Cathode Materials For Zinc-ion Batteries Research Articles

Oxygenated copper vanadium selenide composite nanostructures as a cathode material for zinc-ion batteries with high stability up to 10 000 cycles.

The development of aqueous zinc-ion batteries (AZiBs) towards practical implementations is hampered by unsuitable host cathode materials. Herein, we reported a high-capacity, stable, and long-cycle-life (10 000 cycles) oxygenated copper vanadium selenide composite material (Cu0.59V2O5/Cu0.828V2O5@Cu1.8Se1/Cu3Se2, denoted as O-CuVSe) as a cathode for AZiBs. The newly constructed O-CuVSe composite cathode can be operated in the wide potential window of 0.4-2.0 V, exhibiting a high specific capacity of 154 mA h g-1 at 0.2 A g-1 over 100 cycles. Interestingly, the O-CuVSe composite cathode delivered excellent specific capacities of 117 and 101.4 mA h g-1 over 1000 cycles at 1 and 2 A g-1, respectively. Even at a high current density of 5 A g-1, the cathode delivered a high reversible capacity of 74.5 mA h g-1 over an ultra-long cycling life of 10 000 cycles with no obvious capacity fading. Apart from this, the cathode exhibited excellent rate capability at different current densities. The superior electrochemical properties originate from the synergistic effects between the oxygen vacancy engineering and interlayer doping of Cu ions to increase the structural stability during the cycling, enhancing the electron/ion transport kinetics. Moreover, the Zn2+ storage mechanism in the Zn/O-CuVSe aqueous rechargeable battery was explored. This study provides a new opportunity for the fabrication of different kinds of a new class of cathode materials for high-voltage and high-capacity AZiBs and other energy storage devices.

Defect Chemistry in Zn3V4(PO4)6

Zinc-ion batteries have attracted great interest for their low cost, safety, and high energy density. Recently, Zn3V4(PO4)6 has been reported to be a promising cathode material for zinc-ion batteries. The defect chemistry, diffusion of Zn-ions, and solution of dopants are examined by advanced simulation techniques. The simulation results show that the most favorable intrinsic defect is the Zn-V anti-site. A zig-zag pattern of long-range Zn2+ diffusion is observed and the activation energy of 1.88 eV indicates that the ionic conductivity of this material is low. The most promising isovalent dopants on the Zn site are Ca2+ and Fe2+. Although the solution of Ga3+, Sc3+, In3+, Y3+, Gd3+, and La3+ on the V site is exoergic, the most promising is In3+. Different reaction routes for the formation of Zn3V4(PO4)6 are considered and the most thermodynamically favorable reaction consists of binary oxides (ZnO, V2O3, and P2O5) as reactants.

Ni‐MnO2/Graphene as Cathode Material for Super‐Capacity Aqueous Rechargeable Zn‐Ion Battery

The development of cathode materials is an effective way to improve the electrochemical performance of zinc‐ion batteries (ZIBs). Herein, Ni2+‐doped MnO2/graphene nanocomposites (denoted as NMO/rGO) are synthesized by hydrothermal and mechanical ball milling methods as cathode materials for ZIBs. The NMO/rGO electrode shows a super capacity, excellent rate performance, and good cycling stability. The specific discharge capacity can reach 431.5 mAh g−1 at 0.1 A g−1. Moreover, the specific capacity retention rate is 56% after 2200 cycles at 2 A g−1. The excellent electrochemical performance is attributed on the one hand to the stable insertion of Ni2+, which affects the MnO bond and weakens the electrostatic interaction between MnO2 and Zn2+ and on the other hand, the strong interaction (MnOC bond) is formed between NMO and rGO through ball milling, which improves the electrical conductivity and mitigates the volume expansion. Notably, mechanical ball milling can also introduce oxygen vacancies for MnO2, thus increasing the active sites for redox reactions and significantly improving the electrochemical performance of the materials.

