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[Display omitted] Affinity and storage capacity for zinc ions of the electrode materials are crucial factors on the properties of zinc ion hybrid capacitors (ZHICs). Wasted pulping liquor with abundant carbohydrates, lignin and inorganic matter served as a unique precursor to produce embedded oxygen-doped hierarchical porous carbon directly through a one-step carbonization process in this investigation. In carbonization process, lignin can serve effectively as the carbon framework, carbohydrates not only act as sacrificial templates but also offer a plentiful oxygen source which can increase the affinity for Zn2+, and sodium-containing inorganic substances plays a role as hard templates to optimize the pore structure. The resulting porous carbon under carbonization temperature of 800 °C shows a high specifical area of 2186 m2g−1 with oxygen content of 4.8 %, which can reduce the adsorption energy of Zn2+ from −0.16 eV to −0.32 eV through electrochemical techniques and density functional theory (DFT) calculations, the incorporation of oxygen was demonstrated to enhance the adsorption and desorption kinetics of Zn2+, suggesting a bright future for application in the domain of energy storage. The resulting ZIHC assembly showcases a notable energy density of 84.6 Wh kg−1 at a power density of 359 W kg−1. Remarkably, even after 10,000 charge and discharge cycles, it exhibits exceptional cycle stability with retaining 86.56 % of its capacity. Consequently, this approach provides fresh insights for exploring the facile and commercial fabrication of biomass-derived cathodes for ZIHCs, thereby propelling the progress of eco-friendly energy storage devices. [ABSTRACT FROM AUTHOR]

High-energy and ultra-stable dual-ion capacitors are constructed based on nanospherical carbon frameworks cathodes deriving from hydrogen-bonded micelle assembly directed conjugated microporous polymers. [Display omitted] • Nanospherical carbon frameworks (CNS-2) derived from CMPs are synthesized by a hydrogen-bonded micelle self-assembly strategy. • Maximized accessibility of surface-active sites and dual-ion storage mechanism ensure high charged ion storage efficiency. • The assembled Zn-ion hybrid capacitor based on CNS-2 delivers ultrahigh energy density and super-stable cycle lifespan. Well-orchestrated carbon nanostructure with superb stable framework and high surface accessibility is crucial for zinc-ion hybrid capacitors (ZIHCs). Herein, a hydrogen-bonded micelle self-assembly strategy is proposed for morphology-controllable synthesis of conjugated microporous polymers (CMPs) derived carbon to boost zinc ion storage capability. In the strategy, F127 micellar assembly through intermolecular hydrogen bonds serves as structure-directed agents, directing CMPs' oligomers grow into nanospherical assembly. The nanospherical carbon frameworks derived from CMPs (CNS-2) have shown maximized surface accessibility due to their plentiful tunable porosity and hierarchical porous structure with abundant mesoporous interconnected channels, and superb stability originating from CMPs' robust framework, thus the CNS-2-based ZIHCs exhibit ultrahigh energy density of 163 Wh kg−1 and ultralong lifespan with 93 % capacity retention after 200, 000 cycles at 20 A g−1. Charged ion storage efficiency also lies in dual-ion alternate uptake of Zn2+ and CF 3 SO 3 − as well as chemical redox of Zn2+ with carbonyl/pyridine motifs forming O–Zn–N bonds. Maximized surface accessibility and dual-ion storage mechanism ensure excellent electrochemical performance. Thus, the hydrogen-bond-guide micelle self-assembly strategy has provided a facile way to design nanoarchitectures of CMPs derived carbon for advanced cathodes of ZIHCs. [ABSTRACT FROM AUTHOR]

Zinc ion hybrid capacitors (ZIHCs) show promise for large‐scale energy storage because of their low cost, highly intrinsic safety, and eco‐friendliness. However, their energy density has been limited by the lack of advanced cathodes. Herein, a high‐capacity cathode material named N‐doped porous carbon (CFeN‐2) is introduced for ZIHCs. CFeN‐2, synthesized through the annealing of coal pitch with FeCl3·6H2O as a catalytic activator and melamine as a nitrogen source, exhibits significant N content (10.95 wt%), a large surface area (1037.66 m2 g−1), abundant lattice defects and ultrahigh microporosity. These characteristics, validated through theoretical simulations and experimental tests, enable a dual‐ion energy storage mechanism involving Zn2+ ions and CF3SO3− anions for CFeN‐2. When used as a cathode in ZIHCs, CFeN‐2 achieves a high‐energy density of 142.5 W h kg−1 and a high‐power density of 9500.1 W kg−1. Furthermore, using CFeN‐2 ZIHCs demonstrate exceptional performance with 77% capacity retention and nearly 100% coulombic efficiency after 10 000 cycles at 10 A g−1, showcasing substantially superior performance to current ZIHCs. This study offers a pathway for developing high‐energy and high‐power cathodes derived from coal pitch carbon for ZIHC applications. [ABSTRACT FROM AUTHOR]

The metal‐free rocking chair type Zn‐ion batteries (ZIBs) provide a promising approach toward the promotion of the Zn‐based batteries by circumventing the challenges including dendrite growth, hydrogen evolution reaction (HER), and surface corrosion. In order to sufficiently exploit the available capacity of this metal‐free batteries, it is necessary to effectively enhance the sluggish reaction kinetics of divalent zinc ions. Equally important is to achieve a balance in the kinetics between cathode and anode. Here, hetero‐valent doping and oxygen vacancy engineering are employed to effectively enhance the reaction dynamics of V2O5 cathodes and MoO3 anodes. Moreover, to the best of the knowledge, for the first time, the strategy of kinetics matching between the two electrodes is applied to the construction of rocking‐chair zinc ion batteries, enabling the cathode and anode to share similar zinc ion migration rates, and achieving a high energy density of up to 58.7 Wh kg−1 (based on the total electrode mass) as well as excellent cycling stability (90% after 500 cycles). This work demonstrates the importance of kinetics matching in zinc‐ion full‐cell performance and pave a benefitable avenue to for the pursuit of advanced multi‐valent metal‐ion batteries. [ABSTRACT FROM AUTHOR]

The redox activities of polyaniline (PANI) are hindered by the instability of pernigraniline salt (PS) state which degrades into oligo‐aniline. In this work, the use of protic additives is examined to mitigate capacity fading and increase utilization of PANI in nonaqueous electrolytes. The protic additive propylene glycol, with its hydrogen‐bonding capabilities, stabilizes the PS PANI and promotes reversible redox reactions, facilitating high capacity and an extended cycle lifetime for applications in metal ion supercapacitors. The use of this protic nonaqueous electrolyte in a PANI–zinc device results in an energy density of 255 Wh kg−1 at a power density of 1.8 kW kg−1 and a robust cycle lifetime of 3,850 charge/discharge cycles. The PANI at a high current density of 6.5 mA cm−2 reaches a capacity of 257 mAh g−1, equivalent to 87% of the its theoretical capacity, showcasing the effectiveness of the protic additive in improving both capacity and cycle life in electrochemical supercapacitors. [ABSTRACT FROM AUTHOR]

Vanadate is one of the promising cathode materials for aqueous zinc ion batteries (AZIBs) due to its abundant resources and various valence states. However, the further development is restricted by their sluggish reaction kinetics between zinc ions and the host materials. In this work, several kinds of gallium ions pre‐intercalated vanadate electrode materials through a simple hydrothermal strategy are designed. Ga‐NHVO‐0.5 sample achieves a specific capacity of 438.23 mAh g−1 at current density of 0.2 A g−1. At the same time, it delivers an energy density of 250.34 Wh kg−1 at a power density of 55 W kg−1. The assembled button cells retain 83.84% of its initial capacity after 4000 times cycling, revealing their promising applications in portable power devices. Moreover, the devices still possess a favorable stability under different bending conditions. [ABSTRACT FROM AUTHOR]

