Aqueous Zinc Batteries Research Articles

Partial Sulfidation of the Electrochemically Exfoliated Layered Double Hydroxides toward Advanced Aqueous Zinc Batteries

AbstractAqueous zinc‐based batteries are a promising alternative to lithium batteries. These batteries, however, persistently suffer from uncontrollable dendrite growth and sustained water consumption at the Zn anodes, along with low and often fading capacity at the cathodes. Herein, Zn metal is simply encapsulated into a chitosan‐containing polymer gel that not only suppresses hydrogen evolution but also enables dendrite‐free Zn plating/stripping. A binder‐free cathode based on the electrochemically exfoliated and partially sulfidated Ni–Co–Fe layered double hydroxide‐reduced graphene oxide (SNS‐rGO) nanocomposite is also reported. The fabricated devices (based on either Zn or chitosan‐coated Zn) deliver near record‐high values of specific capacity (756 mA h g−1cathode at 1 A g−1) and specific energy (1284 W h kg−1cathode), along with an outstanding specific power (108 kW kg−1cathode), an excellent output voltage (up to 1.9 V), and prolonged cycling stability at 100% depth‐of‐discharge. This interface engineering strategy, supported by the density functional theory calculations, provides a solid basis for further practical applications of aqueous Zn batteries.

Mechanism of Chalcophanite Nucleation in Zinc Hydroxide Sulfate Cathodes in Aqueous Zinc Batteries.

Aqueous Zn-ion batteries with MnO2-based cathodes have seen significant attention owing to their high theoretical capacities, safety, and low cost; however, much debate remains regarding the reaction mechanism that dominates energy storage. In this work, we report our electron microscopy study of cathodes containing zinc hydroxide sulfate (Zn4SO4(OH)6·xH2O, ZHS) together with carbon nanotubes cycled in electrolytes containing ZnSO4 with varied amounts of MnSO4 incorporated. The primary Mn-containing phase is formed in situ in the cathode during cycling, where a dissolution-deposition reaction is identified between ZHS and chalcophanite (ZnMn3O7·3H2O). Mechanistic details of this reaction, in which the chalcophanite nucleates then separates from the ZHS flakes as the ZHS dissolves while acting as the primary Zn source for the reaction, are revealed using surface sensitive methods. These findings indicate the reaction is local to the ZHS flakes, providing new insight toward the importance of ZHS and the cathode microstructure.

Epitaxial Core–Shell MnFe Prussian Blue Cathode for Highly Stable Aqueous Zinc Batteries

Epitaxial Core–Shell MnFe Prussian Blue Cathode for Highly Stable Aqueous Zinc Batteries

Preferred Orientation Deposition via Multifunctional Gel Electrolyte with Molecular Anchor Enabling Highly Reversible Zn Anode.

The high activity of water molecules results in a series of awful parasitic reaction, which seriously impede the development of aqueous zinc batteries. Herein, a new gel electrolyte with multiple molecular anchors is designed by employing natural biomaterials from chitosan and chlorophyll derivative. The gel electrolyte firmly anchors water molecules by ternary hydrogen bonding to reduce the activity of water molecules and inhibit hydrogen evolution reaction. Meanwhile, the multipolar charged functional groups realize the gradient induction and redistribution of Zn2+ , which drives oriented Zn (002) plane deposition of Zn2+ and then achieves uniform Zn deposition and dendrite-free anode. As a result, it endows the Zn||Zn cell with over 1700h stripping/plating processes and a high efficiency of 99.4% for the Zn||Cu cell. In addition, the Zn||V2 O5 full cells also exhibit capacity retention of 81.7% after 600 cycles at 0.5 A g-1 and excellent long-term stability over 1600 cycles at 2 A g-1 , and the flexible pouch cells can provide stable power for light-emitting diodeseven after repeated bending. The gel electrolyte strategy provides a reference for reversible zinc anode and flexible wearable devices.