De/protonation associated sustainable conversion reaction applicable to high-capacity zinc storage in mildly acidic aqueous system

We introduce an unexpected finding of the de/protonation associated conversion reaction occurred in K2V3O8 as a promising cathode material for zinc-ion batteries. The structure undergoes a conversion reaction between amorphous V5+2O5 and V3+OOH upon cycling when a cut-off voltage up to 1.9 V is applied. A combination of operando X-ray diffraction, in situ Raman spectroscopy, X-ray photoelectron spectroscopy, time-of-flight secondary-ion mass spectroscopy, and operando pH measurement analyses reveal that the reaction of the proton (H+) is indispensable for progression of the conversion reaction. The conversion reaction results in a large reversible capacity of 362 mAh g−1 (∼97 % of theoretical capacity) at 0.1 C (37 mA g−1) on discharge and an activity even at a rate of 7 C (187 mAh g−1), with the two-electron reaction by the V5+/3+ redox pair evidenced by operando X-ray absorption spectroscopy analysis. These findings underscore the importance of conversion reversibility associated with the proton reaction for a high cut-off voltage, contributing additional capacity to reach the theoretical capacity for cathode materials of zinc-ion batteries in mildly acidic aqueous systems.

Organic Zinc-Ion Battery: Planar, π-Conjugated Quinone-Based Polymer Endows Ultrafast Ion Diffusion Kinetics.

A novel poly(phenazine-alt-pyromellitic anhydride) (PPPA) has been successfully designed and synthesized via a condensation polymerization strategy as promising cathode material in organic zinc-ion batteries. Electrochemical quartz crystal microbalance (EQCM), FTIR and XPS characterizations verify a reversible Zn2+ -coordination mechanism in our PPPA cathode. Intriguingly, an ultrahigh Zn2+ diffusion coefficient of 1.2×10-7 cm2 s-1 was found in this large π-conjugated system, which is the highest one among all organic cathode materials for zinc-ion batteries. Theoretical calculations reveal the extended π-conjugated plane in our PPPA sample results in a significant reduction on energy gap, effectively accelerating intramolecular electron transfer during charge/discharge process. Our finding provides insights to achieve high zinc-ion transport kinetics by a design strategy on planar polymer system.

One-step co-precipitation of MnSe2/CNTs as a high-performance cathode material for zinc-ion batteries

One-step room temperature liquid-phase co-precipitation technology is applied in the field of energy storage, which has the advantages of mass production and simple operation. Using this technique, we have directly synthesized MnO2 and amorphous MnSe2. By compounding with carbon nanotubes, the prepared electrodes achieved high discharge capacity (451.1 mAh·g−1 at 0.1 A g−1) and remarkable cycling stability (87.24% after 2000 cycles). The Zn//MnSe2/CNTs battery shows excellent power density (3762 W kg−1) and energy density (301 Wh·Kg−1). This work is expected to achieve mass production of electrode materials, which provides great potential for the application of Selenium in zinc-ion batteries.

Sn-Doped Hydrated V2O5 Cathode Material with Enhanced Rate and Cycling Properties for Zinc-Ion Batteries

Water molecules and cations with mono, binary, and triple valences have been intercalated into V2O5 to significantly improve its electrochemical properties as a cathode material of zinc-ion batteries. Sn as a tetravalent element is supposed to interact aggressively with the V2O5 layer and have a significant impact on the electrochemical performance of V2O5. However, it has been rarely investigated as a pre-intercalated ion in previous works. Hence, it is intriguing and beneficial to develop water molecules and Sn co-doped V2O5 for zinc-ion batteries. Herein, Sn-doped hydrated V2O5 nanosheets were prepared by a one-step hydrothermal synthesis, and they demonstrated that they had a high specific capacity of 374 mAh/g at 100 mA/g. Meanwhile, they also showed an exceptional rate capability with 301 mAh/g even at a large current density of 10 A/g, while it was only 40 mAh/g for the pristine hydrated V2O5, and an excellent cycling life (87.2% after 2500 cycles at 5 A/g), which was far more than the 25% of the pure hydrated V2O5. The dramatic improvement of the rate and cycling performance is mainly attributed to the faster charge transfer kinetics and the enhanced crystalline framework. The remarkable electrochemical performance makes the Sn-doped hydrate V2O5 a potential cathode material for zinc-ion batteries.

