Proton Insertion Chemistry of a Zinc–Organic Battery

Proton storage in rechargeable aqueous zinc-ion batteries (ZIBs) is attracting extensive attention owing to the fast kinetics of H⁺ insertion/extraction. However, it has not been achieved in organic materials-based ZIBs with a mild electrolyte. Now, aqueous ZIBs based on diquinoxalino [2,3-a:2′,3′-c] phenazine (HATN) in a mild electrolyte are developed. Electrochemical and structural analysis confirm for the first time that such Zn–HATN batteries experience a H⁺ uptake/removal behavior with highly reversible structural evolution of HATN. The H⁺ uptake/removal endows the Zn–HATN batteries with enhanced electrochemical performance. Proton insertion chemistry will broaden the horizons of aqueous Zn–organic batteries and open up new opportunities to construct high-performance ZIBs.     

Design Strategies for High-Performance Aqueous Zn/Organic Batteries

Organic electroactive compounds are attractive to serve as the cathode materials of aqueous zinc-ion batteries (ZIBs) because of their resource renewability, environmentally friendliness and structural diversity. Up to now, various organic electrode materials have been developed and different redox mechanisms are observed in aqueous Zn/organic battery systems. In this Minireview, we present the recent developments in the energy storage mechanisms and design of the organic electrode materials of aqueous ZIBs, including carbonyl compounds, imine compounds, conductive polymers, nitronyl nitroxides, organosulfur polymers and triphenylamine derivatives. Furthermore, we highlight the design strategies to improve their electrochemical performance in the aspects of specific capacity, output voltage, cycle life and rate capability. Finally, we discuss the challenges and future perspectives of aqueous Zn/organic batteries.     

V-MOF@graphene derived two-dimensional hierarchical V2O5@graphene as high-performance cathode for aqueous zinc-ion batteries

Rechargeable aqueous zinc-ion batteries (ZIBs) are attracting growing attention in the field of grid-scale energy storage systems due to their reliable safety and low cost. However, it is still hindered by the limited choices of suitable cathode materials with high performance for aqueous ZIBs. Herein, we developed a V-MOF@graphene derived two-dimensional hierarchical V₂O₅@graphene for the first time, where the porous V₂O₅ nanosheets are homogeneously attached to the 2D graphene substrate. Benefiting from the unique 2D composite structure with excellent electronic and ionic conductivity, adequate active sites, as well as the synergistic effect between the ultrathin V₂O₅ nanosheets and graphene, the V₂O₅@graphene here exhibits outstanding electrochemical performance in aqueous ZIBs. Particularly, it delivered an ultrahigh reversible capacity of 378 mAh/g at a current density of 2 A/g. What is more, a high specific capacity of 305 mAh/g after 100 cycles at 0.1 A/g and 200 mAh/g after 1,000 cycles at 1 A/g can be achieved. These ideal results suggest that the V₂O₅@graphene cathode hold great promise for high-performance aqueous zinc-ion batteries.     

Interfacial parasitic reactions of zinc anodes in zinc ion batteries:Underestimated corrosion and hydrogen evolution reactions and their suppression strategies

Featured with high power density,improved safety and low-cost,rechargeable aqueous zinc-ion batteries(ZIBs) have been revived as possible candidates for sustainable energy storage systems in recent years.However,the challenges inherent in zinc(Zn) anode,namely dendrite formation and interfacial parasitic reactions,have greatly impeded their practical application.Whereas the critical issue of dendrite formation has attracted widespread concern,the parasitic reactions of Zn anodes with mildly acidic electrolytes have received very little attentions.Considering that the low Zn reversibility that stems from interfacial parasitic reactions is the major obstacle to the commercialization of ZIBs,thorough understanding of these side reactions and the development of correlative inhibition strategies are significant.Therefore,in this review,the brief fundamentals of corrosion and hydrogen evolution reactions at Zn surface is presented.In addition,recent advances and research efforts addressing detrimental side reactions are reviewed from the perspective of electrode design,electrode-electrolyte interfacial engineering and electrolyte modification.To facilitate the future researches on this aspect,perspectives and suggestions for relevant investigations are provided lastly.     

