Cathode For Aqueous Zinc-ion Batteries Research Articles

Unlocking a new storage mechanism of high performance VN@N/S–C cathode: Role of electrochemical reduction

Vanadium-based compounds have earned incremental attention as cathode for aqueous zinc ion batteries (AZIBs) due to their ideal electrical conductivity, rich valence states and flexible crystal structures. Unfortunately, their storage mechanisms are confusing and not well-established, especially for nitride. Herein, we have constructed a cubic vanadium nitride and nitrogen/sulfur doped carbon composite (VN@N/S–C) as a cathode for AZIBs. An in-depth examination of ex-situ XRD and XPS reveal that the electrochemical reduction during the first discharge process promotes a structural transformation of cubic VN to layered Zn3+x(OH)2V2O7·2H2O, thus permitting subsequent insertion of Zn2+ in such layered structure. Ex-situ SEM studies of electrodes further identify a morphology change of nanoparticles to nanosheets, corresponding to VN and Zn3+x(OH)2V2O7·2H2O, respectively. New storage mechanism-the electrochemical reduction combined with the contributions from Zn2+ (de)intercalation, furnishes the VN@N/S–C cathode a high discharge capacity of 232 mA h g−1 after 400 cycles at 4 A g−1 and good rate performance (252 mA h g−1 at 6 A g−1). Even at a low temperature of 0 °C, the cathode still delivers an excellent capacity of 361 mA h g−1 after 300 cycles at 1 A g−1. This study offers a hint to improve the understanding on cubic structure for AZIBs.

Na+ Intercalated V2O5 Derived from V-MOF as High-Performance Cathode for Aqueous Zinc-Ion Batteries

Layered vanadium oxides have been considered as highly promising cathode materials for aqueous zinc-ion batteries (ZIBs) due to their unique open crystal structure and high theoretical specific capacity. However, the structural instability and sluggish Zn2+ diffusion kinetics limit their further application in ZIBs. Here, a novel and stable cathode (porous Na-V2O5) for aqueous ZIBs is rationally constructed by using a straightforward MOF-assisted synthetic method. The Na-V2O5 exhibits remarkable capacity of 306 mAh g−1 at 0.1 A g−1, exceptional rate characteristics (264.3 mAh g−1 at 2.0 A g−1), and great cycling capabilities over 1000 cycles with a capacity-retention of 83.4% when examined as a cathode for ZIBs. Higher pseudo-capacitance, quicker charge-transfer/ion-diffusion kinetics, and a robust architecture have been attained in the Na-V2O5 cathode, which are in charge of the superior zinc-ion storage performance. This has been made possible by the pre-intercalated Na+ cations and the resulting layer structure. Additionally, the Zn2+ and H+ co-intercalation/extraction-based energy storage method has been validated. This research may help rationally design layer-structured V2O5 cathodes for high energy and power density aqueous energy storage systems.

Tailoring Local Chemical Coordination in Vanadium Pentoxide to Enable High Efficiency Zinc Ion Storage

Vanadium oxides-based materials are one of promising cathode materials for aqueous zinc ion batteries (AZIBs) owing to their various chemical coordination and oxidation states rendering high theoretical specific capacity. However, the poor electronic conductivity and structural instability limit their practical application in AZIBs. In this study, these drawbacks of vanadium pentoxide are mitigated by introducing Al ions into the interlayer space (V2O5-Al). Compared with pristine V2O5, the V2O5-Al possesses an increased proportion of oxygen vacancy and improved diffusivity because of the tailored local chemical coordination and the strong chemical bonding from Al-O bonds. First-principles calculations suggest that pre-inserted Al ions embedded into the V2O5 layers enhances structural stability and improves the electrical conductivity of V2O5. While used as cathode for AZIBs, V2O5-Al electrode delivers a high capacity of 260 mAh g−1 at 4 A·g−1 and the 108% initial capacity maintained over 4400 cycles as well as an energy density of 260 Wh·kg−1 at 405 W·kg−1 based on the cathode. These superior electrochemical suggest the as-prepared Al-doped V2O5 hold great potential as the promising low-cost cathode materials in the ZIBs.

Mn2+-Doped MoS2/MXene Heterostructure Composites as Cathodes for Aqueous Zinc-Ion Batteries.

