Cathode For Aqueous Zinc-ion Batteries Research Articles

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.

Hydrothermal Synthesis of Special Cubic Form MnO2 and MnCO3 Composite Material for Zinc Ion Battery and its Electrochemical Performance Test

In this paper, the aqueous zinc ion battery cathode material composed of manganese dioxide and manganese carbonate were synthesized by hydrothermal method. By optimizing the temperature and time in both hydrothermal and calcination process, the optimal synthesis conditions were discovered. Then, in order to survey and analysis the characteristics of the material, XRD, SEM, EDS and XPS tests were conducted. It can be seen from XRD test that the main crystal structure is MnO2 and MnCO3, and no other obvious impurity peaks are found. In the SEM test, it can be seen that the main shape of the material is regular cube, and there is triangular pyramidal bulge on the surface of the cube, which can increase the surface area of the material. As can be seen from EDS and element distribution diagram, Mn, O and C elements are evenly distributed. The XPS test shows that the valence states of the synthesized materials are consistent with those of MnO2 and MnCO3. According to the infrared test and Raman test, the characteristic peak vibration of the synthesized material is also consistent with those of MnO2 and MnCO3, indicating that the composite of MnO2 and MnCO3 with high electrochemical stability has been synthesized by hydrothermal method.

Mechanism of High-Rate Cycling Stability of Anthraquinone Cathode for Aqueous Zinc-Ion Batteries

Aqueous zinc-ion batteries (ZIBs) are an appealing rechargeable battery technology for next-generation energy storage devices, known for their low cost and high safety. Among the promising cathode materials used for aqueous ZIBs, anthraquinone (AQ) stands out due to its high theoretical specific capacity, low cost, and environmental friendliness. In this study, we investigate the cyclic stability of AQ in aqueous ZIBs. We demonstrate that AQ exhibits a good capacity retention at a high current density even after 1000 charge–discharge cycles, while more obvious capacity fading is observed at a low current density. Density functional theory calculations reveal that the mechanism of the rapid capacity fading under a low current density is due to the significant structural deformation of AQ crystal during Zn insertion into the AQ bulk. Furthermore, the energy barrier of Zn ions that diffuse into the AQ bulk is much higher than the diffuse on the AQ surface, leading to an irreversible Zn insertion. However, under a high current density, Zn ions prefer to adsorb and diffuse on the AQ surface without bulk insertion and structural deformation, rending a higher cycling stability. These insights into the factors influencing the cycling stability of AQ-based electrodes offer a guidance to improve their performance for practical applications.

Engineered nitrogen doping on VO2(B) enables fast and reversible zinc-ion storage capability for aqueous zinc-ion batteries

Vanadium-based compounds with high theoretical capacities and relatively stable crystal structures are potential cathodes for aqueous zinc-ion batteries (AZIBs). Nevertheless, their low electronic conductivity and sluggish zinc-ion diffusion kinetics in the crystal lattice are greatly obstructing their practical application. Herein, a general and simple nitrogen doping strategy is proposed to construct nitrogen-doped VO2(B) nanobelts (denoted as VO2-N) by the ammonia heat treatment. Compared with pure VO2(B), VO2-N shows an expanded lattice, reduced grain size, and disordered structure, which facilitates ion transport, provides additional ion storage sites, and improves structural durability, thus presenting much-enhanced zinc-ion storage performance. Density functional theory calculations demonstrate that nitrogen doping in VO2(B) improves its electronic properties and reduces the zinc-ion diffusion barrier. The optimal VO2-N400 electrode exhibits a high specific capacity of 373.7 mA h g−1 after 100 cycles at 0.1 A g−1 and stable cycling performance after 2000 cycles at 5 A g−1. The zinc-ion storage mechanism of VO2-N is identified as a typical intercalation/de-intercalation process.

