustainable development. Aqueous zinc ion batteries (…

Safety issues of energy storage devices in daily life are receiving growing attention, together with resources and environmental concerns. Aqueous zinc ion batteries (AZIBs) have emerged as promising alternatives for extensive energy storage due to their ultra-high capacity, safety, and eco-friendliness. Manganese-based compounds are key to the functioning of AZIBs as the cathode materials thanks to their high operating voltage, substantial charge storage capacity, and eco-friendly characteristics. Despite these advantages, the development of high-performance Mn-based cathodes still faces the critical challenges of structural instability, manganese dissolution, and the relatively low conductivity. Primarily, the charge storage mechanism of manganese-based AZIBs is complex and subject to debate. In view of the above, this review focuses on the mostly investigated MnO2-based cathodes and comprehensively outlines the charge storage mechanisms of MnO2-based AZIBs. Current optimization strategies are systematically summarized and discussed. At last, the perspectives on elucidating advancing MnO2 cathodes are provided from the mechanistic, synthetic, and application-oriented aspects.

This research reports the presence of a synergistic effect among vacancies, lattice water and nickel ions on enhancing the hydrated protons hopping via the Grotthuss mechanism for high performance zinc ion battery cathodes.

Rechargeable zinc–manganese dioxide batteries that use mild aqueous electrolytes are attracting extensive attention due to high energy density and environmental friendliness. Unfortunately, manganese dioxide suffers from substantial phase changes (e.g., from initial α-, β-, or γ-phase to a layered structure and subsequent structural collapse) during cycling, leading to very poor stability at high charge/discharge depth. Herein, cyclability is improved by the design of a polyaniline-intercalated layered manganese dioxide, in which the polymer-strengthened layered structure and nanoscale size of manganese dioxide serves to eliminate phase changes and facilitate charge storage. Accordingly, an unprecedented stability of 200 cycles with at a high capacity of 280 mA h g−1 (i.e., 90% utilization of the theoretical capacity of manganese dioxide) is achieved, as well as a long-term stability of 5000 cycles at a utilization of 40%. The encouraging performance sheds light on the design of advanced cathodes for aqueous zinc-ion batteries. Zn-MnO2 batteries offer high energy density, but phase changes that lead to poor cathode stability hinder development of rechargeable versions. Here the authors report structurally reinforced polyaniline-intercalated MnO2 nanolayers that boost performance by eliminating phase transformation.

Aqueous zinc‐ion batteries (AZIBs) have emerged as a promising energy storage solution due to their eco‐friendly aqueous electrolytes, high theoretical capacity of zinc anodes, and abundant global zinc reserves. Among the reported cathode materials, manganese‐based cathodes are widely used in AZIBs due to their high theoretical capacity and low cost. However, practical applications of manganese‐based cathodes face several challenges, including structural instability, low electrical conductivity, and slow diffusion kinetics. This review begins by exploring the crystalline structures of manganese‐based compounds commonly used in AZIBs, systematically analyzing their reaction mechanisms. Furthermore, it examines the main challenges currently encountered by manganese‐based compounds in AZIBs. Addressing these challenges, this review summarizes corresponding optimization strategies, providing valuable references and insights for the development and application of manganese‐based cathodes in AZIBs.

… This review provides an overview of Zinc-ion storage … Furthermore, the challenges faced by manganese-based cathode … ZIBs assembled by manganese-based cathode materials in …

Low‐cost and highly safe zinc‐manganese batteries are expected for practical energy storage and grid‐scale application. The electrolyte adjustment is further combined to boost their performance output; however, the mechanism behind the electrochemical contrast caused by electrolyte composition remains unclear, which has held back the development of these systems. Hence, new insight into the electrochemical activation of manganese‐based cathodes, which is induced by the aqueous zinc‐ion electrolyte, is provided. The relationship between the desolvation of Zn2+ from [Zn(OH2)6]2+‐solvation shell and the electrolyte/electrode interfacial reaction to form Zn4SO4(OH)6·4H2O phase or its analogues is established, which is the key for the electrochemical activation. Further electrolyte optimization promotes the cycling stability of Zn/LiMn2O4 battery with a long life span over 2000 cycles. This work illuminates the confused direction in exploring electrolyte for zinc‐manganese batteries.

Abstract The growing demand for energy storage has inspired researchers’ exploration of advanced batteries. Aqueous zinc ion batteries (ZIBs) are promising secondary chemical battery system that can be selected and pursued. Rechargeable ZIBs possess merits of high security, low cost, environmental friendliness, and competitive performance, and they are received a lot of attention. However, the development of suitable zinc ion intercalation-type cathode materials is still a big challenge, resulting in failing to meet the commercial needs of ZIBs. Both vanadium-based and manganese-based compounds are representative of the most advanced and most widely used rechargeable ZIBs electrodes. The valence state of vanadium is +2 ∼ +5, which can realize multi-electron transfer in the redox reaction and has a high specific capacity. Most of the manganese-based compounds have tunnel structure or three-dimensional space frame, with enough space to accommodate zinc ions. In order to understand the energy storage mechanism and electrochemical performance of these two materials, a specialized review focusing on state-of-the-art developments is needed. This review offers access for researchers to keep abreast of the research progress of cathode materials for ZIBs. The latest advanced researches in vanadium-based and manganese-based cathode materials applied in aqueous ZIBs are highlighted. This article will provide useful guidance for future studies on cathode materials and aqueous ZIBs.

Aqueous zinc ion batteries (ZIBs) are attracting considerable attentions for practical energy storage because of their low cost and high safety. Nevertheless, the traditional manganese …

This review summarizes the recent research progress in vanadium/manganese-based composite materials, focusing on green synthesis strategies employing the composite support materials CNTs, GO, MOF-derived carbon, MXenes and other hybrid carriers.