电解液调控策略提升水系锌离子电池正极材料电化学性能

水系锌离子电池(ZIBs)因安全性高、成本低、环境友好,以及负极锌高的理论容量(820 mAh·g^-1)和低的氧化还原电位(-0.76 V vs.SHE)等优点而受到研究者们的广泛关注,有望应用于大规模储能领域,但循环寿命仍是限制其规模化应用的瓶颈之一。通过电解液优化调控策略,可有效抑制正极材料的溶解、结构坍塌和界面副反应等问题,从而提高水系ZIBs的电化学性能。本文综述了电解液调控策略提升水系ZIBs正极材料电化学性能的研究进展,讨论了该策略所解决的具体问题和局限性,并对电解液体系的发展方向进行了展望。     

Thermal-Gated Polymer Electrolytes for Smart Zinc-Ion Batteries

Smart self-protection is essential for addressing safety issues of energy-storage devices. However, conventional strategies based on sol-gel transition electrolytes often suffer from unstable self-recovery performance. Herein, smart separators based on thermal-gated poly(N-isopropylacrylamide) (PNIPAM) hydrogel electrolytes were developed for rechargeable zinc-ion batteries (ZIBs). Such PNIPAM-based separators not only display a pore structure evolution from opened to closed states, but also exhibit a surface wettability transition from hydrophilic to hydrophobic behaviors when the temperature rises. This behavior can suppress the migration of electrolyte ions across the separators, realizing the self-protection of ZIBs at high temperatures. Furthermore, the thermal-gated behavior is highly reversible, even after multiple heating/cooling cycles, because of the reversibility of temperature-dependent structural evolution and hydrophilic/hydrophobic transition. This work will pave the way for designing thermal-responsive energy-storage devices with safe and controlled energy delivery.     

Design Strategies for Vanadium‐based Aqueous Zinc‐Ion Batteries

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.     

Realizing high-voltage aqueous zinc-ion batteries with expanded electrolyte electrochemical stability window

Aqueous zinc-ion batteries(AZIBs) have aroused significant research interest around the world in the past decade. The use of low-cost aqueous electrolytes and a metallic Zn anode with a suitable redox potential and high energy density make AZIBs a potential alternative to commercial Li-ion batteries in the development of next-generation batteries. However, owing to the narrow electrochemical stability window(ESW) of aqueous electrolytes, the choice of cathode materials is limited, because of whi...     

Cathodes for Aqueous Zn-Ion Batteries: Materials,Mechanisms, and Kinetics

As concerns about the safety of lithium-ions batteries (LIBs) increases, aqueous zinc-ion batteries (ZIBs) with a lower cost, higher safety, and higher co-efficiency have attracted more and more interest. However, finding suitable cathode materials is still an urgent problem in ZIBs. In recent years, a lot of significant works have been reported, including manganese-based cathodes, vanadium-based cathodes, Prussian blue analog-based materials, and sustainable quinone cathodes. In this review, some typical cathode materials are introduced. The detailed storage mechanisms and methods for improving the reaction kinetics of the zinc ions are summarized. Finally, the issues, challenges, and the research directions are provided.     

客体预嵌策略提升水系锌离子电池正极材料电化学性能

随着人们对电子通讯器件、新能源汽车以及电网级储能技术的需求日益增长,开发安全、高效且兼具环保、低成本等优点的二次电池显得至关重要。近年来,水系锌离子电池因其高安全性、高容量、低成本以及环境友好等优点受到了广泛关注。在与锌负极相匹配的众多正极材料中,具有多电子转移特性的钒基和锰基材料表现出了广阔的应用前景。然而这些正极材料在电池循环过程通常面临着结构坍塌、组分溶解、衍生副反应、反应动力学缓慢等问题,严重制约了其商业化进程。近年来,大量研究表明,客体离子或分子预嵌正极宿主结构可以有效缓解上述问题,提升水系锌离子电池正极材料的电化学性能。本文综述了客体预嵌策略应用于水系锌离子电池钒、锰基正极材料的研究进展,对该策略所解决的问题以及其局限性进行了讨论和总结,并对未来水系锌离子电池钒基和锰基正极材料的研究发展方向进行了展望。     

Manganese-based cathode materials for aqueous rechargeable zinc-ion batteries: recent advance and future prospects

Zinc-ion batteries (ZIBs), which use mild aqueous electrolyte, have attracted increasing attention, due to their unique advantages such as low cost, high safety, environmental friendliness, and ease of manufacture. At present, developing a kind of cathode materials with stable structures and large capacities for ZIBs is a hot research topic. Among all ZIBs cathode materials, manganese-based cathode materials have the advantages of low cost, abundant reserves, low toxicity, rich valence states, and high zinc storage capacity, which make them one of the most promising candidates. In recent years, manganese-based composites with different crystal structures have been extensively studied as cathode materials of ZIBs. In this paper, the reaction mechanism of ZIBs cathodes is discussed in detail, and the challenges faced by manganese-based cathode materials and the latest research progress are examined deeply. In addition, a number of optimization strategies aimed at improving the electrochemical performance of the cathode of ZIBs are outlined. Finally, the future prospect of ZIBs is presented.     

