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Reversibility of metallic Zn anode serves as the corner stone for the development of aqueous Zn metal battery, which motivates scrutinizing the electrolyte‐Zn interface. As the representative organic zinc salt, zinc trifluorosulfonate (Zn(OTf)2) facilitates a broad class of aqueous electrolytes, however, the stability issue of Zn anode remains crucial. The great challenge lies in the lack of Zn anode protection by the pristinely formed surface structure in aqueous Zn(OTf)2 electrolytes. Accordingly, an electrochemical route was developed to grow a uniform zinc trifluorosulfonate hydroxide (ZTH) layer on Zn anode as an artificial SEI, via regulation on metal dissolution and strong coordination ability of zinc ions. Co‐precipitation was proposed to be the formation mechanism for the artificial SEI, where the reduction stability of OTf− anion and the low‐symmetry layer structure of ZTH was unmasked. This artificial SEI favors interfacial kinetics, depresses side reactions, and well maintains its integrity during cycling, leading to a prolonged lifespan of Zn stripping/plating with a high DOD of ~85 %, and an improved cycling stability of ~92 % retention rate for V2O5/Zn cell at 1 A g−1. The unveiled role of anion on Zn anode drives the contemplation on the surface chemistry for the blooming aqueous rechargeable battery. [ABSTRACT FROM AUTHOR]

Aqueous potassium‐ion batteries (AKIBs) with mild aqueous electrolytes can significantly mitigate the safety and environmental issues raised from traditional nonaqueous batteries, positioning them as promising candidates for grid‐scale applications. Nonetheless, the progression of AKIBs is currently impeded by the insufficient energy density, largely attributed to the limited voltage window of aqueous electrolytes. This review aims to introduce foundational knowledge about aqueous batteries, illustrates recent advancements in AKIBs, and offers valuable perspectives on designing electrode materials and optimizing electrolytes. To provide a systematic overview, the focus is on the following seven key sections: i) development history, ii) electrode materials, iii) electrolyte design, iv) current collectors, v) aqueous interphase chemistry, vi) full cell configurations, and vii) future prospects. Finally, constructive insights and suggestions are provided for the development of AKIBs with higher energy density. [ABSTRACT FROM AUTHOR]

The article delves into the synthesis and characterization of MoS2-carbon-based materials, holding promise for applications in supercapacitors and ion batteries. The synthesis process entails the preparation of MoS2 and its carbon hybrids through exfoliation, hydrothermal treatment, and subsequent pyrolysis. Various analytical techniques were employed to comprehensively examine the structural, compositional, and morphological properties of the resulting materials. The article explores the electrochemical performance of these electrode materials in supercapacitors and ion batteries (LiB, SiB, KiB). Electrochemical measurements were conducted in aqueous electrolyte for supercapacitors and various aprotic electrolytes for ion batteries. Results highlight the impact of the synthesis process on electrochemical performance, emphasizing factors such as capacitance, rate capability, and charge/discharge cycle performance. Hydrothermally treated MoS2-carbon exhibited a specific capacitance of approximately 150 F g-1 in supercapacitors, attributed to its high surface area and efficient charge storage mechanisms. Additionally, for Li-ion battery materials without hydrothermal treatment showed impressive capacity retention of around 88% after 500 charge-discharge cycles, starting with an initial specific capacity of about 920 mAh/g. Long-term stability was demonstrated in both supercapacitors and lithium-ion batteries, with minimal capacitance degradation even after extensive charge-discharge cycles. This research underscores the potential of MoS2-based materials as effective energy storage solutions. [ABSTRACT FROM AUTHOR]

Aqueous rechargeable metal batteries have recently garnered considerable attention owing to their low cost, sufficient capacity, and the use of non‐flammable water‐based electrolytes. Among them, manganese batteries are particularly favored because of their stability, abundance, affordability, and high energy density. Despite their advantages, Mn storage host structures remain underexplored. Therefore, developing innovative host materials is crucial for advancing this field. In this paper, the study reports for the first time, the use of Ag0.33V2O5 as a cathode material in aqueous manganese batteries. The study explains the displacement/intercalation behavior of manganese and silver using electrochemical, structural, and spectroscopic analyses. Additionally, it is shown that cation (Ag+, Mn2+, H+) diffusion pathways can be simulated using diffusion‐barrier calculations. Finally, the study demonstrates high‐performance manganese batteries that exhibit a remarkable reversible capacity of ≈261.9 mAh g−1 at a current of 0.1 A g−1 and an excellent cycle retention of 69.1% after 2000 cycles at a current density of 1.5 A/g. The findings of this study contribute to the advancement of aqueous manganese battery technology, offering a promising pathway for developing safer, more cost‐effective, and high‐performance energy storage systems. [ABSTRACT FROM AUTHOR]

Aqueous zinc-ion batteries (AZIBs) have garnered significant attention in the realm of large-scale and sustainable energy storage, primarily owing to their high safety, low cost, and eco-friendliness. Aqueous electrolytes, serving as an indispensable constituent, exert a direct influence on the electrochemical performance and longevity of AZIBs. Nonetheless, conventional aqueous electrolytes often encounter formidable challenges in AZIB applications, such as the limited electrochemical stability window and the zinc dendrite growth. In response to these hurdles, a series of advanced aqueous electrolytes have been proposed, such as "water-in-salt" electrolytes, aqueous eutectic electrolytes, molecular crowding electrolytes, and hydrogel electrolytes. This comprehensive review commences by presenting an in-depth overview of the fundamental compositions, principles, and distinctive characteristics of various advanced aqueous electrolytes for AZIBs. Subsequently, we systematically scrutinizes the recent research progress achieved with these advanced aqueous electrolytes. Furthermore, we summarizes the challenges and bottlenecks associated with these advanced aqueous electrolytes, along with offering recommendations. Based on the optimization of advanced aqueous electrolytes, this review outlines future directions and potential strategies for the development of high-performance AZIBs. This review is anticipated to provide valuable insights into the development of advanced electrolyte systems for the next generation of stable and sustainable multi-valent secondary batteries. [ABSTRACT FROM AUTHOR]

Designing next‐generation alternative energy storage devices that feature high safety, low cost, and long operation lifespan is of the utmost importance for future wide range of applications. Aqueous zinc‐ion batteries play a vital part in promoting the development of portability, sustainability, and diversification of rechargeable battery systems. Based on the theory of electrolyte solvation chemistry, deep understanding of interaction between electrolyte components and their impact on the chemical properties has achieved a series of research progress. Analyzing the solvation shell of electrolyte or structure–performance relationship, and establishing more stable and high‐energy battery chemistries are inevitable requirements to suppress the electrolyte–electrode interphase side reaction and realize the functional use of zinc‐ion batteries. In this critical review, the attempt is to overview the current comprehension regarding the electrolyte solvation structure in zinc battery technology. Advanced methodology toward the interactions between zinc cations, solvent molecules, and anions in zinc aqueous electrolytes and the general rules for electrolyte design from the atomic level are summarized. Methods for viable solvation modification are then introduced regarding overcoming the remained challenges for transferring the laboratory results to next‐generation practical applications. Possible research direction with the aim of investigating the ultimate choice for future high‐performance electrolyte solvation construction is also outlined. [ABSTRACT FROM AUTHOR]