The porous structure is critical for carbonaceous electrode‐based zinc‐ion capacitors (ZICs) to achieve excellent electrochemical performance, but the corresponding porous structure‐electrochemical performance relationship is yet to be fully understand. Herein, three types of N‐doped carbons with different porous structures are developed to investigate the relationship between the pore size distribution and the electrochemical performance of the devices. The optimized porous carbon (LVCR) exhibits large electrochemical surface area, plentiful oxygen functional groups, and hierarchical porous structure that facilitates electron transfer and ion diffusion. Consequently, the LVCR‐based ZIC exhibits a remarkable peak power density of 31.4 kW kg−1 and an impressive specific energy density of 126.6 Wh kg−1. Moreover, it demonstrates exceptional longevity, retaining the capacitance of 97.7% even after undergoing 50 000 cycles. Systematic characterization demonstrates that the macroporous and mesoporous structures determine the different stages of Zn2+ storage kinetics. The excellent Zn2+ storage and electrochemical performance of LVCR are attributed to the fast ion transport channels provided by the hierarchical porous structure and facilitated reversible chemisorption and desorption. This work not only deepens the understanding of charge storage mechanism, but also provides guidelines for rationally designing carbonaceous materials toward high‐performance ZICs in the view of porous structure‐electrochemical performance relationship. [ABSTRACT FROM AUTHOR]

Zinc‐ion hybrid capacitors (ZHC) have been considered as emerging sustainable electrochemical energy storage devices. They integrate the benefits of high‐energy density of aqueous zinc ion battery (ZIB) with high‐power density of supercapacitor (SC). Metal‐organic frameworks (MOFs) have been widely used to design electrode materials for portable devices, especially in some energy storage fields because of their large specific surface area and adjustable pore structures. In this work, we prepare porous Mn3O4/C nanosheets with Mn‐BDC as a precursor. The assembled device delivers a specific capacitance of 155.3 mAh g−1 at a current of 3 A g−1 and keeps a retention rate of 97.7 % after 10,000 cycles. Moreover, it provides an energy density of 464.5 Wh kg−l at a power density of 100 W kg−1. [ABSTRACT FROM AUTHOR]

This work confirms that the reasonable control of the d-band center of O d -MVO-0.5 cathode is the key to improve the conductivity, adsorption energy, reduce the migration energy barrier, and accelerate the rapid extraction and insertion of zinc ions. [Display omitted] Vanadium-based oxides have good application prospects in aqueous zinc ion batteries (AZIBs) due to their structures suitable for zinc ion extraction and intercalation. However, their poor conductivity limits their further development. The d-band center plays a key role in promoting adsorption of ions, which promotes the development of electrode materials. Here, a series of MoV 2 O 8 compounds with oxygen defect (O d -MoV 2 O 8) were synthesized by a simple hydrothermal process and a subsequent vacuum calcination process through strict control of the deoxidation time. Theoretical calculations reveal that the abundant oxygen vacancies in MoV 2 O 8 effectively regulate the d-band center of the zinc ion adsorption site. This precise control of the d-band center enhances the zinc ion adsorption energy of MoV 2 O 8 , lowers the migration energy barrier for zinc ions, and ultimately significantly boosts zinc storage performance. The specific capacity is as high as 282.4 mAh/g after 100 cycles at 0.1 A/g, and it also shows excellent performance and outstanding cycle life. In addition, the maximum energy density of O d -MVO-0.5 (MoV 2 O 8 sample deoxidized for 0.5 h) is 343.3 Wh kg−1. Importantly, the mechanism of Zn2+ storage in O d -MoV 2 O 8 was revealed by the combination of in situ and ex situ characterization techniques. [ABSTRACT FROM AUTHOR]

Supercapacitors, distinguished by their high power density, rapid charge‐discharge rates, and prolonged cycle life, hold significant promise in various technological applications. However, limited lower energy density still hinder their practical application. Enhancing intrinsic conductivity by smart choice of elemental combination along with design of nanostructures has the potential to significantly improve the electrochemical performance. Herein, a self‐template method was used for the synthesis of Zn‐doped hydrolyzed NiCo‐glycerate nanosphere (ZnNiCo−G−H) electrode material, assembled with a large number of nanosheets by simple hydrothermal reaction, which can provide abundant active sites and thus achieve superior electrochemical performance. The optimized electrode material displayed a specific capacitance of 1145 F g−1 at 1 A g−1. The fabricated asymmetric supercapacitor, composed of ZnNiCo−G−H and activated carbon as two electrodes, delivered excellent cycling performance with a capacitance retention of 93.8 % after 5000 cycles at the current density of 5 A g−1 and a high energy density of 40 Wh kg−1 at 825 W kg−1, offering great potential as a qualified candidate for the electrochemical energy storage devices. [ABSTRACT FROM AUTHOR]

\nResearch highlightsThe study examines the impact of zinc ions on energy storage in solvothermal-synthesised graphene-zinc oxide nanocomposites. In recent years, there has been extensive research focus on graphene and metal oxides, particularly in heterostructures and composites. These materials have a broad range of applications, like energy storage. Faradaic processes were shown by the observation of redox peaks in the CV analysis of a three-electrode system. The estimated specific capacitances of graphene at scan rates of (1, 50, and 100) mVS−1 were (1250, 562.5, and 390.6) Fg−1. The G-ZnO (2 w%) and G-ZnO (3 w%) gave the specific capacitance of (1354, 750, and 520) Fg−1 and (1422, 818, and 568) Fg−1 at the same scan rates of 1, 50, and 100 mV/s. Applying a potential to the material reveals its pseudo-capacitive properties. The XRD results for G-ZnO (2 w%) and G-ZnO (3 w%) show diffraction peaks at 2θ = 20.56°, 32.95°, 40.69°, 47.41°, 59.02°, and 69.04°, which correspond to the diffraction planes 011, 100, 101, 102, 110, and 200, respectively. The study examines the impact of zinc ions on energy storage in solvothermal-synthesised graphene-zinc oxide nanocomposites.Faradaic processes were confirmed by the observation of redox peaks in the CV analysis of a three-electrode system.The estimation of specific capacitances of graphene was carried out at scan rates of (1, 50, and 100) mVS−1, and it yielded values of (1250, 562.5, and 390.6) Fg−1.The study examines the impact of zinc ions on energy storage in solvothermal-synthesised graphene-zinc oxide nanocomposites.Faradaic processes were confirmed by the observation of redox peaks in the CV analysis of a three-electrode system.The estimation of specific capacitances of graphene was carried out at scan rates of (1, 50, and 100) mVS−1, and it yielded values of (1250, 562.5, and 390.6) Fg−1. [ABSTRACT FROM AUTHOR]

