High-performance Aqueous Zinc-ion Batteries Research Articles

Fabrication of a 3D structure MnO2 electrode with high MnO2 mass loading as the cathode for high-performance aqueous zinc-ion batteries

Benefiting from the remarkable advantages (eco-friendly, cost-effective, and high safety) of rechargeable aqueous zinc-ion batteries (AZIBs), AZIBs are regarded as viable alternatives to traditional Lithium-ion batteries (LIBs). However, in prevailing research, the excellent electrochemical performance usually achieved by ultra-low active material loadings (e.g., <1 mg/cm²), which is far from the active material mass loading of commercial electrodes in practical (≥10 mg/cm²). Balancing superior properties with high mass loading has posed a challenge. To surmount this, an innovative method combined ultrasonic processing, freeze-drying, and 3D printing technologies is used to engineer a high MnO2 mass loading cathode for AZIBs (3D cathode). Notably, the grid structure of 3D cathode substantially augmenting the surface area for redox reactions during charge/discharge processes, which greatly enhanced the pseudo-capacitance process of cathode. Additionally, the uniform and stable microstructure exhibited the dual capability of expediting ion/electron transfer and sustaining the structural integrity throughout charge/discharge cycles. Consequently, the 3D cathode demonstrated superior comprehensive electrochemical properties at the MnO2 high mass loading of 10 mg/cm2 (138.7 mAh/g at 1 A/g, 87.4 mAh/g after 500 cycles, 82 % energy efficiency) and 15 mg/cm2 (113.3 mAh/g at 1 A/g, 56.3 mAh/g after 400 cycles, 81 % energy efficiency).

Unravelling the proton hysteresis mechanism in vacancy modified vanadium oxides for High-Performance aqueous zinc ion battery

Rechargeable aqueous zinc-ion batteries, as one of the most promising next-generation energy storage devices, have attracted increasing attentions because of their low cost, environmental benignity, and intrinsic safety. However, their practical application is severely hindered by the low energy density, unsatisfying power density, and poor long-term cycling stability. Herein, a hierarchical vacancy-modified vanadium oxide coated by soft carbon layer is elaborately designed as cathodes for zinc ion batteries. Consequently, the vanadium oxide cathodes deliver an ultrahigh capacity of 587 mAh/g at 0.1 A/g, highly enhanced rate performance with a reversible capacity of 367 mAh/g at 20 A/g, and excellent long-term cycling stability with a decay rate of 0.0058% per cycle after 5000 cycles, which are among the best performances of vanadium-based cathodes. More importantly, an intriguing phenomenon of proton hysteresis was, for the first time, observed during the electrochemical processes. Based on the experimental results and theoretical calculations, we demonstrate that the synergistic effect of vacancy and proton hysteresis on the excellent electrochemical performance in zinc ion batteries. This work not only demonstrates the huge potential of the deliberately designed vanadium oxide in practical application, but also provides a refreshing understanding of the electrochemical mechanism in zinc ion batteries.

Anhydride-Based Compound with Tunable Redox Properties as Advanced Organic Cathodes for High-Performance Aqueous Zinc-Ion Batteries.

Organic materials with multiple active sites and flexible structural designs are becoming popular for use in aqueous zinc-ion batteries (AZIBs). However, their applicability is limited due to the low specific capacity and poor cycle stability originating from the introduction of inactive units and high solubility. Herein, three organic molecules with tunable redox properties were synthesized using anhydride (PMDA, 1,2,4,5-benzenetetracarboxylic anhydride-1,2-diaminoanthraquinone, NTCDA, 1,4,5,8-naphthalenetetracarboxylic dianhydride-1,2-diaminoanthraquinone, and PTCDA, 3,4,9,10-perylenetetracarboxylic dianhydride-1,2-diaminoanthraquinone, referred to as PM12, NT12, and PT12) in the solid-phase method. Density functional theory (DFT) simulations and experiments identified that NT12 exhibits superior electrochemical performance compared with PM12 and PT12 because of the low energy gap and large aromatic conjugated structure. They demonstrated specific capacities of 106.7, 192.9, and 124.9 mA h g-1 at 0.05 A g-1, respectively. Especially, NT12 displayed excellent initial specific capacity (85.4 mA h g-1 at 1 A g-1) and remarkable capacity retention (64.1% for 3000 cycles) due to dual active centers (C═N and C═O). The all-NT12 full-cell also had excellent performance (127.1 mA h g-1 under 1 A g-1 and 80.6% over 200 cycles). The organic compounds synthesized in this work have potential applications of AZIBs, highlighting the importance of molecular design to develop the next generation of advanced materials.

