Low-Dimensional Vanadium-Based High-Voltage Cathode Materials for Promising Rechargeable Alkali-Ion Batteries

Owing to their rich structural chemistry and unique electrochemical properties, vanadium-based materials, especially the low-dimensional ones, are showing promising applications in energy storage and conversion. In this invited review, low-dimensional vanadium-based materials (including 0D, 1D, and 2D nanostructures of vanadium-containing oxides, polyanions, and mixed-polyanions) and their emerging applications in advanced alkali-metal-ion batteries (e.g., Li-ion, Na-ion, and K-ion batteries) are systematically summarized. Future development trends, challenges, solutions, and perspectives are discussed and proposed. Mechanisms and new insights are also given for the development of advanced vanadium-based materials in high-performance energy storage and conversion.

One-dimensional H2V3O8 nanorods and two-dimensional lamellar MXene composites as efficient cathode materials for aqueous rechargeable zinc ion batteries

The energy crisis is a the worldwide problem which needs humans to solve immediately. To solve this problem, it is necessary to develop energy storage batteries. It is worth mentioning the aqueous rechargeable zinc ion batteries (ARZBs) which have some advantages, such as low cost, good safety and no need for an organic electrolyte as in the traditional lithium-ion batteries. However, it is still a challenge to find suitable and reliable electrode materials. In this work, as-prepared H2V3O8 nanorods and MXene composites are used as cathode materials in ARZBs which were designed well using a hydrothermal method after optimizing the reaction time. The results showed that H2V3O8/MXene ARZBs could provide a good transport path for zinc ions, which were based on special 1D H2V3O8 nanorods and 2D multi-layered MXene materials, which exhibited an outstanding initial specific discharge capacity of 373 mA h g-1 at 200 mA g-1, good rate capability and a long lifecycle with only 15.8% capacity decay at 500 mA g-1 after 5000 cycles. The H2V3O8/MXene composites with a good electrochemical performance bring insight into their promising applications for energy storage batteries. They provided enhanced rate performance and excellent cycling stability, which was ascribed to the multi-step and multi-mode zinc ion insertion/extraction process. This was confirmed by the use of the 1D/2D integrated structure of the H2V3O8/MXene composites, which was conductive to zinc ion diffusion.

Mg2+ Ion Pre-Insertion Boosting Reaction Kinetics and Structural Stability of Ammonium Vanadates for High-Performance Aqueous Zinc-Ion Batteries

Aqueous zinc-ion batteries (AZIBs) attract much attention owing to their high safety, environmentally friendliness and low cost. However, the unsatisfactory performance of cathode materials is one of the unsolved important factors for their widespread application. Herein, we report NH4 V4 O10 nanorods with Mg2+ ion preinsertion (Mg-NHVO) as a high-performance cathode material for AZIBs. The preinserted Mg2+ ions effectively improve the reaction kinetics and structural stability of NH4 V4 O10 (NHVO), which are confirmed by electrochemical analysis and density functional theory calculations. Compared with pristine NHVO, the intrinsic conductivity of Mg-NHVO is improved by 5 times based on the test results of a single nanorod device. Besides, Mg-NHVO could maintain a high specific capacity of 152.3 mAh g-1 after 6000 cycles at the current density of 5 A g-1 , which is larger than that of NHVO (only exhibits a low specific capacity of 30.5 mAh g-1 at the same condition). Moreover, the two-phase crystal structure evolution process of Mg-NHVO in AZIBs is revealed. This work provides a simple and efficient method to improve the electrochemical performance of ammonium vanadates and enhances the understanding about the reaction mechanism of layered vanadium-based materials in AZIBs.