Conspectus Zinc-ion batteries (ZIBs) are highly promising for large-scale energy storage because of their safety, high energy/power density, low cost, and eco-friendliness. Vanadium-based compounds are attractive cathodes because of their versatile structures and multielectron redox processes (+5 to +3), leading to high capacity. Layered structures or 3-dimensional open tunnel frameworks allow easy movement of zinc-ions without breaking the structure apart, offering superior rate-performance. However, challenges such as dissolution and phase transformation hinder the long-term stability of vanadium-based cathodes in ZIBs. Although significant research has been dedicated to understanding the mechanisms and developing high-performance vanadium-based cathodes, uncertainties still exist regarding the critical mechanisms of energy storage and dissolution, the actual active phase and the specific optimization strategy. For example, it is unclear whether materials such as α-V2O5, VO2, and V2O3 serve as the active phase or undergo phase transformations during cycling. Additionally, the root cause of V-dissolution and the role of byproducts such as Zn3(OH)2V2O7·2H2O in ZIBs are debated. In this account, we aim to outline a clear and comprehensive roadmap for V-based cathodes in ZIBs. On the basis of our studies, we analyzed intrinsic crystal structures and their correlation with performance to guide the design of V-based materials with high-capacity and high-stability for ZIBs. Then, we revealed the underlying mechanisms of energy storage and instability, enabling more effective design and optimization of V-based cathodes. After identifying the key challenges, we proposed effective design principles to achieve high cycling performance of V-based cathodes and outlined future development directions toward their practical application. Vanadium-based compounds include [VO4] tetrahedrons, [VO5] square pyramids, and [VO6] octahedra, which are connected through a cocorner, coedge and coplane. The [VO4] tetrahedron is inactive, and the [VO5] square pyramid is unstable in aqueous solutions because water attacks the exposed vanadium, whereas stable [VO6] octahedra are desirable because of their ability to reduce from +5 to +3 with minimal structural distortion. Therefore, high-performance vanadium-based oxides in ZIBs should maintain intact [VO6] octahedra while avoiding [VO4] tetrahedra or [VO5] square pyramids. The energy storage mechanism involves H2O/H+/Zn2+ coinsertion. The existence of interlayer water in V-based cathodes significantly improves the rate and cycling performance by expanding galleries, screening Zn2+ electrostatically via solvation, reducing ion diffusion energy barriers, and increasing layer flexibility. The insertion of H+/Zn2+ and the instability of V-based cathodes lead to the formation of byproducts such as basic zinc salts (i.e., Zn4SO4(OH)6·nH2O) and dead vanadium (Zn3(OH)2V2O7·2H2O), whose reversibility strongly affects long-term stability. To increase the cycling stability of vanadium-based cathodes, strategies such as electrolyte modulation and coating have been proposed to decrease water attack on the surface of V-oxides, thereby affecting the formation of byproducts. Additionally, in situ electrochemical transformation, ion preintercalation, and ion exchange were explored to prepare intrinsically stable V-based cathodes with enhanced performance. Furthermore, future research should focus on revealing atomic-scale mechanisms through advanced in situ characterization and theoretical calculations, enhancing rate-performance by facilitating ion/electron diffusion, promoting cycling stability by developing highly stable cathodes and refining interface engineering, and scaling up vanadium-based cathodes for practical ZIB applications.

Aqueous zinc‐ion batteries (AZIBs) stand out among many monovalent/multivalent metal‐ion batteries as promising new energy storage devices because of their good safety, low cost, and environmental friendliness. Nevertheless, there are still many great challenges to exploring new‐type cathode materials that are suitable for Zn2+ intercalation. Vanadium‐based compounds with various structures, large layer spacing, and different oxidation states are considered suitable cathode candidates for AZIBs. Herein, the research advances in vanadium‐based compounds in recent years are systematically reviewed. The preparation methods, crystal structures, electrochemical performances, and energy storage mechanisms of vanadium‐based compounds (e.g., vanadium phosphates, vanadium oxides, vanadates, vanadium sulfides, and vanadium nitrides) are mainly introduced. Finally, the limitations and development prospects of vanadium‐based compounds are pointed out. Vanadium‐based compounds as cathode materials for AZIBs are hoped to flourish in the coming years and attract more and more researchers' attention.

Abstract Aqueous zinc‐ion batteries (ZIBs) are considered promising energy storage devices for large‐scale energy storage systems as a consequence of their safety benefits and low cost. In recent years, various vanadium‐based compounds have been widely developed to serve as the cathodes of aqueous ZIBs because of their low cost and high theoretical capacity. Furthermore, different energy storage mechanisms are observed in ZIBs based on vanadium‐based cathodes. In this Minireview, we present a comprehensive overview of the energy storage mechanisms and structural features of various vanadium‐based cathodes in ZIBs. Furthermore, we discuss strategies for improving the electrochemical performance of vanadium‐based cathodes; including, insertion of metal ions, adjustment of structural water, selection of conductive additives, and optimization of electrolytes. Finally, this Minireview offers insight into potential future directions in the design of innovative vanadium‐based electrode materials.

Rechargeable aqueous zinc‐ion batteries (AZIBs) are recognized as one of the most competitive next generation energy storage systems due to the high theoretical capacity (820 mAh g−1), abundant reserves, low expense, and environmental friendliness. However, in comparison to that monovalent ion secondary battery, the multivalent ion rechargeable battery faces larger metal ion sizes and higher charge/discharge number in the electrochemical reaction process, thereby suffering from larger steric resistance and the electrostatic repulsion in the intercalation–deintercalation process. At present, a great deal of research has shown that the guest ion pre‐embedded host structured cathodes can effectively alleviate the above problems and improve the comprehensive performance of aqueous zinc ion battery. In this review, the development of vanadium oxide ion‐intercalated cathode materials in AZIBs is reviewed, mainly including MXV2O5∙nH2O, MXV3O8∙nH2O, MXV6O13∙nH2O, MXV6O16∙nH2O, and MXV10O25∙nH2O type materials. The reaction mechanisms and electrochemical performance of these materials are described, and the future research directions are prospected. It is expected to provide fundamental and engineering guidance for the development of high performance AZIBs cathode materials.

Vanadium-based cathodes have received widespread attention in the field of aqueous zinc-ion batteries, presenting a promising prospect for stationary energy storage applications. However, the rapid capacity decay at low current densities has hampered their development. In particular, capacity stability at low current densities is a requisite in numerous practical applications, typically encompassing peak load regulation of the electricity grid, household energy storage systems, and uninterrupted power supplies. Despite possessing notably high specific capacities, vanadium-based materials exhibit severe instability at low current densities. Moreover, the issue of stabilizing electrode reactions at these densities for vanadium-based materials has been explored insufficiently in existing research. This review aims to investigate the matter of stability in vanadium-based materials at low current densities by concentrating on the mechanisms of capacity fading and optimization strategies. It proposes a comprehensive approach that includes electrolyte optimization, electrode modulation, and electrochemical operational conditions. Finally, we presented several crucial prospects for advancing the practical development of vanadium-based aqueous zinc-ion batteries.

