Fast Zn2 Research Articles

Regulating the Interlayer Spacing of Vanadium Oxide by In Situ Polyaniline Intercalation Enables an Improved Aqueous Zinc-Ion Storage Performance.

Vanadium pentoxide (V2O5) possesses great potential for application as cathode materials for aqueous zinc-ion batteries due to abundant valences of vanadium. Unfortunately, the inferior electronic conductivity and confined interlayer spacing of pristine V2O5 are not able to support fast Zn2+ diffusion kinetics, leading to significant capacity degradation, the dissolution of active species, and unsatisfactory cycling life. Herein, Zn2+ (de)intercalation kinetics is improved by the design of in situ polyaniline (PANI)-intercalated V2O5. The intercalated PANI can not only improve the conductivity and structural stability of V2O5 but also efficiently expand its interlayer spacing (1.41 nm), offering more channels for facile Zn2+ diffusion. Benefiting from these virtues, a high specific capacity of 356 mA h g-1 at 0.1 A g-1 is achieved for the PANI-intercalated V2O5 (PVO) cathode as well as a superior cycling performance (96.3% capacity retention after 1000 cycles at 5 A g-1) in an aqueous electrolyte. Furthermore, the Zn2+ storage in PVO is mainly dominated by the capacitive contribution. This work suggests that intercalating PANI in V2O5 may aid in the future development of advanced cathodes for other multivalent metal ion batteries.

La0.14V2O5/Reduced Graphene Oxide Composite for Aqueous Zinc−Ion Batteries with Long Cycle Life

Rechargeable aqueous zinc−ion batteries (ZIBs) with cost−effective and environmentally friendly characteristics show great potential for large−scale energy storage systems. Among all cathode material candidates, layered vanadates are promising owing to their suitable open structure for accommodating Zn2+/H+. However, the unsatisfactory rate capability and cycling stability of vanadate cathodes have hindered the practical application. Thus, the exploration of high−performance and structural stable cathode materials is urgently needed. In this study, a La0.14V2O5/reduced graphene oxide composite material (denoted as LaVO/rGO) can be successfully synthesized by a facile hydrothermal procedure. With the pillar La3+ ions and highly conductive rGO, the layered LaVO/rGO has the merits of large interlayer distance (14.7 Å), low charge transfer resistance, and high diffusion coefficient that guarantee fast kinetics of Zn2+/H+ intercalation/de−intercalation. As a result, the LaVO/rGO cathode delivers a high−rate performance which obtains high capacity of 298 mAh g−1 at 0.3 A g−1. Even up to 8 A g−1, high capacity of 166 mAh g−1 can be achieved. Stable cycle performance with the capacity retention of 88% over 6000 cycles is attained, benefiting from fast and reversible Zn2+/H+ storage in the host material.

Cr3+ pre-intercalated hydrated vanadium oxide as an excellent performance cathode for aqueous zinc-ion batteries

Rechargeable aqueous zinc-ion batteries (ZIBs) are regarded as the next promising large scale energy storage systems owing to their low cost, high safety and environmental friendliness. Vanadium-based materials are one of the most important cathodes of ZIBs due to their high abundance and multielectron transfer of various oxidations of vanadium. Nevertheless, the strong electrostatic interaction between Zn2+ and cathodes, intrinsic poor electronic conductivity and solubility of vanadium-based cathodes in electrolytes bring about inferior electrochemical performance. In this work, we introduce aliovalent Cr3+ into the interlayer of hydrated vanadium oxide (Cr-VOH) as pillar to significantly increase the structural stability and electrochemical reversibility. The pre-intercalation of Cr3+ also provides an enhanced electronic conductivity and fast Zn2+ diffusion dynamics, enabling superior Zn2+ storage performance of the Cr-VOH cathode. As a result, the Cr-VOH cathode exhibits a high reversible discharge capacity of ~380 mAh g−1 at 50 mA g−1, excellent rate capacity of 166 mAh g−1 at 8 A g−1 and prolonged cycling stability over 500 cycles. Furthermore, it displays a high energy density of 273.6 W h kg−1 at 0.05 A g−1 and the power density of 4960 W kg−1 at 8 A g−1, contributing to the practical application potential of aqueous ZIBs.