A hybrid composite of H2V3O8 and graphene for aqueous lithium-ion batteries with enhanced electrochemical performance

Aqueous rechargeable lithium-ion batteries (ARLBs) are regarded as a competitive challenger for large-scale energy storage systems because of their high safety, modest cost, and green nature. A kind of modified composite material composed of H₂V₃O₈ nanorods and graphene sheets (HVO/G) has been effectively made by a one-step hydrothermal method and following calcination at 523 K. XRD, SEM, TEM, and TG are used to determine the phase structures and morphologies of the composite materials. Owing to the advantage of the layered structure of H₂V₃O₈ nanorods, the excellent conductivity of the graphene sheets, and the 3D network structure of the modified composite, the ARLBs with HVO/G can deliver an adequate specific capacity of 271 mA h g^-1 at 200 mA g^-1 and have a retention rate of 73.4% after 50 cycles. The average discharge capacity of ARLB with HVO/G as anode has a considerable improvement over that of HVO/CNTs and HVO, whatever the current rate used. Moreover, we find that the diffusion coefficient of lithium-ion increases by an order of magnitude through the theoretical calculation for HVO/G ARLB. The new ARLB with HVO/G electrode is a potential energy storage system with great advantages, such as simple preparation, easy assembly process, excellent safety and low-cost environmental protection.

Resolving the structure of V3O7·H2O and Mo-substituted V3O7·H2O

Vanadate compounds, such as V₃O₇·H₂O, are of high interest due to their versatile applications as electrode material for metal-ion batteries. In particular, V₃O₇·H₂O can insert different ions such as Li⁺, Na⁺, K⁺, Mg²⁺ and Zn²⁺. In that case, well resolved crystal structure data, such as crystal unit-cell parameters and atom positions, are needed in order to determine the structural information of the inserted ions in the V₃O₇·H₂O structure. In this work, fundamental crystallographic parameters, i.e. atomic displacement parameters, are determined for the atoms in the V₃O₇·H₂O structure. Furthermore, vanadium ions were substituted by molybdenum in the V₃O₇·H₂O structure [(V_2.85Mo_0.15)O₇·H₂O] and the crystallographic positions of the molybdenum ions and their oxidation state are elucidated.

The Emergence of 2D MXenes Based Zn-Ion Batteries: Recent Development and Prospects

Rechargeable zinc-ion batteries (ZIBs) with exceptional theoretical capacity have garnered significant interest in large-scale electrochemical energy storage devices due to their low cost, abundant material, inherent safety, high specific energy, and ecofriendly nature. Metal carbides/nitrides, known as MXenes, have emerged as a large family of 2D transition metal carbides or carbonitrides with excellent properties, e.g., high electrical conductivity, large surface functional groups (e.g., F, O, and OH), low energy barriers for the diffusion of electrolyte ions with wide interlayer spaces. After a decade of effort, significant development has been achieved in the synthesis, properties, and applications of MXenes. Thus, it has opened up various exciting opportunities to construct advanced MXene-based nanostructures for ZIBs with excellent specific energy and power. Herein, this review summarizes the advances across multiple synthesis routes, related properties, morphological and structural characteristics, and chemistries of MXenes for ZIBs. The recent development of MXene-based electrodes is introduced, and electrolytes for ZIBs are elucidated in detail. MXene-based rocking chair ZIBs, strategies to enhance the performance of MXene-based cathodes, suppress the dendrites in MXene-based anodes, and MXene-based flexible ZIBs are pointed out. A rational design and modification of the MXenes as well as the production of composites with metal oxides exhibits promise in solving issues and enhancing the electrochemical performance of ZIBs. Finally, the present challenges and future prospects for MXene-based ZIBs are discussed.

Will Vanadium-Based Electrode Materials Become the Future Choice for Metal-Ion Batteries?

Metal-ion batteries have emerged as promising candidates for energy storage system due to their unlimited resources and competitive price/performance ratio. Vanadium-based compounds have diverse oxidation states rendering various open-frameworks for ions storage. To date, some vanadium-based polyanionic compounds have shown great potential as high-performance electrode materials. However, there has been a growing concern regarding the cost and environmental risk of vanadium. In this Review, all links in the industry chain of vanadium-based electrodes were comprehensively summarized, starting with an analysis of the resources, applications, and price fluctuation of vanadium. The manufacturing processes of the vanadium extraction and recovery technologies were discussed. Moreover, the commercial potentials of some typical electrode materials were critically appraised. Finally, the environmental impact and sustainability of the industry chain were evaluated. This critical Review will provide a clear vision of the prospects and challenges of developing vanadium-based electrode materials.