Hierarchically porous zinc vanadium oxide cathodes contribute to high-rate and ultralong-life aqueous rechargeable zinc batteries. Rechargeable aqueous zinc-ion batteries are promising candidates for large-scale energy storage but are plagued by the lack of cathode materials with both excellent rate capability and adequate cycle life span. We overcome this barrier by designing a novel hierarchically porous structure of Zn-vanadium oxide material. This Zn0.3V2O5·1.5H2O cathode delivers a high specific capacity of 426 mA·h g−1 at 0.2 A g−1 and exhibits an unprecedented superlong-term cyclic stability with a capacity retention of 96% over 20,000 cycles at 10 A g−1. Its electrochemical mechanism is elucidated. The lattice contraction induced by zinc intercalation and the expansion caused by hydronium intercalation cancel each other and allow the lattice to remain constant during charge/discharge, favoring cyclic stability. The hierarchically porous structure provides abundant contact with electrolyte, shortens ion diffusion path, and provides cushion for relieving strain generated during electrochemical processes, facilitating both fast kinetics and long-term stability.

Abstract Aqueous zinc-ion batteries (ZIBs) have got wide attention with the increasing demands for energy resource recently. It has a number of merits compared with lithium-ion batteries, such as enhanced safety, low cost and environmental friendliness. Vanadium-based materials have been developed to serve as the cathodes of ZIBs for many years. But there are also some challenges to construct high performance ZIBs in the future. Herein, we reviewed the research progress of vanadium-based cathodes and discussed the energy storage mechanisms in ZIBs. In addition, we summarized the major challenges faced by vanadium-based cathodes and the corresponding ways to improve electrochemical performance of ZIBs. Finally, some excellent vanadium-based cathodes are summarized to pave the way for future research in ZIBs.

… Aqueous zinc-ion batteries (AZIBs) are favorable competitors in various energy storage … cathode materials is crucial for the large-scale development and application of AZIBs. Vanadium-…

… Vanadium-based materials stand out as promising cathode options for rechargeable aqueous zinc-ion batteries (… Nevertheless, the utilization of vanadium-based cathodes in advancing …

… vanadium oxide cathode material is widely regarded as a promising candidate for aqueous zinc-ion batteries … the detachment and dissolution of vanadium compounds during cycles, …

The developments, challenges and solutions of vanadium-based aqueous zinc ion battery cathodes are reviewed, focusing on the intrinsic connections of ion diffusion channels, mechanisms, and battery performances.

Rechargeable aqueous zinc-ion batteries (AZIBs) are considered for emerging cutting-edge energy storage technologies as an alternative to the existing nonaqueous lithium-ion batteries (LIBs) owing ...

… As an emerging energy storage device with high-safety aqueous electrolytes, low-cost, … aqueous zinc-ion batteries (AZIBs) have attracted more and more attention. Vanadium-based …

Rechargeable aqueous zinc ion batteries (ZIBs) have emerged as a promising alternative to lithium-ion batteries due to their inherent safety, abundant availability, environmental friendliness and cost-effectiveness. However, the cathodes in ZIBs encounter challenges such as structural instability, low capacity, and sluggish kinetics. In this study, we constructed BiVO4@VO2 (BVO@VO) heterojunction cathode material with bismuth vanadate and vanadium dioxide phases for ZIBs, which demonstrate significant advancements in both aqueous and quasi-solid-state ZIBs. Benefitting from the heterojunction structure, the materials present a high capacity of 262 mAh g-1 at 0.1 A g-1, superb cyclic stability with 96% capacity retention after 1000 cycles at 2 A g-1, and outstanding rate property with a specific capacity of 218 mAh g-1 even at a high rate of 5.0 A g-1. Furthermore, the flexible quasi-solid-state ZIBs incorporating the BVO@VO cathode demonstrate prolonged cyclic life performance with a remarkable specific capacity of 234 mAh g-1 over 100 cycles at a current density of 0.1 A g-1. This study potentially paves the way for the utilization of heterointerface-enhanced zinc ion diffusion for vanadium-based materials in ZIBs, thereby providing a new approach for the design and investigation of high-performance zinc-ion systems.

Hollow V4+-V2O5 nanospheres are prepared by a novel and simple method using VOOH as the precursor. V4+-V2O5 with mixed vanadium valences is firstly constructed as an electrochemically active cathode for aqueous zinc-ion batteries. The V4+-V2O5 cathode exhibits a prominent cycling performance up to 1000 cycles and an excellent rate capability. Hollow V4+-V2O5 nanospheres are prepared by a novel and simple method using VOOH as the precursor. V4+-V2O5 with mixed vanadium valences is firstly constructed as an electrochemically active cathode for aqueous zinc-ion batteries. The V4+-V2O5 cathode exhibits a prominent cycling performance up to 1000 cycles and an excellent rate capability. A V4+-V2O5 cathode with mixed vanadium valences was prepared via a novel synthetic method using VOOH as the precursor, and its zinc-ion storage performance was evaluated. The products are hollow spheres consisting of nanoflakes. The V4+-V2O5 cathode exhibits a prominent cycling performance, with a specific capacity of 140 mAh g−1 after 1000 cycles at 10 A g−1, and an excellent rate capability. The good electrochemical performance is attributed to the presence of V4+, which leads to higher electrochemical activity, lower polarization, faster ion diffusion, and higher electrical conductivity than V2O5 without V4+. This engineering strategy of valence state manipulation may pave the way for designing high-performance cathodes for elucidating advanced battery chemistry.