Compact and insoluble Mn3(PO4)2 coating layer confined amorphous MnO2 as cathode for aqueous zinc ion batteries

Manganese-based composites are considered as valid cathodes for aqueous zinc-ion batteries (ZIBs). However, the gradually dissolute and structural collapse of the Mn species are still restricting the practical application. Herein, an electrochemical activated insoluble Mn3(PO4)2 coating layer is tightly encapsulated on soluble amorphous MnO2 nanosheets (AMO@A-MP/CC). The long-range disordered atomic arrangements of amorphous MnO2 can release the strain due to volume changes, while the abundant structural defects can act as ion storage sites with high reversibility, thus effectively enhance the intrinsic capacity and reduce the capacity degradation. Moreover, the compact and insoluble Mn3(PO4)2 coating layer can inhibit the gradual diffusion of Mn2+ into electrolyte and enhance structural stability of amorphous MnO2. Therefore, AMO@A-MP/CC composite delivers ultra-high specific capacity (420.0 mAh g−1 at 0.3 A g−1), remarkable cyclic stability (97.5 % capacity retention after 1000 cycles) and excellent rate capability (224.2 mAh g−1 at 3.0 A g−1). Significantly, the energy-density of 225.0 Wh kg−1 for single electrode and bendable ability can be achieved in the flexible Zn/AMO@A-MP battery, demonstrating the synergistic effect of amorphous structure and surface coating for future ZIBs development.

V-MOF@carbon nanotube derived three-dimensional V2O5@carbon nanotube as high-performance cathode for aqueous zinc-ion batteries

Aqueous zinc ion batteries (ZIBs) are considered as the next generation of power sources due to their high theoretical capacity, low redox potential, and abundant reserves. However, it has still been the main bottleneck limiting cathode materials with superior cyclic performance and rate capability for aqueous ZIBs. Here, a nanorod architecture V-MOF@CNT derived V2O5@CNT is listed as the excellent cathode composite material for ZIBs for the first time. Here, V2O5@CNT has outstanding electrochemical characteristics in aqueous ZIBs by virtue of its unique nanorod composite structure, adequate electrochemical active sites and the synergistic effect of V2O5 and carbon nanotubes. In this regard, the V2O5@CNT nanocomposite shows a high discharge specific capacity of 400 mAh g−1 at a current density of 1 A g−1, showing twice the discharge specific capacity of pure vanadium pentoxide (200 mAh g−1 at 1 A g−1). The capacity retention (84.4% after 100 cycles at 0.1 A g−1) is better than the V2O5 cathode (63.5% after 100 cycles at 0.1 A g−1). These results indicte that the V2O5@CNT cathode should provide the basis for the development of high-performance aqueous zinc ion batteries.

Design of Ti4+/Zr4+ as Dual-Supporting Sites in Na3V2(PO4)3 for the Advanced Aqueous Zinc-Ion Battery Cathode.

The development of aqueous zinc-ion batteries (AZIBs) still faces a huge challenge due to poor cycling stability and slow kinetics of the cathode material. In this work, we report an advanced cathode of Ti4+/Zr4+ as dual-supporting sites in Na3V2(PO4)3 with an expanded crystal structure, exceptional conductivity, and superior structural stability for AZIBs, which exhibits fast Zn2+ diffusion and excellent performance. The results of AZIBs afford remarkably high cycling stability (91.2% retention rate over 4000 cycles) and exceptional energy density (191.3 W h kg-1), outperforming most Na+ superionic conductor (NASICON)-type cathodes. Furthermore, different in/ex situ characterization techniques and theoretical studies reveal the reversible storage mechanism of Zn2+ in an optimal Na2.9V1.9Ti0.05Zr0.05(PO4)3 (NVTZP) cathode and demonstrate that Na+ defects together with Ti4+/Zr4+ sites can intrinsically contribute to the high electrical conductivity and low Na+/Zn2+ diffusion energy barrier of NVTZP. Moreover, the flexible soft-packaged batteries further demonstrate a superior capacity retention rate of 83.2% after 2000 cycles from the perspective of practicality.

