Optimizing the electrolyte salt of aqueous zinc-ion batteries based on a high-performance calcium vanadate hydrate cathode material

It is urgent to develop high-performance cathode materials for the emerging aqueous zinc-ion batteries with a facile strategy and optimize the related components.Herein,a Ca0.23V2O5·0.95 H2O nanobelt cathode material with a rather large interlayer spacing of 13.0 A is prepared via a one-step hydrothermal approach.The battery with this cathode material and 3 M Zn(CF3SO3)2 electrolyte displays high specific capacity(355.2 mAh g^-1 at 0.2 A g^-1),great rate capability(240.8 mAh g^-1 at 5 A g^-1),and excellent cyclability(97.7% capacity retention over 2000 cycles).Such superior performances are ascribed to fast electrochemical kinetics,outstanding electrode/electrolyte interface stability,and nearly dendrite-free characteristic.Instead,when ZnSO4 or Zn(ClO4)2 is used to replace Zn(CF3SO3)2,the electrochemical performances become much inferior,due to the slow electrochemical kinetics,inhomogeneous Zn stripping/plating process,and the formation of large dendrites and byproducts.This work not only discloses a high-performance cathode material for aqueous zinc-ion batteries but also offers a reference for the choice of electrolyte salt.     

Bio-degradable zinc-ion battery based on a prussian blue analogue cathode and a bio-ionic liquid-based electrolyte

Rechargeable zinc-ion batteries are of high interest for electrical energy storage due to their low cost, high safety, and good energy density. The development of stable and high-performance cathode materials and environmentally friendly electrolytes is of interest for practical applications. Despite many efforts in pursuing batteries with high energy density and long cycle life, relatively little attention has been paid on the environmental aspects. Thus, bio-batteries that contain nontoxic materials and which are bio-degradable are an interesting alternative to conventional batteries. In the present paper, we present our first results on a highly reversible zinc/prussian blue analogue (PBA) bio-battery, where nanostructured PBA is used as a cathode material, a bio-degradable ionic liquid-water mixture as electrolyte, and zinc as anode. Both the PBA cathode and the zinc anode exhibit good compatibility with the bio-degradable electrolyte. The Zn/PBA battery shows good electrochemical performance including an open circuit voltage of 1.6 V, a specific capacity of ～54 mAh g^?1 (PBA), and a low self-discharge rate. The zinc anode also shows a good stability since no dendritic growth and shape change are observed after 50 charge-discharge cycles.     

Pre-potassiated hydrated vanadium oxide as cathode for quasi-solid-state zinc-ion battery

Zinc-ion batteries（ZIBs）, in particular quasi-solid-state ZIBs, occupy a crucial position in the field of energy storage devices owing to the superiorities of abundant zinc reserve, low cost, high safety and high theoretical capacity of zinc anode. However, as divalent Zn²⁺ions experience strong electrostatic interactions when intercalating into the cathode materials, which poses challenges to the structural stability and higher demand in Zn²⁺ions diffusion kinetics of the ...     

Freestanding reduced graphene oxide/sodium vanadate composite films for flexible aqueous zinc-ion batteries

With the booming development of portable and wearable electronic devices, flexible energy storage devices have attracted great attention. Among various energy storage devices, aqueous zinc ion batteries(ZIBs) are one of the promising candidates due to their low cost, good safety, high energy and power densities. However, the conventional cathodes of aqueous ZIBs were often prepared by mixing active materials with binders and conductive additives and then coating them onto current collectors. The resultant cathodes often suffer from unsatisfied flexibility. Herein, we fabricated freestanding reduced graphene oxide/NaV_3O_8·1.5H_2O(RGO/NVO) composite films with interlinked multilayered architecture by a vacuum filtrating process. Such composite films exhibit excellent mechanical property and high electronic conductivity. Owing to unique architecture, they display a high capacity of 410 mA h g~(-1) and excellent cycling performance up to 2000 cycles with a high capacity retention of 94%. Moreover, RGO/NVO composite films can directly serve as the cathodes of flexible aqueous ZIBs. As a proof of concept,flexible ZIBs were assembled based on the composite films. Impressively, they exhibit stable performance at different bending states, demonstrating great potential application in flexible energy storage devices.     