Modified vanadium oxide with enhanced diffusion kinetic for high rate aqueous zinc-ion batteries

At present, research on aqueous ion batteries is progressing rapidly and vanadium oxide with fast and stable Zn2+ storage performance has aroused widespread interest in the development of high-performance aqueous zinc-ion batteries (AZIBs). However, it generally has the problems of structural collapse and slow diffusion kinetics, which hinder its promising large-scale application. Herein, a cathode material of self-assembled nanospheres of V2O5 modified with K-ion (KVO) was reported by one-pot hydrothermal method. The introduction of K+ not only considerably improves the conductivity of vanadium oxide, which further enhances the diffusion kinetics of Zn2+, but also successfully increases the interlayer spacing. Hence, the assembled Zn-ion batteries based on KVO cathode demonstrated outstanding rate performance and strong cycle stability with a high discharge capacity of 226 mAh g−1 at 10 A g−1 and a capacity retention rate of 66.9 % after 9000 cycles at the same current density. It also exhibited a high energy density of 262 Wh kg−1 at 1 A g−1. Finally, flexible quasi-solid ZIBs were assembled utilizing KVO as cathode and demonstrated their good Zn2+ storage properties and promising application prospects. This work may provide a direction for designing or developing other layered transition metal oxides cathode for AZIBs.

Nitrogen-doped carbon trapped MnMoO4 microrods toward high performance aqueous zinc-ion battery

Manganese oxides as a class of favorable cathode materials in zinc-ion batteries (ZIBs), have garnered considerable concerns for their low cost, eco-friendliness as well as high energy density. Nonetheless, the practical applications of manganese oxides have been immensely hindered by sluggish reaction kinetics and moderate cycling stability as a result of their poor electronic/ionic conductivity. In this regard, nitrogen-doped carbon-coated MnMoO4 (MnMoO4@NC) is firstly designed with enhanced electrochemical kinetics in this work. The nitrogen-doped carbon coating on MnMoO4 enhances electric conductivity, inhibits Mn and Mo dissolution, and provides a large surface area, thereby increasing the contact area between cathode and electrolyte and offering more Zn2+/ H+ storage sites. What’s more, the MnMoO4@NC heterostructure formed built-in electric field with accelerated charge transfer is also elucidated by the first-principle calculations, which is in favor of the fast insertion/extraction of Zn2+ and H+. As a result, the MnMoO4@NC-2 exhibits optimal circulation endurance with a reversible capacity of 242.1 mA h g−1 together with capacity retention of 147.8 % at 1 A g−1 after 380 cycles. This study provides a new pathway for building durable ZIBs.

Massive anionic fluorine substitution two-dimensional δ-MnO2 nanosheets for high-performance aqueous zinc-ion battery

As one of the most promising materials for rechargeable aqueous zinc ion batteries (AZIBs), manganese oxide (δ-MnO2) need overcome the fatal limitations of structural instability and manganese dissolution for future practical application. Crystal high-orientated two-dimensional δ-MnO2 nanosheets with massive anionic fluorine were synthesized by a lava method with quenching treatment. When employed as a cathode material for zinc ion batteries, it exhibits a long cycling lifespan and high multiplicity performance. The fluorine atoms substitution can not only stabilize the manganese‑oxygen octahedron [MnO6] structure by introducing fluorine‑manganese chemical bonding, but also regulate the Mn3+/Mn4+ ratio by increasing the Mn3+ concentration content. Meanwhile, the obtained high-orientated 2D nanosheets structure can accelerate the ions kinetic behaviors for high rate electrochemical performance by shortening the ion translation and increasing the electronic conductivity. The optimized δ-MnO2 nanosheets exhibit a superior electrochemical performance of 288 mAh g−1 at current densities of 100 mA g−1. An excellent cycling lifespan up to 96 % capacity retention is indicated as well after 200 cycles at a current density of 200 mA g−1. This element doping strategy by molten salt quenching method has the benefits of simple synthesis steps and high yield with high economic efficiency.