Typical layered transition-metal chalcogenide materials, especially MoS2, are gradually attracting widespread attention as aqueous Zn-ion battery (AZIB) cathode materials by virtue of their two-dimensional structure, tunable band gap, and abundant edges. The metastable phase 1T-MoS2 exhibits better electrical conductivity, electrochemical activity, and zinc storage capacity compared to the thermodynamically stable 2H-MoS2. However, 1T-MoS2 is still limited by the phase stability and layered structure destruction for AZIB application. Thus, a three-dimensional interconnected network heterostructure (Mn-MoS2/MXene) consisting of Mn2+-doped MoS2 and MXene with a high percentage of 1T phase (82.9%) was synthesized by hydrothermal methods and investigated as the cathode for AZIBs. It was found that S-Mn-S covalent bonds between MoS2 interlayers and Ti-O-Mo bonds at heterogeneous interfaces can act as "electron bridges" to facilitate electron and charge transfer. And the doping of Mn2+ and the combination of MXene not only expanded the interlayer spacing of MoS2 but also maintained the metastable structure of 1T-MoS2 nanosheets, acting to reduce the activation energy for Zn2+ intercalation and enhance specific capacity. The obtained Mn-MoS2/MXene contains more 1T-MoS2 and provides an improved specific capacity of 191.7 mAh g-1 at 0.1 A g-1. Compared with Mn-MoS2 and pure MoS2, it also exhibits enhanced cycling stability with a capacity retention of 80.3% after 500 cycles at 1 A g-1. Besides, the conductivity of Mn-MoS2/MXene is significantly improved, which induces a lower activation energy of the zinc ions during intercalation/deintercalation.

Atomically Coupled 2D MnO2/MXene Superlattices for Ultrastable and Fast Aqueous Zinc-Ion Batteries.

The delta manganese dioxide (δ-MnO2) has sparked a great deal of scientific research for application as the cathode in aqueous zinc-ion batteries (AZIBs) owing to its characteristic layered structure. However, further development and commercial application of the δ-MnO2 cathode are hindered by the low rate performance and poor cycling stability, which are derived from its inherently poor electrical conductivity and structural instability during the charge/discharge process. Herein, we report the fabrication of the 2D MnO2/MXene superlattice by the solution-phase assembly of unilamellar MnO2 and Ti3C2Tx MXene nanosheets, where the unilamellar MnO2 nanosheet is separated and stabilized between unilamellar MXene nanosheets. The MXene nanosheets can not only serve as structural stabilizers to isolate the MnO2 nanosheets and prevent them from aggregating but also act as conductive contributors to strengthen the electrical conductivity, thus maintaining the overall structural stability and realizing the rapid electron transport. Additionally, the regular stacking with a repeating periodicity of the 2D MnO2/MXene can lead to highly exposed active sites, promoting ion diffusion. As a consequence, the large specific capacity of 315.1 mAh g-1 at 0.2 A g-1, prominent rate performance of 149.8 mAh g-1 at 5 A g-1, and excellent long-term cycling stability after 5000 cycles with 88.1% capacity retention are obtained for the MnO2/MXene cathode in AZIBs. Meanwhile, the superior H+/Zn2+ diffusion kinetics and desirable pseudocapacitive behaviors are elucidated by electrochemical measurements and density functional theory computations. This study provides an advanced perspective for the innovation of manganese oxide-based cathode materials in AZIBs.

High-capacity cathode for aqueous zinc-ion battery based on MnOx-modified bismuth vanadate

Aqueous Zn-ion batteries (AZIBs) are a perspective energy storage technical due to their excellent safety levels while maintaining cost-effectiveness, and large theoretical specific capacity. However, the capability mismatch between cathode and anode brings the low specific capacity and unsatisfactory cycle life, which blocks the large-scale application of AZIBs for renewable energy sources and the smart grid industry. Herein, we constructed a decahedral BiVO4/MnOx nanosheets cathode to boost the charge/discharge performance of AZIB by a directional drive strategy. Due to the MnOx nanosheets selectivity growth on {110} facet of decahedral BiVO4 and the laminar structure of the BiVO4/MnOx composite, the channels of electron transfer are established between BiVO4 and MnOx nanosheets, which restrain the instability of manganese oxides and accelerate the insertion/extraction of Zn2+, and further enhance the specific capacity and cycle life of AZIB. The BiVO4/MnOx cathode shows a high specific capacity of 567.5 mAh g−1 and the assembled AZIB exhibits an outstanding energy density of 365.5 Wh kg−1, superior rate performance, stable long cycle life, and superior long-cycle capability (6600 cycles at 3 A g−1). The above findings provide a new way for high capacity and high life cathode materials of AZIBs.