Surface engineering towards high-energy carbon cathode for advanced aqueous zinc-ion hybrid capacitors

Opportunities coexist with challenges for the development of carbon-based cathodes with a high energy density applied for zinc ion hybrid capacitors (ZIHCs). In the present study, a facile and effective surface engineering approach is demonstrated to greatly improve the energy storage ability of commercial carbon paper (CP) in ZIHC. Benefiting from the introduced oxygen functional groups, larger surface area and improved surface wettability upon air calcination, the assembled aqueous ZIHC with the functionalized carbon paper (FCP) exhibits a much higher areal capacity of 0.22 mAh/cm² at 1 mA/cm², outperforming the counterpart with blank CP by over 5000 times. More importantly, a superior energy density and power density of 130.8 µWh/cm² and 7460.5 µW/cm², are respectively delivered. Furthermore, more than 90% of the initial capacity is retained over 10000 cycles. This surface engineering strategy to improve the energy storage capability is potentially applicable to developing a wide range of high-energy carbon electrode materials.     

Cauliflower-like nanostructured ZnV2S4 as a potential cathode material to boost-up high capacity and durability of the aqueous zinc-ion battery

Owing to their unique design and development, high safety and low-cost efficient cathode is still at the forefront of research for rechargeable zinc-ion batteries. However, the suitable cathode operating with ultrahigh capacity with a dendrite-free anode reaction mechanism remains challenging. In this, the first archetype of a high-rate and morphologically stabled cathode material is constructed from novel cauliflower-like nano-ZnV₂S₄ for aqueous zinc-ion batteries. Thus, nano-ZnV₂S₄ was prepared with an anion exchange reaction using ZnV₂(OH)₈ cauliflower-like nanostructured array as a template interestingly no morphological and shape changes were detected. The as-prepared nano-ZnV₂S₄ electrode reveals a specific discharge capacity of 348.2 mAh/g during 0.5 A/g with enhanced rate capability and excellent capacity retention of 89.2% at 4 A/g current density even after completing 1000 cycles.     

Accelerated discovery of novel high-performance zinc-ion battery cathode materials by combining high-throughput screening and experiments

Aqueous zinc ion batteries (AZIBs) have attracted much attention in recent years due to their high safety, low cost, and decent electrochemical performance. However, the traditional electrodes development process requires tedious synthesis and testing procedures, which reduces the efficiency of developing high-performance battery devices. Here, we proposed a high-throughput screening strategy based on first-principles calculations to aid the experimental development of high-performance spinel cathode materials for AZIBs. We obtained 14 spinel materials from 12,047 Mn/Zn-O based materials by examining their structures and whether they satisfy the basic properties of electrodes. Then their band structures and density of states, open circuit voltage and volume expansion rate, ionic diffusion coefficient and energy barrier were further evaluated by first-principles calculations, resulting in five potential candidates. One of the promising candidates identified, Mg₂MnO₄, was experimentally synthesized, characterized and integrated into an AZIB based cell to verify its performance as a cathode. The Mg₂MnO₄ cathode exhibits excellent cycling stability, which is consistent with the theoretically predicted low volume expansion. Moreover, at high current density, the Mg₂MnO₄ cathode still exhibits high reversible capacity and excellent rate performance, indicating that it is an excellent cathode material for AZIBs. Our work provides a new approach to accelerate the development of high-performance cathodes for AZIBs and other ion batteries.     