Zinc ion batteries (ZIBs) are emerging as a promising and cost‐effective alternative energy storage system compared to other metal‐ion batteries. Aqueous electrolytes have been extensively studied in Zn‐ion batteries which has shown issues related to cathode dissolution. In comparison, little has been looked into the use of organic electrolytes in ZIBs. Here, we have studied both protic and aprotic forms of formamide‐based organic electrolytes containing Zn trifluoromethanesulfonate and their influence on the Zn solvation chemistry, electrochemistry, and performance of Zn‐MnO2 battery. It was observed that protic‐based electrolytes gave a much better capacity and stability for the Zn‐MnO2 battery. A capacity close to 150 mAh g−1 was obtained with formamide electrolyte at a current density of 0.25 A g−1. For all the other formamide‐based electrolytes tested, the capacity was lower. After 100 cycles, an average capacity retention of 72 % was obtained for formamide‐based electrolyte. This study shows that protic‐based electrolytes might be a suitable option for non‐aqueous‐based Zn‐ion batteries. [ABSTRACT FROM AUTHOR]

Aqueous zinc ion batteries hold promise as alternative systems to lithium‐based batteries. However, practical development faces critical challenges due to parasitic side reactions and dendrite growth in zinc anodes. While introducing electrolyte additives is promising, monofunctional additives offer limited protection to the zinc anode from a single aspect. Herein, a disodium succinate additive is presented to establish a hydrophobic and zincophilic dual electric layer structure on the Zn surface, regulate the solvation structure of Zn2+, and act as a pH buffer during cycling. As a result, the symmetrical cell with an electrolyte containing 0.2 m SADS shows a durable life of over 2200 h, and the Zn||MnO2 full cell still maintains an 80% capacity retention after 1000 cycles. In addition, SADS both show wide applicability in the match with NVO and I2 cathode. This work provides a low‐cost and multifunctional electrolyte additive, facilitating the development of high‐performance aqueous zinc ion batteries. [ABSTRACT FROM AUTHOR]

A dual-additive-based aqueous electrolyte was designed with a pH-buffering additive (Zn(OAc)2) and an electrostatic shielding additive (TMAOAc) for high Zn plating/stripping efficiency. The buffering pair, OAc−/HOAc, can stabilize the pH value to suppress side hydrogen evolution reactions. Meanwhile, TMA+ acts as a competitive cation being preferentially adsorbed on the uneven surface of the Zn anode and exerts an electrostatic shielding effect to facilitate flat Zn deposition. Such a dual-additive-based electrolyte promotes an ultra-high Zn plating/stripping efficiency of 99.9% at 1 mA cm−2 and long-term cycling stability for 3600 h at 0.5 mA cm−2, offering valuable insights for advanced aqueous batteries. [ABSTRACT FROM AUTHOR]

Organic cathode materials for aqueous rechargeable zinc batteries (ARZBs) are rapidly gaining prominence, while the exploration of compounds with affordable synthesis, satisfactory electrochemical performance, and understandable mechanisms still remains challenging. In this study, 6,8,15,17‐tetraaza‐heptacene‐5,7,9,14,16,18‐hexaone (TAHQ) as an easily synthesized organic cathode material with novel quinone/pyrazine alternately conjugated molecule structure is presented. This organic electrode exhibits good capacity with highly reversible redox reactions, and the influence of multi‐active structures on the Zn2+/H+ loading behavior is systematically investigated by ex situ spectroscopy, electrochemical tests, and computation. Both experimental and theoretical studies effectively address the Zn2+/H+ intercalation/deintercalation kinetics. Benefitting from the fused active functionalities, the assembled Zn//TAHQ battery displays a maximum discharge specific capacity of 254.3 mAh g−1 at 0.5 A g−1, and it maintains remarkable cycle performance with 71% capacity retention after 1000 cycles under 5 A g−1. [ABSTRACT FROM AUTHOR]

Aqueous zinc‐ion batteries (AZIBs) attract attention due to their safety and high specific capacity. However, their practical applications are constrained by Zn anode corrosion, dendritic growth, and poor temperature adaptability induced by a strong hydrogen‐bond network in aqueous electrolytes. Herein, a universal strategy to design strong solvating electrolytes is proposed, in which the hydrogen‐bond network and solvation structures are reconstructed by regulating the dipolar‐dipolar and ion‐dipolar interactions simultaneously. Consequently, the hydrogen‐bond network in free water is largely weakened, and the water content in the Zn2+ solvated sheath is reduced, while the hydrogen‐bond network between solvents is strengthened, which effectively broadens the operating temperature range and suppresses Zn dendrites and corrosion. As a result, Zn anodes exhibit excellent platting/stripping efficiency with an average Coulombic Efficiency up to 99.89% after 2000 cycles at 0.5 mA cm−2, impressive cycling stability (5000 h, 0.5 mA cm−2/0.5 mA h cm−2), and a wide operating temperature range of 140 °C (−50–90 °C). Moreover, the Zn//V2O3 full cells also display enhanced temperature‐resistance, implying that the designed strong solvation electrolyte has practical application potential in extreme environments. This study suggests a promising strategy to design ideal electrolytes for high‐performance AZIBs with safety, ultralong cycling life, and satisfying temperature‐resistance. [ABSTRACT FROM AUTHOR]

Unstable Zn interface with serious detrimental parasitic side‐reactions and uncontrollable Zn dendrites severely plagues the practical application of aqueous zinc‐ion batteries. The interface stability was closely related to the electrolyte configuration and Zn2+ depositional behavior. In this work, a unique Zn‐ion anchoring strategy is originally proposed to manipulate the coordination structure of solvated Zn‐ions and guide the Zn‐ion depositional behavior. Specifically, the amphoteric charged ion additives (denoted as DM), which act as zinc‐ion anchors, can tightly absorb on the Zn surface to guide the uniform zinc‐ion distribution by using its positively charged −NR4+ groups. While the negatively charged −SO3− groups of DM on the other hand, reduces the active water molecules within solvation sheaths of Zn‐ions. Benefiting from the special synergistic effect, Zn metal exhibits highly ordered and compact (002) Zn deposition and negligible side‐reactions. As a result, the advanced Zn||Zn symmetric cell delivers extraordinarily 7000 hours long lifespan (0.25 mA cm−2, 0.25 mAh cm−2). Additionally, based on this strategy, the NH4V4O10||Zn pouch‐cell with low negative/positive capacity ratio (N/P ratio=2.98) maintains 80.4 % capacity retention for 180 cycles. A more practical 4 cm*4 cm sized pouch‐cell could be steadily cycled in a high output capacity of 37.0 mAh over 50 cycles. [ABSTRACT FROM AUTHOR]