Vanadium dissolution restraint and conductive assistant in MnV12O31·10H2O to boost energy storage property for aqueous zinc-ion batteries

Hydrated vanadates have gained significant attentions as cathode ingredients for aqueous zinc-ion batteries (AZIBs) on account of their broad open channels in the structural framework together with the existence of crystal water for stabilizing the structure. Yet, the ambiguous zinc storage mechanism and sluggish electrochemical reaction dynamics are always challenging questions for the development of hydrated vanadate cathodes. Herein, a novel hydrated manganese vanadate MnV12O31·10H2O (MVOH) nanobelt assembled microparticle materials is synthesized and combined with carbon nanofibers (CNFs) to generate MVOH-CNFs composite through electrostatic attraction in the condition of hydrothermal environment. The zinc storage mechanism of the formed MVOH substance as a cathode for AZIBs is clarified by a combined in- and ex-situ characterizations. The advantages of the crystal structure of MVOH to restrain vanadium dissolution and the assistance of CNFs to meliorate reaction kinetics are clarified based on the density functional theory calculations. The MVOH-CNFs cathode with a CNF content of 10.1% exhibits a reversible capacity of 302 mAh g−1 at 2 A g−1 after 100 cycles and 105 mAh g−1 at 8 A g−1 after 5000 cycles with robust structural stability. It also delivers excellent areal and volumetric capacity especially at high current density. A quasi-solid MVOH-CNFs//Zn pouch battery based on a gel electrolyte exhibits stable electrochemical performance and could be curled into a circular shape on the wrist to power a smart watch. This work paves a way for the furtherance of hydrated manganese vanadate cathodes in the application of high performance AZIBs.

A Layered Bi2 Te3 @PPy Cathode for Aqueous Zinc-Ion Batteries: Mechanism and Application in Printed Flexible Batteries.

Low-cost, safe, and environmental-friendly rechargeable aqueous zinc-ion batteries (ZIBs) are promising as next-generation energy storage devices for wearable electronics among other applications. However, sluggish ionic transport kinetics and the unstable electrode structure during ionic insertion/extraction hamper their deployment. Herein, a new cathode material based on a layered metal chalcogenide (LMC), bismuth telluride (Bi2 Te3 ), coated with polypyrrole (PPy) is proposed. Taking advantage of the PPy coating, the Bi2 Te3 @PPy composite presents strong ionic absorption affinity, high oxidation resistance, and high structural stability. The ZIBs based on Bi2 Te3 @PPy cathodes exhibit high capacities and ultra-long lifespans of over 5000 cycles. They also present outstanding stability even under bending. In addition, here the reaction mechanism is analyzed using in situ X-ray diffraction, X-ray photoelectron spectroscopy, and computational tools and it is demonstrated that, in the aqueous system, Zn2+ is not inserted into the cathode as previously assumed. In contrast, proton charge storage dominates the process. Overall, this work not only shows the great potential of LMCs as ZIB cathode materials and the advantages of PPy coating, but also clarifies the charge/discharge mechanism in rechargeable ZIBs based on LMCs.

Selenium incorporated sodium vanadate nanobelts as high-performance electrode material for long-lasting aqueous zinc-ion batteries and supercapacitors

