Rechargeable Aqueous Zn-ion Batteries Research Articles

Mechanistic investigation of silver vanadate as superior cathode for high rate and durable zinc-ion batteries

Rechargeable aqueous Zn-ion batteries have shown considerable potential for stationary grid-scale energy storage systems owing to their characteristics of low cost and non-pollution. Nevertheless, the development of high-performance cathode materials is still a formidable challenge. In this work, for the first time, we report a superior silver vanadate (β-AgVO3) cathode for Zn-ion batteries, and demonstrate the fundamental Zn2+ storage mechanism in detail. In sharp contrast to the previously-reported layered vandium-based materials, the β-AgVO3 cathode experiences an initial phase transition to form a layered Zn3V2O7(OH)2·2H2O through a displacement/reduction reaction of Zn2+/Ag+ in the first discharge process. The in situ generated Ag0 along with the residual Ag+ and structural water within the framework afford high electronic/ionic conductivity, thus enabling enhanced Zn2+ intercalation/deintercalation kinetics in the layered phase. As a consequence, the cathode can deliver remarkable rate performance (103 mAh g−1 at 5000 mA g−1) and long-term cycling stability (95 mAh g−1 after 1000 cycles at 2000 mA g−1). The present study offers a totally new insight into the exploration of non-layered-structured vandium-based cathodes for high performance Zn-ion batteries.

Ammonium Vanadium Oxide [(NH4)2V4O9] Sheets for High Capacity Electrodes in Aqueous Zinc Ion Batteries

Aqueous rechargeable Zn-ion batteries (ARZIBs) are being extensively investigated for large scale energy storage applications owing to their high safety, low cost, and environmental friendliness. I...

Fabrication of (NH4)2V3O8 nanoparticles encapsulated in amorphous carbon for high capacity electrodes in aqueous zinc ion batteries

Aqueous rechargeable Zn-ion batteries (ARZIBs) are being extensively investigated for large scale energy storage applications owing to their high safety, low cost, sustainability and environmental friendliness. Tremendous attention has been paid to developing the high capacity cathode materials, with stable host structures and fast channels for diffusions of Zn2+ giving rise to high performance. Herein, we report (NH4)2V3O8 nanoparticles encapsulated into amorphous carbon matrix [denoted as (NH4)2V3O8/C] as a high capacity cathode for ARZIBs, for the first time. It is demonstrated to exhibit much enhanced overall electrochemical performance, including high capacities of 356, 327, 299, 261 and 232 mA h g−1 at 0.1, 0.2, 0.3, 0.4 and 0.5 A g−1, respectively, high rate capacity as well as excellent cycle lifespan with 212 mA h g−1 after 50 cycles at 0.1 A g−1, 201 mA h g−1 after 100 cycles at 0.2 A g−1, and 135 mA h g−1 after 2000 cycles at 1 A g−1, respectively. The Zn//(NH4)2V3O8/C battery thus assembled delivers a high energy density of 334 Wh kg−1 at 294 W kg−1, which are superior to some of the state-of-the-art cathode materials for ARZIBs. In parallel with the electrochemical performance demonstrated, we have clarified the key reaction mechanisms involved in the reversible (de)intercalation of Zn2+, studied by multiple analytical methods.

In Situ Encapsulating Metal Oxides into Core-Shell Hierarchical Hybrid Fibers for Flexible Zinc-Ion Batteries toward High Durability and Ultrafast Capability for Wearable Applications.