Sodium vanadate microflowers as cathode for high-capacity and long-life aqueous zinc-ion battery

Aqueous zinc-ion batteries (ZIBs) have become increasingly popular in energy storage devices on account of their high safety, low cost, high theoretical specific capacity and low redox potential. However, the practical application of ZIBs has been hindered by cathode materials that usually exhibit low capacity or poor cycling performance. In our work, sodium vanadium oxide (NaV8O20) microflowers with nanosheet structure were prepared by hydrothermal method. As cathode materials of ZIBs, NaV8O20 microflowers deliver a high initial specific capacity of 427.6 mAh g−1 at 0.1 A g−1. Surprisingly, the capacity retention rate is about 77% after 7000 cycles at a high current density of 15 A g−1. These excellent electrochemical performances can be attributed to the pre-intercalation of Na+ ions to enhance the electrode stability and the nanosheet structure to increase the number of active sites, indicating that the aqueous ZIBs based on NaV8O20 microflowers has potential application value for large-scale energy storage.

Engineering hydrated vanadium oxide by K+ and Ni2+ incorporation for aqueous zinc ion batteries

It is confirmed that K+ introduction is a feasible approach to lead hydrated vanadium pentoxide to a new phase of KVOH which is considered a cathode material with substantial potential for aqueous zinc ion batteries (ZIBs). Nevertheless, the desire to pursue higher value of specific capacity is still a barrier to its development of applications. Herein, a Ni-doped KVOH (KNiVOH) is developed to achieve higher value of specific capacity. Besides, Ni2+ introduction can intensify the conductivity and encourage the electronic rearrangement, which is advantageous to the electrochemical characteristic and chemical kinetics of the KNiVOH. Furthermore, Ni2+ can make KVOH's K–O bond become more stable by decreasing the energy of formation. As regards the specific capacity value, KNiVOH displays the value of 275 mAh g−1 at 5A g−1, which is better than KVOH (266 mAh g−1). Consequently, these properties recommend KNiVOH as a promising cathode material candidate of ZIBs, indicating it is a practical strategy to combine potassium with other transition metals to synthesize new cathode materials for ZIBs in the future.

AmV2O5 with Binary Phases as High-Performance Cathode Materials for Zinc-Ion Batteries: Effect of the Pre-Intercalated Cations A and Reversible Transformation of Coordination Polyhedra.

In this work, five vanadium oxide materials with a series of pre-intercalated cations A (AmV2O5), including Zn2+, Mg2+, NH4+, Li+, and Ag+, have been successfully prepared by a two-step method. All of them possess binary monoclinic and orthorhombic V2O5 phases with an open layered structure that allows the ionic storage and diffusion of hydrated cations. The interlayer space for the monoclinic V2O5 phase is strongly dependent on the radii of hydrated cations A, while the one for the orthorhombic V2O5 phase remains the same regardless of the radii of cations A. Among them, AmV2O5 with pre-intercalated Zn2+ (ZVO) has the best storage ability of Zn2+ with a reversible capacity close to 400 mAh g-1, and AmV2O5 with pre-intercalated Ag+ shows the highest rate capacity with a nearly 40% capacity retention at a current of 20 A g-1 (≈25 C). Kinetic studies have clearly shown that pseudocapacitive behavior dominates the electrochemical reaction on ZVO. During the Zn2+ (de)intercalation reaction, a highly reversible transformation of binary monoclinic or orthorhombic V2O5 phases into a single triclinic ZnxV2O5·nH2O phase is demonstrated on ZVO. Vanadium atoms are identified as the redox centers that undergo the mutual transition among the chemical states of V3+, V4+, and V5+. They together with oxygen atoms constitute reasonable V-O coordination polyhedra to generate a layered structure with a suitable interlayer space for the insertion or removal of zinc ions. Actually, the intrinsic coordination chemistry changes between VO5 square pyramids and VO6 octahedra account for the phase transformation during the Zn2+-(de)intercalation reaction.