A bi-component polyoxometalate-derivative cathode material showed impressive electrochemical performance for the aqueous zinc-ion batteries

Rechargeable aqueous zinc-ion batteries are recently gaining incremental attention because of low cost and material abundance, but their development is plagued by limited choices of cathode materials with satisfactory cycling performance. The polyoxometalates perform formidable redox stability and able to participate in multi-electron transfer, which was well-suited for energy storage. Herein, a bi-component polyoxometalate-derivative KNiVO (K₂[Ni(H₂O)₆]₂[V₁₀O₂₈]·4H₂O polyoxometalates after annealing) is firstly demonstrated as a cathode material for aqueous ZIBs. The layered KV₃O₈ (KVO) In the bi-component material constitutes Zn²⁺ migration and storage channels (K⁺ were substantially replaced by Zn²⁺ in the activation phase), and the three-dimensional NiV₃O₈ (NiVO) part acts as skeleton to stabilize the ion channels, which assist the cell to demonstrate a high-rate capacity and specific energy of 229.4 mAh/g and satisfactory cyclability (capacity retention of 99.1% after 4500 cycles at a current density of 4 A/g). These results prove the feasibility of POM as cathode materials precursor and put forward a novel pattern of the Zn²⁺ storage mechanism in the activated-KNiVO clusters, which also provide a new route for selecting or designing high-performance cathode for aqueous ZIBs and other advanced battery systems.     

Calcium ion pinned vanadium oxide cathode for high-capacity and long-life aqueous rechargeable zinc-ion batteries

Science China Chemistry - Rechargeable aqueous zinc ion batteries (ZIBs), with the easy operation, cost effectiveness, and high safety, are emerging candidates for high-energy wearable/portable...     

Manganese-based cathode materials for aqueous rechargeable zinc-ion batteries: recent advance and future prospects

Zinc-ion batteries (ZIBs), which use mild aqueous electrolyte, have attracted increasing attention, due to their unique advantages such as low cost, high safety, environmental friendliness, and ease of manufacture. At present, developing a kind of cathode materials with stable structures and large capacities for ZIBs is a hot research topic. Among all ZIBs cathode materials, manganese-based cathode materials have the advantages of low cost, abundant reserves, low toxicity, rich valence states, and high zinc storage capacity, which make them one of the most promising candidates. In recent years, manganese-based composites with different crystal structures have been extensively studied as cathode materials of ZIBs. In this paper, the reaction mechanism of ZIBs cathodes is discussed in detail, and the challenges faced by manganese-based cathode materials and the latest research progress are examined deeply. In addition, a number of optimization strategies aimed at improving the electrochemical performance of the cathode of ZIBs are outlined. Finally, the future prospect of ZIBs is presented.     

A carbonyl-rich covalent organic framework as a high-performance cathode material for aqueous rechargeable zinc-ion batteries

Aqueous rechargeable zinc-ion batteries (ZIBs) provide high theoretical capacity, operational safety, low-cost and environmental friendliness for large-scale energy storage and wearable electronic devices, but their future development is plagued by low capacity and poor cycle life due to the lack of suitable cathode materials. In this work, a covalent organic framework (Tp-PTO-COF) with multiple carbonyl active sites is synthesized and successfully introduced in aqueous rechargeable ZIBs for the first time. Tp-PTO-COF delivers high specific capacities of 301.4 and 192.8 mA h g⁻¹ at current densities of 0.2 and 5 A g⁻¹, respectively, along with long-term durability and flat charge–discharge plateaus. The remarkable electrochemical performance is attributed to the abundance of nucleophilic carbonyl active sites, well defined porous structure and inherent chemical stability of Tp-PTO-COF. Moreover, the structural evolution and Zn²⁺ ion intercalation mechanism are discussed and revealed by the experimental analysis and density functional theory calculations. These results highlight a new avenue to develop organic cathode materials for high performance and sustainable aqueous rechargeable ZIBs.

A covalent organic framework (Tp-PTO-COF) with carbonyl active sites was proposed as a novel cathode material and successfully applied in aqueous rechargeable zinc-ion batteries (ZIBs).     