Rechargeable aqueous Zn-ion batteries are promising power sources for the advanced electronics because of their low cost, high safety, environmental friendliness, etc. However, their practical applications are severely restricted by the low energy density, poor rate capability, and low mass loading. In this work, a new type of the core-shell hierarchical structured hybrid fiber with encapsulated metal oxide nanoparticles is reported, which is used as a flexible cathode for aqueous Zn-ion batteries. The hierarchical hybrid fibers, consisting of one-dimensional (1D) central hollow shell and inside carbon network, build bicontinuous conductive pathways and highly porous networks for the in situ formed metal oxide nanoparticles. The core-shell hierarchical structure facilitates fast electron/ion transport and high mass loading; moreover, the 1D structure ensures good pliability and high flexibility. Two transition metal oxides, i.e., Zn2V2O7 and V2O5, are employed to construct the hybrid fibers. Both hybrid fibers exhibit excellent electrochemical properties and superior high rate capabilities. They achieve the capacities of 162 mAh g-1 (for Zn2V2O7) and 409 mAh g-1 (for V2O5) even at a high current density of 8 A g-1. Moreover, the flexible Zn-ion batteries are fabricated on the basis of the hybrid fibers. The superior energy/power density and good long-term cycling stability demonstrate their good energy storage capability and fast charge/discharge capability. Especially, the well-retained performance under high degree of outside deformations further promotes their applications in wearable electronics.

Ultrafast Zinc-Ion Diffusion Ability Observed in 6.0-Nanometer Spinel Nanodots.

Rechargeable aqueous Zn-ion batteries (ZIBs) have recently attracted much attention due to their low cost and superior safety. Unfortunately, their low capacity and poor cycle life still hinder their practical application. Here, we have developed a general synthesis strategy for ultrasmall spinel oxide nanodots (Mn3O4, CoMn2O4, MnCo2O4.5, Co3O4, and ZnMn2O4) with abundant oxygen vacancies and highly active surface. Among them, 6.0-nanometer-sized Mn3O4 nanodots deliver the best Zn-ion storage ability with a high reversible capacity of 386.7 mA h g-1 at 0.1 A g-1, excellent rate performance, and a long-term stability of 500 cycles at 0.5 A g-1. Taking advantage of the highly activated surficial atoms, shortened transfer pathway, and introduction of numerous oxygen vacancies, an ultrahigh Zn2+ diffusion coefficient of 2.4 × 10-10 cm2 s-1 has been detected during the discharge process. This value is more than 2 orders of magnitude higher than that of other spinel oxide nanostructures in previous reports and also the highest one in all of the as-reported ZIB cathode materials to date. Our finding offers promising opportunities for the development of ZIB cathode materials with high energy density, long-term cycling stability, excellent flexibility, and wearability.

Realizing high-performance Zn-ion batteries by a reduced graphene oxide block layer at room and low temperatures

Abstract Rechargeable aqueous Zn-ion batteries (ZIBs) have attracted great attention due to their cost-effectiveness, high safety, and environmental friendliness. However, some issues associated with poor structural instability of cathode materials and fast self-discharge hinder the further development of ZIBs. Herein, a new configuration is introduced by placing a reduced graphene oxide film as a block layer between the separator and the V2O5·nH2O cathode. This layer prevents the free diffusion of dissolved active materials to the anode and facilitates the transport of Zn ion and electrons, largely improving the cyclic stability and alleviating the self-discharge. Accordingly, the optimized battery delivers a remarkable capacity of 191 mAh g−1 after 500 cycles at 2 A g−1. Moreover, a high capacity of 106 mAh g−1 is achieved after 100 cycles at −20 °C. The strategy proposed is expected to be applicable to other electrode systems, thus offering a new approach to circumvent the critical challenges facing aqueous batteries.

Comparative study on ternary spinel cathode Zn–Mn–O microspheres for aqueous rechargeable zinc-ion batteries

We demonstrate the cation ratio-controlled synthesis of ZnMn2O4 and Zn1.67Mn1.33O4 aggregated microspheres. The carbonate precursor was synthesized by a solvothermal reaction, and then completely converted to oxide by calcination at 600 °C with a controlled cationic ratio. The prepared ternary oxide has a nanoparticle-aggregated morphology and uniform size distribution. The electrochemical properties were investigated by cyclic voltammetry and constant current charge-discharge measurements. The Zn1.67Mn1.33O4 electrode reveals better performance for Zn2+ storage than the other, delivering 175 mA h g−1 after 40 cycles. After the electrochemical test, ex situ analysis was conducted to identify the Zn2+ storage mechanisms. From these results, we confirm that the Zn1.67Mn1.33O4 cathode is a promising Zn2+ storage material for environmental friendly aqueous rechargeable Zn-ion batteries.