Benefiting from high safety, low cost, and competitive energy density, aqueous zinc ion batteries (AZIBs) have emerged as very promising technology for grid energy storage. However, the lifetime of AZIBs is severely affected by uncontrolled zinc dendritic growth and undesirable side reaction. To address the problem, natural aluminum silicate hydroxide covered glass fibers separator (AlSi‐GF) is prepared herein using a simple spraying method. Aluminum silicate hydroxide is a complex oxide, where a large number of adsorption sites can adsorb Zn2+ and guide its deposition process. In particular, the Maxwell–Wagner polarization of aluminum silicate hydroxide under an applied electric field contributes to homogenizing the electric field distribution around the interface, thereby modulating zinc deposition and reducing the nucleation overpotential. Impressively, AlSi‐GF separator enables high‐performance zinc‐metal batteries. The symmetric battery with AlSi‐GF separator has a stable voltage polarization and an ultra‐long cycle life of 2280 h at a current density of 1 mA cm−2, and the Zn//V2O5 full cell based on AlSi‐GF separator can exhibit a high specific capacity of 123 mAh g−1 after 1500 cycles at 1 A g−1. This study provides new insights into the design of reliable and cost‐effective separators for metal anodes in energy storage devices. [ABSTRACT FROM AUTHOR]

Aqueous Zn–metal batteries have attracted increasing interest for large-scale energy storage owing to their outstanding merits in terms of safety, cost and production. However, they constantly suffer from inadequate energy density and poor cycling stability due to the presence of zinc ions in the fully hydrated solvation state. Thus, designing the dehydrated solvation structure of zinc ions can effectively address the current drawbacks of aqueous Zn–metal batteries. In this case, considering the lack of studies focused on strategies for the dehydration of zinc ions, herein, we present a systematic and comprehensive review to deepen the understanding of zinc-ion solvation regulation. Two fundamental design principles of component regulation and pre-desolvation are summarized in terms of solvation environment formation and interfacial desolvation behavior. Subsequently, specific strategy based distinct principles are carefully discussed, including preparation methods, working mechanisms, analysis approaches and performance improvements. Finally, we present a general summary of the issues addressed using zinc-ion dehydration strategies, and four critical aspects to promote zinc-ion solvation regulation are presented as an outlook, involving updating (de)solvation theories, revealing interfacial evolution, enhancing analysis techniques and developing functional materials. We believe that this review will not only stimulate more creativity in optimizing aqueous electrolytes but also provide valuable insights into designing other battery systems. [ABSTRACT FROM AUTHOR]

Mn‐based oxides promise high energy density and low toxicity cathodes for aqueous zinc‐ion batteries (ZIBs) but suffer from complex irreversible phase transitions, accompanied by continuous disproportionation reactions and manganese dissolution. Tailor‐made reversible and robust crystal structure in Mn‐based material is crucial and challenging. Here a controllable electrochemical oxidation induced crystal transition strategy is developed for the transformation of cubic α‐Mn2O3 into amorphous Zn0.17MnO2−n·0.52H2O, which serves as the host of Zn2+, empowering more highly accessible built‐in zincophilic sites whilst alleviating the lattice repulsion of Zn2+ (de)intercalation. As confirmed by crystal structure evolution characterizations and theoretical simulations, the amorphous Zn0.17MnO2−n·0.52H2O with excellent electronic properties and low zinc‐ion migration barrier can be reversibly converted into ZnMn3O7·3H2O. This stabilized dynamic electrochemical crystal transition equilibrium contributes ultrahigh capacity (558 mAh g−1), high‐energy density (696 Wh kg−1@6 kW kg−1), and superior stability (5000 cycles). The approach can also extend to Mn3O4 and α‐MnO2, opening new insights into electrochemical oxidation induced crystal conversion to build highly reversible and durable ZIBs. [ABSTRACT FROM AUTHOR]

Cathode materials with conversion mechanisms for aqueous zinc-ion batteries (AZIBs) have shown a great potential as next-generation energy storage materials due to their high discharge capacity and high energy density. However, improving their cycling stability has been the biggest challenge plaguing researchers. In this study, CuO microspheres were prepared using a simple hydrothermal reaction, and the morphology and crystallinity of the samples were modulated by controlling the hydrothermal reaction time. The as-synthesized materials were used as cathode materials for AZIBs. The electrochemical experiments showed that the CuO-4h sample, undergoing a hydrothermal reaction for 4 h, had the longest lifecycle and the best rate of capability. A discharge capacity of 131.7 mAh g−1 was still available after 700 cycles at a current density of 500 mA g−1. At a high current density of 1.5 A g−1, the maintained capacity of the cell is 85.4 mA h g−1. The structural evolutions and valence changes in the CuO-4h cathode material were carefully explored by using ex situ XRD and ex situ XPS. CuO was reduced to Cu2O and Cu after the initial discharge, and Cu was oxidized to Cu2O instead of CuO during subsequent charging processes. We believe that these findings could introduce a novel approach to exploring high-performance cathode materials for AZIBs. [ABSTRACT FROM AUTHOR]

Aqueous zinc-ion batteries (ZIBs) offer numerous advantages, such as high energy density, enhanced safety, and low cost, making them an ideal choice for energy storage and conversion applications in the “postlithium” era. Hydrogel electrolytes, as the key component of flexible ZIBs, combine the ionic conductivity of traditional water electrolytes with the dimensional stability of solid polymer electrolytes. However, it remains a challenge to design comprehensive and appropriate hydrogel electrolytes to provide flexible ZIBs with good reversibility and versatility. This review discusses the engineering design of hydrogel electrolytes required for flexible ZIBs from the viewpoint of an electrolyte designer. The basic properties of the hydrogel electrolytes, zinc anodes, cathodes and electrolyte stabilization effects are described in detail. Furthermore, we explore the various challenges faced by hydrogel electrolytes and propose corresponding strategies. Finally, the review offers insights into the future development of hydrogel-stabilized ZIBs. [ABSTRACT FROM AUTHOR]

The rapid advancement of wearable devices and flexible electronics has spurred an increasing need for high-performance, thin, lightweight, and flexible energy storage devices. In particular, thin and lightweight zinc-ion batteries require battery materials that possess exceptional flexibility and mechanical stability to accommodate complex deformations often encountered in flexible device applications. Moreover, the development of compact and thin battery structures is essential to minimize the overall size and weight while maintaining excellent electrochemical performance, including high energy density, long cycle life, and stable charge/discharge characteristics, to ensure their versatility across various applications. Researchers have made significant strides in enhancing the battery's performance by optimizing crucial components such as electrode materials, electrolytes, separators, and battery structure. This review provides a comprehensive analysis of the design principles essential for achieving thinness in zinc-ion batteries, along with a summary of the preparation methods and potential applications of these batteries. Moreover, it delves into the challenges associated with achieving thinness in zinc-ion batteries and proposes effective countermeasures to address these hurdles. This review concludes by offering insights into future developments in this field, underscoring the continual advancements and innovations that can be expected. [ABSTRACT FROM AUTHOR]

Vanadium nitride (VN) is a potential cathode material with high capacity and high energy density for aqueous zinc batteries (AZIBs). However, the slow kinetics resulting from the strong electrostatic interaction of the electrode materials with zinc ions is a major challenge for fast storage. Here, VN clusters with nitrogen‐vacancy embedded in carbon (C) (Nv‐VN/C‐SS‐2) are prepared for the first time to improve the slow reaction kinetics. The nitrogen vacancies can effectively accelerate the reaction kinetics, reduce the electrochemical polarization, and improve the performance. The density functional theory (DFT) calculations also prove that the rapid adsorption and desorption of zinc ions on Nv‐VN/C‐SS‐2 can release more electrons to the delocalized electron cloud of the material, thus adding more active sites. The Nv‐VN/C‐SS‐2 exhibits a specific capacity and outstanding cycle life. Meanwhile, the quasi‐solid‐state battery exhibits a high capacity of 186.5 mAh g−1, ultra‐high energy density of 278.9 Wh kg−1, and a high power density of 2375.1 W kg−1 at 2.5 A g−1, showing excellent electrochemical performance. This work provides a meaningful reference value for improving the comprehensive electrochemical performance of VN through interface engineering. [ABSTRACT FROM AUTHOR]