An aqueous electrolyte densified by perovskite SrTiO3 enabling high-voltage zinc-ion batteries

The conventional weak acidic electrolyte for aqueous zinc-ion batteries breeds many challenges, such as undesirable side reactions, and inhomogeneous zinc dendrite growth, leading to low Coulombic efficiency, low specific capacity, and poor cycle stability. Here, an aqueous densified electrolyte, namely, a conventional aqueous electrolyte with addition of perovskite SrTiO3 powder, is developed to achieve high-performance aqueous zinc-ion batteries. The densified electrolyte demonstrates unique properties of reducing water molecule activity, improving Zn2+ transference number, and inducing homogeneous and preferential deposition of Zn (002). As a result, the densified electrolyte exhibits an ultra-long cycle stability over 1000 cycles in Zn/Ti half cells. In addition, the densified electrolyte enables Zn/MnO2 cells with a high specific capacity of 328.2 mAh g−1 at 1 A g−1 after 500 cycles under an extended voltage range. This work provides a simple strategy to induce dendrite-free deposition characteristics and high performance in high-voltage aqueous zinc-ion batteries.

Boosting uniform nucleation and suppressing hydrogen evolution with an in-situ formed zinc hyaluronate protective film on zinc anodes

Developing long-cycle stable Zn-ion batteries encounters significant challenges associated with Zn anodes. To address these issues, we propose an interface engineering strategy using an artificial protective layer called zinc hyaluronate (ZH) on the Zn anode surface. The ZH film acts as a barrier, preventing direct contact between Zn anode and electrolyte, reducing hydrogen evolution and corrosion. Its carboxyl and hydroxyl groups create uniform and plentiful nucleophilic sites for Zn2+ ions, promoting uniform Zn deposition and suppressing dendrite growth. Remarkably, a Zn//Zn symmetric cell assembled with ZH-decorated Zn foil (Zn@ZH) exhibits outstanding cycle life, lasting 3600 h at a current density of 5 mA cm−2 and a capacity density of 5 mAh cm−2, much better than cells with pristine Zn anode. Even under extremely tough conditions of 10 mA cm−2 and 10 mAh cm−2, the battery life exceeds 1300 h. Furthermore, the Zn@ZH//V2O5 full cell demonstrates superior capacity retention compared to the Zn//V2O5 cell after 1000 cycles at a current density of 10 A g−1. These results highlight the benefits of the artificial protective layer strategy for advanced Zn anodes, providing insights into the underlying mechanism and promoting the development of high-performance aqueous zinc ion batteries.

Ferroelectric-Enhanced cathode kinetics toward High-Performance aqueous Zinc-Ion batteries

Rechargeable aqueous zinc ion batteries (AZIBs) offer promising potential for large-scale energy storage systems due to their high affordability and safety. However, their practical applications are hindered by the undesired rate capability and cycling stability of the used cathode, attributed to sluggish ions kinetics during charge–discharge process. Herein, we propose an electric field balancing strategy to regulate the electrolyte ions behavior by constructing a ferroelectric interface on the cathode surface using a prototypical of MnO2-based cathode. An appropriate thickness coating of ferroelectric materials coating (i.e., β-PVDF) on the MnO2 surface is theoretically and experimentally demonstrated to enhance the ion kinetics due to the optimized electrical distribution during electrochemical operations. Further comprehensive electrochemical mechanism studies reveal that the ferroelectric interface on the MnO2@β-PVDF not only promotes the diffusion of Zn2+ but also reduces the electrochemical overpotential (17.6 mV), resulting in improved electrochemical reversibility and capacity performance. The resultant MnO2@β-PVDF cathode exhibits the highest capacity of 277.6 mAh g−1 (at 0.1 A g−1) and capacity retention of 68.6% after 120 cycles, surpassing both the pristine MnO2 and non-ferroelectric materials coated MnO2 electrodes. This success presents a new approach to enhance the overall electrochemical performance of the cathodes for the practical application of AZIBs.

Rational Design of Nanostructured MnO2 Cathode for High-performance Aqueous Zinc Ion Batteries

Rational Design of Nanostructured MnO2 Cathode for High-performance Aqueous Zinc Ion Batteries

Ultrathin Nanosheet Assemblies of Three-Dimensional Spongy Carbon/Nitrogen-Doped Vanadium Nitride Cathode for High-Performance Aqueous Zinc-Ion Batteries

Ultrathin Nanosheet Assemblies of Three-Dimensional Spongy Carbon/Nitrogen-Doped Vanadium Nitride Cathode for High-Performance Aqueous Zinc-Ion Batteries

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.