(Invited) Grid Scale Energy Storage Poised for Success: Developing New Technologies, Finding New Value Propositions Towards Long Duration Energy Storage

Energy storage (ES) has become one of the hottest topics to the world’s clean energy future. Research on materials and devices has made successful progress in reducing the cost of Li-ion systems and of several flow battery systems. However, safety, material sustainability, and other factors such as maintenance and decommissioning costs that affect the levelized cost of storage also need to be considered in developing a circular economy to enable reliable, resilient, and flexible electric grid.ES in the United States (US) has become a resounding success. We have done well in short-duration energy storage, by developing viable business models, evaluation and planning tools, and so on. ES has achieved a great feat in frequency regulation, smoothing renewable energy, demand charge reduction, and substation upgrade deferrals. Going forward, energy storage of medium and long duration as well as short duration with further lower cost will be needed.The presentation will give a high-level overview on the current state of DOE’s Office of Electricity (OE) supported energy storage technologies. Sodium-ion batteries, aqueous zinc batteries, and several new lines with earth abundant, inexpensive materials, and reliable supply chains and a wide industrial base will be covered. Reliability, safety, and representative examples of the successful deployment of OE technologies across multiple states in US will be touched.As the return on investment is what really counts for the commercial success of energy storage applications, the presentation also will discuss several real cases of diverse monetized and unmonetized benefit streams from multi-megawatt deployments and how these assessments are needed for new technologies and longer duration applications.

High Performance Zinc-Based Anodes for Aqueous Zinc Batteries

In the past thirty years, there has been significant development in the search for alternative energy sources such as secondary battery systems. Zinc (fourth-most mined material) has attracted much attention due to its abundance, low-cost, and recyclability. Moreover, as zinc-based batteries can be manufactured with aqueous-based electrolytes that benefits from many advantages of Zn anode, such as low redox protentional (-0.76V vs SHE), high theoretical capacity (820mAh/g), and enhanced safety. These features allow for high applicability in large-scale stationary energy storage system. Zinc-based batteries (MnO2/Zinc) have been previously commercialized and are one of the dominant technologies in the primary battery market. However, the alkaline MnO2/Zn battery is not currently considered re-chargeable due to the formation of zinc-dendrites, passivation of Zn metal, and cathode poisoning. In contrast to the alkaline system, the mild acidic system does not suffer from zinc passivation as there is negligible generation of zinc oxide/zinc hydroxide.In this work, we report a proof-of concept work where electrodeposited zinc-based anodes (zinc and zinc-alloys) are used in mild acidic aqueous electrolyte. The study provides a comparison of commercial zinc foil, and electrodeposited zinc/zinc-alloy. The anodes are further analyzed structurally through X-ray diffraction and scanning electron microscopy. To evaluate the feasibility of each anode. further electrochemical characterization was carried out in coin cells as symmetric and full cells. The electrodeposited zinc-based anodes exhibit low electrode polarization (~0.030-0.045V), and more stable cycling performance at 10 mA cm-2 compared to commercial zinc foil. Furthermore, full cells with an electrodeposited zinc or zinc-alloy anode, DTT cathode, in 2M ZnSO4 delivered comparable capacities but higher stability compared to commercial zinc. Consequently, this work points toward a further development for anode materials in rechargeable aqueous zinc batteries for scalable applications.