In Situ Induced Core–Shell Carbon‐Encapsulated Amorphous Vanadium Oxide for Ultra‐Long Cycle Life Aqueous Zinc‐Ion Batteries

AbstractInevitable dissolution in aqueous electrolytes, intrinsically low electrical conductivity, and sluggish reaction kinetics have significantly hampered the zinc storage performance of vanadium oxide‐based cathode materials. Herein, core–shell N‐doped carbon‐encapsulated amorphous vanadium oxide arrays, prepared via a one‐step nitridation process followed by in situ electrochemical induction, as a highly stable and efficient cathode material for aqueous zinc‐ion batteries (AZIBs) are reported. In this design, the amorphous vanadium oxide core provides unobstructed ions diffusion routes and abundant active sites, while the N‐doped carbon shell can ensure efficient electron transfer and greatly stabilize the vanadium oxide core. The assembled AZIBs exhibit remarkable discharge capacity (0.92 mAh cm−2 at 0.5 mA cm−2), superior rate capability (0.51 mAh cm−2 at 20 mA cm−2), and ultra‐long cycling stability (≈100% capacity retention after 500 cycles at 0.5 mA cm−2 and 97% capacity retention after 10 000 cycles at 20 mA cm−2). The working mechanism is further validated by in situ X‐ray diffraction combined with ex situ tests. Moreover, the fabricated cathode is highly flexible, and the assembled quasi‐solid‐state AZIBs present stable electrochemical performance under large deformations. This work offers insights into the development of high‐performance amorphous vanadium oxide‐based cathodes for AZIBs.

Ultralarge layer spacing and superior structural stability of V2O5 as high-performance cathode for aqueous zinc-ion battery

Ultralarge layer spacing and superior structural stability of V2O5 as high-performance cathode for aqueous zinc-ion battery

Engineering Oxygen Vacancies on VO2 multilayered Structures for Efficient Zn2+ Storage.

Vanadium dioxide (VO2(B)) is a proper cathode for aqueous zinc-ion batteries (ZIBs) due to its shear structure and high theoretical capacity. However, the sluggish kinetics and structure instability derived from the strong electrostatic interaction between Zn2+ and the VO2 host hinder its further application. Defect engineering is a useful way to circumvent the limitations. Herein, oxygen-defect VO2 (O d -VO2) with tunable oxygen vacancy concentration are obtained via a facile one-step hydrothermal method by adjusting ascorbic acid addition. It's proved that oxygen vacancies can provide extra active sites for Zn2+ storage and reduced electrostatic barrier for Zn2+ transportation, but excessive vacancy content would lead to a reverse effect. The O d -VO2 cathode with optimum oxygen vacancy concentration achieves an outstanding performance with a high capacity of 380 mAhg-1 at 0.2 A g-1, excellent cycle stability with 92.6% capacity retention after 2000 cycles at 3 A g-1 and a high energy density of 197 Wh kg-1 at the power density of 0.641 kW kg-1. Therefore, this defect engineering method for O d -VO2 provide an attractive way for high-performance aqueous ZIB cathodes.

Preparation of polyaniline intercalated V2O5 composites and study of their self-charging mechanism

Vanadium oxides are an important aqueous zinc ion battery cathode material with the advantage of abundant reserves and high specific capacity. However, the strong interaction between the zinc ions and the main lattice of the material results in poor cycling stability and multiplicative performance of the cell. In this paper, we propose a molecular pre-embedding modification strategy for in situ intercalation of polyaniline. Flower cluster-like organic-inorganic (PANI-V2O5, PVO) hybrid materials with adjustable layer spacing were synthesized by simultaneous oxidative polymerization using vanadate and aniline as precursors without the introduction of inactive cations. PVO-60 exhibits a large specific capacity (391.1 mAh·g−1 at a current density of 0.2 A·g−1). The results of density flooding calculations demonstrate that the polyaniline layer blocks the electrostatic interaction between Zn2+ and the V2O5 backbone, thus promoting Zn2+ kinetics. Drawing on the air battery structure, a battery device that allows for air self-charging was designed using PVO-60 as the positive electrode. This work not only provides ideas for the design of vanadium oxides, but also offers the prospect of broadening the application of zinc ion batteries.