MnO2 cathode materials with the improved stability via nitrogen doping for aqueous zinc-ion batteries

The research and exploration of manganese-based aqueous zinc-ion batteries have been controversial of cycle stability and mechanism investigation,thus improving the stability and exploring storage mechanism are still the most main issue.Defect engineering has become an effective method to improve cycle stability.Herein,a nitrogen-doped ε-MnO₂(MnO₂@N) has been prepared using electrochemical deposition and heat treatment under nitrogen atmosphere.As the cathode for zinc-ion b...     

V-MOF@graphene derived two-dimensional hierarchical V2O5@graphene as high-performance cathode for aqueous zinc-ion batteries

Rechargeable aqueous zinc-ion batteries (ZIBs) are attracting growing attention in the field of grid-scale energy storage systems due to their reliable safety and low cost. However, it is still hindered by the limited choices of suitable cathode materials with high performance for aqueous ZIBs. Herein, we developed a V-MOF@graphene derived two-dimensional hierarchical V₂O₅@graphene for the first time, where the porous V₂O₅ nanosheets are homogeneously attached to the 2D graphene substrate. Benefiting from the unique 2D composite structure with excellent electronic and ionic conductivity, adequate active sites, as well as the synergistic effect between the ultrathin V₂O₅ nanosheets and graphene, the V₂O₅@graphene here exhibits outstanding electrochemical performance in aqueous ZIBs. Particularly, it delivered an ultrahigh reversible capacity of 378 mAh/g at a current density of 2 A/g. What is more, a high specific capacity of 305 mAh/g after 100 cycles at 0.1 A/g and 200 mAh/g after 1,000 cycles at 1 A/g can be achieved. These ideal results suggest that the V₂O₅@graphene cathode hold great promise for high-performance aqueous zinc-ion batteries.     

Cascading V2O3/N-doped carbon hybrid nanosheets as high-performance cathode materials for aqueous zinc-ion batteries

In recent years, especially when there is increasing concern about the safety issue of lithium-ion batteries（LIBs）, aqueous Zn-ion batteries（ZIBs） have been getting a lot of attention because of their costeffectiveness, materials abundance, high safety, and ecological friendliness. Their working voltage and specific capacity are mainly determined by their cathode materials. Vanadium oxides are promising cathode materials for aqueous ZIBs owing to their low cost, abundant resources, and multivale...     

An aqueous rechargeable lithium-ion battery based on LiCoO2 nanoparticles cathode and LiV3O8 nanosheets anode

Nanoparticles of lithium cobalt oxide (LiCoO₂) and nanosheets of lithium vanadium oxide (LiV₃O₈) were synthesized by a citrate sol–gel combustion route. The physical characterizations of the electrodic materials were carried out by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and also X-ray diffraction (XRD) measurements. Near spherical nanoparticles of ≈100 nm and compact nanosheets with a few nanometers thick were observed by SEM and TEM for LiCoO₂ and LiV₃O₈, respectively. XRD data indicated that the as-prepared active materials presented pure phase of rhombohedral LiCoO₂ with R-3m symmetry and monoclinic LiV₃O₈ with p2₁/m symmetry. The kinetics of electrochemical intercalation of lithium ion into the nanoparticles of LiCoO₂ and nanosheets of LiV₃O₈ from 1.0 mol l⁻¹ LiNO₃ aqueous solution were investigated by cyclic voltammetry and chronoamperometry. An aqueous rechargeable lithium-ion battery consisting of LiCoO₂ nanoparticles as positive and LiV₃O₈ nanosheets as negative electrode was assembled. This battery represented a discharge voltage of about 1 V with good cycling performance.     