Modified H2 V3 O8 to Enhance the Electrochemical Performance for Li-ion Insertion: The Influence of Prelithiation and Mo-Substitution

Nanostructured H₂ V₃ O₈ is a promising high-capacity cathode material, suitable not only for Li⁺ but also for Na+, Mg²⁺ , and Zn²⁺ insertion. However, the full theoretical capacity for Li⁺ insertion has not been demonstrated experimentally so far. In addition, improvement of cycling stability is desirable. Modifications like substitution or prelithiation are possibilities to enhance the electrochemical performance of electrode materials. Here, for the first time, the substitution of vanadium sites in H₂ V₃ O₈ with molybdenum was achieved while preserving the nanostructure by combining a soft chemical synthesis approach with a hydrothermal process. The obtained Mo-substituted vanadate nanofibers were further modified by prelithiation. While pristine H₂ V₃ O₈ showed an initial capacity of 223 mAh g^-1 and a retention of 79 % over 30 cycles, combining Mo substitution and prelithiation led to a superior initial capacity of 312 mAh g^-1 and a capacity retention of 94 % after 30 cycles.

In Situ Electrochemical Transformation Reaction of Ammonium-Anchored Heptavanadate Cathode for Long-Life Aqueous Zinc-Ion Batteries

Rechargeable aqueous zinc-ion batteries (ZIBs) are promising portable and large-scale grid energy storage devices, as they are safe and economical. However, developing suitable ZIB cathode materials with excellent cycling performance characteristics remains a challenging task. Here, ammonium heptavanadate (NH₄)₂V₇O₁₆·3.2H₂O (NHVO) nanosquares with mixed-valence V⁵⁺/V⁴⁺ as a cathode are developed for high-performance ZIBs. The layered NHVO shows a capacity of 362 mA h g^-1 at 0.05 A g^-1, with a high energy density of 263.5 W h kg^-1. It exhibits an initial specific capacity of 250.7 mA h g^-1 at a current density of 4 A g^-1 and retains 255 mA h g^-1 capacity after 1000 charge/discharge cycles. The V₇O₁₆-based cathode was demonstrated with a phase transition to the V₂O₅-based cathode upon initial cycling. Moreover, the in situ generated V₂O₅-based cathodes show excellent electrochemical properties, which provide a different perspective on the electrochemical reaction of cathode materials for aqueous ZIBs.

Vanadium oxide bronzes as cathode active materials for non-lithium-based batteries

Lithium as critical resource prompted interest for non-lithium-based batteries. This highlight review discusses vanadium oxide bronzes as one of the material families being considered as cathode for non-lithium-based batteries.

Vanadium-based nanowires for sodium-ion batteries

Sodium-ion batteries (SIBs) have received great attention because of the abundance source and low cost. To date, some Na⁺ storage materials have achieved great performance, but the larger Na⁺ radius and more complex Na⁺ storage mechanism compared with Li⁺ still limit the energy density and power density. This review systematically summarizes emerging synthetic technologies of vanadium-based materials from simple nanowires to complicated modified/optimized structures. In addition, vanadium-based nanowire materials are reviewed at both the cathode and anode side, and advantages and drawbacks are proposed to explain the challenges facing application of novel materials. Furthermore, a vanadium-based single-nanowire device is reported to reveal the Na⁺ storage mechanism, which contributes to the understanding of the reaction in SIBs. Finally, this review summarizes the current development challenges of SIBs and looks forward to the future development prospects of vanadium-based nanowires, providing a new direction for further applications of SIBs.