K-doped V2O5 derived from V-MOF precursor as high-performance cathode for aqueous zinc-ion batteries

The safety and low toxicity of aqueous zinc-ion batteries (ZIBs) are piqueing intense scientific interest. Slow reaction kinetics and substantial structural degradation of the cathode materials, however, prevent the creation of ZIBs. As a better cathode for ZIBs, tunnel-structured V2O5 hierarchical with a high preintercalated K cation content (K-V2O5) are proposed here. The K-V2O5 are specifically made using a self-sacrificial template approach that also involves hydrothermal intercalation in a neutral solvent and phase change during annealing. A subsequent H+ and Zn2+ intercalation procedure at various voltage platforms is clarified when tested as cathodes for ZIBs. Prior to the subsequent insertion of Zn2+ into V2O5, the water-solvated H+ first enters tunnel cavities, which partially transforms the V2O5 phase from a tunnel-type structure to a layered-type structure. The pre-intercalated K cations with a high content that act as pillars in the layered-type matrix stabilize the layered structures and widen the migration channels for Zn2+, which can aid in the diffusion of Zn2+ in the V2O5 cathodes.

V2+-doped VS2 with rich defects for high-performance zinc storage in aqueous zinc-ion batteries

Layered VS2 material has been considered as a promising cathode for aqueous zinc-ion batteries. However, the insufficient active sites and sluggish ionic transfer kinetic stunt its development. Here, V2+-doped VS2 is developed as a cathode material for aqueous zinc-ion battery. These V2+-doped VS2 nanosheets are rich in defects in the interlayers and basal plane. The presence of defects brings about large number of active sites and diffusion paths for zinc ion storage and transfer. As a result, the V2+-doped VS2 cathode delivers a high reversible capacity of 156.3 mAh g−1 at 100 mA g−1, high-rate capacity of 123.4 mAh g−1 at 1000 mA g−1 and excellent cycle stability of 79.2% capacity retention at specific current of 1000 mA g−1 after 980 cycles. Moreover, ex-situ characterizations indicate that the V2+-doped VS2 undergoes a reversible Zn2+ and H+ (de)intercalation reaction during the discharge-charge process. This work will provide an ideal to cathode materials for aqueous zinc-ion batteries.

Advanced In Situ Electrochemical Induced Dual-Mechanism Heterointerface toward High-Energy Aqueous Zinc-Ion Batteries.

In situ electrochemical activation brings unexpected electrochemical performance improvements to electrode materials, while the mechanism behind is still needed to study deeply. Herein, an in situ electrochemically approach is developed for the activation of heterointerface MnOx /Co3 O4 by inducing Mn-defect, wherein the Mn defects are formed through a charge process that converts the MnOx with poor electrochemical activities toward Zn2+ into high electrochemically active cathode for aqueous zinc-ion batteries (ZIBs). Guided by the coupling engineering strategy, the heterointerface cathode exhibits an intercalation/conversion dual-mechanism without structural collapse during storage/release of Zn2+ . The heterointerfaces between different phases can generate built-in electric fields, reducing the energy barrier for ion migration and facilitating electron/ion diffusion. As a consequence, the dual-mechanism MnOx /Co3 O4 shows an outstanding fast charging performance and maintains a capacity of 401.03 mAh g-1 at 0.1 A g-1 . More importantly, a ZIB based on MnOx /Co3 O4 delivered an energy density of 166.09Wh kg-1 at an ultrahigh power density of 694.64W kg-1 , which outperforms those of fast charging supercapacitors. This work provides insights for using defect chemistry to introduce novel properties in active materials for highly for high-performance aqueous ZIBs.