Rechargeable aqueous zinc–metal batteries (AZBs) are a promising complimentary technology to the existing lithium‐ion batteries and the re‐emerging lithium–metal batteries to satisfy the increasing demands on energy storage. Despite considerable progress achieved in the past years, the fundamental understanding of the solid‐electrolyte interphase (SEI) formation and how its composition influences the SEI properties are limited. This review highlights the functionalities of anion‐tuned SEI on the reversibility of zinc–metal anode, with a specific emphasis on new structural insights obtained through advanced characterizations and computational techniques. Recent efforts in terms of key variables that govern the interfacial behaviors to improve the long‐term stability of zinc anode, i.e., Coulombic efficiency, plating morphology, dendrite formation, and side‐reactions, are comprehensively reviewed. Lastly, the remaining challenges and future perspectives are presented, providing insights into the rational design of practical high‐performance AZBs. [ABSTRACT FROM AUTHOR]

The effects of current collectors on the battery performance have significant role, especially in aqueous electrolyte Al-ion batteries, as corrosion effects lead to rapid capacity degradation over cycles. To overcome this problem, we present a study investigating the selection of suitable current collectors and their impact on battery performance. Four different current collectors are selected for this. Stainless steel (SS), nickel foil (Ni), titanium foil (Ti) and graphite plate (GP). It has been proven by corrosion tests, cyclic voltammetry and charge-discharge studies that GP is the best current collector by minimizing the corrosion effect and H2 evolution reaction (HER). The anatase phase TiO2 used with GP current collector provides a 249 mAh g−1 initial discharge capacity at a current density of 3 A g−1, while inferior or no electrochemical activity is observed with Ti, SS, Ni current collectors. The observations here provide insights into the selection of corrosion-resistant current collectors to achieve stable battery performance in the field of aqueous electrolyte Al-ion batteries. [ABSTRACT FROM AUTHOR]

Aqueous zinc‐ion batteries (AZIBs) have gained significant attention as a promising technology for grid scale energy storage due to their high safety and low cost. Nevertheless, side reactions on the zinc anodes result in a decrease in effi‐ciency decay and capacity loss, hindering the wide‐spread application of AZIBs. Recently, great efforts have been con‐ducted to tackle these challenges, such as modifying the inter‐nal structure of zinc anodes, coating protection on the surface of zinc anodes, and optimizing the electrolytes. However, there is a lack of systematic summary on the design of side reac‐tions‐suppressed zinc anodes, especially through the optimi‐zation strategies of aqueous electrolytes. Herein, this review systematically summarizes the main mechanisms and influence factors of side reactions. Subsequently, we present the main modification strategies based on electrolyte engineering for alleviating side reactions, with a particular emphasis on poly‐mer electrolytes. Lastly, we shed light on the potential research directions and perspectives of aqueous electrolytes, which may promote the development of AZIBs. [ABSTRACT FROM AUTHOR]

The pursuit of alternative anode materials featuring inexpensive, efficient, and adaptable is shaping the future of rechargeable zinc‐ion batteries. The Zn powder anodes stand out among contenders due to their cost‐effectiveness, exceptional processability, and adjustability. However, their widespread use is hampered by significant challenges, including volume expansion and dendrite growth. To counter these issues, a gamut of optimization strategies for Zn powder anodes has been explored and developed. This review systematically encapsulates these research findings, offering a comprehensive understanding of various enhancement methods, such as three‐dimensional printing, in‐situ surface engineering, scalable electrostatic self‐assembly, and epoxy oligomer binding. These methodologies are discussed in detail in the context of their unique synthesis methods and underlying mechanisms. The paper concludes by outlining prospective research trajectories aimed at further optimizing the use of Zn powder anodes in aqueous zinc‐ion batteries, thereby illuminating potential avenues for future exploration and development. [ABSTRACT FROM AUTHOR]

Aqueous rechargeable batteries (ARBs) are generally safer than non-aqueous analogues, they are also less-expensive, and more friendly to the environment. However, the inherent disadvantage of the narrow electrochemical window of H2O seriously restricts the energy density and output voltage of ARBs, especially aqueous rechargeable Fe-based batteries. Herein, we introduce a new battery system: the anode contains C@Fe/Fe2O3 composite, which is interfaced with an alkaline electrolyte; the cathode contains LiMn2O4 in contact with a neutral electrolyte. A Li+-conducting membrane is carefully selected to decouple the electrode-electrolyte, which effectively widens the electrochemical window to above 2.65 V, thereby enables an aqueous rechargeable iron battery. Its average output voltage is 1.83 V and its energy density is 235.3 Wh/kg at 549 W/kg. In this work, we propose the energy storage mechanism with the aid of density functional theory (DFT). The calculated reduction potential of the anode agrees with the experimental value. Furthermore, this battery system demonstrates long cycle lifespan of approximately 2500 cycles at 2 A/g, corresponding to a capacity retention of 82.1%. These results are very far superior than those of mainstream aqueous rechargeable Fe-based batteries, which guarantee future investigation for storing electricity energy. [ABSTRACT FROM AUTHOR]

Hydrogels hold great promise as electrolytes for emerging aqueous batteries, for which establishing a robust electrode‐hydrogel interface is crucial for mitigating side reactions. Conventional hydrogel electrolytes fabricated by ex situ polymerization through either thermal stimulation or photo exposure cannot ensure complete interfacial contact with electrodes. Herein, we introduce an in situ electropolymerization approach for constructing hydrogel electrolytes. The hydrogel is spontaneously generated during the initial cycling of the battery, eliminating the need of additional initiators for polymerization. The involvement of electrodes during the hydrogel synthesis yields well‐bonded and deep infiltrated electrode‐electrolyte interfaces. As a case study, we attest that, the in situ‐formed polyanionic hydrogel in Zn‐MnO2 battery substantially improves the stability and kinetics of both Zn anode and porous MnO2 cathode owing to the robust interfaces. This research provides insight to the function of hydrogel electrolyte interfaces and constitutes a critical advancement in designing highly durable aqueous batteries. [ABSTRACT FROM AUTHOR]

Aqueous lithium-ion batteries (ALIBs) featuring high-safety, low-cost, and environmental friendliness have dramatic potential in the area of energy storage batteries. The progress of aqueous lithium-ion batteries is restricted by the advanced electrode materials, which can maintain a robust structure after long-term cycling. In this work, we report a novel "rocking-chair" type aqueous full lithium-ion battery with titanium phosphate nanosheets (Ti(HPO4)2·H2O) as the anode material. The fabricated aqueous full lithium-ion battery achieves a high capacity retention of 83% after 1000 cycles even at the high-voltage of 2.4 V, as well as an excellent rate performance. [ABSTRACT FROM AUTHOR]