Ultrafast Rechargeable Aqueous Zinc‐Ion Batteries Based on Stable Radical Chemistry

AbstractAqueous zinc‐ion batteries (ZIBs) are a promising candidate for fast‐charging energy‐storage systems due to its attractive ionic conductivity of water‐based electrolyte, high theoretical energy density, and low cost. Current strategies toward high‐rate ZIBs mainly focus on the improvement of ionic or electron conductivity within cathodes. However, enhancing intrinsic electrochemical reaction kinetics of active materials to achieve fast Zn2+ storage has been greatly omitted. Herein, for the first time, stable radical intermediate generation is demonstrated in a typical organic electrode material (methylene blue [MB]), which effectively decreases the reaction energy barrier and enhances the intrinsic kinetics of MB cathode, enabling ultrafast Zn2+ storage. Meanwhile, anionic co‐intercalation essentially avoids MB molecules rearranging their configuration and sharing Zn2+ with adjacent functional groups, thus keeps the structure stable. As a result, Zn–MB batteries exhibit an excellent rate capability up to 500C and ultralong life of 20 000 cycles with a negligible 0.07% capacity decay per cycle at 100C, which is superior to that of most reported aqueous ZIBs batteries. This work provides a novel strategy of stable radical chemistry for ultrafast‐charging aqueous ZIBs, which can be introduced to other appropriate organic materials and multivalent ion battery systems.

Redistributing Zn-ion flux by interlayer ion channels in Mg-Al layered double hydroxide-based artificial solid electrolyte interface for ultra-stable and dendrite-free Zn metal anodes

The growth of Zn dendrites and self-corrosion reaction during electrochemical cycling is a long-standing issue impeding the practical application of zinc-ion batteries. Although various surface engineering strategies have shown great promise in suppressing zinc dendrites, the protective layers unavoidably hinder Zn2+ diffusion, resulting in increased internal impedance/polarization. Therefore, constructing smart interface protective layers with fast Zn2+ transfer kinetics is highly desirable but remains a key challenge. Here, an Mg-Al layered double hydroxide (LDH)-based artificial solid electrolyte interface (SEI) with Zn-ion diffusion channels is proposed. The well-aligned interlayer channels in the Mg-Al LDH skeleton is proved to efficiently engineer the distribution of Zn2+ ions and facilitate Zn2+ diffusion between the electrode/electrolyte interface, thus giving rise to stable Zn deposition. Moreover, the mechanically robust Mg-Al LDH artificial SEI acts as an interfacial layer to constrain H2O-induced corrosion and hydrogen evolution reaction. Consequently, the Mg-Al LDH artificial SEI improves the Coulombic efficiency to 99.2% for more than 2000 cycles, and an ultralong lifespan of 1400 h has been achieved at 0.5 mA cm−2. Notably, the zinc-ion capacitors by pairing the Zn@LDH anode and high-loading active carbon cathode deliver outstanding cycling stability with a high capacity retention of 93.7% up to 10000 cycles at the high areal current density of 37.5 mA cm−2, portending the feasibility of practical applications.

Sodium vanadate/PEDOT nanocables rich with oxygen vacancies for high energy conversion efficiency zinc ion batteries

Aqueous zinc-ion batteries (ZIBs) have received an increasing attention for large-scale energy storage due to its low cost and high safety. However, the sluggish kinetics stemming from the limited Zn2+ diffusion pathway and the strong electrostatic interaction between Zn2+ and the anion sublattice in the host crystal are great challenges for high-efficient Zn2+ storage. To circumvent these hurdles, bridge-oxygen sited oxygen vacancies are introduced in sodium vanadate Na0.76V6O15 (NVO) through the in-situ polymerization of 3,4-ethylenedioxythiophene. In the resultant oxygen-vacancy rich NVO/poly(3,4-ethylenedioxythiophene) (PEDOT) nanocables (noted as Vo¨-PNVO), the interplanar space is enlarged and the electrostatic interaction is weakened by the introduction of “oxygen vacancies” for fast reversible Zn2+ diffusion and intercalation. The conductive PEDOT coating also provides desired electronic conductivity and improves the structural integrity of NVO. Consequently, Vo¨-PNVO based ZIBs exhibit an enhanced specific capacity (355 mA h g−1 at 50 mA g−1), significantly enhanced energy conversion efficiency (>80%), and long lifespan (99% of the initial capacity remained after 2600 cycles).