The development of transition metal oxide cathodes with high capacity and ultralong lifespan is one of the keys to promoting the performance of aqueous zinc–ion batteries, but it remains a crucial challenge. Herein, cobalt oxide is applied as an example to demonstrate that low‐degree fluorination is a novel approach to synergistically boost charge storage kinetics and stability. Specifically, partial substitution of O2− with F− intensifies electron delocalization of Co 3d orbitals, which reduces bulk charge transfer impedance and endows surface active sites with higher reactivity, thus achieving boosted redox kinetics and energy density. Moreover, the modification of coordination structure with the highest‐electronegativity F− can effectively inhibit irreversible phase transition and structural deformation, which assures significantly optimized cycling stability. As a result, the fluorinated Co3O4 demonstrates a distinctly improved specific capacity of 406 mAh g−1 at 1 A g−1, approximately a threefold increase compared to one of pristine Co3O4 (131 mAh g−1). The assembled fluorinated Co3O4//Zn battery delivers an ultrahigh energy density of 658 Wh kg−1 at 3.5 kW kg−1 and 95.7% capacity retention after 10 000 cycles. This work offers a new understanding of the electronic engineering of metal oxides toward high‐performance energy storage applications. [ABSTRACT FROM AUTHOR]

Aqueous Zinc Ion Batteries (ZIBs), characterized by their high theoretical capacity, cost-effectiveness, and robust safety profile, stand out as one of the most promising contenders for the next-generation of electrochemical energy storage applications. Nevertheless, the commercialization of ZIBs encounters obstacles of unsatisfactory energy density and suboptimal cycling stability, which are related to the unstable interfaces of Zn anodes and cathodes. Herein, the research advances in Zn anodes and cathode materials and corresponding interface engineering in recent years are systematically reviewed. The rationalization of these research can guide further investigations in the design of cathode/anode materials in ZIBs. [ABSTRACT FROM AUTHOR]

The development of a high specific capacity and stable vanadium-based cathode material is very attractive for aqueous zinc-ion batteries (ZIBs). Herein, an in situ electrochemically oxidized cathode is fabricated based on a V2O3@MXene cathode for Zn-ion storage. V2O3@MXene undergoes a phase transition to Zn3(OH)2V2O7·2H2O and ZnyVOz on the first charge, thus allowing for the subsequent insertion/de-insertion of zinc ions, which can be regulated by the amount of H2O in the electrolyte. The MXene in the composite was also beneficial to electron transfer and cycling stability. V2O3@MXene delivered a high capacity of 450 mA h g−1 at 0.2 A g−1, ultra-high-rate performance and cycling stability as well as high energy density. [ABSTRACT FROM AUTHOR]

Zinc ion batteries (ZIBs) exhibit significant promise in the next generation of grid‐scale energy storage systems owing to their safety, relatively high volumetric energy density, and low production cost. Despite substantial advancements in ZIBs, a comprehensive evaluation of critical parameters impacting their practical energy density (Epractical) and calendar life is lacking. Hence, we suggest using formulation‐based study as a scientific tool to accurately calculate the cell‐level energy density and predict the cycling life of ZIBs. By combining all key battery parameters, such as the capacity ratio of negative to positive electrode (N/P), into one formula, we assess their impact on Epractical. When all parameters are optimized, we urge to achieve the theoretical capacity for a high Epractical. Furthermore, we propose a formulation that correlates the N/P and Coulombic efficiency of ZIBs for predicting their calendar life. Finally, we offer a comprehensive overview of current advancements in ZIBs, covering cathode and anode, along with practical evaluations. This Minireview outlines specific goals, suggests future research directions, and sketches prospects for designing efficient and high‐performing ZIBs. It aims at bridging the gap from academia to industry for grid‐scale energy storage. [ABSTRACT FROM AUTHOR]

Developing low‐cost and safe batteries with high energy density is promising for large‐scale energy storage applications. Currently, aqueous zinc ion batteries (AZIBs) using Zn metal as the anode have attracted tremendous research attention as the next generation of energy storage devices due to their advantages of high energy density, environmental friendliness, and natural Zn abundance. The utilization of synchrotron X‐ray analytical techniques for in situ/ex situ characterizations offers a comprehensive understanding of the atomic local structure, crystalline structure, chemical states, coordination environment, interface properties, morphologies, and other physicochemical properties of materials on a variety of temporal and length scales, providing valuable insights into the fundamental mechanisms of AZIBs. This review highlights the recent advances and accomplishments of various synchrotron X‐ray techniques, which have been employed to investigate different components of AZIBs and show great promise for battery research and development. [ABSTRACT FROM AUTHOR]

Aqueous zinc‐ion batteries (AZIBs) comprising zinc anodes hold intrinsic safety and high energy density ideally for distributed and large‐scale energy storage, thus have generated intriguing properties and increasing research interests. Unlike organic batteries, AZIBs require different, sometimes even opposite design principles and preparation strategies in solvent, electrolyte, and separator. This is especially true for the polymer materials that are widely used as critical components in stabilizing metal anodes and functioning as high‐performance safe cathode materials. This review discusses the explicit compositional and structural requisite of polymeric components in AZIBs, with an emphasis on the exclusive molecular structure–property relationship that governs the stability, reversibility, and capacity of these devices. The usage of polymers is classified into five categories aligning with the primary architecture of AZIBs: separators, additives, hydrogel electrolytes, coatings, and electrode materials. The most recent advances in the structure/property interplay of polymers by novel synthesis and preparation techniques targeting stable AZIBs are summarized and discussed. The challenges and perspectives of multifunctional polymers in developing high‐performance AZIBs are also proposed. [ABSTRACT FROM AUTHOR]

As a promising candidate to replace lithium-ion batteries, rechargeable aqueous zinc ion batteries (AZIB) are receiving increasing attention due their high energy density, high safety, low cost and environmental friendliness. In this study, metal ions may be introduced into the interlayer gap of layered vanadium oxide nanobelts through a one-step hydrothermal process, without changing their original structure. Moreover, we have demonstrated by density functional theory computations that Mn metal ions not only serve as structural pillars but also enhance the conductivity of MnxVO2·0.2H2O, facilitating the migration of Zn ions. As a result, the electrochemical performance of MnxVO2·0.2H2O as an AZIB cathode has significantly improved; after 100 cycles at 0.5 A g−1, it exhibits a high reversible capacity of 350 mA h g−1. With a high current density of 5 A g−1, the initial capacity can still reach 295 mA h g−1. This paper suggests an effective method to maximize the efficiency of AZIB electrode materials. [ABSTRACT FROM AUTHOR]