Metal-ion inserted vanadium oxide nanoribbons as high-performance cathodes for aqueous zinc-ion batteries

The current energy and environmental crises are driving the burgeoning demand for efficient and reliable energy storage devices. Aqueous zinc-ion batteries (ZIBs) are currently considered to be promising candidates because of their excellent safety in operation and low cost. However, the real-world application of ZIBs has been impeded by a lack of cost effective cathode materials with the requisite high capacities and stability. Here we report the preparation and relevant properties of a special class of layered materials, which can be described as metal ion-inserted vanadium oxide (MVO, M = Zn, K, Na, and Ca) nanoribbons, as cathode materials for ZIBs. Metal ions are inserted into vanadium oxide by mixing the respective metal chloride with V2O5 particles in aqueous solution at room temperature, resulting in layered MVOs with expanded interlayer spaces. When used as the cathode material for ZIBs, ZnVO nanoribbons delivered specific capacities of 414.8, 368.6, 318.2, 271.2, 225.8 and 163.5 mAh g−1 at current rates of 0.1, 0.2, 0.5, 1, 2 and 5 A g−1, respectively. Also, a capacity of 409.6 mAh g−1 was retained after current rate was returned to 0.1 A g−1. After cycling at 2 A g−1 for 1500 cycles, 84.4% of the initial capacity was retained, much higher than that possible using pristine V2O5. The synthesis strategy can be easily scaled up to a 10-liter reaction scale, demonstrating its potential for the large scale production of cathode materials for high-performance aqueous ZIBs.

High-capacity zinc vanadium oxides with long-term cyclability enabled by in-situ electrochemical oxidation as zinc-ion battery cathode

The rechargeable aqueous zinc ion batteries hold great promise owing to their non-flammability and low cost, but are extremely limited by the lack of suitable cathode materials. Vanadium oxides such as V2O5·nH2O, Zn0.25V2O5·nH2O, Ca0.24V2O5·0.83H2O, and so on have been exploited owing to their high Zn2+ storage activity. However, due to the structural disintegration because of the impact of Zn2+ transportation and poor conductivity, their low capacity, poor cyclability and rate property hinder further utilization. Herein, we report the stable zinc vanadium oxides Zn0.36V2O5·nH2O as cathode material for zinc-ion batteries. The zinc vanadium oxides with different stoichiometry converted from in-situ electrochemical oxidation of VOOH precursors in various space groups. The introduction of zinc atoms improves the conductivity of the materials and stabilizes the host structure by bonding with the host oxygen atoms without hindering the interlayer migration of mobile Zn2+, thus greatly optimizing the comprehensive behaviors of the batteries. Ex-situ XRD spectra collected at various states show no shift during (dis)charging and the electrode morphology under different cycles remains intact, indicating the high reversibility and stability. The as-prepared Zn0.36V2O5·nH2O presents a high specific capacity of 508.3 mAh g−1 and 343 mAh g−1 at current densities of 0.5 A g−1 and 5.0 A g−1, and excellent capacity retention of 95% and 80% after 2000 and 5000 cycles respectively. The role of interlayer intercalated-Zn on the stability of vanadium oxides is revealed via density functional theory simulations. In addition, materials with low crystallinity provide shortcuts for ion transportation. The in-situ conversion mechanism of zinc vanadium oxides and the later dual ion energy storage mechanism of which are illustrated in detail.

Organic materials‐based cathode for zinc ion battery

AbstractThe quest for advanced energy storage devices with cheaper, safer, more resource‐abundant storage has triggered intense research into zinc ion batteries (ZIBs). Among them, organic materials as cathode materials for ZIBs have attracted great interest due to their flexible structure designability, high theoretical capacity, environmental friendliness, and sustainability. Although numerous organic electrode materials have been studied and different redox mechanisms have been proposed in the past decade, their electrochemical performance still needs further improvement, and the mechanisms require further exploration. This paper provides a systematical overview of three types of organic materials (bipolar‐type conductive polymer, n‐type conjugated carbonyl compounds, and p‐type material) on the energy storage mechanisms and distinct characteristics. We then focus on discussing the design strategies to improve electrochemical performance. Furthermore, the challenges and future research directions are discussed to provide a foundation for further developing organic‐based ZIBs.