Stabilized Molybdenum Trioxide Nanowires as Novel Ultrahigh-Capacity Cathode for Rechargeable Zinc Ion Battery.

Exploration of high‐performance cathode materials for rechargeable aqueous Zn ion batteries (ZIBs) is highly desirable. The potential of molybdenum trioxide (MoO3) in other electrochemical energy storage devices has been revealed but held understudied in ZIBs. Herein, a demonstration of orthorhombic MoO3 as an ultrahigh‐capacity cathode material in ZIBs is presented. The energy storage mechanism of the MoO3 nanowires based on Zn2+ intercalation/deintercalation and its electrochemical instability mechanism are particularly investigated and elucidated. The severe capacity decay of the MoO3 nanowires during charging/discharging cycles arises from the dissolution and the structural collapse of MoO3 in aqueous electrolyte. To this end, an effective strategy to stabilize MoO3 nanowires by using a quasi‐solid‐state poly(vinyl alcohol)(PVA)/ZnCl2 gel electrolyte to replace the aqueous electrolyte is developed. The capacity retention of the assembled ZIBs after 400 charge/discharge cycles at 6.0 A g−1 is significantly boosted, from 27.1% (in aqueous electrolyte) to 70.4% (in gel electrolyte). More remarkably, the stabilized quasi‐solid‐state ZIBs achieve an attracting areal capacity of 2.65 mAh cm−2 and a gravimetric capacity of 241.3 mAh g−1 at 0.4 A g−1, outperforming most of recently reported ZIBs.

Tailoring Three-Dimensional Composite Architecture for Advanced Zinc-Ion Batteries.

Rechargeable aqueous Zn-ion batteries (ZIBs) are of considerable interest for future energy storage. Their main limitation, however, is developing suitable cathode materials capable of sustaining the Zn2+ repeated intercalation/deintercalation. Herein, a three-dimensional polypyrrole (PPy)-encapsulated Mn2O3 composite architecture is developed for advanced ZIBs. The engineering can be easily realized via in situ phase transformation of MnCO3 microboxes with subsequent self-initiated polymerization of PPy. The abundant open-up pores (∼30 nm) throughout the construction accelerate ion migration and provide a more active interface for Zn2+ storage in the Mn2O3@PPy bulk electrode. Meanwhile, the PPy skin uniformly wrapped on the Mn2O3 microbox not only guarantees a good conductive network for faster electron transport but also inhibits the dissolution of Mn2O3 and protects the integrity of the electrode from structural damage. As a result, the Mn2O3@PPy electrode can operate at reversible capacity exceeding those of most other cathode materials, but can still provide longer lifetime (no capacity decay over 2000 cycles at 0.4 A g-1) and higher rate performance than others. Furthermore, theoretical studies show the H+ and Zn2+ coinsertion storage mechanism and reaction dynamics. The results show that this three-dimensional Mn2O3@PPy architecture is a promising cathode material for high-performance ZIBs.

Hierarchical Carbon Nanofiber/Birnessite-MnO2 Nanosheets Cathode for High Performance and Low-Cost Aqueous Rechargeable Zinc Ion Battery