Controlled Hydrothermal Growth and Li+ Storage Performance of 1D VOx Nanobelts with Variable Vanadium Valence

One-dimensional (1D) vanadium oxide nanobelts (VO_x NBs) with variable V valence, which include V₃O₇·H₂O NBs, VO₂ (B) NBs and V₂O₅ NBs, were prepared by a simple hydrothermal treatment under a controllable reductive environment and a following calcination process. Electrochemical measurements showed that all these VO_x NBs can be adopted as promising cathode active materials for lithium ion batteries (LIBs). The Li⁺ storage mechanism, charge transfer property at the solid/electrolyte interface and Li⁺ diffusion characteristics for these as-synthesized 1D VO_x NBs were systematically analyzed and compared with each other. The results indicated that V₂O₅ NBs could deliver a relatively higher specific discharge capacity (213.3 mAh/g after 50 cycles at 100 mA/g) and median discharge voltage (~2.68-2.71 V vs. Li/Li⁺) during their working potential range when compared to other VO_x NBs. This is mainly due to the high V valence state and good crystallinity of V₂O₅ NBs, which are beneficial to the large Li⁺ insertion capacity and long-term cyclic stability. In addition, the as-prepared VO₂ (B) NBs had only one predominant discharge plateau at the working potential window so that it can easily output a stable voltage and power in practical LIB applications. This work can provide useful references for the selection and easy synthesis of nanoscaled 1D vanadium-based cathode materials.

Synthesis and electrochemical performance of NaV3O8 nanobelts for Li/Na-ion batteries and aqueous zinc-ion batteries

NaV₃O₈ nanobelts were successfully synthesized for Li/Na-ion batteries and rechargeable aqueous zinc-ion batteries (ZIBs) by a facile hydrothermal reaction and subsequent thermal transformation. Compared to the electrochemical performance of LIBs and NIBs, NaV₃O₈ nanobelt cathode materials in ZIBs have shown excellent electrochemical performance, including high specific capacity of 421 mA h g⁻¹ at 100 mA g⁻¹ and good cycle stability with a capacity retention of 94% over 500 cycles at 5 A g⁻¹. The good diffusion coefficients and high surface capacity of NaV₃O₈ nanobelts in ZIBs were in favor of fast Zn²⁺ intercalation and long-term cycle stability.

Compared to the electrochemical performance for LIBs and NIBs, NaV₃O₈ nanobelts electrode for ZIBs shows excellent electrochemical performance, including high specific capacity of 421 mA h g⁻¹ at 100 mA g⁻¹, good rate performance and cycle performance.

Preparation and electrochemical performance of VO2(A) hollow spheres as a cathode for aqueous zinc ion batteries

Rechargeable aqueous zinc ion batteries (ZIBs), owing to their low-cost zinc metal, high safety and nontoxic aqueous electrolyte, have the potential to accelerate the development of large-scale energy storage applications. However, the desired development is significantly restricted by cathode materials, which are hampered by the intense charge repulsion of bivalent Zn²⁺. Herein, the as-prepared VO₂(A) hollow spheres via a feasible hydrothermal reaction exhibit superior zinc ion storage performance, large reversible capacity of 357 mA h g⁻¹ at 0.1 A g⁻¹, high rate capability of 165 mA h g⁻¹ at 10 A g⁻¹ and good cycling stability with a capacity retention of 76% over 500 cycles at 5 A g⁻¹. Our study not only provides the possibility of the practical application of ZIBs, but also brings a new prospect of designing high-performance cathode materials.

VO₂(A) hollow spheres exhibit superior zinc ion storage performance, large reversible capacity of 357 mA h g⁻¹ at 0.1 A g⁻¹, and good cycling stability with a capacity retention of 76% over 500 cycles at 5 A g⁻¹

Double-layer carbon protected CoS2 nanoparticles as an advanced anode for sodium-ion batteries

The outstanding electrochemical performance is ascribed to the novel structure design of CoS₂@GC@B-CNT.