Aqueous zinc (Zn) batteries have attracted global attention for energy storage. Despite significant progress in advancing Zn anode materials, there has been little progress in cathodes. The predominant cathodes working with Zn2+/H+ intercalation, however, exhibit drawbacks, including a high Zn2+ diffusion energy barrier, pH fluctuation(s) and limited reproducibility. Beyond Zn2+ intercalation, alternative working principles have been reported that broaden cathode options, including conversion, hybrid, anion insertion and deposition/dissolution. In this review, we report a critical assessment of non-intercalation-type cathode materials in aqueous Zn batteries, and identify strengths and weaknesses of these cathodes in small-scale batteries, together with current strategies to boost material performance. We assess the technical gap(s) in transitioning these cathodes from laboratory-scale research to industrial-scale battery applications. We conclude that S, I2 and Br2 electrodes exhibit practically promising commercial prospects, and future research is directed to optimizing cathodes. Findings will be useful for researchers and manufacturers in advancing cathodes for aqueous Zn batteries beyond Zn2+ intercalation. [ABSTRACT FROM AUTHOR]

• The critical factors affecting Mg-0.15 Ca discharge voltage loss. • A semi-empirical expression of voltage drop is established. • A 2D model describes the changes in voltage of Mg anode during discharge. • The rationality and applicability of this model are validated. The voltage drop appearing at Mg anode-electrolyte interface is a critical issue for the battery power and energy density of aqueous primary Mg-air batteries. The respective voltage loss is typically assigned to the deposits layer forming on the anode surface during discharge. In this work, we experimentally and computationally investigate the critical factors affecting the voltage drop at Mg anode towards a deeper understanding of the contribution of deposit and its growth. A two-dimensional (2D) mathematical model is proposed to compute the voltage drop of Mg-0.15Ca wt.% alloy (Mg-0.15Ca) by means of a semi-empirical formulas and experiments-based modification model, considering the effect of discharge current density, the negative difference effect (NDE) and surface deposits layer itself. This model is utilized to simulate the discharge potential of the anode at predefined experimental current densities. The computed voltage drop (half-cell voltage) is in good agreement with the experimental value. The applicability of the mathematical model is successfully validated on the second material (namely high-purity Mg). [ABSTRACT FROM AUTHOR]

Aqueous rechargeable batteries (ARBs) have attracted wide attention due to their rich resources, environmental friendliness, and safety. The high ionic conductivity, safety and interfacial wettability of the aqueous electrolyte are essential for energy storage devices. However, the narrow electrochemical stability window (ESW) of the aqueous electrolyte and the side reactions of the electrode/electrolyte lead to the low energy density of the ARBs. In the past studies, the above problems were generally solved by improving the ion transport characteristics of the electrolyte and the electrode/electrolyte interface. Herein, we discuss the background, limitations, and key concepts for performance improvement of aqueous electrolytes, aiming to provide a comprehensive perspective and inspiration for further research on aqueous electrolytes and promote their development and application in the field of energy storage. [ABSTRACT FROM AUTHOR]

With growing demand for energy storage alternatives, silicon‐air batteries have gained attention due to their impressive theoretical specific energy (8470 Wh kgSi−1) and theoretical specific capacity (3820 mAh gSi−1). Although current challenges, such as corrosion, low anode mass conversion efficiency, and limited power output, restrict their practical use and commercialization potential, the ongoing advancement of materials and efficient electronic components open up a range of potential applications for Silicon‐air (Si‐air) batteries. This study investigates the feasibility of employing a single alkaline or non‐aqueous silicon‐air battery to power low‐power transient electronic device. Initially, their electrochemical behavior, corrosion parameters, and performance were assessed, yielding crucial parameters for the circuit design. Short‐term galvanostatic discharge experiments demonstrated the effective operation of Si‐air battery under varying current densities in both electrolytes without passivation issues. Subsequently, a proof‐of‐concept for self‐consumed and self‐destructive transient electronic device is presented, wherein a full‐cell Si‐air battery with non‐aqueous and aqueous electrolytes was operated while powering a light‐emitting diode (LED) as a practical illustrative application. [ABSTRACT FROM AUTHOR]

Aqueous aluminum ion batteries (AAIBs) have drawn considerable attention due to their intrinsic safety, cost‐effectiveness, eco‐friendliness, and high theoretical capacity of aluminum. Currently, suitable anode materials are crucial for the development of high‐performance AAIBs. For the first time, a hydrophilic (ZnCr2O4) and hydrophobic (PVDF) layer modified zinc anode paired with an aluminum‐based aqueous electrolyte to construct a high‐performance aluminum–zinc hybrid ion battery. The Hydrophilic ZnCr2O4 layer of anode endows the battery with low polarization by boosting the pre‐desolvation and deposition kinetics of aluminum/zinc ions. Meanwhile, the hydrophobic PVDF layer suppresses water‐induced corrosion of the anode. The synergistic effect of the hydrophilic and hydrophobic layers of the anode stimulates the battery to exhibit unprecedented cycle life (> 6000 cycles) and considerable discharge capacity (280 mAh g−1), compared to the batteries proposed in previous works paired with aluminum alloy anodes and aluminum‐based aqueous electrolytes. This novel anode provides powerful backing for the development of long‐life and high‐capacity aqueous polyvalent ion batteries due to its low cost and simple fabrication process. [ABSTRACT FROM AUTHOR]

Rechargeable aqueous zinc-ion batteries have attracted a lot of attention owing to their cost effectiveness and plentiful resources, but less research has been conducted on the aspect of high volumetric energy density, which is crucial to the space available for the batteries in practical applications. In this work, highly crystalline V2O5 microspheres were self-assembled from one-dimensional V2O5 nanorod structures by a template-free solvothermal method, which were used as cathode materials for zinc-ion batteries with high performance, enabling fast ion transport, outstanding cycle stability and excellent rate capability, as well as a significant increase in tap density. Specifically, the V2O5 microspheres achieve a reversible specific capacity of 414.7 mAh g−1 at 0.1 A g−1, and show a long-term cycling stability retaining 76.5% after 3000 cycles at 2 A g−1. This work provides an efficient route for the synthesis of three-dimensional materials with stable structures, excellent electrochemical performance and high tap density. [ABSTRACT FROM AUTHOR]

The practical application of aqueous rechargeable batteries faces several challenges due to the limited stability window of electrolytes and parasitic side reactions, such as corrosion, passivation, gas evolution, and co‐intercalations. The solid electrolyte interphase (SEI) formed at the electrode/electrolyte interface plays a critical role in determining interfacial properties and battery performance. Efforts are being made to develop effective SEIs, functionalize interphase layers, and explore various aqueous hybrid electrolytes that facilitate SEI formation. This review highlights the role of interphasial structures in aqueous batteries. First, common issues encountered by aqueous batteries and specific characteristics of aqueous lithium‐ion, sodium‐ion, zinc‐ion, and aluminum‐ion batteries are outlined. Then the tactics used to improve cycle stability of aqueous batteries are introduced and compared and the working principles and key parameters from the context of interphasial modification are discussed. Finally, constructive insights and suggestions for developing high‐performance batteries are offered, with a focus on SEI formation and interphase layer design. [ABSTRACT FROM AUTHOR]