SP@Bicrystalline-MnO2 as an advanced cathode for aqueous zinc-ion battery

Rechargeable aqueous zinc-ion battery (ZIB) using MnO2 as the cathode material have great potential for development due to its merits of high safety, low cost, and environmental friendliness. However, MnO2 cathode undergoes a dissolution-redeposition reaction mechanism, resulting in poor structural stability and cyclability. Herein, a ZIB cathode material (SP@Bicrystalline-MnO2) with two crystal forms structure of MnO2 and conductive carbon (super p, SP) was obtained. As the cathode material of zinc-ion battery with the electrolyte of 2 M ZnSO4 which containing no Mn2+, it exhibits an initial discharge capacity of 300 mAh g−1 and nearly 100% coulombic efficiency. This simple strategy has certain value for the market application of cathode materials for zinc-ion batteries.

One-pot synthesis of 1T MoS2/MWCNT hybrids for enhanced zinc-ion storage

Two-dimensional transition metal dichalcogenides are regarded as the ideal hosts for zinc-ions. Herein, a facile hydrothermal method is proposed to fabricate the metallic phase (1T phase) MoS2/multi-walled carbon nanotube (MWCNT) hybrids serving as the cathode materials for zinc-ion batteries (ZIBs). By virtue of the exertion of phase engineering and the synergy between the 1T MoS2 nanosheets and MWCNT framework, the transfer kinetics of zinc-ions of the prepared hybrid are remarkably accelerated, leading to boosted electrochemical properties at both room temperature and low temperatures. The hybrid electrode delivers a high reversible capacity of 161.5 mAh g−1 after 100 cycles at 0.1 A g−1, and good cycling stability with a desired capacity retention of 84.6% over 500 cycles at 1 A g−1. Furthermore, its boosted capability of zinc-ion storage in a low-temperature atmosphere is revealed. This work not only provides an effective way to squeeze the values of phase engineering of MoS2 in ZIBs, but also reveals the great potential of MoS2-based composites in low-temperature energy storage devices.

Recent Advance and Modification Strategies of Transition Metal Dichalcogenides (TMDs) in Aqueous Zinc Ion Batteries.

In recent years, aqueous zinc ion batteries (ZIBs) have attracted much attention due to their high safety, low cost, and environmental friendliness. Owing to the unique layered structure and more desirable layer spacing, transition metal dichalcogenide (TMD) materials are considered as the comparatively ideal cathode material of ZIBs which facilitate the intercalation/ deintercalation of hydrated Zn2+ between layers. However, some disadvantages limit their widespread application, such as low conductivity, low reversible capacity, and rapid capacity decline. In order to improve the electrochemical properties of TMDs, the corresponding modification methods for each TMDs material can be designed from the following modification strategies: defect engineering, intercalation engineering, hybrid engineering, phase engineering, and in-situ electrochemical oxidation. This paper summarizes the research progress of TMDs as cathode materials for ZIBs in recent years, discusses and compares the electrochemical properties of TMD materials, and classifies and introduces the modification methods of MoS2 and VS2. Meanwhile, the corresponding modification scheme is proposed to solve the problem of rapid capacity fading of WS2. Finally, the research prospect of other TMDs as cathodes for ZIBs is put forward.

Potassium Ammonium Vanadate with Rich Oxygen Vacancies for Fast and Highly Stable Zn-Ion Storage.

Vanadium-based materials have been extensively studied as promising cathode materials for zinc-ion batteries because of their multiple valences and adjustable ion-diffusion channels. However, the sluggish kinetics of Zn-ion intercalation and less stable layered structure remain bottlenecks that limit their further development. The present work introduces potassium ions to partially substitute ammonium ions in ammonium vanadate, leading to a subtle shrinkage of lattice distance and the increased oxygen vacancies. The resulting potassium ammonium vanadate exhibits a high discharge capacity (464 mAh g-1 at 0.1 A g-1) and excellent cycling stability (90% retention over 3000 cycles at 5 A g-1). The excellent electrochemical properties and battery performances are attributed to the rich oxygen vacancies. The introduction of K+ to partially replace NH4+ appears to alleviate the irreversible deammoniation to prevent structural collapse during ion insertion/extraction. Density functional theory calculations show that potassium ammonium vanadate has a modulated electron structure and a better zinc-ion diffusion path with a lower migration barrier.

