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.     

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.     

Recent advances of vanadium-based cathode materials for zinc-ion batteries

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.     

Recent Advances in Graphene-Based Materials for Zinc-Ion Batteries

Zinc-ion batteries (ZIBs) are a promising alternative for large-scale energy storage due to their advantages of environmental protection, low cost, and intrinsic safety. However, the utilization of their full potential is still hindered by the sluggish electrode reaction kinetics, poor structural stability, severe Zn dendrite growth, and narrow electrochemical stability window of the whole battery. Graphene-based materials with excellent physicochemical properties hold great promise for addressing the above challenges foe ZIBs. In this review, the energy storage mechanisms and challenges faced by ZIBs are first discussed. Key issues and recent progress in design strategies for graphene-based materials in optimizing the electrochemical performance of ZIBs (anode, cathode, electrolyte, separator and current collector) are then discussed. Finally, some potential challenges and future research directions of graphene-based materials in high-performance ZIBs are proposed for practical applications.     

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.     

聚吡咯@二氧化锰/碳纳米管薄膜电极的制备及在高性能锌离子电池中的应用

中性/弱酸性水系锌锰电池因其能量密度高、价格低廉、环境友好等优势受到广泛关注。然而,现有的二氧化锰正极材料存在导电性能差,在充放电过程中易于溶解等问题。这严重影响了电池的倍率性能和循环稳定性,阻碍了中性锌锰电池的应用。为了解决上述问题,本文设计了以碳纳米管(CNT)网络薄膜为导电基底沉积聚吡咯(PPy)包覆二氧化锰(PPy@MnO₂/CNT)的多级结构电极。碳纳米管和聚吡咯组装形成高比表面积的三维交联导电网络,为活性材料提供了快速的电子、离子传输通道;聚吡咯包覆纳米级二氧化锰能够有效地抑制二氧化锰的溶解,进而提升电池的倍率特性和循环稳定性。以PPy@MnO₂/CNT作为正极材料组装的水系锌锰电池在1 A·g^-1的电流密度下,比容量达到210 mAh·g^-1,循环1000圈后,电池依然具有较高的容量保持率(85.7%)。本工作的导电聚合物包覆活性物质的策略可为发展高稳定柔性储能器件提供新思路。     

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.     

Cascading V2O3/N-doped carbon hybrid nanosheets as high-performance cathode materials for aqueous zinc-ion batteries

In recent years, especially when there is increasing concern about the safety issue of lithium-ion batteries（LIBs）, aqueous Zn-ion batteries（ZIBs） have been getting a lot of attention because of their costeffectiveness, materials abundance, high safety, and ecological friendliness. Their working voltage and specific capacity are mainly determined by their cathode materials. Vanadium oxides are promising cathode materials for aqueous ZIBs owing to their low cost, abundant resources, and multivale...     

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。     

Recent Progress in the Electrolytes of Aqueous Zinc-Ion Batteries

Rechargeable aqueous zinc-ion batteries (ZIBs) have garnered tremendous attention in the field of next energy storage devices due to their high safety, low cost, abundant resources, and eco-friendliness. As an important component of the zinc-ion battery, the electrolyte plays a vital role in the electrochemical properties, since it will provide a pathway for the migrations of the zinc ions between the cathode and anode, and determine the ionic conductivity, electrochemically stable potential window, and reaction mechanism. In this Minireview, a brief introduction of electrochemical principles of the aqueous ZIBs is discussed and the recent advances of various aqueous electrolytes for ZIBs, including liquid, gel, and multifunctional hydrogel electrolytes are also summarized. Furthermore, the remaining challenges and future directions of electrolytes in aqueous ZIBs are also discussed, which could provide clues for the following development.     

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。     

Organic Positive Materials for Magnesium Batteries: A Review

Magnesium batteries, like lithium-ion batteries, with higher abundance and similar efficiency, have drawn great interest for large-scale applications such as electric vehicles, grid energy storage and many more. On the other hand, the use of organic electrode materials allows high energy-performance, metal-free, environmentally friendly, versatile, lightweight, and economically efficient magnesium storage devices. In particular, the structural diversity and the simple activity of organic molecules make redox properties, and hence battery efficiency, easy to monitor. While organic magnesium batteries still in their infancy, this field becomes more and more promising because significant results were reported. To summarize the achievements in studies on organic cathodes for magnesium systems, their synthesis is discussed, combined with electrode design to provide the basis for controlling the electrochemical properties. Moreover, the techniques to synthesize organic materials with high-yield are mentioned. Finally, potential problems and prospects are explored to further improve organic cathodes.     

Thermal Stability and Outgassing Behaviors of High-nickel Cathodes in Lithium-ion Batteries

LiNiO₂-based high-nickel layered oxide cathodes are regarded as promising cathode materials for high-energy-density automotive lithium batteries. Most of the attention thus far has been paid towards addressing their surface and structural instability issues brought by the increase of Ni content (>90 %) with an aim to enhance the cycle stability. However, the poor safety performance remains an intractable problem for their commercialization in the market, yet it has not received appropriate attention. In this review, we focus on the gas generation and thermal degradation behaviors of high-Ni cathodes, which are critical factors in determining their overall safety performance. A comprehensive overview of the mechanisms of outgassing and thermal runaway reactions is presented and analyzed from a chemistry perspective. Finally, we discuss the challenges and the insights into developing robust, safe high-Ni cathodes.     