Interlayer-modified pseudocapacitive ammonium vanadium with high reversibility and stability enabling high-performance aqueous zinc-ion battery

Vanadium oxides are vital electrode material for zinc-ion batteries (ZIBs). However, the structural instability of vanadium oxides and sluggish reaction kinetics of large radius Zn2+ hinder the development of ZIBs. In this work, interlayer engineering and intercalation pseudocapacitance are adopted by phosphating to obtain modified NH4V4O10 with a stable structure, stronger intercalation pseudocapacitive behavior, and high reversibility for ion transportation. The phosphating introduces phosphate groups and oxygen vacancies in the lattice of NH4V4O10. The phosphate groups strengthen the connection between [VO] layers and immobilize the intrinsic interlayer NH4+ through electrostatic interaction to inhibit the irreversible transport of NH4+. The phosphating treatment disorders the crystal structure of the material and enlarges the crystal plane spacing to accelerate the diffusion of the ions, leading to high reversibility and structural stability, which prevents the irreversible phase transition of active material to inactive by-product during the cycle. Combined with the kinetics analysis and density functional theory (DFT), the phosphating enhances the intercalation pseudocapacitive response (pseudocapacitive contribution of 84.9%), reduces the migration barrier of Zn2+, as well as improves the electronic conductivity of cathode and affords extra electrons for energy storage, thus resulting in superior performance. Therefore, the P-NVO-2 electrode delivers a brilliant rate performance of 300.9 mAh g−1 at 10 A g−1, and high capacity retention of 92.3% after 7000 cycles at 10 A g−1. P-NVO-2 exhibits brilliant electrochemical performance when applied to the flexible soft-packaged battery, confirming the application potential. Therefore, the exploration of phosphating to vanadium oxides supplies a promising route for designing high-rate and long-cyclicality zinc-ion batteries.

Proton-self-doped PANI@CC as the cathode for high-performance aqueous zinc-ion battery

Aqueous zinc-ion batteries (AZIB) have several advantages such as low cost, large theoretical capacity and good safety. However, the development of polyaniline (PANI) cathode materials has been limited by slow diffusion kinetics. Herein, proton-self-doped polyaniline@carbon cloth (CC) (PANI@CC) was prepared via in-situ polymerization, where polyaniline was deposited on an activated carbon cloth. The PANI@CC cathode exhibits a high specific capacity of 234.3 mA h g−1 at 0.5 A g−1, and excellent rate performance, delivering a capacity of 143 mA h g−1 at 10 A g−1. Furthermore, the reversible redox conversion during the charge–discharge process was studied using ex-situ X-ray photoelectron spectroscopy (XPS) and ex-situ Raman spectra. The results show that the excellent performance of the PANI@CC battery can be attributed to the formation of a conductive network between the carbon cloth and polyaniline. Also, a mixing mechanism involving insertion/extraction of Zn2+/H+ and a double-ion process is proposed. PANI@CC electrode is a novel idea for developing high-performance batteries.

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.

Rationally designed hierarchical three-dimensional amorphous V2O5@Ti3C2Tx microsphere for high performance aqueous zinc-ion batteries

As candidates of the next generation batteries, aqueous zinc-ion batteries (ZIBs) have drawn widespread attention owing to the advantages of environmental friendliness, low cost and ultrahigh theoretical capacity. In order to obtain superior zinc ions (Zn2+) storage ability, the cathode materials with eminent electrochemical property are placed great expectations. Herein, the hierarchical 3D a-V2O5@Ti3C2Tx microsphere is prepared by a simple spray drying process. In the heterostructure, the amorphous V2O5 not only endows abundant active sites for Zn2+ storage but also effectively alleviates Ti3C2Tx MXene nanosheets restacking. Meanwhile, the presence of conductive Ti3C2Tx MXene framework significantly enhances the conductivity and reaction kinetics of the electrode material. As a result, the 3D a-V2O5@Ti3C2Tx exhibits an impressive Zn2+ storage ability, including the high reversible capacity (604 mAh g−1 at 0.5 A g−1), the superior rate performance and the splendid cycling stability. Furthermore, the relevant mechanism is illustrated via various characterizations. Moreover, the as-fabricated pouch ZIBs based on the 3D a-V2O5@Ti3C2Tx displays a potential practical application prospect as flexible energy storage devices. Hence, this work may provide an inspiration for the rational design of high performance ZIBs cathode materials.