Highly stable aqueous rechargeable Zn-ion battery: The synergistic effect between NaV_6O_(15) and V_2O_5 in skin-core heterostructured nanowires cathode

The aqueous rechargeable Zn-ion batteries based on the safe,low cost and environmental benignity aqueous electrolytes are one of the most compelling candidates for large scale energy storage applications.However,pursuing suitable insertion materials may be a great challenge due to the strong electrostatic interaction between Zn^{^(2+})and cathode materials.Hence,a novel NaV₆O₁₅/V₂O₅ skin-core heterostructure nanowire is reported via a one-step hydrothermal method and subsequent calcination for high-stable aqueous Zn-ion batteries(ZIBs).The NaV₆O₁₅/V₂O₅ cathode delivers high specific capacity of 390 m Ah/g at 0.3 A/g and outstanding cycling stability of 267 m Ah/g at 5 A/g with high capacity retention over 92.3%after 3000 cycles.The superior electrochemical performances are attributed to the synergistic effect of skin-core heterostructured NaV₆O₁₅/V₂O₅,in which the sheath of NaV₆O₁₅ possesses high stability and conductivity,and the V₂O₅ endows high specific capacity.Besides,the heterojunction structure not only accelerates intercalation kinetics of Zn²⁺transport but also further consolidates the stability of the layers of V₂O₅ during the cyclic process.This work provides a new perspective in developing feasible insertion materials for rechargeable aqueous ZIBs.     

Tuning the layer structure of molybdenum trioxide towards high-performance aqueous zinc-ion batteries

Aqueous zinc-ion batteries (ZIBs) have attracted significant attentions because of low cost and high reliability. However, conventional ZIBs are severely limited by the development of high energy density cathode materials with reversible Zn²⁺ insertion/extraction. Herein, a conducting polymer intercalated MoO₃ (PMO) with extensively extended interlayer spacing is developed as a high-performance ZIBs cathode material. The interlayer spacing of PMO is prominently increased which results in an improved Zn²⁺ mobility during charge and discharge process. More significantly, the electrochemical results reveals that the intercalation of PANI facilitates the charge storage and reinforces the layered structure of MoO₃, leading to a high capacity and good cycling stability. DFT calculation further reveals the intercalation of PANI into MoO₃ significantly lower Zn²⁺ diffusion barrier. Benefit from these advantages, the ZIBs based on PMO electrode delivers a considerable capacity of 157 mAh/g at 0.5 A/g and ameliorative stability with 63.4% capacity retention after 1000 cycles.     

Reversible Oxygen Redox Chemistry in Aqueous Zinc‐Ion Batteries

Rechargeable aqueous zinc‐ion batteries (ZIBs) are promising energy‐storage devices owing to their low cost and high safety. However, their energy‐storage mechanisms are complex and not well established. Recent energy‐storage mechanisms of ZIBs usually depend on cationic redox processes. Anionic redox processes have not been observed owing to the limitations of cathodes and electrolytes. Herein, we describe highly reversible aqueous ZIBs based on layered VOPO₄ cathodes and a water‐in‐salt electrolyte. Such batteries display reversible oxygen redox chemistry in a high‐voltage region. The oxygen redox process not only provides about 27 % additional capacity, but also increases the average operating voltage to around 1.56 V, thus increasing the energy density by approximately 36 %. Furthermore, the oxygen redox process promotes the reversible crystal‐structure evolution of VOPO₄ during charge/discharge processes, thus resulting in enhanced rate capability and cycling performance.     

Proton Insertion Chemistry of a Zinc–Organic Battery

Proton storage in rechargeable aqueous zinc‐ion batteries (ZIBs) is attracting extensive attention owing to the fast kinetics of H⁺ insertion/extraction. However, it has not been achieved in organic materials‐based ZIBs with a mild electrolyte. Now, aqueous ZIBs based on diquinoxalino [2,3‐a:2′,3′‐c] phenazine (HATN) in a mild electrolyte are developed. Electrochemical and structural analysis confirm for the first time that such Zn–HATN batteries experience a H⁺ uptake/removal behavior with highly reversible structural evolution of HATN. The H⁺ uptake/removal endows the Zn–HATN batteries with enhanced electrochemical performance. Proton insertion chemistry will broaden the horizons of aqueous Zn–organic batteries and open up new opportunities to construct high‐performance ZIBs.     