Introduction: This review assesses the current challenges in energy supply, underscores the limitations of LIBs, and presents rechargeable ZIBs as a promising alternative, providing a comprehensive overview of recent developments and potential applications in the context of sustainable energy solutions. Working principle of ZINC‐ION Battery: This section outlines the operational similarities and distinct parameter differences between rechargeable ZIBs and LIBs, emphasizing challenges posed by zinc ions' size and optimization strategies, show casing ZIBs as a compelling alternative with enhanced electrochemical performance and consideration for material availability, safety, and environmental factors. Materials: Recent studies have intricately examined and optimized the components of ZIBs, including the anode, cathode, electrolyte, and separator, utilizing novel materials and strategies to enhance electrochemical performance and address challenges, marking significant progress in advancing ZIB technology. Performance metrics of ZIBS: Monitoring and optimizing parameters such as energy density, power density, and safety considerations in ZIB is essential for their competitive viability against LIBs, with ongoing research addressing performance gaps and highlighting ZIB's inherent safety advantages. Recent advancements in Rechargeable ZIBS: The current global focus on ZIB research centers on material enhancements, incorporating strategies such as pillar engineering, conductive material hybridization, and cationic/anionic doping to optimize cathode materials, Zn anode, and electrolyte components, reflecting a growing yet evolving technology with ongoing efforts to refine material assembly for future applications. Challenges of ZIB Technology: Critical challenges in developing ZIBs as a viable alternative to LIBs include addressing issues with cathode stability, electronic conductivity, dendrite growth in the Zinc anode, and optimization difficulties in electrolytes and separators, necessitating ongoing research efforts for the commercial success and broader application of ZIB technology in the battery market. Applications of ZIBs: Rechargeable batteries like ZIBs demonstrate imminent potential as alternatives to address the energy crisis, finding applications in stationary energy storage and digital/electronic devices, offering safety, cost advantages, and a promising solution to alleviate the strain on global demand LIBs. Environmental impact and Sustainability: ZIBs present an environmentally superior and sustainable alternative to LIBs, as evidenced by life cycle assessment studies showcasing lower environmental impacts, enhanced recyclability, and the absence of harmful heavy metals. Future prospect, Outlook, and Conclusion: The promising future of ZIBs is characterized by their safety, abundant zinc resources, and potential dominance in diverse applications, with ongoing research addressing challenges for commercialization and integration into the energy landscape. [ABSTRACT FROM AUTHOR]

As a new type of secondary ion battery, aqueous zinc‐ion battery has a broad application prospect in the field of large‐scale energy storage due to its characteristics of low cost, high safety, environmental friendliness, and high‐power density. In recent years, manganese dioxide (MnO2)‐based materials have been extensively explored as cathodes for Zn‐ion batteries. Based on the research experiences of our group in the field of aqueous zinc ion batteries and combining with the latest literature of system, we systematically summarize the research progress of Zn−MnO2 batteries. This article first reviews the current research progress and reaction mechanism of Zn−MnO2 batteries, and then respectively expounds the optimization of MnO2 cathode, Zn anodes, and diverse electrolytes and their effects on battery performance. Additionally, primary challenges related to different components and their respective strategies for mitigating them are discussed, with the ultimate objective of offering comprehensive guidance for the design and fabrication of high‐performance Zn−MnO2 batteries. Finally, the future research and development direction of aqueous Zn−MnO2 batteries with high energy density, high safety and long life is envisioned. [ABSTRACT FROM AUTHOR]

Aqueous zinc ion batteries are gaining popularity due to their high energy density and environmental friendliness. However, random deposition of zinc ions on the anode and sluggish migration of zinc ions on the interface would lead to the growth of zinc dendrites and poor cycling performance. To address these challenges, we developed a fluorinated solid‐state‐electrolyte interface layer composed of Ca5(PO4)3F/Zn3(PO4)2 via an in situ ion exchange strategy to guide zinc‐ion oriented deposition and fast zinc ion migration on the anode during cycling. The introduction of Ca5(PO4)3F (FAP) can increase the nucleation sites of zinc ions and guide the oriented deposition of zinc ions along the (002) crystal plane, while the in situ formation of Zn3(PO4)2 during cycling can accelerate the migration of zinc ions. Benefited from our design, the assembled Zn//V2O5 ⋅ H2O batteries based on FAP‐protected Zn anode (FAP‐Zn) achieve a higher capacity retention of 84 % (220 mAh g−1) than that of bare‐Zn based batteries, which have a capacity retention of 23 % (97 mAh g−1) at 3.0 A g−1 after 800 cycles. This work provides a new solution for the rational design and development of the solid‐state electrolyte interface layer to achieve high‐performance zinc‐ion batteries. [ABSTRACT FROM AUTHOR]

The main bottlenecks that hinder the performance of rechargeable zinc electrochemical cells are their limited cycle lifetime and energy density. To overcome these limitations, this work studied the mechanism of a dual-ion Zn-Cu electrolyte to suppress dendritic formation and extend the device cycle life while concurrently enhancing the utilization ratio of zinc and thereby increasing the energy density of zinc ion capacitors (ZICs). The ZICs achieved a best-in-class energy density of 41 watt hour per kilogram with a negative-to-positive (n/p) electrode capacity ratio of 3.10. At the n/p ratio of 5.93, the device showed a remarkable cycle life of 22,000 full charge-discharge cycles, which was equivalent to 557 hours of discharge. The cumulative capacity reached ~581 ampere hour per gram, surpassing the benchmarks of lithium and sodium ion capacitors and highlighting the promise of the dual-ion electrolyte for delivering high-performance, low-maintenance electrochemical energy supplies. [ABSTRACT FROM AUTHOR]

Compared with aqueous single‐ion batteries, rechargeable aqueous hybrid ion batteries, especially Li+/Zn2+hybrid ion batteries, are receiving extensive interest owing to their low cost, high operating voltage, and energy density. However, their working voltage and lifespan are limited by the decomposition of water and the growth of Zn dendrites. Herein, detrimental side reactions induced by the water reduction and the Zn dendrite growth are successfully suppressed by a poly(propylene glycol) (PPG)‐based hybrid ion electrolyte [(1 m Zn(TFSI)2 + 10 m LiTFSI) in PPG/H2O]. The addition of PPG in the electrolyte can not only enhance the bonding strength of hydrogen‐bond in water but also tailor the solvation sheath of Zn2+ as revealed by synchrotron X‐rays. The participated solvation of PPG with Zn2+ can weaken Zn−H2O interactions and redistribute Zn2+ flux on the surface of the Zn anode, thus inducing favorably even deposition of Zn. In addition, the decomposition of TFSI− contributes a ZnF2 ‐enriched solid electrolyte interface at the Zn anode to further prevent water decomposition and restrain Zn dendrites. The PPG‐based electrolyte enables 2.1 V LiMnO2//Zn batteries to deliver high specific capacities (121.7 mAh g−1 for a coin cell and 90 mAh g−1 for a pouch cell), and maintain 80% of the capacity over 700 cycles at 0.5 C, suggesting a promising pathway for highly reversible aqueous hybrid ion batteries. [ABSTRACT FROM AUTHOR]

Manganese-based materials have received more attention as cathodes for aqueous zinc ion hybrid capacitors (AZIHCs) due to their advantages such as abundant reserves, low cost, and large theoretical capacity. However, manganese-based materials have the disadvantage of poor electrical conductivity. Herein, a solid-phase method was used to synthesize a hierarchical carbon-coated calcium manganate (CaMn2O4/C) network framework as the cathode for AZIHCs. Thanks to the unique structural/componential merits including conductive carbon coating and hierarchical porous architecture, the achieved CaMn2O4/C cathode shows an exceptionally long life of close to 5000 cycles at 2.0 A g−1, with a reversible specific capacity of 195.6 mAh g−1. The assembled CaMn2O4/C-based AZIHCs also display excellent cycling stability with a capacity retention rate of 84.9% after 8000 cycles at 1.0 A g−1, and an energy density of 21.3 Wh kg−1 at an output power density of 180.0 W kg−1. [ABSTRACT FROM AUTHOR]