Tailoring porous three-dimensional (Co,Mn)(Co,Mn)2O4/PPy architecture towards high-performance cathode for aqueous zinc-ion batteries

Aqueous zinc-ion batteries (AZIBs) have gained extensive interest due to their cost-effective and safe nature. Nonetheless, the long-term performance of AZIBs is restricted by the conductivity and structural stability of cathode materials. Herein, the porous (Co,Mn)(Co,Mn)2O4/PPy (CMO@PPy) core–shell microspheres have been favorably synthesized using a facile solvothermal method followed by a self-polymerization process. The porous structure endows CMO@PPy with more active sites which can facilitate ion and electrolyte diffusion. And PPy as coating layers not only improve the conductivity but also buffer the structural strain of cathode material, as well as inhibit the dissolution of Mn2+. Additionally, the core–shell nanostructure can effectively release the volume expansion of cathode during the cycling process. Benefitting from the unique structure, the CMO@PPy cathode delivers a high capacity of 305.2 mAh g−1 at 0.1 A g−1 and superior long-term cycling stability (90.8 mAh g−1 at 1 A g−1 after 1000 cycles with a decay of only 0.037% per cycle). Also, the enhanced electrochemical kinetic of CMO@PPy is evaluated by Galvanostatic intermittent titration technique. Additionally, the assembled flexible ZIBs demonstrate stable electrochemical properties at different bending states, indicating their potential practical applications.

Facile and effective defect engineering strategy boosting ammonium vanadate nanoribbon for high performance aqueous zinc-ion batteries

Vanadium-based oxides have gained widespread attention as promising cathode materials for aqueous zinc-ion batteries (AZIBs) due to their abundant valences, high theoretical capacity and low cost. However, the intrinsic sluggish kinetics and unsatisfactory conductivity have severely hampered their further development. Herein, a facile and effective defect engineering strategy was developed at room temperature to prepare the defective (NH4)2V10O25·8H2O (d-NHVO) nanoribbon with plenty of oxygen vacancies. Owing to the introduction of oxygen vacancies, the d-NHVO nanoribbon possessed more active sites, excellent electronic conductivity and fast ion diffusion kinetics. Benefiting from these advantages, the d-NHVO nanoribbon as an aqueous zinc-ion battery cathode material exhibited superior specific capacity (512 mAh g−1 at 0.3 A g−1), excellent rate capability and long-term cycle performance. Simultaneously, the storage mechanism of the d-NHVO nanoribbon was clarified via comprehensive characterizations. Furthermore, the pouch battery based on the d-NHVO nanoribbon was fabricated and presented eminent flexibility and feasibility. This work provides a novel thought for simple and efficient development of high- performance vanadium-based oxides cathode materials for AZIBs.

3D printing of customized MnO2 cathode for aqueous zinc-ion batteries

In order to overcome the problems of inferior cycling stability and slow ion diffusion of MnO2 cathode in aqueous zinc-ion battery, a high-accuracy customized 3D printed MnO2 cathode was prepared via direct ink writing. The rheological test showed that the printing ink indicated shear-thinning behavior with the storage modulus platform value over 105 Pa. The SEM images displayed that the customized mesh—layer structure was well maintained after 100 cycles. The 3D structure with excellent mechanical strength could effectively alleviate the internal stress and provide a greater specific surface area. The specific capacity of the 3D printing cathode was three times higher than that of the 2D one at 50 mA/g after 110 stable cycles. The energy storage mechanism of the reversible Mn2+/Mn4+ double redox for 3D printing battery was also studied through a variety of ex-situ experiments.

Single crystalline Na2/3Ni1/3Mn2/3O2 microrods as a high-performance cathode for aqueous zinc-ion batteries

Aqueous zinc-ion batteries (ZIBs) receive considerable focuses due to their low flammability and high energy density. Herein, a single crystalline Na2/3Ni1/3Mn2/3O2 microrods cathode is elaborately designed and synthesized in this work for ZIBs. After 2500 cycles, it exhibits a reversible capacity of 130 mAh g−1 at 5 A g−1. The excellent performance suggests that Ni doping modified Mn-based cathode material is a reasonable method to design high-performance ZIBs cathodes.