Molybdate intercalation significantly reduces the thickness of cobalt–nickel layered hydroxide, greatly increases its specific surface area, regulates its pore distribution, increases the crystal plane spacing, promotes the diffusion rate of hydroxide in it, and increases its specific capacity. Meanwhile, the bilayered MCN-LDH@CP electrode significantly improved the areal energy density and peak power density and cycle stability of the CoNi//Zn battery. The quasi-solid-state MCN-LDH@CP//Zn battery can still charge a mobile phone even when hammered and pierced, showing excellent safety and reliability. [Display omitted] Seeking cathode materials with high areal capacity and excellent cycling tolerance is a key step to develop aqueous rechargeable zinc-based alkaline batteries with high energy density, power density and excellent stability. Here, the bilayered cathode composite (MCN-LDH@CP) of molybdate intercalated cobalt–nickel layered hydroxide nanosheets (MCN-LDH) grown on cobalt phosphate octahydrate microsheet (CP) was prepared by a two-step hydrothermal process. Molybdate intercalation significantly reduces the thickness of cobalt–nickel layered hydroxide, greatly increases its specific surface area, regulates its pore distribution, increases the crystal plane spacing, promotes the diffusion rate of hydroxide in it, and increases its specific capacity. Meanwhile, the bilayered MCN-LDH@CP electrode significantly improved the areal energy density (2.89 mWh/cm2) and peak power density (111.22 mW/cm2) and cycle stability (97.8 % after 7000 cycles) of the CoNi//Zn battery. The excellent stability is mainly due to the fact that the MCN-LDH overlay inhibits the loss of P element of CP and improves the structural stability of the sample. The quasi-solid-state MCN-LDH@CP//Zn battery can still charge a mobile phone even when hammered and pierced, showing excellent safety and reliability. This work opens a new avenue to develop CoNi//Zn batteries with high energy density, power density and excellent tolerance. [ABSTRACT FROM AUTHOR]

The utilization rate of active sites in cathode materials for Zn‐based batteries is a key factor determining the reversible capacities. However, a long‐neglected issue of the strong electrostatic repulsions among divalent Zn2+ in hosts inevitably causes the squander of some active sites (i.e. gap sites). Herein, we address this conundrum by unraveling the "gap‐filling" mechanism of multiple charge carriers in aqueous Zn‐MoS2 batteries. The tailored MoS2/(reduced graphene quantum dots) hybrid features an ultra‐large interlayer spacing (2.34 nm), superior electrical conductivity/hydrophilicity, and robust layered structure, demonstrating highly reversible NH4+/Zn2+/H+ co‐insertion/extraction chemistry in the 1 M ZnSO4+0.5 M (NH4)2SO4 aqueous electrolyte. The NH4+ and H+ ions can act as gap fillers to fully utilize the active sites and screen electrostatic interactions to accelerate the Zn2+ diffusion. Thus, unprecedentedly high rate capability (439.5 and 104.3 mAh g−1 at 0.1 and 30 A g−1, respectively) and ultra‐long cycling life (8000 cycles) are achieved. [ABSTRACT FROM AUTHOR]

The limited lifespan of aqueous zinc‐ion batteries (with vanadium‐oxide based cathodes) is constrained by practical applications due to corrosion accelerated by vanadium ions leaching from the cathode and uneven dendrite growth on the zinc metal anode. To address these issues, the difference in size between hydrated zinc ions (4.30 Å) in electrolyte and vanadium ions (8.34 Å) is considered. Uniformly coating the MOF‐801 nanoparticles (with a pore size of 6.0 Å) on the zinc foil formed a selective ion transport layer. The uniform zinc ion flux generated by the selective ion transport layer allows hydrated zinc ions to be transported evenly and promotes uniform zinc deposition, leading to a low overpotential (17.4 mV) and high cycle stability (1000 h) in the symmetric cell. Moreover, the selective ion transport layer, having pores smaller than vanadium ions, blocked vanadium ions from migrating toward the zinc anode, thereby reducing its corrosion and contributing to a capacity retention of 86% after 2000 cycles under full‐cell conditions. This study demonstrates that the pore size of the coating layer influences the long‐term stability of aqueous zinc‐ion batteries and may serve as a guide when selecting interface modification materials for various metal batteries. [ABSTRACT FROM AUTHOR]

Aqueous zinc–iodine (Zn−I2) batteries are gaining significant attention due to their low‐cost, high safety and high theoretical capacity. Nevertheless, their long cycle and durability have been hampered due to the use of aqueous media that, over time, lead to Zn dendrite formation, hydrogen evolution reaction, and polyiodide dissolution. Xiao et al. recently reported the addition of an imidazolium‐based ionic liquid (IL) to an aqueous electrolyte and found that the IL plays a key role in modifying the solvation of Zn2+ ions in the bulk electrolyte and the inner Helmholtz plane, repelling H2O molecules away from the Zn anode surface. UV/Vis and NMR spectroscopy also indicates a strong interaction between imidazolium cation [EMIM]+ and I3−, thereby reducing polyiodide shuttling and enhancing the cycle life of the battery. Overall, a capacity decay rate of only 0.01 % per cycle after over 18,000 cycles at 4 A g−1, is observed, making the use of IL additives in aqueous electrolytes highly promising candidates for Zn−I2 batteries. [ABSTRACT FROM AUTHOR]

V2CTx MXene is a "rising star" cathode material for aqueous zinc‐based batteries (AZBs) owing to its large/flexible interlayer spacing, rich redox chemistry of V, and high electronic conductivity. Nevertheless, the plentiful F surface terminations generated during the common preparation (fluorine‐containing acid etching process) of V2CTx generally result in high hydrophobicity, poor Zn affinity, and sluggish ion‐diffusion kinetics. Herein, a novel OH‐termination‐rich V2CTx material with interlayer "K+‐pillars" (alk‐V2CTx) is fabricated via a facile one‐step alkalization method, which features excellent hydrophilicity, expanded ion‐transport channels, and robust layered structure. Impressively, the tailored alk‐V2CTx cathode enables highly reversible and rapid Li+/Zn2+ co‐insertion/extraction electrochemistry in the formulated 15 m LiTSFI + 1 m Zn(CF3SO3)2 aqueous electrolyte, meanwhile, the "self‐exfoliation" phenomenon of MXenes upon cycling significantly increases the active sites, rendering the superior rate performance (498.2/195.1 mAh g−1 at 0.1/30 A g−1, respectively) and exceptional cycling life (96.2% capacity retention over 20 000 cycles). Systematic in situ/ex situ analyses and theoretical computations elucidate the above hybrid‐ion storage mechanisms. Finally, flexible quasi‐solid‐state rechargeable Zn batteries employing the alk‐V2CTx cathode exhibit inspiring energy output even under severe deformation conditions and low temperatures. This study provides new perspectives for designing high‐performance MXene‐based cathodes for AZBs by modulating surface terminations. [ABSTRACT FROM AUTHOR]