Abstract Vanadium oxides are promising candidates for cathode materials in aqueous zinc-ion batteries (ZIBs) with low cost and high capacity yet requirements for long cycling necessitate the development of increasingly stable structure. This study reports a structural engineering method by incorporating K+ into hydrated vanadium pentoxide (V2O5·nH2O, VOH) to achieve unique hydrated vanadate (KV12O30-y·nH2O, KVOH). In contrast to previously reported works, K+ introduction leads to a new phase of KVOH with faster ion diffusion kinetics and better long-term cycling stability. This work establishes an understanding of the role of K+ incorporation in KVOH which goes beyond its conventional categorization as an agent for interlayer spacing adjustment, reflecting in maintaining structure flexibility for effective Zn2+ insertion/extraction even at high rates, improving materials conductivity by the electron hoping of V4+/V5+ and acting as a stabilizer to accommodate structural contraction/expansion with smaller voltage hysteresis and higher reversibility. KVOH displays a remarkable capacity of 436 mAh g−1 at 0.05 ​A ​g−1, maintains 227 mAh g−1 at 10 ​A ​g−1, which is better than VOH and the majority of reported monovalent and multivalent metal ions introduced in vanadates. KVOH exhibits excellent cycling stability with 92% capacity retention over 3000 cycles at 5 ​A ​g−1, high energy density (308 ​Wh kg−1) and power density (7502 ​W ​kg−1), as well as improved energy efficiency. These characteristics recommend KVOH cathodes for use in high-performance aqueous ZIBs.

Vanadium oxides, known for their multi‐oxidation states and deformable V─O polyhedra, are promising cathodes for aqueous zinc‐ion batteries (AZIBs), yet suffer from limited interlayer spacing and structural instability. Here, an inorganic–organic co‐intercalated cathode (AlVO‐DMF2) is developed by partially replacing crystalline water in Al2.65V6O13·2.07H2O with dimethylformamide (DMF). Interlayer Al3⁺ serve as structural supports, preventing structural damage during the removal of crystalline water from nanobelts. They also anchor polar DMF molecules between layers via electrostatic adsorption. The strong attraction between C═O groups and Al3⁺ reduces Zn2⁺ affinity to DMF, facilitating reversible Zn2⁺ (de)intercalation and improving structural stability. The Zn//AlVO‐DMF2 battery delivers a high average discharge capacity of 430.56 mAh·g−1 at 0.1 A·g−1 and recovers to 418.84 mAh·g−1 when the current returns to 0.05 A·g−1 after high‐rate cycling, demonstrating excellent rate capability. This study provides a promising strategy for designing advanced inorganic–organic co‐intercalated vanadium‐based cathodes for AZIBs.

… In this review, the latest progress in vanadium-based cathodes … vanadium-based cathode materials for AZIBs and the perspectives for future development of vanadium-based cathode …

Expanding hydrated vanadate with transition metal cations collectively promotes and catalyzes fast and more Zn-ion intercalation in aqueous batteries.

… manganese-oxide based cathodes have garnered considerable attention for aqueous zinc-ion batteries … vanadium-oxide//Zn batteries and low specific capacity of manganese-oxide//Zn …

… vanadates have gained significant attentions as cathode ingredients for aqueous zinc-ion batteries (AZIBs) … This work paves a way for the furtherance of hydrated manganese vanadate …

Vanadium compounds are promising cathode materials for aqueous zinc-ion batteries (AZIBs) due to their high specific capacity. However, the narrow interlayer spacing, low intrinsic conductivity and the vanadium dissolution still restrict their further application. Herein, we present an oxygen-deficient vanadate pillared by carbon nitrides (C3N4) as the cathode for AZIBs through a facile self-engaged hydrothermal strategy. Of note, C3N4 nanosheets can act as both the nitrogen source and pre-intercalation species to transform the orthorhombic V2O5 into layered NH4V4O10 with expanded interlayer spacing. Owing to the pillared structure and abundant oxygen vacancies, both the Zn2+ ion (de)intercalation kinetics and the ionic conductivity in the NH4V4O10 cathode are promoted. As a result, the NH4V4O10 cathode delivers exceptional Zn-ion storage ability with a high specific capacity of 398.7 mAh g-1 at 0.5 A g-1, a high-rate capability of 194.7 mAh g-1 at 20 A g-1 and a stable cycling performance of 10000 cycles.

Aqueous zinc-ion batteries have attracted attention due to their low cost and high safety. Unfortunately, dendrite growth, hydrogen evolution reactions, cathodic dissolution, and other problems are more serious; not only that, but also the cathodic and anodic materials' lattices contract when the temperature drops, and charge transfer and solid phase diffusion become slow, seriously aggravating dendrite growth. At present, there are few studies on the low-temperature system, and studies on retaining high specific capacity are even more rare. Herein, ethylene glycol (EG) and manganese sulfate (MSO) are selected as additives, and the manganese vanadate (MVO) cathode is used to find a high-performance solution at low temperature. MVO can provide higher specific capacity and better structural stability than MnO2 to adapt to a low-temperature environment. At the same time, Mn2+ in MSO can produce a cationic shield covering the initial zinc tip at an appropriate concentration to avoid the tip effect and inhibit the dissolution of MVO. EG can not only reduce the freezing point of the electrolyte but also promote the desolvation of [Zn(H2O)6]2+. The synergistic effect of the three elements prevents the dissolution equilibrium of Mn2+ in MVO from fluctuating greatly due to the change of temperature. Therefore, when we use EG@0.2 M MnSO4 + 2 M ZnSO4 (EG + 0.2Mn/2ZSO) electrolyte at -30 °C, the Zn||Zn batteries which used this type of electrolyte can remain 350 h at 1 mA cm-2 without failure. The Zn||Cu batteries can retain 100% Coulombic efficiency after more than 2000 cycles at 0.2 mA cm-2. The Zn||MVO battery can reach 231.13 mA h g-1 at its first cycle, and the capacity retention rate is still above 85% after 1000 cycles, which is higher than that of the existing low-temperature research system.

Aqueous zinc‐ion batteries (AZIBs) are widely attractive by virtue of its high safety and low cost. However, their development for widespread applications is limited due to unstable cathode materials. Herein, a manganese vanadium oxide (Mn2V2O7/V2O3) (MnVO) composite is fabricated and can be utilized as a superior intercalated cathode for AZIBs. The extraction of Zn2+ from the MnVO composite causes the phase transition during the initial charge cycle to form electrochemically reversible MnV10O26·10H2O. The phase transformation modifies morphology and the as‐formed MnV10O26·10H2O phase acts as a Zn2+ host for the subsequent cycles, leading to excellent electrochemical performances. As a result, the electrode delivers a superior reversible capacity of 204 mA h g−1 at 1 A g−1 over 1000 cycles and is also sustainable over a long‐life span of 3000 cycles even at 10 A g−1. Additionally, the Zn/MnVO battery exhibits a high energy density of 256.31 Wh kg−1 at a power density of 410 W kg−1. The exceptional reversible capacity even at different current densities over a long‐life span makes them a promising candidate for fabricating the safe and reliable AZIBs. Also, the Zn2+ storage mechanism in MnVO composite cathode for rechargeable AZIBs is demonstrated.