Abundant and safe charge carrying feedstock with high energy density have made aqueous zinc-ion batteries (ZIBs), specifically the Zn/MnO2 system, a highly promising candidate for large-scale energy storage device. The traditional alkaline Zn/MnO2 batteries have become dominant in primary battery chemistry. Great efforts have been devoted to developing rechargeable alkaline Zn/MnO2 batteries, however, they are plagued by poor cycling stability. Very recently, the Zn/MnO2 systems in near neutral electrolyte have emerged to demonstrate improved capacities, cyclability and rechargeability. However, the commonly used tunnel-type MnO2 cathode with low conductivity usually undergoes phase transition to layered structure upon discharge-charge cycles, leading to collapse of framework and thus poor cycling and rate performance. To address these issues, it is proposed that directly using birnessite-MnO2 with layered structure as a cathode may minimize the “sacrificial capacity” induced by phase transition and integrating birnessite-MnO2 with a conductive substrate may enhance the conductivity. In this work, the hierarchical core-shell carbon nanofiber@MnO2 (CNF@MnO2) cathode was prepared by a facile wet-chemistry method, where vertically aligned birnessite-MnO2 nanosheets were in situ grown on the surface of carbon nanofibers. The self-supported CNF@MnO2 cathode showed excellent electrochemical performance for Zn-ion batteries in a near neutral electrolyte due to its structural stability and enhanced conductivity. A high discharge capacity of 306 mA h g−1 has been reached after 100 cycles at current density of 300 mA g−1. Even at a high rate of 1.5 A g−1, CNF@MnO2 still maintained a high capacity of 258 mA h g-1 upon 100 cycles. Such remarkable performance is attributed to the unique core-shell structure and intimate contact between CNF and layered MnO2, in which the conductive CNF core facilitates the electron transfer and layered MnO2 minimizes the structural collapse and promotes the kinetics for co-insertion and extraction of Zn2+/H+ ions. Given the simplicity of preparation, exceptional electrochemical performance and low cost, CNF@MnO2 cathode holds substantial promise for aqueous rechargeable Zn-ion batteries. Figure 1. Scanning electron microscopy image of carbon nanofiber@MnO2 (CNF@MnO2) cathode for aqueous rechargeable Zn-ion batteries in near neutral electrolyte. Figure 1

Reaction Mechanisms for Long-Life Rechargeable Zn/MnO2 Batteries

Rechargeable aqueous Zn-ion batteries (ZIBs) are very promising for large-scale grid energy storage applications owing to their low cost, environmentally benign constituents, excellent safety, and relatively high energy density. Their usage, however, is largely hampered by the fast capacity fade. The complexity of the reactions has resulted in long-standing ambiguities of the chemical pathways of Zn/MnO2 system. In this study, we find that both H+/Zn2+ intercalation and conversion reactions occur at different voltages and that the rapid capacity fading can clearly be ascribed to the rate-limiting and irreversible conversion reactions at a lower voltage. By limiting the irreversible conversion reactions at ∼1.26 V, we successfully demonstrate ultrahigh power and long life that are superior to most of the reported ZIBs or even some lithium-ion batteries.

A review on recent developments and challenges of cathode materials for rechargeable aqueous Zn-ion batteries

This review highlights the recent developments of cathode materials for aqueous zinc-ion batteries, which are cost effective and have good safety.

Forming bubble-encapsulated double-shelled hollow spheres towards fast kinetics and superior high rate performance for aqueous rechargeable Zn-ion batteries

“Bubble-encapsulated double-shelled” hollow spheres significantly promote the fast kinetics and superior rate capability of the zinc vanadate oxide for Zn-ion batteries.

RETRACTED: MoS2 nanosheets with expanded interlayer spacing for rechargeable aqueous Zn-ion batteries

Abstract Recently, rechargeable Zn-ion batteries (ZIBs) have attracted incremental attention as prospective energy storage devices for grid-scale applications and flexible devices, due to their low cost, environmental benignity, high safety and unique properties of the Zn metal. However, the sustained development of high-performance ZIBs is hindered by the limited availability of cathode materials. Here, for the first time, we demonstrate MoS2 with expanded inter-layer spacing (E-MoS2) can be a promising cathode candidate for rechargeable and flexible ZIBs. By X-ray diffraction (XRD) and Raman studies, a reversible Zn2+ ion intercalation/deintercalation mechanism was revealed. The E-MoS2 electrode delivers a specific capacity of 202.6 mA h g−1 at 0.1 A g−1, a desirable energy density of 148.2 Wh kg−1 and good cycle stability with a capacity retention ratio of 98.6% over 600 cycles. By using the newly-developed starch/ polyacrylamide (PAM) based polymer electrolyte with high zinc ion conductivity, a quasi-solid Zn/E-MoS2 battery was developed, which exhibits decent electrochemical performance even under various heavy deformations, holding great potential for applications in future flexible and wearable devices.