Seeking new cathode chemistry with high onset potential and compatibility with electrolytes has become a challenge for aqueous Zn ion batteries. Anion intercalation in graphite (4.5 V vs Li+/Li) possesses the potentiality but usually shows a competitive relationship with oxygen evolution reaction (OER) in aqueous solutions. Herein, a decoupled design is proposed to optimize a full utilization of perchlorate ion intercalation in graphite cathode by pH adjustment. Benefiting from the decoupled design, high Coulombic efficiency is obtained by decelerating the kinetic of OER in acidic media. The decoupled Zn‐graphite battery exhibits a wide potential window of 2.01 V, as well as an attractive energy density of 231 Wh kg−1. In addition, a Zn‐graphite battery with SO42−${\mathrm{SO}}_4^{2 - }$ insertion is assembled, which demonstrates the capability of the proposed decoupled strategy to integrate novel electrode chemistries for high‐performance aqueous Zn‐based energy storage systems. [ABSTRACT FROM AUTHOR]

Toward the construction of rechargeable batteries utilizing Zn metal has a high theoretical capacity, one of the solutions is to combine with the insertion/deinsertion of Na ions into/from hosts, but in the presence of two coexisting metal cations in dual‐salt electrolytes, it has been often left to spontaneity to determine which cations the host materials react with preferentially. The hybrid aqueous electrolytes containing 1 m Zn‐salt and 6 m Na‐salt were used, and the counter anions were TFSA− and Cl−, respectively. In the TFSA‐based electrolyte, the ligands for Zn ions and Na ions are water molecules to form positively‐charged hydrated cations. In contrast, for the Cl‐based electrolyte, Zn ions undergo partially solvation of Cl− to be stabilized as [ZnCl4(H2O)2]2− with negative charges while Na ions are predominantly hydrated. The galvanostatic discharge/charge tests, AC impedance measurements, and field‐emission electron probe micro analyzer revealed that in the Zn(TFSA)2/NaTFSA system, where both the cations are positively charged, Zn ions with higher charge density were inserted into the FePO4. On the other hand, in the ZnCl2/NaCl system, the FePO4 accommodated Na ions positively charged in the electrolyte solution rather than negatively charged Zn ions. [ABSTRACT FROM AUTHOR]

Flexible, scalable, and low‐cost energy storage solutions are required for the widespread use of renewable energy and the mitigation of climate change. State‐of‐the‐art lithium‐ion batteries provide high specific energy density; however, designing a safe and cost‐effective grid‐scale lithium‐ion battery is still a major challenge. Redox flow batteries are scalable due to their ability to decouple power and energy; however, the commercial applications of these batteries are limited because of expensive ion‐selective membranes. In this paper, we report a modified battery design approach in which Bi/BiOCl and V4+/V5+ reaction‐based redox couples are utilized while employing a gel‐based architecture. We show, for the first time, that Bi/BiOCl conversion reaction based redox couple can reversibly work against traditional vanadium‐based redox pair in an aqueous electrolyte. Redox active materials in this cell design are in the gel form, and a traditional membrane or a separator is not required. This proof‐of‐concept battery delivers 0.9 V with a volumetric energy density of 22.14 Wh/L. [ABSTRACT FROM AUTHOR]

We report the electrochemistry of Al3+ ion storage in copper tetrathiovanadate (Cu3VS4) in an aqueous electrolyte for the first time. It is found that Cu3VS4 could deliver an initial discharge capacity of 111 mA h g−1 at a current rate of 0.5 A g−1 and 77 mA h g−1 up to the 300th cycle at 2 A g−1 along with an excellent rate capability. The better electrochemical performance may be attributed to the high theoretical capacity of sulfur and the superior conductivity of copper which allows facile Al3+ ion diffusion in Cu3VS4. The electrochemical mechanism of Al3+ ion storage is also illustrated. [ABSTRACT FROM AUTHOR]

Zinc‐bromine batteries (ZBBs) have recently gained significant attention as inexpensive and safer alternatives to potentially flammable lithium‐ion batteries. Zn metal is relatively stable in aqueous electrolytes, making ZBBs safer and easier to handle. However, Zn metal anodes are still affected by several issues, including dendrite growth, Zn dissolution, and the crossover of Br species from cathodes to corrode anodes, resulting in self‐discharge and fast performance fading. Similarly, Br2 undergoes sluggish redox reactions on cathodes, which brings several issues such as poor reaction kinetics, the highly corrosive nature of Br species leading to corrosion of separators and poisoning of anodes, and the volatile nature of Br species causing increased internal pressures, etc. These issues are compounded in flowless ZBB configuration as no fresh electrolyte is available to provide extra/fresh reaction species. In this review, the factors controlling the performance of ZBBs in flow and flowless configurations are thoroughly reviewed, along with the status of ZBBs in the commercial sector. The review also summarizes various novel methodologies to mitigate these challenges and presents research areas for future studies. In summary, this review will offer a perspective on the historical evolution, recent advancements, and prospects of ZBBs. [ABSTRACT FROM AUTHOR]

The narrow electrochemical stability window of water poses a challenge to the development of aqueous electrolytes. In contrast to non‐aqueous electrolytes, the products of water electrolysis do not contribute to the formation of a passivation layer on electrodes. As a result, aqueous electrolytes require the reactions of additional components, such as additives and co‐solvents, to facilitate the formation of the desired solid electrolyte interphase (SEI) on the anode and cathode electrolyte interphase (CEI) on the cathode. This review highlights the fundamental principles and recent advancements in generating electrolyte interphases in aqueous batteries. [ABSTRACT FROM AUTHOR]

Structure deterioration and side reaction, which originated from the solvated H2O, are the main constraints for the practical deployment of both cathode and anode in aqueous Zn-ion batteries. Here we formulate a weakly solvating electrolyte to reduce the solvating power of H2O and strengthen the coordination competitiveness of SO42− to Zn2+ over H2O. Experiment results and theoretical simulations demonstrate that the water-poor solvation structure of Zn2+ is achieved, which can (i) substantially eliminate solvated-H2O-mediated undesirable side reactions on the Zn anode. (ii) boost the desolvation kinetics of Zn2+ and suppress Zn dendrite growth as well as structure aberration of the cathode. Remarkably, the synergy of these two factors enables long-life full cells including Zn/NaV3O8·1.5H2O, Zn/MnO2 and Zn/CoFe(CN)6 cells. More importantly, practical rechargeable AA-type Zn/NVO cells are assembled, which present a capacity of 101.7 mAh and stability of 96.1% capacity retention after 30 cycles at 0.66 C. The practical deployment of aqueous zinc-ion batteries is hindered by the structure deterioration and side reactions at electrodes. Here, the authors introduce a weakly solvating electrolyte with butanone as an electrolyte additive to stabilize both the cathode and anode of aqueous zinc-ion batteries simultaneously. [ABSTRACT FROM AUTHOR]