Layered vanadates are ideal energy storage materials due to their multielectron redox reactions and excellent cation storage capacity. However, their practical application still faces challenges, such as slow reaction kinetics and poor structural stability. In this study, we synthesized [Me2NH2]V3O7 (MNVO), a layered vanadate with expended layer spacing and enhanced pH resistance, using a one‐step simple hydrothermal gram‐scale method. Experimental analyses and density functional theory (DFT) calculations revealed supportive ionic and hydrogen bonding interactions between the thin‐layered [Me2NH2]+ cation and [V3O7]− anion layers, clarifying the energy storage mechanism of the H+/Zn2+ co‐insertion. The synergistic effect of these bonds and oxygen vacancies increased the electronic conductivity and significantly reduced the diffusion energy barrier of the insertion ions, thereby improving the rate capability of the material. In an acidic electrolyte, aqueous zinc‐ion batteries employing MNVO as the cathode exhibited a high specific capacity of 433 mAh g−1 at 0.1 A g−1. The prepared electrodes exhibited a maximum specific capacity of 237 mAh g−1 at 5 A g−1 and maintained a capacity retention of 83.5% after 10,000 cycles. This work introduces a novel approach for advancing layered cathodes, paving the way for their practical application in energy storage devices.

The development of new battery technologies requires to be well established in the same era of lithium ion batteries (LIBs), a well commercialized technology, and the merits should surpass over oth...

Abstract Rechargeable aqueous zinc-ion batteries (ZIBs) are feasible for grid-scale applications due to their unique attributes such as safe, sustainable, and low-cost. However, it is limited by cathode materials, which requires a stable host structure and fast channel for zinc ions diffusion. Here, we develop various kinds of potassium vanadates (K2V8O21, K0.25V2O5, K2V6O16·1.57H2O and KV3O8) as cathodes for aqueous ZIBs. K2V8O21 and K0.25V2O5 with tunnel structure can maintain a stable structure and are conducive to the faster zinc ion diffusion during repeated cycles compared to the layered KV3O8 and K2V6O16·1.57H2O that suffer from structural collapse. The optimal K2V8O21 cathode exhibits excellent zinc storage performance, with a high capacity of 247 mA h g−1 at 0.3 A g−1 and a good rate at 6 A g−1 as well as excellent cyclic stability up to 300 cycles. The results suggest K2V8O21 is a very promising cathode for aqueous ZIBs, which could be extended to construct other high-performance cathode materials with a similar crystal structure (e.g. β-Na0.33V2O5, Li0.3V2O5, Ag0.33V2O5, etc.) for zinc storage.

Aqueous rechargeable zinc ion batteries are promising candidates for grid-scale applications owing to their low cost and high safety. However, they are plagued by the lack of suitable cathode and anode materials. Herein, we report on potassium vanadate (KVO) nanobelts as a promising cathode for an aqueous zinc ion battery, which shows a high discharge capacity of 461 mA h g-1 at 0.2 A g-1 and exhibits a capacity retention of 96.2% over 4000 cycles at 10 A g-1. Furthermore, to enhance the energy efficiency in an aqueous zinc ion battery, a facile and effective method on the anode is demonstrated. The energy efficiency increases from 47.5% for Zn//KVO coupled with the zinc foil anode to 66.5% for AB-Zn//KVO coupled with an acetylene black film improved zinc foil anode at 10 A g-1. The remarkable electrochemical performance makes AB-Zn//KVO a strong candidate for a high-performance aqueous zinc ion battery.

… process, we prepared manganese oxides by annealing manganese-based metal organic … manganese oxides and vanadium oxides in a sensible way. Additionally, binary metal oxides …

… development of aqueous rechargeable zinc-ion batteries (ZIBs) … battery) and alkaline manganese oxide–zinc batteries, even in … as a perfect negative cathode in different secondary and …

… A series of cathode materials are tailored for ZIBs, such as tunnel-type manganese-based oxides, layered vanadium-based oxides with intercalation reactions, transition-metal sulfur …

Phase structure in manganese vanadium oxide is very important for zinc ion battery. This work aims to regulate the phase structure of manganese vanadium oxide from MnV 12 O 31 ·…

… Hydrated vanadates are promising layered cathodes for aqueous zinc-ion batteries. However… study, manganese-ions (Mn 2+ ) and polyaniline are co-inserted into vanadium pentoxide (…

Rechargeable aqueous zinc-metal batteries (ZMBs) are considered as potential energy storage devices for stationary applications. Despite the significant developments in recent years, the performance of ZMBs is still limited due to the lack of advanced cathode materials delivering high capacity and long cycle life. In this work, we report a low-temperature and scalable synthesis method following a surfactant-assisted route for preparing manganese-doped hydrated vanadium oxide (MnHVO-30) and its application as the cathode material for ZMB. The as-prepared material possesses a porous architecture and expanded interlayer spacing. Therefore, the MnHVO-30 cathode offers fast and reversible insertion of Zn2+ ions during the charge/discharge process and delivers 341 mAh g-1 capacity at 0.1 A g-1. Moreover, the MnHVO-30||Zn cell retains 82% of its initial capacity over 1200 stability cycles, which is higher compared to that of the undoped system. Besides, a quasi-solid-state home-made pouch cell with an area of 3.3 × 1.6 cm2 and 3.6 mg cm-2 loading is assembled, achieving 115 mAh g-1 capacity over 100 stability cycles. Therefore, this work provides an easy and attractive way for preparing efficient cathode materials for aqueous ZMBs.

… -cycling cathode materials. In this work, we present an intercalation mechanism-based cathode materials for AZIB, ie the vanadium oxide with pre-intercalated manganese ions and …

… vanadium oxide cathode with high utilization of >90 % has never been realized. A breakthrough is urgently needed to achieve high cathodic capacity of AZIB cathodes … and manganese …

Manganese-based oxide is arguably one of the most well-studied cathode materials for zinc ion battery due to its wide oxidation states, cost-effectiveness, and matured synthesis process. As a result, there are numerous reports that show significant strides in the progress of Mn-based oxides as ZIB cathode. However, ironically, due to the sheer number of Mn-based oxides that have been published in recent years, there remains certain contemplations with regards to the electrochemical performance of each type of Mn-based oxides and their performance comparison among various Mn polymorphs and oxidation states. Thus, to provide a clearer indication of the development of Mn-based oxide, the recent progress in Mn-based oxides as ZIB cathode is summarized systematically in this review. More specifically, we will discuss the (1) classification of Mn-based oxides based on the oxidation states, i.e. , MnO 2 , Mn 3 O 4 , Mn 2 O 3 , and MnO, (2) their respective polymorphs, i.e. , a-MnO 2 and δ-MnO 2 , as ZIB cathode, (3) the modification strategies commonly employed to enhance the performance, and the (4) effects of these modification strategies on the performance enhancement. Lastly, perspectives and outlook of Mn-based oxides as ZIB cathode are discussed at the end of this review.