High-Performance Aqueous Zinc-Ion Batteries Based on Multidimensional V2O3 Nanosheets@Single-Walled Carbon Nanohorns@Reduced Graphene Oxide Composite and Optimized Electrolyte.

The drawbacks of poor electronic conductivity and structural instability during the cycling process limit the electrochemical property of vanadium-based cathode materials for aqueous zinc-ion batteries. In addition, continuous growth and accumulation of zinc dendrites can puncture the separator and cause an internal short circuit in the battery. In this work, a unique multidimensional nanocomposite is designed by a facile freeze-drying method with subsequent calcination, consisting of V2O3 nanosheets and single-walled carbon nanohorns (SWCNHs) crosslinked together and wrapped by reduced graphene oxide (rGO). The multidimensional structure can largely enhance the structural stability and electronic conductivity of the electrode material. Besides, additive Na2SO4 in the ZnSO4 aqueous electrolyte not only prevents the dissolution of cathode materials but also suppresses the Zn dendrite growth. After considering the influence of additive concentration on ionic conductivity and electrostatic force for electrolyte, V2O3@SWCNHs@rGO electrode delivers a high initial discharge capacity of 422 mAh g-1 at 0.2 A g-1 and a high discharge capacity of 283 mAh g-1 after 1000 cycles at 5 A g-1 in 2m ZnSO4 + 2m Na2SO4 electrolyte. Experimental techniques reveal that the electrochemical reaction mechanism can be expressed as the reversible phase transformation between V2O5 and V2O3 with Zn3(VO4)2.

Kinetic and thermodynamic synergy of organic small molecular additives enables constructed stable zinc anode

An organic small molecule additive zinc formate is introduced to construct stable Zn metal interphase by electrochemical kinetic control and thermodynamic adjustment. It partially forms a water-formate concomitant dipole layer at the internal Helmholtz electrical double layers (HEDLs) under the preferential adsorption function of formate on Zn surface, reducing the occurrence of side reactions at phase interface. Meanwhile, free formate in HEDLs regulates the Zn2+ solvation sheath structure to accelerate the de-solvation, transference, and deposition kinetics of Zn2+. Besides, the hydrolysis reaction of zinc formate increases the hydrogen evolution overpotential, inhibiting the thermodynamic tendency of hydrogen evolution. Consequently, it presents stable cycle for more than 2400 h at 5 mA cm−2, as well as an average Coulombic efficiency of 99.8% at 1 A g−1 after 800 cycles in the Zn||VO2 full cell. The interphase engineering strategy zinc anode by organic small molecular brings new possibility towards high-performance aqueous zinc-ion batteries.

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.

Ionic-Liquid-Assisted Synthesis of Mixed-Phase Manganese Oxide Nanorods for a High-Performance Aqueous Zinc-Ion Battery

Aqueous zinc-ion batteries (ZIBs) provide a safer and cost-effective energy storage solution by utilizing nonflammable water-based electrolytes. Although many research efforts are focused on optimizing zinc anode materials, developing suitable cathode materials is still challenging. In this study, one-dimensional, mixed-phase MnO2 nanorods are synthesized using ionic liquid (IL). Here, the IL acts as a structure-directing agent that modifies MnO2 morphology and introduces mixed phases, as confirmed by morphological, structural, and X-ray photoelectron spectroscopy (XPS) studies. The MnO2 nanorods developed by this method are utilized as a cathode material for ZIB application in the coin-cell configuration. As expected, Zn//MnO2 nanorods show a significant increase in their capacity to 347 Wh kg-1 at 100 mA g-1, which is better than bare MnO2 nanowires (207.1 Wh kg-1) synthesized by the chemical precipitation method. The battery is highly rechargeable and maintains good retention of 86% of the initial capacity and 99% Coulombic efficiency after 800 cycles at 1000 mA g-1. The ex situ XPS, X-ray diffraction, and in-depth electrochemical analysis confirm that MnO6 octahedra experience insertion/extraction of Zn2+ with high reversibility. This study suggests the potential use of MnO2 nanorods to develop high-performance and durable battery electrode materials suitable for large-scale applications.