Metallic vanadium trioxide intercalated with phase transformation for advanced aqueous zinc-ion batteries

Aqueous zinc-ion batteries have broad application prospects due to the eco-friendliness, cost-economy and high safety. However, the scarcity of high-performance cathodes with outstanding rate capability and long lifespan has affected their development. Herein, we report a metallic vanadium trioxide material intercalated with phase transformation as cathode applied in aqueous zinc-ion batteries. It offers satisfactory electrochemical performances with a high specific capacity (435 mAh g−1 at 0.5 A g−1), decent power density (5.23 kW kg−1) and desired energy density (331 Wh kg−1), as well as good cyclability. The superior performance originates from the stable structure and fast Zn2+ diffusion, enabled by the pre-intercalation of Zn2+ and water molecules.

Oxygen-deficient ammonium vanadate for flexible aqueous zinc batteries with high energy density and rate capability at −30 °C

Aqueous zinc batteries (AZBs) have received significant attention owing to environmental friendliness, high energy density and inherent safety. However, lack of high-performance cathodes has become the main bottleneck of AZBs development. Here, oxygen-deficient NH4V4O10−x·nH2O (NVOH) microspheres are synthesized and used as cathodes for AZBs. The experimental test and theoretical calculations demonstrate that the oxygen vacancies in the lattice lower the Zn2+ diffusion energy barrier, which enables fast Zn2+ diffusion and good electrochemical performance in a wide temperature range. The suppressed side reactions also can help to improve the low temperature performance. NVOH shows a high energy density of 372.4 Wh kg−1 and 296 Wh kg−1 at room temperature and −30°C, respectively. Moreover, NVOH maintains a 100% capacity retention after 100 cycles at 0.1 A g−1 and ∼94% capacity retention after 2600 cycles at 2 A g−1 and −30°C. Investigation into the mechanism of the process reveals that the capacity contribution of surface capacitive behaviors is dominant and capacity attenuation is mainly caused by the decay of diffusion-controlled capacity. Furthermore, flexible AZBs can steadily power portable electronics under different bending states, demonstrating its great potential in wide-temperature wearable device.

A Co-intercalation enhanced V-based cathode material for fast charge aqueous zinc ion batteries.

H2O-H-Na co-intercalation is beneficial to enhance the structure of open framework V-based materials, leading to the improvement of Zn2+ transport kinetics and solid-state solubility in V-based electrodes. Zn|Zn(CF3SO3)2|HNaV6O16·4H2O exhibits an excellent specific capacity of 432.4 mA h g-1 and a long-term cyclic performance up to 800 cycles at 2.0 A g-1 with a reversible phase transformation. For the fast charge capability, a high specific capacity of 411.2 mA h g-1 is achieved with a coulomb efficiency of 100%. The co-intercalation structure can provide a new strategy for the design of fast charge cathode materials in aqueous zinc ion batteries (AZIBs).

Minimization of ion transport resistance: diblock copolymer micelle derived nitrogen-doped hierarchically porous carbon spheres for superior rate and power Zn-ion capacitors

N-doped hierarchically porous carbon spheres are fabricated for Zn-ion capacitors, and they possess isotropic Zn2+diffusion routes and abundant active sites, resulting in minimized transport resistance for fast Zn2+storage and high capacity.

Mass-Producible, Quasi-Zero-Strain, Lattice-Water-Rich Inorganic Open-Frameworks for Ultrafast-Charging and Long-Cycling Zinc-Ion Batteries.