Polyaniline was inserted into the interlayer of vanadium-metal–organic framework-derived V 2 O 5 to take advantage of the (1 1 0) crystal plane of V 2 O 5 selective growth. PANI80-V 2 O 5 had excellent electrochemical properties that benefit from the large layer spacing and the strong synergistic coupling of oxygen vacancy defects with the large specific surface area. [Display omitted] The development of structurally stable, highly conductive layered materials as cathode materials for aqueous zinc-ion batteries (AZIBs) is essential. Herein, polyaniline (PANI) was inserted into the interlayer of a vanadium-metal–organic framework-derived V 2 O 5 to take advantage of the selective growth of the (1 1 0) crystal plane of V 2 O 5 , facilitating sufficient diffusion of aniline within the V 2 O 5 interlayer along the vertical direction of the spatial c -axis while stabilizing the interlayer structure. The synthesized composite (PANI80-V 2 O 5) exhibited excellent electrochemical properties owing to the increase in the material layer spacing from 5.76 Å to 14.31 Å and the strong synergistic effect of the oxygen vacancies and large specific surface area of the material. In addition, the π-conjugated structure of PANI prevented the active material from dissolving in the electrolyte, further stabilizing its lamellar structure, which tended to collapse during electrochemical cycling. The PANI80-V 2 O 5 electrode exhibited an ultrahigh discharge capacity of 516.90 mAh g−1 at a current density of 0.1 A g−1. Moreover, it exhibited a discharge capacity of 268.80 mAh g−1 at a current density of 10 A g−1 and a capacity retention rate of 97.77% after 3000 cycles. Therefore, this study provided a reference for developing structurally superior cathode materials for AZIBs. [ABSTRACT FROM AUTHOR]

Aluminum‐sulfur batteries (AlSBs) exhibit significant potential as energy storage systems due to their notable attributes, including a high energy density, cost‐effectiveness, and abundant availability of aluminum and sulfur. In order to commercialize AlSBs, an understanding of their working principles is necessary. In this review, we examine the current advancements in cathodes, both in theory and practice, as well as the progress made in aqueous and nonaqueous electrolytes. We also explore the modifications made to separators and the theoretical understanding of problems associated with AlSBs. Furthermore, we discuss future research directions aimed at resolving these issues. Our aim is to summarize the current progress in AlSBs and, based on recent progress and understanding of the mechanism, help design a battery to overcome the challenges that such batteries have been facing. [ABSTRACT FROM AUTHOR]

Aqueous rechargeable multivalent metal‐ion batteries (ARMMBs) have attracted considerable attention due to their high capacity, high energy density, and low cost. However, their performance is often limited by low temperature operation, which requires the development of anti‐freezing electrolytes. In this review, we summarize the anti‐freezing mechanisms and optimization strategies of anti‐freezing electrolytes for aqueous batteries (especially for Zn‐ion batteries). Besides, we investigate the possible interactions and side reactions between electrolytes and electrodes. We also analyze the problems between electrolytes and electrodes at low temperature, and propose possible solutions. The research progress in the field of low temperature energy storage for aqueous Mg‐ion, Ca‐ion, and Al‐ion batteries, and the challenges faced in their anti‐freezing electrolytes are investigated in detail. Last but not least, the outlook on the energy storage applications of ARMMBs is provided to guide the future research. [ABSTRACT FROM AUTHOR]

Increasing the electrodeposition efficiency of metallic zinc from quasi‐neutral aqueous electrolytes is one of the major key requirements for the commercialization of rechargeable aqueous Zn‐ion batteries. Several strategies have been recently reported in the literature. Unfortunately, electrochemical studies on the effect of different current densities on the zinc electrodeposition efficiency usually are not recorded in realistic experimental conditions: e. g. depth of discharges <1–10 %, use of negative electrodes with infinite reservoir of Zn2+, etc. Here, the effect of the current density on the zinc electrodeposition onto optimized bismuth‐indium substrates cycled with 33 % of depth of discharge in a ZnSO4‐containing aqueous solution has been investigated. It was found that low Zn plating/stripping current densities displayed higher electrodeposition efficiencies over 200 Zn electrodeposition/dissolution cycles, more homogeneous distribution of the zinc deposits and lower amounts of inactive zinc passivation products. When higher current densities were applied during the Zn plating/stripping cycles, lower electrodeposition efficiencies and a greater amount of inactive zinc hydroxides and dead zinc were observed on the electrode surface. [ABSTRACT FROM AUTHOR]

Aqueous solutions are crucial to most domains in biology and chemistry, including in energy fields such as catalysis and batteries. Water‐in‐salt electrolytes (WISEs), which extend the stability of aqueous electrolytes in rechargeable batteries, are one example. While the hype for WISEs is huge, commercial WISE‐based rechargeable batteries are still far from reality, and there remain several fundamental knowledge gaps such as those related to their long‐term reactivity and stability. Here, we propose a comprehensive approach to accelerating the study of WISE reactivity by using radiolysis to exacerbate the degradation mechanisms of concentrated LiTFSI‐based aqueous solutions. We find that the nature of the degradation species depends strongly on the molality of the electrolye, with degradation routes driven by the water or the anion at low or high molalities, respectively. The main aging products are consistent with those observed by electrochemical cycling, yet radiolysis also reveals minor degradation species, providing a unique glimpse of the long‐term (un)stability of these electrolytes. [ABSTRACT FROM AUTHOR]

Iodine (I2) shows great promising as the active material in aqueous batteries due to its distinctive merits of high abundance in ocean and low cost. However, in conventional aqueous I2‐based batteries, the energy storage mechanism of I−/I2 conversion is only two‐electron redox reaction, limiting their energy density. Herein, six‐electron redox chemistry of I2 electrodes is achieved via the synergistic effect of redox‐ion charge‐carriers and halide ions in electrolytes. The redox‐active Cu2+ ions in electrolytes induce the conversion between Cu2+ ions and I2 to CuI at low potential. Simultaneously, the Cl− ions in electrolytes activate the I2/ICl redox couple at high potential. As a result, in our case, I2‐based battery system with six‐electron redox is developed. Such energy storage mechanism with six‐electron redox leads to high discharge potential and capacity, excellent rate capability, as well as stable cycling behavior of I2 electrodes. Impressively, six‐electron‐redox I2 cathodes can match various aqueous metal (e.g. Zn, Mn and Fe) anodes to construct metal||I2 hybrid batteries. These hybrid batteries not only deliver enhanced capacities, but also exhibit higher operate voltages, which contributes to superior energy densities. Therefore, this work broadens the horizon for the design of high‐energy aqueous I2‐based batteries. [ABSTRACT FROM AUTHOR]