Aqueous zinc ion batteries (ZIBs) are considered as promising energy storage devices in the post-lithium-ion era, due to their high energy density, low cost, high safety, and environmental benignity, however their commercialization is hindered by the sluggish diffusion kinetics of cathode materials due to the large hydrate Zn2+ radius. In this work, we propose a unique structure inheritance strategy for preparing Bi2S3 micro-straws in which a metal–organic framework (MOF) denoted as Bi-PYDC (PYDC2− = 3,5-pyridinedicarboxylate) with a string of [Bi2O2]2+ chains is judiciously selected as the structure-directing template to induce the formation of micro-straws based on a topochemical reaction. The distinctive hollow structure significantly enhances the ionic storage kinetics. Impressively, the obtained battery exhibits an ultra-long cycle life of more than 10 000 cycles at a current density of 1 A g−1 while maintaining a capacity of more than 153.4 mA h g−1. In addition, the Zn2+ insertion/extraction mechanism of Bi2S3 micro-straws is also investigated by multiple analytical methods, revealing the involvement of Zn2+ rather than H+ in the electrochemical storage process. This work may lead a new direction for constructing high performance cathodes of Zn-ion batteries through a MOF-based structure-directing template. [ABSTRACT FROM AUTHOR]

Conformal PEDOT skin formed by in-situ polymerization could effectively enhance the structural stability and improve the electrical conductivity of MOP-5. A new energy storage mechanism of ε-MnO 2 (ε-MnO 2 transformed to ZnMn 3 O 7) was first put forward. [Display omitted] Manganese dioxide (MnO 2) is an important active material for energy storage. Constructing microsphere-structured MnO 2 is key for practical application due to the high tapping density for high volumetric energy density. However, the unstable structure and poor electrical conductivity hinder the development of MnO 2 microspheres. Herein, Poly 3,4-ethylene dioxythiophene (PEDOT) is painted conformally on ε-MnO 2 microspheres to stabilize the structure and enhance the electrical conductivity via in-situ chemical polymerization. When used for Zinc ion batteries (ZIBs), the obtained material (named MOP-5) with high tapping density (1.04 g cm−3) delivers a superior volumetric energy density (342.9 mWh cm−3) and excellent cyclic stability (84.5% after 3500 cycles). Moreover, we find the structure transformation of ε-MnO 2 to ZnMn 3 O 7 during the initial few cycles of charge and discharge, and the ZnMn 3 O 7 provides more reaction sites for Zinc ions from analysis of the energy storage mechanism. The material design and theoretical analysis of MnO 2 in this work may provide a new idea for future commercial applications of aqueous ZIBs. [ABSTRACT FROM AUTHOR]

Zinc-ion hybrid capacitors with neutral electrolytes have good safety, excellent power density, and energy density. However, zinc-ion hybrid capacitors rely on expensive porous carbon cathode materials. Additional chemical reagents are required to activate precursor during the pore-forming process. Therefore, it is essential to develop porous carbon with low preparation costs and high performance. In this work, low-cost calcium lignosulfonate (CLS) as a carbon source was used to prepare N, O, and S tri-doped hierarchical porous carbon (LHPC) by a one-step carbonization method without additional pore-forming agents. During high-temperature carbonization, the self-pyrolysis of CLS yields a variety of gaseous products as well as inorganic salts like calcium carbonate and calcium sulfate, which work as pore-forming agents. Used as a cathode, LHPC-700 was assembled into an asymmetric zinc ion electrochemical capacitor. The capacitor exhibits a gravimetric specific capacitance of 178.7 F g−1 at a current density of 0.1 A g−1 and an energy density of 63.5 W h kg−1. This study provides an idea for the sustainable utilization of lignin resources to prepare three-dimensional hierarchical porous carbon electrode materials. [ABSTRACT FROM AUTHOR]

Cobalt hydroxide is a widely studied electrode material for supercapacitor and alkaline zinc ion batteries. The large interlayer spacing of Co(OH)2 is also attractive to store Zn ions. However, Co(OH)2 is quite unstable in the acidic ZnSO4 electrolyte due to its amphoteric nature. Herein, we synthesized a mixed phase of Co(OH)2/CoOOH via a two-step electrochemical preparation. As the cathode material for an aqueous zinc ion battery (AZIB), Co(OH)2/CoOOH delivered a maximum capacity of 164 mAh g−1 at 0.05 A g−1 and a high energy density of 275 Wh kg−1. Benefiting from the low charge-transfer resistance, a capacity of 87 mAh g−1 was maintained at 1.6 A g−1, showing a good rate performance of the mixed phase. Various spectroscopy analyses and simulations based on the density functional theory (DFT) suggested a higher thermal stability of the mixed phase than pure Co(OH)2, due to its less local structural disorder. The reduced Co-Co and Co-O shells increased the mechanical strength of the mixed phase to accommodate Zn2+ ions and endure the electrostatic repulsion, resulting in an enhanced cycling stability. The mixed phased also delivered a good stability at the current density of 0.05 A g−1. After 200 cycles, a capacity retention of 78% was retained, with high Coulombic efficiencies. These results provide a new route to synthesize high-performance LDH for aqueous zinc ion batteries. [ABSTRACT FROM AUTHOR]

Constructing hierarchically ordered macro/meso−microporous structures of carbonaceous cathode with matchable pore size and adequate active sites is significant toward large Zn2+ storage, but remains a formidable challenge. Herein, a new perspective is reported for synthesizing phosphorus and nitrogen dual‐doped hierarchical ordered porous carbon (PN‐HOPC) by eliminating the micropore confinement effect and synchronously introducing multi‐chemisorption sites. The interconnected macropore can effectively facilitate long‐distance mass transfer, and meso−microporous wall can promote accessibility of active sites. Density functional theory (DFT) calculations identify that the P and N co‐doping markedly contributes to the reversible adsorption/desorption of zinc ions and protons. Consequently, the optimized PN‐HOPC exhibits outstanding Zn2+ storage capabilities in terms of high capacity (211.9 mAh g−1), superb energy density (169.5 Wh kg−1), and ultralong lifespan (99.3% retention after 60 000 cycles). Systematic ex situ measurements integrating with in situ Raman spectroscopy and electrochemical quartz crystal microbalance (EQCM) techniques elucidate that the superior electrochemical capability is ascribed to the synergistic effect of the Zn2+, H+, and SO42− co‐adsorption mechanism, as well as invertible chemical adsorption. This study not only provides new insights to design advanced carbon materials toward practical applications but also sheds lights on a deeper understanding of charge storage mechanism for zinc‐ion capacitors (ZICs). [ABSTRACT FROM AUTHOR]

The development of aqueous zinc‐ion capacitors (ZICs) is an effective approach to improve the safety and environmental friendliness of energy storage devices. In this paper, TiC/CNTs core‐shell array structures (TCT) were synthesized on titanium substrate through in‐situ simple chemical vapor deposition and carbon reduction and used as self‐supporting cathodes for aqueous ZICs. As expected, as‐prepared TCT electrode exhibited excellent electrochemical performance in aqueous electrolytes, demonstrating a high specific capacitance of 275.13 F g−1 at a current density of 1.0 A g−1 and maintaining 90.5 % of its initial capacity after 10000 charge‐discharge cycles. The assembled Zn//TCT ZIC displays excellent rate capability, delivering an excellent specific capacitance of 298.2 F g−1 at 0.5 A g−1 and 193.5 F g−1 at a high current density of 10 A g−1. Zn//TCT device can provide an ultra‐high energy density of 24.8 Wh kg−1 at a power of 6984.1 W kg−1. DFT calculations further demonstrate that a large number of electrons are transferred at the TiC/CNT interface and stable TIC−C bonds can be formed. This work provides a new strategy for rationally designing transition metal carbide electrodes and constructing ZICs with high energy and power densities. [ABSTRACT FROM AUTHOR]