Low-cost and high-safety aqueous Zn-ion batteries are an exceptionally compelling technology for grid-scale energy storage. However, their development has been plagued by the lack of stable cathode materials allowing fast Zn2+ -ion insertion and scalable synthesis. Here, a lattice-water-rich, inorganic-open-framework (IOF) phosphovanadate cathode, which is mass-producible and delivers high capacity (228 mAh g-1 ) and energy density (193.8Wh kg-1 or 513Wh L-1 ), is reported. The abundant lattice waters functioning as a "charge shield" enable a low Zn2+ -migration energy barrier, (0.66eV) even close to that of Li+ within LiFePO4 . This fast intrinsic ion-diffusion kinetics, together with nanostructure effect, allow the achievements of ultrafast charging (71% state of charge in 1.9 min) and an ultrahigh power density (7200 W kg-1 at 107Wh kg-1 ). Equally important, the IOF exhibits a quasi-zero-strain feature (<1% lattice change upon (de)zincation), which ensures ultrahigh cycling durability (3000 cycles) and Coulombic efficiencies of 100%. The cell-level energy and power densities reach ≈90Wh kg-1 and ≈3320 W kg-1 , far surpassing commercial lead-acid, Ni-Cd, and Ni-MH batteries. Lattice-water-rich IOFs may open up new opportunities for exploring stable and fast-charging Zn-ion batteries.

Electrochemically Induced Metal-Organic-Framework-Derived Amorphous V2 O5 for Superior Rate Aqueous Zinc-Ion Batteries.

The electrochemical performance of vanadium-oxide-based cathodes in aqueous zinc-ion batteries (ZIBs) depends on their degree of crystallinity and composite state with carbon materials. An in situ electrochemical induction strategy was developed to fabricate a metal-organic-framework-derived composite of amorphous V2 O5 and carbon materials (a-V2 O5 @C) for the first time, where V2 O5 is in an amorphous state and uniformly distributed in the carbon framework. The amorphous structure endows V2 O5 with more isotropic Zn2+ diffusion routes and active sites, resulting in fast Zn2+ transport and high specific capacity. The porous carbon framework provides a continuous electron transport pathway and ion diffusion channels. As a result, the a-V2 O5 @C composites display extraordinary electrochemical performance. This work will pave the way toward design of ZIB cathodes with superior rate performance.

Electrochemically Induced Metal–Organic‐Framework‐Derived Amorphous V2O5 for Superior Rate Aqueous Zinc‐Ion Batteries

AbstractThe electrochemical performance of vanadium‐oxide‐based cathodes in aqueous zinc‐ion batteries (ZIBs) depends on their degree of crystallinity and composite state with carbon materials. An in situ electrochemical induction strategy was developed to fabricate a metal–organic‐framework‐derived composite of amorphous V2O5 and carbon materials (a‐V2O5@C) for the first time, where V2O5 is in an amorphous state and uniformly distributed in the carbon framework. The amorphous structure endows V2O5 with more isotropic Zn2+ diffusion routes and active sites, resulting in fast Zn2+ transport and high specific capacity. The porous carbon framework provides a continuous electron transport pathway and ion diffusion channels. As a result, the a‐V2O5@C composites display extraordinary electrochemical performance. This work will pave the way toward design of ZIB cathodes with superior rate performance.

Intercalation Pseudocapacitive Zn2+ Storage with Hydrated Vanadium Dioxide toward Ultrahigh Rate Performance.

The weak van der Waals interactions enable ion-intercalation-type hosts to be ideal pseudocapacitive materials for energy storage. Here, a methodology for the preparation of hydrated vanadium dioxide nanoribbon (HVO) with moderate transport pathways is proposed. Out of the ordinary, the intercalation pseudocapacitive reaction mechanism is discovered for HVO, which powers high-rate capacitive charge storage compared with the battery-type intercalation reaction. The main factor is that the defective crystalline structure provides suitable ambient spacing for rapidly accommodating and transporting cations. As a result, the HVO delivers a fast Zn2+ ion diffusion coefficient and a low Zn2+ diffusion barrier. The electrochemical results with intercalation pseudocapacitance demonstrate a high reversible capacity of 396 mAh g-1 at 0.05 A g-1 , and even maintain 88 mAh g-1 at a high current density of 50 A g-1 .