Na‐ion batteries based on abundant and sustainable materials might become one of the leading alternative technologies especially suitable for large‐scale stationary storage. Various (mixed)phosphate framework materials are attracting much interest mainly due to their high structural stability and diversity. In this study, we report on the successful synthesis of mixed phosphate‐pyrophosphate Na7V4(PO4)(P2O7)4, Na4Fe3(PO4)2P2O7, and Na4Mn3(PO4)2P2O7. The electrochemical properties of these materials are comprehensively characterized in different organic and aqueous electrolytes. The findings reveal that Na7V4(PO4)(P2O7)4 and Na4Fe3(PO4)2P2O7 exhibit very good cycling performance and rate capability in organic solvent‐based electrolytes. However, their performance deteriorates significantly even in 'water‐in‐salt' aqueous electrolytes due to the rapid electrochemical degradation. Na4Mn3(PO4)2P2O7 demonstrates limited electrochemical activity in organic electrolytes and virtually no activity in 'water‐in‐salt' electrolytes, likely due to degradation processes resulting in blocking interphasial layers on electrode particles. These results underscore the need for further research to optimize the performance of these materials and identify potential strategies for enhancing their stability and activity in different electrolytes. [ABSTRACT FROM AUTHOR]

Aqueous zinc-ion batteries (ZIBs) gain attention as promising energy storage devices due to their high safety. However, the narrow electrochemical window and unfavorable side reactions induced by water decomposition restrict their development. Thus, confining water activity to enhance stability and enlarge the electrochemical window is required. Herein, a 2.9 m (mol kgsolvent-1) Zn(ClO4)2-CO(NH2)2-H2O ternary aqueous eutectic electrolyte is prepared with restricted water activity at room temperature. The strong intermolecular interactions between CO(NH2)2 and H2O decrease the free H2O molecules and reduce their activity to suppress the parasitic reactions. Compared to conventional aqueous electrolytes, this urea-modified electrolyte exhibits similar ionic conductivity (6.83 mS cm-1) and viscosity (29.5 mPa s) but with a significantly expanded electrochemical stability window (2.6 V) than the conventional one (1.7 V). Additionally, the preferential adsorption and reduction of urea molecules on the zinc surface mediate the formation of an organic solid electrolyte interphase, which passivates the anode and facilitates homogeneous zinc deposition. As a result, this ternary aqueous electrolyte enables high-voltage zinc/vanadium batteries with a capacity of 125 mAh g-1 for 300 cycles at 5 A g-1. This finding demonstrates a low-cost and practicable approach for realizing stable aqueous zinc-ion batteries with an enlarged electrochemical stability window. [ABSTRACT FROM AUTHOR]

Large‐scale energy storage with aqueous Zn batteries (AZBs) have bright future, but their practical application is impeded by H2 evolution reaction (HER), which results in poor stability of Zn–metal anodes. Here, using linear sweep voltammetry in dilute salt aqueous electrolytes, it is discovered that as the salt concentration decreases, HER is gradually suppressed, which is contrary to prior beliefs. Combining calculations and experiments, it is demonstrated that HER derives predominantly from the sum of Zn2+‐solvated water rather than the average amount of water in the Zn2+‐solvation structural unit or free water without interaction with Zn2+, which answers the puzzle from above. This result, which differs fundamentally from the previous understandings, sheds new light on the mysterious role of water chemistry in controlling HER and contributes to a more rational design of advanced electrolytes for AZBs. [ABSTRACT FROM AUTHOR]

[Display omitted] The advantages of aqueous Zn-ion batteries lie in the affordability and environmental friendliness. Nonetheless, the use of aqueous Zn-ion batteries is severely hindered by key issues such dendrite formation and side reactions in Zn metal anodes. It is able to works well so as to create a stable interface layer, which controls the development of dendrites and adverse reactions. In this study, it is recommended that the coating formed by nano-semiconductor material graphitic carbon nitride (g-C 3 N 4) should be applied to the surface of Zn metal to evenly disperse the electric field, as well as inhibit the development of tip effect, thus preventing Zn dendrite growth. Zn deposition occurs quickly and steadily as a result of Zn2+ ions being adsorbed and the Zn2+ ion flow being reallocated by the zincophilicity of N atoms in the coating. The Zn symmetrical battery can be stable cycled for 1,000 h at a current density of 0.5 mA cm−2, with its overall areal capacity of 0.5mAh cm−2, which is attributed to these benefits of the coating. It can be stable circulated for 500 h at a high current density of 5 mA cm−2, with its total areal capacity of 1mAh cm−2. The completely constructed Zn-g-C 3 N 4 //V 2 O 5 according exhibits exceptional long-term cycle stability. Under the current density of 2 A/g, the initial capacity is 312.3 mAh g−1, which can cycle be stable circulated for 1,000 cycles. Under the high current density of 5 A/g, the whole battery's capacity keeping holding rate is 70% after 2000 cycles, and the coulomb efficiency (CE) is extremely near to 100%. [ABSTRACT FROM AUTHOR]

Protons in aqueous electrolytes can perform as an additional type of charge carrier for insertion/extraction in addition to the primary carrier cations in aqueous rechargeable batteries. Despite many diverse claims regarding the effect of protons, mutually conflicting experimental results and their interpretations without direct evidence have been reported over the last decade. Systematic examinations and analyses are thus imperative to clarify the conditions of proton insertion in aqueous rechargeable batteries. Utilizing V2O5 as a model cathode and beaker‐type cells with a sufficient amount of ZnSO4 aqueous electrolytes in this work, it is demonstrated that protons are inserted into the cathode prior to Zn‐ions in low‐pH conditions (pH ≤ 3.0). In stark contrast, the influence of protons on the discharge voltage and capacity is insignificant, when either the pH becomes higher (pH ≥ 4.0) or the electrolyte volume is considerably low in coin‐type cells. Similar behavior of pH‐dependent proton insertion is also verified in Na–, Mg–, and Al‐ion electrolytes. Providing a resolution to the controversy regarding proton insertion, the present study emphasizes that the influence of protons substantially varies depending on the pH and relative volume of electrolytes in aqueous batteries. [ABSTRACT FROM AUTHOR]

This study introduces a versatile electrolyte additive, nicotinamide, for zinc anodes, aiming to facilitate uniform deposition and suppress water-induced side reactions. The molecular structure, consisting of a pyridine ring and an amide function group, endows NTA molecules with the ability to regulate electrolyte pH, enhance nucleation overpotential, and constrain 2D diffusion of Zn2+. As a result, the full battery configuration with this additive achieved an impressive lifespan of over 10 000 cycles. [ABSTRACT FROM AUTHOR]