Aqueous zinc-ion batteries (AZIBs) have raised wide concern as a new generation energy storage device due to their high capacity, low cost, and environmental friendliness. It is a crucial step to develop the ideal cathode materials that match well with the Zn anode. In this work, we report polypyrrole-(PPy)-encapsulated MnO2 nanowires as cathode materials for AZIBs. The assembled Zn//MnO2@PPy batteries deliver a reversible capacity of 385.7 mAh g−1 at a current density of 0.1 A g−1. Also, they possess an energy density of 192 Wh kg−1 at a power density of 50 W kg−1. The cells show long-term cycling stability, with a retention rate of 96% after 1000 cycles. The outstanding electrochemical performance indicates their potential applications in large-scale energy storage. [ABSTRACT FROM AUTHOR]

Manganese oxide as the star cathode material of aqueous zinc ion batteries is vigorously developed because of its environmental protection, outstanding theoretical capacity, and high voltage. However, severe Jahn–Teller distortion of trivalent Mn has detrimental effect on cyclic stability. Herein, 1D core‐shell bimetal oxide with cross‐doping of heteroatom is successfully designed by self‐template method via one‐step hydrothermal reaction. Specifically, the thick shell of Mo‐doped α‐MnO2 with increased nanopores, expanded lattice spacing, and high oxidation state not only contributes high capacity but also suppresses the lattice distortion due to the doping of high‐valent Mo6+; While the thin core of Mn‐doped MoO3 nanobelt supplies a shaped template, important Mo source, and improved conductive path. Therefore, this composite exhibits a superior capacity of 366.2 mAh g−1 at 0.2 A g−1 and 100% capacity retention after 100 cycles, which effectively increases to 4.1 times from 1.5 times of pure α‐MnO2 based battery. Besides promoting the electrochemical performance in coin‐cell batteries, composite materials also balance the electrochemical and mechanical performances in flexible micro‐batteries with area energy density of 261.2 µWh cm−2. Therefore, this synergetic self‐template and cross‐doping strategy can extend to the material design of other high‐performance metal oxides for energy storage application. [ABSTRACT FROM AUTHOR]

Aqueous zinc‐ion micro‐batteries (ZIMBs) have attracted considerable attention owing to their reliable safety, low cost, and great potential for wearable devices. However, current ZIMBs still suffer from various critical issues, including short cycle life, poor mechanical stability, and inadequate energy density. Herein, the fabrication of flexible planar ZIMBs with ultrahigh energy density by interfacial engineering in the screen‐printing process based on high‐performance MnO2‐based cathode materials is reported. The Ce‐doped MnO2 (Ce‐MnO2) exhibits significantly enhanced capacity (389.3 mAh g−1), considerable rate capability and admirable cycling stability than that of the pure MnO2. Importantly, the fabrication of micro‐electrodes with ultrahigh mass loading of Ce‐MnO2 (24.12 mg cm−2) and good mechanical stability is achieved through optimizing the interfacial bonding between different printed layers. The fabricated planar ZIMBs achieve a record high capacity (7.21 mAh cm−2 or 497.31 mAh cm−3) and energy density (8.43 mWh cm−2 or 573.45 mWh cm−3), as well as excellent flexibility. Besides, a wearable self‐powered sensing system for environmental monitoring is further demonstrated by integrating the planar ZIMBs with flexible solar cells and a multifunctional sensor array. This work sheds light on the development of high‐performance planar ZIMBs for future self‐powered and eco‐friendly smart wearable electronics. [ABSTRACT FROM AUTHOR]

A hierarchical spheroidal MnO@C heterogeneous interface as a cathode material for AZIBs and synthesized through a MOF, which exhibits the excellent cycling stability. [Display omitted] Aqueous zinc-ion batteries (AZIBs) have shown great potential as energy storage devices owing to their high energy density, low cost, and low toxicity. Typically, high performance AZIBs incorporate manganese-based cathode materials. Despite their advantages, these cathodes are limited by significant capacity fading and poor rate performance due to the dissolution and disproportionation of manganese. Herein, hierarchical spheroidal MnO@C structures were synthesized from Mn-based metal–organic frameworks, which benefit from a protective carbon layer to prevent manganese dissolution. The spheroidal MnO@C structures were incorporated onto a heterogeneous interface to act as a cathode material for AZIBs, which exhibited excellent cycling stability (160 mAh g−1 after 1000 cycles at 3.0 A g−1), good rate capability (165.9 mAh g−1 at 3.0 A g−1), and appreciable specific capacity (412.4 mAh g−1 at 0.1 A g−1) for AZIBs. Moreover, the Zn2+ storage mechanism in MnO@C was comprehensively investigated using ex-situ XRD and XPS studies. These results demonstrate that hierarchical spheroidal MnO@C is a potential cathode material for high-performing AZIBs. [ABSTRACT FROM AUTHOR]

Zinc ion batteries are favored by researchers because of their intrinsic safety, low cost, and high theoretical energy density. The serious dendrite growth of Zn anode during electrochemical deposition inhibits the development of zinc ion batteries currently. Many research works have been carried out to modify the zinc metal anode surface and aqueous electrolyte. Significantly, as the carrier of electrolyte and the bridge of ions, the separators show promising potential of inhibiting dendrites growth by regulating the ions migration and the electric field of the electrolyte-anode interface. However, a technical review about the separators of zinc ion batteries is still rare. In this review, the basic requirements of separators and the latest development of modification materials and mechanisms are summarized. Finally, the perspectives for further developments on the separators of zinc ion batteries are outlined. This review could offer useful information for the further development of separators for zinc ion batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] Researchers have recently redirected their attention toward aqueous batteries in pursuit of safety and affordability. The water-based electrolyte promises many appealing merits such as non-flammability and environmental friendliness but is also cursed with low energy density. In an attempt of lifting the curse, many efforts have been made to re-formulate the aqueous electrolyte, which seems unlikely to succeed without understanding the interplay between electrolytes' physical properties and electrochemical performance. Starting from the composition of electrolytes, we discuss how various formulas of zinc ion battery electrolytes lead to diverse electrochemical performances. By evaluating the electrochemical performance of batteries in five metrics, it provides a la carte electrolyte designing strategies with different battery purposes. [ABSTRACT FROM AUTHOR]

Aqueous Zn‐ion batteries (AZIBs) and Zn‐ion hybrid supercapacitors (AZHSCs) are considered promising energy‐storage alternatives to Li‐ion batteries due to the attractive merits of low‐price and high‐safety. However, the lack of suitable cathode materials always hinders their large‐scale application. Herein, amorphous K‐buserite microspheres (denoted as K‐MnOx) are reported as cathode materials for both AZIBs and AZHSCs, and the energy‐storage mechanism is systematically revealed. It is found that K‐MnOx is composed of rich amorphous K‐buserite units, which can irreversibly be transformed into amorphous Zn‐buserite units in the first discharge cycle. Innovatively, the transformed Zn‐buserite acts as active materials in the following cycles and is highly active/stable for fast Zn‐diffusion and superhigh pseudocapacitance, enabling the achievement of high‐efficiency energy storage. In the AZIBs, K‐MnOx delivers 306 mAh g−1 after 100 cycles at 0.1 A g−1 with 102% capacity retention, while in the AZHSCs, it shows 515.0/116.0 F g−1 at 0.15/20.0 A g−1 with 92.9% capacitance retention at 5.0 A g−1 after 20 000 cycles. Besides, the power/energy density of AZHSCs device can reach up to 16.94 kW kg−1 (at 20 A g−1)/206.7 Wh kg−1 (at 0.15 A g−1). This work may provide some references for designing next‐generation aqueous energy‐storage devices with high energy/power density. [ABSTRACT FROM AUTHOR]