Recent advances in cathodes for all-solid-state lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries have been regarded as the candidate for the next-generation energy storage system due to the high theoretical specific capacity (1675 mAh/g), energy density (2600 Wh/kg) and the abundance of elemental sulfur, but the application of Li-S batteries is impeded by a series of problems. Recently, all-solid-state Li-S batteries (ASSLSBs) have drawn great attention because many drawbacks such as safety issues caused by metallic lithium anodes and organic liquid electrolytes can be overcome through the use of solid-state electrolytes (SEs). However, not only the problems brought by sulfur cathodes still exist, but more trouble arouses from the interfaces between SEs and cathodes, hampering the practical application of ASSLSBs. Therefore, in order to deal with the problems, enormous endeavors have been done on ASSLSB cathodes during the past few decades, including engineering of cathode active materials, cathode host materials, cathode binder materials and cathode structures. In this review, the electrochemical mechanism and existing problems of ASSLSBs are briefly introduced. Subsequently, the strategies for developing cathode materials and designing cathode structures are presented. Then there follows a brief discussion of SE problems and expectations, and finally, the challenges and perspectives of ASSLSBs are summarized.     

A High-Energy Aqueous All-Sulfur Battery

Rechargeable aqueous batteries are promising energy storage devices because of their high safety and low cost. However, their energy densities are generally unsatisfactory due to the limited capacities of ion-inserted electrode materials, prohibiting their widespread applications. Herein, a high-energy aqueous all-sulfur battery was constructed via matching S/Cu₂S and S/CaS_x redox couples. In such batteries, both cathodes and anodes undergo the conversion reaction between sulfur/metal sulfides redox couples, which display high specific capacities and rational electrode potential difference. Furthermore, during the charge/discharge process, the simultaneous redox of Cu²⁺ ion charge-carriers also takes place and contributes to a more two-electron transfer, which doubles the capacity of cathodes. As a result, the assembled aqueous all-sulfur batteries deliver a high discharge capacity of 447 mAh g⁻¹ based on total mass of sulfur in cathode and anode at 0.1 A g⁻¹, contributing to an enhanced energy density of 393 Wh kg⁻¹. This work will widen the scope for the design of high-energy aqueous batteries.     

关于水系锌离子电池中无氧钒基正极材料的综述

水系锌离子电池具有功率密度高、环境友好、安全性高、低成本和锌资源丰富等优点，被认为具有潜力成为下一代电化学储能系统。然而，正极材料较差的电化学性能制约了水系锌离子电池的未来发展。尽管氧化锰、氧化钒、普鲁士蓝类似物、有机材料等多种材料已被广泛研究，设计具有高性能的理想正极材料仍面临着巨大挑战。无氧钒基化合物由于具有高的电导率、大的层间距、低的离子扩散势垒和高的理论比容量，受到越来越多的关注。本文总结了无氧钒基化合物的研究进展，包括电极材料的设计、改善其电化学性能的有效途径以及复杂的储能机制，提出了无氧钒基化合物目前面临的挑战和未来的发展前景，为进一步制备新型高性能钒基正极材料提供指导。     

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.     

锂离子电池3d 过渡金属氧化物负极微/纳米材料

与传统的碳材料相比,锂离子电池3d 过渡金属氧化物(M_xO_y,M = Co、Fe、Cu、Ni) 负极材料具有更高的容量、倍率及安全性能,更适于锂离子电池在移动电子设备、电动汽车、备用储能和智能电网等领域的应用,因此备受关注。本文介绍了M_xO_y 负极材料的充放电机理,并以零维、一维、二维、三维等纳米结构及空心、核壳等多种微/纳米结构为出发点,详细讨论了过渡金属氧化物电极材料的电化学性能与结构特征之间的关系,分析了具有不同结构特征的负极材料的合成方法;展望了3d 过渡金属氧化物负极微/纳米材料的研究趋势和发展前景。     

电化学储钠材料的研究进展

大规模储能的二次电池不仅需要具有适宜的电化学性能,更需考虑资源、成本和环境效益等应用要求. 锂离子电池储能的大规模应用也将受到制约. 从资源与环境方面考虑,钠离子电池作为储能电池更具应用优势. 然而,从目前的技术现状来看,几类不同的嵌钠正极材料虽显现出可观的嵌钠容量与较好的循环性,但能量密度与功率密度尚待提高. 硬碳材料和合金负极最有希望用于钠离子电池,这类材料的初始充放电效率和循环稳定性仍有待改善. 本文简要分析了锂离子电池与钠离子电池在材料要求方面的差异,回顾了近年来钠离子电池材料探索中的突破性进展,并主要结合本课题组的研究工作讨论了钠离子电池及其关键材料的发展方向.     

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.