Recent Advances in Nanowire-Based, Flexible, Freestanding Electrodes for Energy Storage

The rational design of flexible electrodes is essential for achieving high performance in flexible and wearable energy-storage devices, which are highly desired with fast-growing demands for flexible electronics. Owing to the one-dimensional structure, nanowires with continuous electron conduction, ion diffusion channels, and good mechanical properties are particularly favorable for obtaining flexible freestanding electrodes that can realize high energy/power density, while retaining long-term cycling stability under various mechanical deformations. This Minireview focuses on recent advances in the design, fabrication, and application of nanowire-based flexible freestanding electrodes with diverse compositions, while highlighting the rational design of nanowire-based materials for high-performance flexible electrodes. Existing challenges and future opportunities towards a deeper fundamental understanding and practical applications are also presented.

Novel layered iron vanadate cathode for high-capacity aqueous rechargeable zinc batteries

A layered iron vanadate Fe5V15O39(OH)9·9H2O nanosheet is first introduced to an aqueous zinc battery system as a cathode material, which delivers a high capacity of 385 mA h g-1 at 0.1 A g-1 and remarkable cycling performance at high current density (over 80% capacity retention after 300 cycles at 5 A g-1).

One-Dimensional Hetero-Nanostructures for Rechargeable Batteries

Rechargeable batteries are regarded as one of the most practical electrochemical energy storage devices that are able to convert and store the electrical energy generated from renewable resources, and they function as the key power sources for electric vehicles and portable electronics. The ultimate goals for electrochemical energy storage devices are high power and energy density, long lifetime, and high safety. To achieve the above goals, researchers have tried to apply various morphologies of nanomaterials as the electrodes to enhance the electrochemical performance. Among them, one-dimensional (1D) materials show unique superiorities, such as cross-linked structures for external stress buffering and large draw ratios for internal stress dispersion. However, a homogeneous single-component electrode material can hardly have the characteristics of high electronic/ionic conductivity and high stability in the electrochemical environment simultaneously. Therefore, designing well-defined functional 1D hetero-nanostructures that combine the advantages and overcome the limitations of different electrochemically active materials is of great significance. This Account summarizes fabrication strategies for 1D hetero-nanostructures, including nucleation and growth, deposition, and melt-casting and electrospinning. Besides, the chemical principles for each strategy are discussed. The nucleation and growth strategy is suitable for growing and constructing 1D hetero-nanostructures of partial transition metal compounds, and the experimental conditions for this strategy are relatively accessible. Deposition is a reliable strategy to synthesize 1D hetero-nanostructures by decorating functional layers on 1D substrate materials, on the condition that the preobtained substrate materials must be stable in the following deposition process. The melt-casting strategy, in which 1D hetero-nanostructures are synthesizes via a melting and molding process, is also widely used. Additionally, the main functions of 1D hetero-nanostructures are summarized into four aspects and reviewed in detail. Appropriate surface modification can effectively restrain the structure deterioration and the regeneration of the solid-electrolyte interphase layer caused by the volume change. A porous or semihollow external conducting material coating provides advanced electron/ion bicontinuous transmission. Suitable atomic heterogeneity in the crystal structure is beneficial to the expansion and stabilization of the ion diffusion channels. Multiphase-assisted structural design is also an accessible way for the sulfur electrode material restriction. Moreover, some outlooks about the further industrial production, more effective and cheaper fabrication strategies, and new heterostructures with smaller-scale composition are given in the last part. By providing an overview of fabrication methods and performance-enhancing mechanisms of 1D hetero-nanostructured electrode materials, we hope to pave a new way to facile and efficient construction of 1D hetero-nanostructures with practical utility.

1D Nanomaterials: Design, Synthesis, and Applications in Sodium-Ion Batteries

Sodium-ion batteries (SIBs) have received extensive attention as ideal candidates for large-scale energy storage systems (ESSs) owing to the rich resources and low cost of sodium (Na). However, the larger size of Na⁺ and the less negative redox potential of Na⁺ /Na result in low energy densities, short cycling life, and the sluggish kinetics of SIBs. Therefore, it is necessary to develop appropriate Na storage electrode materials with the capability to host larger Na⁺ and fast ion diffusion kinetics. 1D materials such as nanofibers, nanotubes, nanorods, and nanowires, are generally considered to be high-capacity and stable electrode materials, due to their uniform structure, orientated electronic and ionic transport, and strong tolerance to stress change. Here, the synthesis of 1D nanomaterials and their applications in SIBs are reviewed. In addition, the prospects of 1D nanomaterials on energy conversion and storage as well as the development and application orientation of SIBs are presented.