The newly emerging rechargeable batteries beyond lithium‐ion, including aqueous and nonaqueous Na‐/K‐/Zn‐/Mg‐/Ca‐/Al‐ion batteries, are rapidly developing toward large‐scale energy storage application. The properties of electrode materials are determinant for electrochemical performance of the batteries. By virtue of the prominent features of low cost, non‐toxicity, high voltage, and rich valence states, Mn‐based electrode materials have attracted increasing attention. The big family of Mn‐based materials with rich composition and polymorphs, provides great possibilities for exploring and designing advanced electrode materials for these emerging rechargeable batteries. In this review, three main categories of Mn‐based materials, including oxides, Prussian blue analogous, and polyanion type materials, are systematically introduced to offer a comprehensive overview about the development and applications of Mn‐based materials in various emerging rechargeable battery systems. Their crystal structure, electrochemical performance, and reaction mechanism are highlighted. In addition, the key issues encountered by many Mn‐based materials, including Jahn–Teller distortion, Mn dissolution, crystal water, impact of electrolyte, etc., are also discussed. Finally, challenges and perspectives on the future development of manganese‐based materials are provided as well. It is believed this review is timely and important to further promote exploration and applications of Mn‐based materials in both aqueous and nonaqueous rechargeable battery systems beyond lithium‐ion.

Manganese oxides (MnO2) are promising cathode materials for various kinds of battery applications, including Li‐ion, Na‐ion, Mg‐ion, and Zn‐ion batteries, etc., due to their low‐cost and high‐capacity. However, the practical application of MnO2 cathodes has been restricted by some critical issues including low electronic conductivity, low utilization of discharge depth, sluggish diffusion kinetics, and structural instability upon cycling. Preintercalation of ions/molecules into the crystal structure with/without structural reconstruction provides essential optimizations to alleviate these issues. Here, the intrinsic advantages and mechanisms of the preintercalation strategy in enhancing electronic conductivity, activating more active sites, promoting diffusion kinetics, and stabilizing the structural integrity of MnO2 cathode materials are summarized. The current challenges related to the preintercalation strategy, along with prospects for the future research and development regarding its implementation in the design of high‐performance MnO2 cathodes for the next‐generation batteries are also discussed.

Multivalent metal‐ion (Mg2+, Zn2+, Ca2+, Al3+) batteries emerge as promising alternatives to current lithium‐ion batteries (LIBs) for grid‐scale energy storage applications because of their high safety and low cost. The bright prospect of these batteries encourages increasing research interests in recent years, hence inspirational achievements have been made over the years. Like in LIB, cathode is the most important component that determines the performance of multivalent metal‐ion batteries. Nevertheless, the development of cathode materials still faces realistic challenges, including sluggish solid‐state diffusion and slow desolvation process at the cathode/electrolyte interface. Herein, recent progresses in intercalation cathode materials for multivalent metal‐ion batteries, including vanadium and manganese oxides and their derivatives, chalcogenides, polyanions frameworks, carbon materials, MOFs (or COFs) and Mxenes are summarized. The discussions focus on the rational design and engineering of structure, morphology, and surface texture of these cathodes with the aim of revealing the material design principles for multivalent metal‐ion storage. We hope this critical review will provide the readers with a clear understanding of current status and future research directions of intercalation cathodes for multivalent metal‐ion batteries.

… cathode is unlikely in the aqueous system; rather, the charge storage process is dominated by proton intercalation … a completely different mechanism featuring H + intercalation into MnO …

The ever-increasing demand for high-energy-density electrochemical energy storage has been driving research on the electrochemical degradation mechanisms of high-energy cathodes, among which manganese-based layered oxide (MLO) cathodes have attracted high...

In the family of Zn/manganese oxide batteries with mild aqueous electrolytes, cubic α‐Mn2O3 with bixbyite structure is rarely considered, because of the lack of the tunnel and/or layered structure that are usually believed to be indispensable for the incorporation of Zn ions. In this work, the charge storage mechanism of α‐Mn2O3 is systematically and comprehensively investigated. It is demonstrated that the electrochemically induced irreversible phase transition from α‐Mn2O3 to layered‐typed L‐ZnxMnO2, coupled with the dissolution of Mn2+ and OH− into the electrolyte, allows for the subsequent reversible de‐/intercalation of Zn2+. Moreover, it is proven that α‐Mn2O3 is not a host for H+. Instead, the MnO2 formed from L‐ZnxMnO2 and the Mn2+ in the electrolyte upon the initial charge is the host for H+. Based on this electrode mechanism, combined with fabricating hierarchically structured mesoporous α‐Mn2O3 microrod array material, an unprecedented rate capability with 103 mAh g−1 at 5.0 A g−1 as well as an appealing stability of 2000 cycles (at 2.0 A g−1) with a capacity decay of only ≈0.009% per‐cycle are obtained.

Abstract The Mn dissolution is a key issue in the application of high-energy-density manganese-based materials, but the use of Mn dissolution to unlock the electrochemical activity of electrode materials is rarely achieved. Here, an in-situ electrochemical approach has been developed for the activation of MnO by inducing Mn-defect, wherein the Mn defects are formed through a charge process that converts the MnO with poor electrochemical activities towards Zn2+ into high electrochemically active cathode for aqueous zinc-ion batteries (ZIBs). More importantly, this cathode exhibits an insertion/extraction mechanism without structural collapse during storage/release of Zn2+. The as-designed Zn/MnO battery delivers a high energy density of 383.88 Wh kg−1 at a power density of 135.6 W kg−1. The results demonstrate that the Mn-defect MnO would be a promising cathode for aqueous ZIBs, which is expected to be used in commercial large-scale energy storage. This work may pave the way for the possibility of using defect chemistry to introduce novel properties in electrode materials for high-performance aqueous ZIBs.