Aqueous zinc-ion batteries (AZIBs) have received growing attention for comprehensive energy storage owing to their affordability and high safety. Still, cathode materials that usually exhibit low capacity or poor cycling performance have hindered the practical application of AZIBs. Herein, the selenium-incorporated sodium vanadate (Na2V6O16) (NVO@Se) nanobelts (NBs) were synthesized via a facile hydrothermal method, followed by calcination under N2 flow. As a cathode for AZIBs, the NVO@Se NBs electrode delivered a high discharge capacity value of 329.15 mA h g−1 at 2 A g−1 with ∼ 99 % coulombic efficiency and excellent rate capability (284.89 and 200.21 mA h g−1 at 4 and 5 A g−1, respectively). Mechanistic analyses of the intercalation reaction in the NVO@Se NBs after cycling using ex-situ X-ray diffraction, field-emission scanning electron microscopy, and X-ray photoelectron spectroscopy techniques revealed their good structural stability and electrochemical reversibility. Developing interactive properties, the NVO@Se NBs material was also studied as a battery-type electrode for hybrid supercapacitors (HSCs). By sandwiching the NVO@Se NBs and activated carbon, the fabricated HSC exhibited good power and energy density values, along with its verification for practical applications. From all the electrochemical characteristic results, the NVO@Se NBs material has good aspects for AZIBs and HSCs, which makes new prospects for the advancement of materials in energy storage applications.

In Situ Electrochemical Tuning of MIL‐88B(V)@rGO into Amorphous V2O5@rGO as Cathode for High‐Performance Aqueous Zinc‐Ion Battery

AbstractThe design and fabrication of advanced cathode materials with excellent electrochemical properties to match the Zn anode is crucial for the development of aqueous zinc‐ion batteries (ZIBs). Herein the synthesis of MIL‐88B(V)@rGO composites is reported, in which MIL‐88B(V) nanorods are anchored on reduced graphene oxide (rGO) sheets, as cathode for ZIBs, where the graphene oxide induces the formation of small‐size nanorods instead of typical prism morphology. During the initial charge/discharge process, the cathode undergoes an in situ irreversible transformation from MIL‐88B(V) to amorphous V2O5 that acts as active site for the subsequent Zn2+ insertion/extraction. The hierarchical structure of the composites and the amorphous V2O5 provide abundant channels and active sites for Zn2+ diffusion and adsorption. The density functional theory calculation reveals that the rGO sheets have two functions, i.e., to improve the conductivity and to reduce the Zn2+ migration energy barrier. Consequently, the MIL‐88B(V)@rGO cathode exhibits an ultrahigh reversible capacity of 479.6 mAh g−1 at 50 mA g−1 and good rate performance of 263.6 mAh g−1 at 5000 mA g−1, which are superior to metal–organic frameworks (MOFs) cathodes reported in literature. This work may shed a new light to the design and fabrication of MOFs‐based cathodes for aqueous ZIBs.

Constructing MOF-derived V2O5 as advanced cathodes for aqueous zinc ion batteries

Aqueous zinc-ion batteries (AZIBs) have become incremental attention due to its low cost, material abundance and environmental friendliness. Unfortunately, the crucial challenge is to develop cathodes with satisfactory superior Zn2+ storage. Here, a hierarchical porous V2O5 nano-bulk (p-V2O5) was synthesized derived from vanadium-based metal-organic framework via carbonization as cathode for AZIBs. The hierarchical mesoporous structure and elevated specific surface area are conducive to promote ion/electron transport. The prepared cathode delivers a high specific capacity of 115 mAh g−1 even at 3 A g−1. We also demonstrate that the Zn2+ storage mechanism is a reversible Zn2+ insertion/extraction in the open-structured Zn3(OH)2V2O7·2H2O and ZnyV2O5·nH2O in the subsequent cycling. The distinguished Zn2+ storage performance makes p-V2O5 a potential cathode for the next generation AZIBs.

Molecular engineering of Mn-based cathode for enhanced intrinsic conductivity towards high mass-loading aqueous zinc-ion batteries

Manganese dioxide (MnO2) is a promising cathode for aqueous zinc-ion batteries (ZIBs) because of its low cost, high energy density and environmental friendliness. However, the intrinsic poor electrical conductivity and sluggish reaction kinetics lead to inferior rate capability, especially under high mass loading, which hinders its commercialization. Herein, we report a molecular engineering strategy that can enhance the intrinsic electrical/ionic conductivity of MnO2 and accelerate reaction kinetics. Electrochemical analysis reveals that boron-modified MnO2 (B-MnO2) delivers improved reaction kinetics since the tailored boron atoms with lower electronegativity can abate the strong electrostatic interactions between the cations and cathode. Theoretical calculations demonstrate that B-MnO2 possesses a smaller bandgap than MnO2, which can enhance its electrical conductivity. As a result, the developed Zn/B-MnO2 batteries display a high specific capacity (325.3 mAh/g at 200 mA g−1) and remarkable rate capability (99.4 mAh/g at 10 A/g). More importantly, at high mass loadings of 25 and 30 mg cm−2, the B-MnO2 cathodes can still deliver high specific capacity of 197.2 and 176.5 mAh/g, respectively. This work will pave a way toward the commercial applications of Mn-based cathodes.