Synthesis and Optimization of ZnMn2O4 Cathode Material for Zinc-Ion Battery by Citric Acid Sol-Gel Method

Zinc manganese spinel composite oxide ZnMn2O4 is an important inorganic material, which is rich in natural resources and environment-friendly. Herein, pure phase ZnMn2O4 was prepared by a simple sol-gel process as cathode material for zinc ion batteries. In order to improve the cycle performance of the material while maintaining the capacity, acetonitrile/aqueous co-solvent electrolyte (0.5 M Zn(CF3SO3)2/AN-H2O) was used as the electrolyte of the zinc ion battery. The influence of different experimental conditions on the electrochemical properties of ZnMn2O4 was studied by orthogonal experiment. In order to improve its electrochemical performance and cycling ability, the non-equivalent substitution of pure ZnMn2O4 was performed by adding Al3+. The non-equivalent substitution of Al3+ reduced the cell volume of ZnMn2O4 and the mixed manganese valence appeared. The specific capacity of initial discharge increases from 52.9 mAh·g−1 to 109.4 mAh·g−1 at 0.05C, and the cycle stability is also greatly improved. After 100 cycles, the capacity retention rate was 82.3%. This work shows that ZnMn2O4 is a promising cathode material for zinc ion batteries, which expands the application of spinel oxide in zinc ion batteries.

Manganese hexacyanoferrate anchoring MnO2 with enhanced stability for aqueous zinc-ion batteries

Aqueous zinc-ion batteries (ZIBs) have provided new opportunities and challenges to the energy storage market due to their low price, high safety and environmentally friendly. Among the cathode materials of ZIBs, MnO2 appears to one of the most promising cathode for ZIBs owing to its high theoretical capacitance, abundant reserves, non-toxicity, and low cost. However, the poor cycling stability and rate performance have been the bottle-neck of MnO2 due to the slow electrochemical kinetics and severe structural damage during cyclic process. Herein, a new strategy is proposed to optimize the cycling stability and rate performance of the pristine MnO2 by a simple surface modification of manganese hexacyanoferrate (MnHCF). The anchored MnHCFs not only relieves the manganese dissolution during the continuous charge and discharge, but also introduces oxygen defects boosting the electrochemical kinetics of MnO2. The as prepared composite delivers a reversible specific capacity of 287 mA h g−1 at 0.1 A g−1 and maintains 87.1% of its initial capacity after 70 cycles.

Influence of Co on the Microstructure, Electrochemical and Pseudocapacitive Properties of Amorphous Manganese Dioxide

Manganese dioxide is a cathode material for zinc-ion batteries which is low in cost and high in performance, whereas, traditional manganese dioxide materials have poor cycle stability and poor conductivity. In response to this problem, many researchers have carried out related research, such as the preparation of various crystal forms of manganese dioxide, element doping (Co, Sn, V, etc.) and so on. However, the research on doping amorphous materials to solve the above problems is in scarcity. In this paper, amorphous manganese oxide and Co doping were combined for the first time, and Co-doped amorphous manganese dioxide was prepared by in-situ liquid phase dispersion coprecipitation method. The influence of Co doping on the microstructure and electrochemical properties of amorphous manganese dioxide were also investigated for the first time. As can be observed from the results, despite that Co doping preserves the abundant structural defects in amorphous manganese dioxide, it transforms the amorphous manganese dioxide particles from spherical to nano-sheet shape, significantly increases the particular area of surface and pore size of amorphous manganese dioxide, and stabilizes its crystal structure. Furthermore, Co doping can not only reduce the impedance of the amorphous manganese dioxide cathode, but also extremely boost the pseudocapacitive performance of amorphous manganese dioxide, thereby greatly improving its discharge specific capacity, the rate performance and the cycle stability. The prepared Co-doped amorphous manganese dioxide cathode has a maximum discharge specific capacity of 325 mAh g−1, and a capacity retention rate of 64% at 600 cycles under a current density of 1 A g−1.