Manganese-based materials are considered as one of the most promising cathodes in zinc-ion batteries (ZIBs) for large-scale energy storage applications owing to their cost-effectiveness, natural availability, low toxicity, multivalent states, high operation voltage, and satisfactory capacity. However, their intricate energy storage mechanisms coupled with unsatisfactory cycling stability hinder their commercial applications. Previous reviews have primarily focused on optimization strategies for achieving high capacity and fast reaction kinetics, while overlooking capacity fluctuation and lacking a systematic discussion on strategies to enhance the cycling stability of these materials. Thus, in this review, the energy storage mechanisms of manganese-based ZIBs with different structures are systematically elucidated and summarized. Next, the capacity fluctuation in manganese-based ZIBs, including capacity activation, degradation, and dynamic evolution in the whole cycle calendar are comprehensively analyzed. Finally, the constructive optimization strategies based on the reaction chemistry of one-electron and two-electron transfers for achieving durable cycling performance in manganese-based ZIBs are proposed.

… -intercalation 13 and reduction-displacement, 14 have also been reported. These mechanisms were explained for oxide cathodes based on … -intercalation reaction, two Zn intercalation …

ConspectusAs the world transitions away from fossil fuels, energy storage, especially rechargeable batteries, could have a big role to play. Though rechargeable batteries have dramatically changed the energy landscape, their performance metrics still need to be further enhanced to keep pace with the changing consumer preferences along with the increasing demands from the market. For the most part, advances in battery technology rely on the continuing development of materials science, where the development of high-performance electrode materials helps to expand the world of battery innovation by pushing the limits of performance of existing batteries. This is where vanadium-based compounds (V-compounds) with intriguing properties can fit in to fill the gap of the current battery technologies.The history of experimenting with V-compounds (i.e., vanadium oxides, vanadates, vanadium-based NASICON) in various battery systems, ranging from monovalent-ion to multivalent-ion batteries, stretches back decades. They are fascinating materials that display rich redox chemistry arising from multiple valency and coordination geometries. Over the years, researchers have made use of the inherent ability of vanadium that undergoes metamorphosis between different coordination polyhedra accompanied by transitions in the oxidation state for reversible intercalation/insertion of more than one guest ions without breaking the structure apart. Such infinitely variable properties endow them with a wide range of electronic and crystallographic structures. The former attribute varies from insulators to metallic conductors while the latter feature gives rise to layered structures or 3D open tunnel frameworks that allow facile movement of a wide range of metal cations and guest species along the gallery. Accompanied by a growing stringent requirements for energy storage applications, most V-compounds face difficulty in resolving the problems of their own lack competitiveness mostly due to their intrinsically low ionic/electronic conductivity. The key to producing vanadium-based electrodes with the desired performance characteristics is the ability to fabricate and optimize them consistently to realize certain specifications through effective engineering strategies for property modulation.In this Account, we aim to provide a comprehensive article that correlates the fundamental of charge storage mechanism to crystallographic forms and design principle for V-compounds. More importantly, the essential roles played by engineering strategies in the property modulation of V-compounds are pinpointed to further explain the rationale behind their anomalous behavior. Apart from that, we further summarize the key theoretical and experimental results of some representative examples for tuning of properties. On the other hand, advances in characterization techniques are now sufficiently mature that they can be relied upon to understand the reaction mechanism of V-compounds by tracing real-time transformation and structural changes at the atomic scale during their working state. The mechanistic insights covered in this Account could be used as a fundamental guidance for several key strategies in electrode materials design in terms of dimension, morphology, composition, and architecture that govern the rate and degree of chemical reaction.

… vanadium-based cathode materials for multivalent batteries and highlight the intercalation mechanism of multivalent ions to vanadium-based … of vanadium-based cathode materials in …

… In the research concerning the structural evolution of electrode materials of aqueous ZIBs … of the Na 2 V 6 O 16 ·2.74H 2 O cathode. The synergistic intercalation kinetics of Zn 2+ and H + …

Abstract Zn-ion batteries (ZIBs) have gained great attention as promising next-generation power sources, because of their low cost, enviable safety, and high theoretical capacity. Recently, massive researches have been devoted to vanadium-based materials as cathodes in ZIBs, owing to their multiple valence states, competitive gravimetric energy density, but the capacity degradation, sluggish kinetics, low operating voltage hinder further optimization of their performance in ZIBs. This review summarizes recent progress to increase the interlayer spacing, structural stability, and the diffusion ability of the guest Zn ions, including the insertion of different ions, introduction of defects, design of diverse morphologies, the combination of other materials. We also focus on approaches to promoting the valuable performance of vanadium-based cathodes, along with the related ongoing scientific challenges and limitations. Finally, the future perspectives and research directions of vanadium-based aqueous ZIBs are provided.

… Nevertheless, the rapid capacity decay attributed to the structural deterioration and by-… Herein, we prepared a flexible self-supported hybrid cathode material VGS-811, composed …

Aqueous Zn‐ion battery systems (AZIBs) have emerged as the most dependable solution, as demonstrated by successful systematic growth over the past few years. Cost effectivity, high performance and power density with prolonged life cycle are some major reason of the recent progress in AZIBs. Development of vanadium‐based cathodic materials for AZIBs has appeared widely. This review contains a brief display of the basic facts and history of AZIBs. An insight section on zinc storage mechanism ramifications is given. A detailed discussion is conducted on features of high‐performance and long life‐time cathodes. Such features include design, modifications, electrochemical and cyclic performance, along with stability and zinc storage pathway of vanadium based cathodes from 2018 to 2022. Finally, this review outlines obstacles and opportunities with encouragement for gathering a strong conviction for future advancement in vanadium‐based cathodes for AZIBs.