High-energy aqueous rechargeable batteries based on WSe2 nano-flower cathode

Journal of Solid State Electrochemistry - “Rocking-chair” zinc-ion batteries (ZIBs) are potential commercial energy storage devices because of their high energy density and safety....     

Electrochemically Induced Metal–Organic-Framework-Derived Amorphous V2O5 for Superior Rate Aqueous Zinc-Ion Batteries

The electrochemical performance of vanadium-oxide-based cathodes in aqueous zinc-ion batteries (ZIBs) depends on their degree of crystallinity and composite state with carbon materials. An in situ electrochemical induction strategy was developed to fabricate a metal–organic-framework-derived composite of amorphous V₂O₅ and carbon materials (a-V₂O₅@C) for the first time, where V₂O₅ is in an amorphous state and uniformly distributed in the carbon framework. The amorphous structure endows V₂O₅ with more isotropic Zn²⁺ diffusion routes and active sites, resulting in fast Zn²⁺ transport and high specific capacity. The porous carbon framework provides a continuous electron transport pathway and ion diffusion channels. As a result, the a-V₂O₅@C composites display extraordinary electrochemical performance. This work will pave the way toward design of ZIB cathodes with superior rate performance.     

Improved Reversible Zinc Storage Achieved in a Constitutionally Crystalline-Stable Mn(VO3)2 Nanobelts Cathode

Rechargeable zinc-ion batteries (ZIBs) are potential for grid-scale applications owing to their safety, low price, and available sources. The development of ZIBs cathode with high specific capacity, wide operating voltage window and stable cyclability is urgently needed in next-generation commercial batteries. Herein, we report a structurally crystalline-stable Mn(VO₃)₂ nanobelts cathode for ZIBs prepared via a facile hydrothermal method. The as-synthesized Mn(VO₃)₂ exhibited high specific capacity of 350 mAh g⁻¹ at 0.1 A g⁻¹, and maintained a capacity retention of 92 % after 10,000 cycles at 2 A g⁻¹. It also showed good rate performance and obtained a reversible capacity of up to 200 mAh g⁻¹ after 600 cycles at 0.2 A g⁻¹ under −20 °C. The electrochemical tests suggest that Mn(VO₃)₂ nanobelts impart fast Zn²⁺ ions migration, and the introduction of manganese atoms help make the structures more indestructible, leading to a good rate performance and prolonged cycle lifespan.     

A bi-component polyoxometalate-derivative cathode material showed impressive electrochemical performance for the aqueous zinc-ion batteries

Rechargeable aqueous zinc-ion batteries are recently gaining incremental attention because of low cost and material abundance, but their development is plagued by limited choices of cathode materials with satisfactory cycling performance. The polyoxometalates perform formidable redox stability and able to participate in multi-electron transfer, which was well-suited for energy storage. Herein, a bi-component polyoxometalate-derivative KNiVO (K₂[Ni(H₂O)₆]₂[V₁₀O₂₈]·4H₂O polyoxometalates after annealing) is firstly demonstrated as a cathode material for aqueous ZIBs. The layered KV₃O₈ (KVO) In the bi-component material constitutes Zn²⁺ migration and storage channels (K⁺ were substantially replaced by Zn²⁺ in the activation phase), and the three-dimensional NiV₃O₈ (NiVO) part acts as skeleton to stabilize the ion channels, which assist the cell to demonstrate a high-rate capacity and specific energy of 229.4 mAh/g and satisfactory cyclability (capacity retention of 99.1% after 4500 cycles at a current density of 4 A/g). These results prove the feasibility of POM as cathode materials precursor and put forward a novel pattern of the Zn²⁺ storage mechanism in the activated-KNiVO clusters, which also provide a new route for selecting or designing high-performance cathode for aqueous ZIBs and other advanced battery systems.     

Water-in-salt electrolytes for high voltage aqueous electrochemical energy storage devices

If were not by their low electrochemical stability, aqueous electrolytes would be the preferred alternative to be used in electrochemical energy storage devices. Their abundance and nontoxicity are key factors for such application, especially in large scale. The development of highly concentrated aqueous electrolytes, so-called water-in-salt electrolytes, has expanded the electrochemical window of aqueous electrolyte up to 3.0 V (whereas salt-in-water electrolytes normally shows up to 1.6 V), showing that water can be an alternative after all. Many devices, ranging from metal-ion batteries to electrochemical capacitors, have been reported recently, making use of such wider electrochemical stability and enhancing devices energy density. Different salts have also been proposed not only to gain in costs but also to improve physicochemical properties.