Reaction Mechanisms for Long Life and Ultra-High Power Rechargeable Zn Ion Batteries

Rechargeable aqueous Zn-ion batteries (ZIBs) are very promising for large-scale grid energy storage applications owing to their low cost, environmentally benign constituent elements, excellent safety, and relatively high-energy density. Their usage, however, is largely hampered by their fast capacity fade. The cycle stability seems to be highly rate-dependent, which poses an additional challenge, but can also play a pivotal role in uncovering the reaction mechanisms. The complexity of the reactions in this electrochmical system has resulted in long-standing ambiguity of the chemical pathways of Zn/MnO2 rechargable battery system, and has led to many controversies with regard to their nature. In this talk, we present a combined experimental and theoretical study of Zn/MnO2 cells. We found that both H+/Zn2+ intercalation and conversion reactions occur at different voltages, and that the rapid capacity fading can clearly be ascribed to the rate-limiting and irreversible conversion reactions at a lower voltage. By avoiding the irreversible conversion reactions at ~ 1.26 V, we successfully demonstrate ultra-high power and long-life Zn/MnO2 cells which, after 1000 cycles, maintain an energy density of ~ 231 Wh kg-1 and 105 Wh kg-1 at a power density of ~ 4 kW kg-1 (9C, ~ 3.1 A g-1) and ~ 15 kW kg-1 (30 C, ~ 10.3 A g-1), respectively. The excellent cycle stability and power capability are superior to most reported ZIBs or even some lithium-ion batteries. The results establish accurate electrochemical reaction mechanisms and kinetics for Zn/MnO2, and identify the interplay of the voltage window and rate determining factors for achieving excellent cycle life.

Na2V6O16·3H2O Barnesite Nanorod: An Open Door to Display a Stable and High Energy for Aqueous Rechargeable Zn-Ion Batteries as Cathodes.

Owing to their safety and low cost, aqueous rechargeable Zn-ion batteries (ARZIBs) are currently more feasible for grid-scale applications, as compared to their alkali counterparts such as lithium- and sodium-ion batteries (LIBs and SIBs), for both aqueous and nonaqueous systems. However, the materials used in ARZIBs have a poor rate capability and inadequate cycle lifespan, serving as a major handicap for long-term storage applications. Here, we report vanadium-based Na2V6O16·3H2O nanorods employed as a positive electrode for ARZIBs, which display superior electrochemical Zn storage properties. A reversible Zn2+-ion (de)intercalation reaction describing the storage mechanism is revealed using the in situ synchrotron X-ray diffraction technique. This cathode material delivers a very high rate capability and high capacity retention of more than 80% over 1000 cycles, at a current rate of 40C (1C = 361 mA g-1). The battery offers a specific energy of 90 W h kg-1 at a specific power of 15.8 KW kg-1, enlightening the material advantages for an eco-friendly atmosphere.

Aqueous rechargeable Zn-ion batteries: an imperishable and high-energy Zn2V2O7 nanowire cathode through intercalation regulation

α-Zn2V2O7 nanowire is utilized as cathode for aqueous Zn-ions energy storage application. This cathode is sustained a high reversible capacity of 138 mA h g−1 after 1000 cycles and displays a high specific energy, added advantage for aqueous battery system.

Highly reversible and long-life cycling aqueous zinc-ion battery based on ultrathin (NH4)2V10O25·8H2O nanobelts

For the first time ultrathin (NH4)2V10O25·8H2O nanobelts are employed as a cathode material for high-rate and durable rechargeable aqueous Zn-ion batteries.

High-performance rechargeable aqueous Zn-ion batteries with a poly(benzoquinonyl sulfide) cathode

Aqueous Zn-ion batteries with a poly(benzoquinonyl sulfide) cathode show good electrochemical performance.

K2V6O16·2.7H2O nanorod cathode: an advanced intercalation system for high energy aqueous rechargeable Zn-ion batteries

Layered K2V6O16·2.7H2O nanorod cathode, utilized for aqueous rechargeable Zn-ion batteries, displays high reversible capacities, exceptional rate capabilities and long cycle-span of 700 (altering three different current densities) and 500 (~82% capacity retention at 6 A g−1) cycles.