"Three-in-one" strategy: Co2+ pre-intercalation synergizing with polyaniline molecular engineering for enhanced diffusion kinetics and structural stability of vanadium-based cathodes - …

… Herein, open-structured ferric vanadate (Fe 2 V 4 O 13 ) has been developed as cathode material for aqueous zinc-ion batteries. Intriguingly, two zinc ion storage mechanism can be …

Aqueous rechargeable metal batteries are intrinsically safe due to the utilization of low-cost and non-flammable water-based electrolyte solutions. However, the discharge voltages of these electrochemical energy storage systems are often limited, thus, resulting in unsatisfactory energy density. Therefore, it is of paramount importance to investigate alternative aqueous metal battery systems to improve the discharge voltage. Herein, we report reversible manganese-ion intercalation chemistry in an aqueous electrolyte solution, where inorganic and organic compounds act as positive electrode active materials for Mn2+ storage when coupled with a Mn/carbon composite negative electrode. In one case, the layered Mn0.18V2O5·nH2O inorganic cathode demonstrates fast and reversible Mn2+ insertion/extraction due to the large lattice spacing, thus, enabling adequate power performances and stable cycling behavior. In the other case, the tetrachloro-1,4-benzoquinone organic cathode molecules undergo enolization during charge/discharge processes, thus, contributing to achieving a stable cell discharge plateau at about 1.37 V. Interestingly, the low redox potential of the Mn/Mn2+ redox couple vs. standard hydrogen electrode (i.e., −1.19 V) enables the production of aqueous manganese metal cells with operational voltages higher than their zinc metal counterparts. Multivalent metal batteries are considered a viable alternative to Li-ion batteries. Here, the authors report a novel aqueous battery system when manganese ions are shuttled between an Mn metal/carbon composite anode and inorganic or organic cathodes.

2D ion‐intercalated metal oxides are emerging promising new electrodes for supercapacitors because of their unique layered structure as well as distinctive electronic properties. To facilitate their application, fundamental study of the charge storage mechanism is required. Herein, it is demonstrated that the application of in situ Raman spectroscopy and electrochemical quartz crystal microbalance with dissipation monitoring (EQCM‐D), provides a sufficient basis to elucidate the charge storage mechanism in a typical 2D cation‐intercalated manganese oxide (Na0.55Mn2O4·1.5H2O, abbreviated as NMO) in neutral and alkaline aqueous electrolytes. The results reveal that in neutral Na2SO4 electrolytes, NMO mainly displays a surface‐controlled pseudocapacitive behavior in the low potential region (0–0.8 V), but when the potential is higher than 0.8 V, an intercalation pseudocapacitive behavior becomes dominant. By contrast, NMO shows a battery‐like behavior associated with OH− ions in alkaline NaOH electrolyte. This study verifies that the charge storage mechanism of NMO strongly depends on the type of electrolyte, and even in the same electrolyte, different charging behaviors are revealed in different potential ranges which should be carefully taken into account when optimizing the use of the electrode materials in practical energy‐storage devices.

Manganese‐based layered oxide cathodes (MLOCs) have emerged as competitive candidates for high‐performance rechargeable batteries. Building on their success in lithium‐ion batteries (LIBs), MLOCs hold great promise for the rapidly developing field of potassium‐ion batteries (PIBs) due to their low cost, high theoretical capacity, and environmental friendliness. However, several technical challenges, including poor structural stability, multiple phase transitions, and potassium deficiency, have hindered their progress in PIB research. This review provides a comprehensive overview of MLOCs, covering their crystal structures, reaction mechanisms, chemical compositions, and applications in PIBs. More importantly, the study critically analyzes the key challenges impeding their development and discusses potential strategies for overcoming these limitations. Recent advances in MLOC‐based potassium‐ion full cells are also summarized, highlighting their progress and future potential. Finally, the study offers perspectives on the future development of MLOCs in next‐generation energy storage technologies. It is hoped that this review will spark strong interest from both academic and industrial communities, driving further research and accelerating the practical application of MLOCs in high‐performance PIBs.

Sodium‐ion batteries have emerged as promising candidates for next‐generation large‐scale energy storage systems due to the abundance of sodium resources, low solvation energy, and cost‐effectiveness. Among the available cathode materials, vanadium‐based sodium phosphate cathodes are particularly notable for their high operating voltage, excellent thermal stability, and superior cycling performance. However, these materials face significant challenges, including sluggish reaction kinetics, the toxicity of vanadium, and poor electronic conductivity. To overcome these limitations and enhance electrochemical performance, various strategies have been explored. These include morphology regulation via diverse synthesis routes and electronic structure optimization through metal doping, which effectively improve the diffusion of Na+ and electrons in vanadium‐based phosphate cathodes. This review provides a comprehensive overview of the challenges associated with V‐based polyanion cathodes and examines the role of morphology and electronic structure design in enhancing performance. Key vanadium‐based phosphate frameworks, such as orthophosphates (Na3V2(PO4)3), pyrophosphates (NaVP2O7, Na2(VO)P2O7, Na7V3(P2O7)4), and mixed phosphates (Na7V4(P2O7)4PO4), are discussed in detail, highlighting recent advances and insights into their structure–property relationships. The design of cathode material morphology offers an effective approach to optimizing material structures, compositions, porosity, and ion/electron diffusion pathways. Simultaneously, electronic structure tuning through element doping allows for the regulation of band structures, electron distribution, diffusion barriers, and the intrinsic conductivity of phosphate compounds. Addressing the challenges associated with vanadium‐based sodium phosphate cathode materials, this study proposes feasible solutions and outlines future research directions toward advancement of high‐performance vanadium‐based polyanion cathodes.

Sodium-ion batteries have become good candidates for energy storage technology. For this purpose it is crucial to search for and optimize new electrode and electrolyte materials. Sodium vanadium fluorophosphates are considered promising cathodes but further studies are required to elucidate their electrochemical and structural behavior. Therefore, this work focuses on the time-resolved in situ synchrotron X-ray powder diffraction study of Na3V2O2x(PO4)2F3−2x (x = 0.8) while electrochemically cycling. Reaction mechanism evolution, lattice parameters and sodium evolution, and the maximum possible sodium extraction under the applied electrochemical constraints, are some of the features that have been determined for both a fresh and an offline pre-cycled cell. The reaction mechanism evolution undergoes a solid solution reaction with a two-phase region for the first lower-potential plateau while a predominantly solid solution behavior is observed for the second higher-potential plateau. Lattice and volume evolution is clearly dependent on the Na insertion/extraction mechanism, the sodium occupancy and distribution amongst the two crystallographic sites, and the electrochemical cycling history. The comparison between the fresh and the pre-cycled cell shows that there is a Na site preference depending on the cell and history and that Na swaps from one site to the other during cycling. This suggests sodium site occupancy and mobility in the tunnels is interchangeable and fluid, a favorable characteristic for a cathode in a sodium-ion battery.