Charge storage mechanism of MOF-derived Mn_2O_3 as high performance cathode of aqueous zinc-ion batteries

Aqueous Zinc-ion batteries(ZIB) are attracting immense attention because of their merits of excellent safety and quite cheap properties compared with lithium-ion batteries(LIB).Manganese oxide is one of the most important cathode materials of ZIB.In this paper,α-Mn2O3 used as cathode of ZIB is synthesized via Metal-Organic Framework(MOF)-derived method,which delivers a high specific capacity of225 mAh g^-1 at 0.05 A g^-1 and 92.7 mAh g^-1 after 1700 cycles at 2 A g^-1.The charge storage mechanism of α-Mn2O3 cathode is found to greatly depend on the discharge current density.At lower current density discharging,the H+ and Zn2+ are successively intercalated into the α-Mn2O3 before and after the turning point of discharge voltage and their discharging products present obviously different morphologies changing from flower-like to large plate-like products.At a higher current density,the low-voltage plateau after the turning point disappears due to the decrease of amount of Zn2+ intercalation and the H+intercalation is dominated in α-Mn2 O3.This study provides significant understanding for future design and research of high-performance Mn-based cathodes of ZIB.     

Rechargeable sodium-ion battery based on a cathode of copper hexacyanoferrate

Journal of Solid State Electrochemistry - In this work, the performance of copper (II) hexacyanoferrate(III) (CuHCF) as a cathode material for sodium-ion batteries was studied. The compound was...     

Anode optimization strategies for aqueous zinc-ion batteries

Zinc-ion batteries (ZIBs) have received much research attention due to their advantages of safety, non-toxicity, simple manufacture, and element abundance. Nevertheless, serious problems still remain for their anodes, such as dendrite development, corrosion, passivation, and the parasitic hydrogen evolution reaction due to their unique aqueous electrolyte system constituting the main issues that must be addressed, which are blocking the further advancement of anodes for Zn-ion batteries. Herein, we conduct an in-depth analysis of the problems that exist for the zinc anode, summarize the main failure types and mechanisms of the zinc anode, and review the main modification strategies for the anode from the three aspects of the electrolyte, anode surface, and anode host. Furthermore, we also shed light on further modification and optimization strategies for the zinc anode, which provide directions for the future development of anodes for zinc-ion batteries.

This review provides a comprehensive summary of the research progress of Zn anodes, including the main challenges of Zn metal anodes, the corresponding optimization strategies, and the perspectives for practical aqueous Zn-ion batteries.     

Recent advances of vanadium-based cathode materials for zinc-ion batteries

Zn-ion batteries (ZIBs) have gained great attention as promising next-generation power sources, because of their low cost, enviable safety and high theoretical capacity. Recently, massive researches have been devoted to vanadium-based materials as cathodes in ZIBs, owing to their multiple valence states, competitive gravimetric energy density, but the capacity degradation, sluggish kinetics, low operating voltage hinder further optimization of their performance in ZIBs. This review summarizes recent progress to increase the interlayer spacing, structural stability, and the diffusion ability of the guest Zn ions, including the insertion of different ions, introduction of defects, design of diverse morphologies, the combination of other materials. We also focus on approaches to promoting the valuable performance of vanadium-based cathodes, along with the related ongoing scientific challenges and limitations. Finally, the future perspectives and research directions of vanadium-based aqueous ZIBs are provided.     

Enhanced reversible capacity of Li-S battery cathode based on graphene oxide

Lithium sulfur battery (LSB) offers several advantages such as very high energy density, low-cost, and environmental-friendliness. However, it suffers from serious degradation of its reversible capacity because of the dissolution of reaction intermediates, lithium polysulfides, into the electrolyte. To solve this limitation, there are many studies using graphene-based materials due to their excellent mechanical strength and high conductivity. Compared with graphene, graphene oxide (GO) contains various oxygen functional groups, which enhance the reaction with lithium polysulfides. Here, we investigated the positive effect of using GO mixed with carbon black on the performance of cathode in LSB. We have observed a smaller drop of capacity in GO mixed sulfur cathode. We further demonstrate that the mechanistic origin of reversibility improvement, as confirmed through CV and Raman spectra, can be explained by the stabilization of sulfur in lithium polysulfide intermediates by oxygen functional groups of GO to prevent dissolution. Our findings suggest that the use of graphene oxide-based cathode is a promising route to significantly improve the reversibility of current LSB.