Polypyrrole Wrapped V2O5 Nanowires Composite for Advanced Aqueous Zinc-Ion Batteries

Aqueous zinc-ion batteries (ZIBs) have obtained increasing attention owing to the high safety, material abundance and environmental benignity. However, the development of cathode materials with high capacity and stable cyclability is still a challenge. Herein, polypyrrole (PPy) wrapped V2O5 nanowires (V2O5/PPy) composite was synthesized by a surface-initiated polymerization strategy, ascribing to the redox reaction between V2O5 and pyrrole. The introduction of PPy on the surface of V2O5 nanowires not only enhanced the electronic conductivity of the active materials, but also reduced the V2O5 dissolution. As a result, the V2O5/PPy composite cathode exhibits a high specific capacity of 466 mAh g-1 at 0.1 A g-1 and a superior cycling stability with 95 % capacity retention after 1000 cycles at a high current density of 5 A g-1. The superior electrochemical performance is ascribed to the large ratio of capacitive contribution (92% at 1 mV s-1) and a fast Zn2+ diffusion rate. This work presents a simple method for fabricatingV2O5/PPy composite towards advanced ZIBs.

Ultrathin VSe2 Nanosheets with Fast Ion Diffusion and Robust Structural Stability for Rechargeable Zinc‐Ion Battery Cathode

The realizing of high-performance rechargeable aqueous zinc-ion batteries (ZIBs) with high energy density and long cycling life is promising but still challenging due to the lack of suitable layered cathode materials. The work reports the excellent zinc-ion storage performance as-observed in few-layered ultrathin VSe2 nanosheets with a two-step Zn2+ intercalation/de-intercalation mechanism verified by ex situX-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) characterizations. The VSe2 nanosheets exhibit a discharge plateau at 1.0-0.7V, a specific capacity of 131.8 mAh g-1 (at 0.1 A g-1 ), and a high energy density of 107.3 Wh kg-1 (at a power density of 81.2 W kg-1 ). More importantly, outstanding cycle stability (capacity retention of 80.8% after 500 cycles) without any activation process is achieved. Such a prominent cyclic stability should be attributed to its fast Zn2+ diffusion kinetics (DZn 2+ ≈ 10-8 cm-2 s-1 ) and robust structural/crystalline stability. Density functional theory (DFT) calculation further reveals a strong metallic characteristic and optimal zinc-ion diffusion pathway with a hopping energy barrier of 0.91eV. The present finding implies that 2D ultrathin VSe2 is a very promising cathode material in ZIBs with remarkable battery performance superior to other layered transitional metal dichalcogenides.

Employing “one for two” strategy to design polyaniline-intercalated hydrated vanadium oxide with expanded interlayer spacing for high-performance aqueous zinc-ion batteries

Several layer-structured hydrated vanadium oxides have been investigated for aqueous zinc-ion batteries (AZIBs), where one of the challenging issues is the relatively narrow interlayer spacing (~4.4 Å for (0 0 1) plane) and the poor electronic conductivity which usually lead to the sluggish Zn2+ ions/electrons transport kinetic and the instability of structure, thus resulting in low capacity, insufficient rate capability and shortened cycling life. Herein, we have successfully employed a “one for two” strategy to design a polyaniline-intercalated hydrated V2O5 composite (PANI/V2O5) through a mild, low consumptive molecule-exchange reaction at room temperature, in which the PANI can not only expand the interlayer spacing of V2O5 which is beneficial to the fast and reversible Zn2+ ions (de)intercalation, but also further improve the specific capacity of the cathode materials. Indeed, the 3D sponge-like architectured PANI/V2O5 composite possesses an expanded interlayer spacing as large as ~14 Å, which offers large space and abundant channels for efficient Zn2+ ions (de)intercalation. As a result, the as-assembled Zn//PANI/V2O5 battery exhibits a high specific capacity up to 353.6 mAh·g−1 at 0.1 A·g−1, and a stable cycling performance. Furthermore, a detailed electrochemical reaction mechanism of such a PANI/V2O5 composite cathode is investigated systematically through a series of in-depth analyses including ex-situ X-ray diffraction, and ex-situ X-ray photoelectron spectroscopy. Our finding provides an effective “one for two” strategy, introducing polyaniline macromolecules to tune the interlayer spacing and structure stability, to design high-performance cathodes for AZIBs and even other multivalent ions storages.