Conventional power sources encounter difficulties in achieving structural unitization with complex‐shaped electronic devices because of their fixed form factors. Here, it is realized that an on‐demand conformal Zn‐ion battery (ZIB) on non‐developable surfaces uses direct ink writing (DIW)‐based nonplanar 3D printing. First, ZIB component (manganese oxide‐based cathode, Zn powder‐based anode, and UV‐curable gel composite electrolyte) inks are designed to regulate their colloidal interactions to fulfill the rheological requirements of nonplanar 3D printing, and establish bi‐percolating ion/electron conduction pathways, thereby enabling geometrical synchronization with non‐developable surfaces, and ensuring reliable electrochemical performance. The ZIB component inks are conformally printed on arbitrary curvilinear substrates to produce embodied ZIBs that can be seamlessly integrated with complicated 3D objects (including human ears). The conformal ZIB exhibits a high fill factor (i.e., areal coverage of cells on underlying substrates, ≈100%) that ensures high volumetric energy density (50.5 mWh cmcell−3), which exceeds those of previously‐reported shape‐adaptable power sources. [ABSTRACT FROM AUTHOR]

Due to their reliability, affordability and high safety, rechargeable aqueous zinc ion batteries (ZIBs) have garnered a lot of attention. Nevertheless, undesirable long-term cycle performance and the inadequate energy density of cathode materials impede the development of ZIBs. Herein, we report a layered CaV4O9-MXene (Ti3C2Tx) composite assembled using CaV4O9 nanosheets on Ti3C2Tx and investigate its electrochemical performance as a new cathode for ZIBs, where CaV4O9 nanosheets attached on the surface of MXene and interlamination create a layered 2D structure, efficiently improving the electrical conductivity of CaV4O9 and avoiding the stacking of MXene nanosheets. The structure also enables fast ion and electron transport. Further discussion is conducted on the effects of adding MXene in various amounts on the morphology and electrochemical properties. The composite shows an improved reversible capacity of 274.3 mA h g−1 at 0.1 A g−1, superior rate capabilities at 7 A g−1, and a high specific capacity of 107.6 mA h g−1 can be delivered after 2000 cycles at a current density of 1 A g−1. The improvement of the electrochemical performance is due to its unique layered structure, high electrical conductivity, and pseudo capacitance behavior. [ABSTRACT FROM AUTHOR]

Zinc ion hybrid supercapacitors (ZHS) have received much attention due to the enhanced potential window range and high specific capacity. However, the appropriate positive materials with high electrochemical performance are still a challenge. Herein, NH4+ and glycerate anions pre-inserted Mo glycerate (N-MoG) spheres are synthesized and serve as the template to form NH4+ intercalated Ni3S2/Ni3O2(OH)4@MoS2 core—shell nanoflower (N-NiMo-OS) in-situ grown on nickel foam (NF) (N-NiMo-OS/NF) by sulfurization treatment. Compared with the product using traditional MoG as a template, N-NiMo-OS/NF inheriting a larger core structure from N-MoG delivers enhanced space for ions transport and volume expansion during the energy storage process, together with the synergistic effects of multi-components and the heterostructure, the as-prepared N-NiMo-OS/NF nanoflower exhibits excellent performance for the battery-type hybrid supercapacitors (BHS) and ZHS devices. Notably, the ZHS device delivers superior electrochemical performance to the BHS device, such as a higher specific capacity of 327.5 mAh·g−1 at 1 A·g−1, a preeminent energy density of 610.6 Wh·kg−1 at 1710 W·kg−1, and long cycle life. The in-situ Raman, ex-situ X-ray photoelectron spectroscopy (XPS), and theoretical calculation demonstrate the extra Zn2+ insertion/extraction storage mechanism provides enhanced electrochemical performance for ZHS device. Therefore, the dual-ion pre-inserted strategy can be extended for other advanced electrode materials in energy storage fields. [ABSTRACT FROM AUTHOR]

The demand for energy storage is growing, and the disadvantages of lithium‐ion batteries are being explored to overcome them. Accordingly, aqueous zinc‐ion batteries (ZIBs) are developing very rapidly, owing to their high safety, environmental friendliness, high abundance of resources, and high cost performance. Over the last decade, ZIBs have made remarkable progress through extensive efforts in the field of electrode materials and through fundamental understanding of non‐electrode components, such as solid‐electrolyte interphase, electrolytes, separators, binders, and current collectors. In particular, the breakthrough in using separators on non‐electrode elements should not be overlooked as such separators have proven key to conferring ZIBs with high energy and power density. In this Review, recent progress in the development of separators in ZIBs is comprehensively summarized based on their functions and roles in ZIBs, including the modification of conventional separators and the development of novel separators. Finally, the prospects and future challenges of separators are also discussed to facilitate ZIBs development. [ABSTRACT FROM AUTHOR]

Independent photo‐charging technologies based on aqueous zinc‐ion batteries (ZIBs) are promising candidates for next‐generation renewable energy systems. The conflict between light utilization and electrochemical performance in the planar electrode severely limits the availability of photo‐charging ZIBs. Herein, 3D light‐trapping structures (LTSs) are proposed and applied in a rigid VO2/C@SiCuOC electrode. A hybrid‐reflection effect driven by LTSs is employed to improve light‐harvesting efficiency. The suitable energy levels of VO2 and C ensure charge transport, while the rigid SiCuOC support meets the stability requirements. Such a 3D VO2/C@SiCuOC electrode exhibits a multiplying photo‐response current density of 42.2 µA cm−2 (≈400% of the plate) and delivers a higher energy density (0.19 mWh cm−2 at 0.51 mW cm−2). More importantly, in a realistic environment (dark for 16 h and light for 8 h), the photo‐charging ZIBs integrated into a roof exhibit an exciting open circuit voltage of 3.176 V (three in series) and supply electricity continuously. The high strength (over 9 MPa) of the photo‐charging ZIBs inherited from the 3D rigid electrode further enables its practical application. The enhanced performance of the photo‐charging ZIBs obtained from structural optimization provides unique inspiration for next‐generation clean energy harvest/storage systems. [ABSTRACT FROM AUTHOR]

Zinc‐based energy storage has lately gained popularity due to natural abundance, operational safety, high energy density. Unfortunately, dendrite growth is a common and intractable issue faced in existing zinc‐ion batteries to shorten cycle lifespan/stability. This review summarizes recent progress in assembly component (e. g. anode, electrolyte, separator) engineering for dendrite‐free zinc‐ion batteries. First, diversiform strategies of Zn surface modification and Zn host design are presented to shield the fundamental adverse effect aroused by uneven zinc deposition on the anode. Then, subtle deployments of electrolyte constituents are illustrated to optimize the Zn2+ solvation structure for ultimate dendrite control and Coulombic efficiency elevation in aqueous systems and beyond (e. g. eutectic electrolytes). Furthermore, rational manipulation of advanced separators and the upgrade of zinc metal‐free Zn2+‐storage devices are briefly discussed to explore the dendrite‐free and high‐level Zn2+‐storage. Finally, challenges and perspectives are proposed to offer research inspirations toward safe, high‐efficiency and long‐lifespan zinc storage. [ABSTRACT FROM AUTHOR]