High-Performance Aqueous Zinc-Ion Battery Based on Layered H2 V3 O8 Nanowire Cathode

Rechargeable aqueous zinc-ion batteries have offered an alternative for large-scale energy storage owing to their low cost and material abundance. However, developing suitable cathode materials with excellent performance remains great challenges, resulting from the high polarization of zinc ion. In this work, an aqueous zinc-ion battery is designed and constructed based on H₂ V₃ O₈ nanowire cathode, Zn(CF₃ SO₃ )₂ aqueous electrolyte, and zinc anode, which exhibits the capacity of 423.8 mA h g^-1 at 0.1 A g^-1 , and excellent cycling stability with a capacity retention of 94.3% over 1000 cycles. The remarkable electrochemical performance is attributed to the layered structure of H₂ V₃ O₈ with large interlayer spacing, which enables the intercalation/de-intercalation of zinc ions with a slight change of the structure. The results demonstrate that exploration of the materials with large interlayer spacing is an effective strategy for improving electrochemical stability of electrodes for aqueous Zn ion batteries.

H2V3O8 Nanowires as High-Capacity Cathode Materials for Magnesium-Based Battery

Magnesium-based batteries have received much attention as promising candidates to next-generation batteries because of high volumetric capacity, low price, and dendrite-free property of Mg metal. Herein, we reported H₂V₃O₈ nanowire cathode with excellent electrochemical property in magnesium-based batteries. First, it shows a satisfactory magnesium storage ability with 304.2 mA h g^-1 capacity at 50 mA g^-1. Second, it possesses a high-voltage platform of ∼2.0 V vs Mg/Mg²⁺. Furthermore, when evaluated as a cathode material for magnesium-based hybrid Mg²⁺/Li⁺ battery, it exhibits a high specific capacity of 305.4 mA h g^-1 at 25 mA g^-1 and can be performed in a wide working temperature range (-20 to 55 °C). Notably, the insertion-type ion storage mechanism of H₂V₃O₈ nanowires in hybrid Mg²⁺/Li⁺ batteries are investigated by ex situ X-ray diffraction and Fourier transform infrared. This research demonstrates that the H₂V₃O₈ nanowire cathode is a potential candidate for high-performance magnesium-based batteries.

Molecular dynamics study of solvated aniline and ethylene glycol monomers confined in calcium silicate nanochannels: a case study of tobermorite

The combination of organic and inorganic materials can result in materials with extraordinary performance.

Ultralong Sb2Se3 Nanowire-Based Free-Standing Membrane Anode for Lithium/Sodium Ion Batteries

Metal chalcogenides have emerged as promising anode materials for lithium ion batteries (LIBs) and sodium ion batteries (SIBs). Herein, a free-standing membrane based on ultralong Sb₂Se₃ nanowires has been successfully fabricated via a facile hydrothermal synthesis combined with a subsequent vacuum filtration treatment. The as-achieved free-standing membrane constructed by pure Sb₂Se₃ nanowires exhibits good flexibility and integrity. Meanwhile, we investigate the lithium and sodium storage behavior of the Sb₂Se₃ nanowire-based free-standing membrane. When applied as the anode for LIBs, it delivers a reversible capacity of 614 mA h g^-1 at 100 mA g^-1, maintaining 584 mA h g^-1 after 50 cycles. When applied as the anode for SIBs, it delivers a reversible capacity of 360 mA h g^-1 at 100 mA g^-1, retaining 289 mA h g^-1 after 50 cycles. Such difference in electrochemical performance can be attributed to the more complex sodiation process relative to the corresponding lithiation process. This work may provide insight on developing Sb₂Se₃-based anode materials for high-performance LIBs or SIBs.

Effects of pore size and surface charge on Na ion storage in carbon nanopores

Na ion batteries (NIBs) are considered as a promising low cost and sustainable energy storage technology.