β-MnO2/three-dimensional graphene-carbon nanotube hybrids as cathode for aqueous zinc-ion battery

Aqueous zinc-ion batteries (RZIBs) are one of the favorable complementary candidates for lithium-ion batteries. The cathode material determines the whole performance. Herein, β-MnO2/3D GPE-CNTs hybrid cathode materials were fabricated by intermittent high-energy vibratory ball milling method. It delivered a higher specific discharge capacity of 313.31 mAh·g−1 and excellent cycling stability compared to the bare β-MnO2 sample. Morphological characterizations revealed that the enhanced electrochemical performance of the β-MnO2/3D GPE-CNTs hybrid was mainly attributed to the three-dimensional framework structure, large specific surface area, and good conductivity of GPE-CNT, as well as its resulting particle refinement with uniform dispersion and partial suppression of grain amorphization. This article provided a new sight of fabricating Mn-based materials/conducting carbon material hybrid for good performance cathode in RZIBs.

A facile strategy to unlock the high capacity of vanadium-based cathode for aqueous zinc-ion batteries

A facile strategy to unlock the high capacity of vanadium-based cathode for aqueous zinc-ion batteries

In Situ Mechanical Measurements in Vanadium Pentoxide Cathodes for Aqueous Zinc-Ion Batteries during Battery Cycling

Aqueous rechargeable zinc-ion batteries (AZIBs) are currently gaining traction as a potential successor to lithium-ion batteries for use in large-scale, stationary energy storage applications due to their inherent safety, low environmental impact, and low-cost. Recent advances have made breakthroughs in these anode and electrolyte stability; however, cathode development still lags preventing the commercial use of AZIBs. Vanadium pentoxide (V2O5) shows promise as a cathode material due to its low cost, environmental friendliness, and high specific capacity versus zinc (in excess of 400 mAh/g)1. V2O5 exhibits a single layer crystal structure which provides a large number of theoretical storage sites2. However, charge storage mechanisms and driving force behind the capacity fade in V2O5 are not well known yet. The lack of understanding surrounding insertion and storage mechanisms of zinc ions into V2O5 cathodes must be addressed to progress toward commercial viability.In this study, we aim to conduct in-operando stress and stress measurements in V2O5 during battery cycling. Curvature interferometry and digital image correlation techniques will be employed for in operando stress and strain measurements, respectively the composite V2O5 cathode will consist of a 7:2:1 ratio of active material, super P, and PVDF binder. By combining stress and strain measurements, coupled with spectroscopy studies, our goal is to identify the how interfacial stress and structural strains play a role on the charge storage mechanisms in V2O5.

Direct synthesis of vanadium pentoxide powder with carbon recombination as aqueous zinc-ion battery cathode

Direct synthesis of vanadium pentoxide powder with carbon recombination as aqueous zinc-ion battery cathode

Tailoring MnCO3 microspheres encapsulated by polypyrrole as cathodes for aqueous zinc-ion batteries

Constructing manganese-based cathode materials featuring high-performance and great stability during the charge or discharge process are vital for the progress of aqueous Zinc-ion batteries. In this study, MnCO3 Microspheres encapsulated by polypyrrole (MnCO3 @PPy) were successfully synthesized through a one-step hydrothermal method followed by in situ chemical oxidation polymerization. The pellicular polypyrrole (PPy) skin warped the MnCO3 microspheres uniformly making its surface smooth and orderly, which not only enhanced the electron and ion conductivity but also maintained the integrity of the cathode structure. As a result, MnCO3 @PPy cathodes displayed elevated cycling stability, reversibility and rate performance over MnCO3 cathodes. It achieved high average discharge specific capacities of 243, 151, 124, 112 and 104 mA h g−1 when cycled at current rates of 200, 400, 600, 800 and 1000 mA g−1, respectively, and delivered 252 mA h g−1 after 110 cycles at the current density of 200 mA g−1 corresponding to 94% of its maximum specific capacity (264 mA h g−1). The results suggest that this MnCO3 @PPy microspheres cathode is serviceable for aqueous zinc-ion batteries.