Ionic liquids-assisted electrolytes in aqueous zinc ion batteries

In the quest for safer and low-cost batteries, zinc ion batteries have remarkable potential in various energy storage applications. However, selecting suitable electrolytes for zinc electrochemistry is challenging due to zinc's passivation and dendritic growth hindering long-term stability. Moreover, the synergy between newly developed electrode materials and electrolytes remains challenging for commercial applications. Therefore, in this study fifty (50) combinations of ionic liquids (ILs) were screened using COSMO-RS simulation to identify suitable ILs for aqueous electrolytes with ZnSO4 salt by comparing activity coefficients at infinite dilution, selectivity, and capacity of ILs to dissolve ZnSO4 salt in the aqueous phase. Further, calcium vanadate (CaV2O6) was synthesized using a modified molten salt method and characterized using a Scanning Electron Microscope and X-ray diffraction to confirm its successful synthesis. Afterwards, the performance of calcium vanadate in aqueous zinc batteries having ILs-assisted electrolytes were also evaluated and compared with conventional electrolyte (aqueous 1 M ZnSO4). Results revealed that ILs based on tetramethyl ammonium cation were suitable for electrolyte applications with ZnSO4 salt. Furthermore, Tetramethylammonium hydrogen sulfate was compared with conventional ZnSO4 electrolyte and an initial discharge capacity of 330 mAh/g for calcium vanadate electrode with ILs-assisted electrolyte was observed as compared to 230 mAh/g with 1 M ZnSO4 aqueous electrolyte. Electrochemical impedance spectroscopy (EIS) measurements showed that ILs-assisted electrolyte's charge transfer and surface film resistance were lower than the conventional electrolyte. However, additional advancement in electrode and electrolytes, i.e. synthesis of electrode materials, and formulation of ILs-assisted electrolytes, may further improve the performance of aqueous zinc ion batteries.

Triple-function Hydrated Eutectic Electrolyte for Enhanced Aqueous Zinc Batteries.

Aqueous rechargeable zinc-ion batteries (ARZBs) are impeded by the mutual problems of unstable cathode, electrolyte parasitic reactions, and dendritic growth of zinc (Zn) anode. Herein, a triple-functional strategy by introducing the tetramethylene sulfone (TMS) to form a hydrated eutectic electrolyte is reported to ameliorate these issues. The activity of H2O is inhabited by reconstructing hydrogen bonds due to the strong interaction of TMS and H2O. Meanwhile, the preferentially adsorbed TMS on the Zn surface increases the thickness of double electric layer (EDL) structure, which provides a shielding buffer layer to suppress dendrite growth. Interestingly, TMS modulates the primary solvation shell of Zn2+-6H2O ultimately to achieve a novel solvent co-intercalation ((Zn-TMS)2+) mechanism, and the intercalated TMS works as a "pillar" that provides more zincophilic sites and stabilize the structure of cathode (NH4V4O10, (NVO)). Consequently, the Zn||NVO battery exhibits a remarkable high specific capacity of 515.6 mAh g-1 at a low current density of 0.2 A g-1 for over 40 days. This multi-functional electrolytes and solvent co-intercalation mechanism will significantly propel the practical development of aqueous batteries.

Enhancing Temperature Adaptability of Aqueous Zinc Batteries via Antifreezing Electrolyte and Site-Selective ZnSe-Ag Interface Layer Design.

Rechargeable aqueous zinc batteries (RAZBs) represent a sustainable, environmentally benign, cost-efficient energy storage solution for the scaled renewable power system. However, the cycling endurance and temperature adaptability of RAZBs are hindered by practical technological barriers such as the subzero freezing point of aqueous electrolyte, severe cation dissolution of the cathode, and dendrite growth on the Zn anode. Herein, we optimize the hybrid electrolyte formulation of 8 M ZnCl2 in the ethylene glycol-water mixed solvent to reconfigure the hydrogen bonding and [Zn(H2O)1.80(EG)0.23]2+ solvation sheath, which well balances the ionic conductivity and the antifreezing property until -125 °C. As monitored by operando X-ray diffraction, meanwhile, the structural dissolution of the V2O5 cathode upon the dynamic cycling and static idling storage at elevated temperature are effectively restrained. At the anode side, the thermally induced substitution between the Ag2Se overcoating and Zn foil in situ constructs the site-selective, mosaic interface layer, in which the solvophilic ZnSe facilitates the desolvation, while the Ag species provide zincophilic nucleation sites for high-throughput Zn deposition. The synergistic coupling of the antifreezing electrolyte and anode interfacial design enables the wide-temperature-range adaptability of the RAZB prototype (10 μm Zn foil and 1 mAh cm-2 V2O5 cathode), which balances the cycling endurance (92.5% capacity retention rate for 1000 cycles), 84.7% mitigation of the self-discharge rate at 55 °C, as well as the secured cyclability even at -40 °C.