Mixed phase sodium manganese oxide as cathode for enhanced aqueous zinc-ion storage

Aqueous zinc-ion batteries have been regarded as a promising alternative to large-scale energy storage, due to associated low-cost, improved safety and environmental friendliness. However, a high-performance cathode material for both rate capability and specific capacity is still a challenge. One kind of the more promising candidates are sodium manganese oxide (NMO) materials, although they suffer from individual issues and need to be further improved. Herein, we present a novel mixed phase NMO material composed of nearly equal amounts of Na0.55Mn2O4 and Na0.7MnO2.05. The structured configuration with particle size of 200–500 nm is found to be beneficial towards improving the ion diffusion rate during the charge/discharge process. Compared with Na0.7MnO2.05 and Na0.55Mn2O4, the mixed phase NMO demonstrates an enhanced rate capability and excellent long-term cycling stability with a capacity retention of 83% after 800 cycles. More importantly, the system also delivers an impressive energy density and power density, as 378 W·h·kg−1 at 68.7 W·kg−1, or 172 W·h·kg−1 at 1705 W·kg−1. The superior electrochemical performance is ascribed to the fast Zn2+ diffusion rate because of a large ratio of capacitive contribution (63.9% at 0.9 mV·s−1). Thus, the mixed phase route provides a novel strategy to enhance electrochemical performance, enabling mixed phase NMO as very promising material towards large-scale energy-storage applications.

Electrochemically Induced Structural and Morphological Evolutions in Nickel Vanadium Oxide Hydrate Nanobelts Enabling Fast Transport Kinetics for High-Performance Zinc Storage.

Suitable intercalation cathodes and fundamental insights into the Zn-ion storage mechanism are the crucial factors for the booming development of aqueous zinc-ion batteries. Herein, a novel nickel vanadium oxide hydrate (Ni0.25V2O5·0.88H2O) is synthesized and investigated as a high-performance electrode material, which delivers a reversible capacity of 418 mA h g-1 with 155 mA h g-1 retained at 20 A g-1 and a high capacity of 293 mA h g-1 in long-term cycling at 10 A g-1 with 77% retention after 10,000 cycles. More importantly, multistep phase transition and chemical-state change during intercalation/deintercalation of hydrated Zn2+ are illustrated in detail via in situ/ex situ analytical techniques to unveil the Zn2+ storage mechanism of the hydrated and layered vanadium oxide bronze. Furthermore, morphological development from nanobelts to hierarchical structures during rapid ion insertion and extraction is demonstrated and a self-hierarchical process is correspondingly proposed. The unique evolutions of structure and morphology, together with consequent fast Zn2+ transport kinetics, are of significance to the outstanding zinc storage capacity, which would enlighten the mechanism exploration of the aqueous rechargeable batteries and push development of vanadium-based cathode materials.

Highly Reversible Zn Anode Enabled by Controllable Formation of Nucleation Sites for Zn‐Based Batteries

AbstractAqueous Zn batteries have drawn tremendous attention for their several advantages. However, the challenges of Zn anodes such as the corrosion and ZnO densification have compromised their application in rechargeable Zn‐based batteries. In this paper, a straightforward strategy is employed to facilitate the uniform Zn stripping/plating of the Zn anode through using a ZrO2 coating layer, which contributes to the controllable nucleation sites for Zn2+ and fast Zn2+ transportation through the favorable Maxwell–Wagner polarization. As a result, the low polarization (24 mV at 0.25 mA cm−2), high Coulombic efficiency (99.36% at 20 mA cm−2), and long cycle life (over 3800 h at 0.25 mA cm−2) can be obtained for the ZrO2‐coated Zn anode. It is believed that the ZrO2 coating layer can also act as an inert physical barrier to decrease the contact of the anode and electrolyte, thus reducing both the Zn corrosion and formation of ZnO densification, and then improve the reversibility of Zn anode. The results demonstrated in this work provide an appealing strategy for the future development of rechargeable Zn‐based batteries.