Molybdenum-optimized electronic structure and micromorphology to boost zinc ions storage properties of vanadium dioxide nanoflowers as an advanced cathode for aqueous zinc-ion batteries

Recently, vanadium dioxide (VO2) has been recognized as one of the most prospective cathodes for aqueous zinc ion batteries (AZIBs) for its high reversible specific capacity; nevertheless, its Zn2+ diffusion kinetics and cycling stability have not yet met expectations. Herein, Mo ions are introduced into VO2 to optimize the intrinsic electronic structure and micromorphology of VO2, achieving significantly enhanced zinc-ion storage. It is found that the substitution of Mo for V narrows the band gap of VO2 and thus enhances the conductivity of the material, while VO2 nanorods are transformed into VO2 nanoflowers which are self-assembled from ultra-thin nanosheets after the introduction of Mo, exposing much more active sites to enhance the migration kinetics of Zn2+. Consequently, the Mo-substituted VO2 (0.5-Mo-VO2) exhibits excellent electrochemical properties, presenting a high initial capacity of 494.5 mAh/g at 0.5 A/g, excellent rate capability of 336 mA h g−1 at 10 A/g and brilliant cycling stability with the capacity retention of 82% over 2000 cycles at 10 A/g. This work provides significant guidance for the design of advanced cathodes for AZIBs by optimizing the electronic structure and tailoring morphology of V-based materials.

Polyvinylpyrrolidone-Intercalated Mn0.07 VOx toward High Rate and Long-Life Aqueous Zinc-Ion Batteries.

Aqueous zinc-ion batteries (AZIBs) are expected to be an attractive alternative in advanced energy storage devices due to large abundance and dependable security. Nevertheless, the undesirable energy density and operating voltage still hinder the development of AZIBs, which is intimately associated with the fundamental properties of the cathode. In this work, polyvinylpyrrolidone (PVP) intercalated Mn0.07 VOx (PVP-MnVO) with a large interlayer spacing of 13.5 Å (against 12.5 Å for MnVO) synthesized by a facile hydrothermal method is adopted for the cathode in AZIBs. The experimental results demonstrate that PVP-MnVO with expanded interlayer spacing provides beneficial channels for the rapid diffusion of Zn2+ , resulting in a high discharge capacity of 402 mAh g-1 at 0.1 A g-1 , superior to that of MnVO (275 mAh g-1 at 0.1 A g-1 ). Meanwhile, the PVP molecule remains in the layer structure as a binder/pillar, which can maintain its structural integrity well during the charging/discharging process. Consequently, PVP-MnVO cathode exhibits superior rate capability and cycling stability (89% retention after 4300 cycles at 10 A g-1 ) compared to that of MnVO (≈51% retention over 500 cycles at 2 A g-1 ). This work proposes a new approach to optimize the performance of vanadium-based electrode materials in AZIBs.

Al3+ intercalated NH4V4O10 nanosheet on carbon cloth for high-performance aqueous zinc-ion batteries

Ammonium vanadium bronze (NH4V4O10) with open crystal structures and superior theoretical capacity is promising cathode for aqueous zinc-ion batteries (AZIBs). However, the sluggish intrinsic ion/electron kinetics and unsatisfied structural stability remain bottlenecks that limit their further development. Herein, we report a facile synthesis of Al+-intercalated NH4V4O10 nanosheet grown on carbon cloth (Al-NVO@CC) via a one-step hydrothermal reaction. The expanded lattice spacing of the synthesized Al-NVO@CC not only facilitates the Zn2+ ion intercalation/deintercalation but also improves the electrochemical stability in AZIBs. As a result, the cathode shows high reversible capacity (475.8 mA h g-1 at 0.2 A g-1), superior long-term cyclability (152.8 mA h g-1 over 2500 cycles at 5.0 A g-1), as well as excellent rate performance. Moreover, the zinc storage process of Al-NVO@CC and underlying mechanism of the enhanced performance are revealed by ex-situ X-ray powder diffraction (XRD), X-ray photoelectron spectra (XPS) and Transmission electron microscope (TEM) analyses. This study provides a reasonable strategy to promote V-based nanomaterials on CC for the development of AZIBs.