Spherical metal mechanism toward revolution of Zn growth for ultrafast plating/stripping kinetics

Aqueous zinc batteries have attracted wide attentions due to their high security and theoretical capacity. However, intrinsic hexagon flake stacking mechanism of Zn metal anode raises uncontrollable Zn dendrite growth and poor electrochemistry property. Herein, innovative spherical Zn metal growth mechanism is firstly proposed assisting by graphene quantum dots (GQDs) through electroplating process. The strongest adsorption energy between Zn2+ and GQDs is formed for preferential GQDs-Zn clusters producing, and then the nucleation of Zn surrounding GQDs is ideally happened. After the subsequent remainder Zn2+ plating, the homogeneous composite Zn spheres are prepared on Cu foam skeleton. Remarkably, GQDs cores fixed in the matrix always lead to the recoverable spherical Zn growth procedure during repetitive plating/stripping processes. Combining the preferential Zn (002) crystal texture, the significant spherical Zn metal anode reaches stable thermodynamics to effective suppression of Zn dendrites growth and side reactions occurrence. Under ultrahigh current density of 20 mA cm−2, the stability of 908 cycles is achieved in half-cell. This work provides a new mechanism for designing neotype Zn metal anode to thoroughly avoid the natural drawbacks of traditional hexagon shape Zn, which is significant for the practice application of aqueous zinc batteries.

A High-Potential Bipolar Phenothiazine Derivative Cathode for Aqueous Zinc Batteries.

Aqueous zinc ion batteries (AZIBs) are gaining popularity as advanced energy storage devices that are economical, safe, and use resource-abundant storage options. In this study, we have synthesized a bipolar phenothiazine organic scaffold known as 3,7-bis(melaminyl)phenothiazin-5-ium iodide (PTDM), which is obtained by undergoing nucleophilic substitution through phenothiazinium tetraiodide hydrate (PTD) and melamine. Electrochemical results indicate that PTDM can act as a high-potential cathode material for rechargeable AZIBs. In detail, the aqueous PTDM//Zn full cell exhibits a high average voltage of approximate 1.13 V, along with a specific capacity of 118.3 mAh g-1at 0.1 A g-1. Furthermore, this demonstrated cell displays moderate long-term cycling stability over 6400 cycles, which is encouraging and suggests potential for developing advanced organic electrode materials for rechargeable AZIBs.

Gel Polymer Electrolyte toward Large‐Scale Application of Aqueous Zinc Batteries

AbstractAqueous zinc batteries are promising candidates for energy storage and conversion devices in the “post‐lithium” era due to their high energy density, high safety, and low cost. The electrolyte plays an important role in zinc batteries by conducting and separating the positive and negative electrodes. However, the issues of zinc dendrites growth, corrosion, by‐product formation, hydrogen evolution and leakage, and evaporation of the aqueous electrolytes affect the commercialization of the batteries. Moreover, the widely used aqueous electrolytes result in large battery sizes, which are not conducive to the emerging smart devices. The intrinsic properties of gel polymer electrolytes (GPEs) can solve the above problems. In order to promote the wider application of GPEs‐based zinc batteries, in this review, the working principle and the current problems of zinc batteries are first introduced, andthe merits of GPEs compared to aqueous electrolytes are then summarized. Subsequently, a series of challenges and corresponding strategies faced by GPE is discussed, and an outlook for its future development is finally proposed.

Electrochemical Performance of Corn Waste Derived Carbon Electrodes Based on the Intrinsic Biomass Properties.

The exploration of cost-effective and sustainable biomass-derived carbon materials as electrodes for energy conversion and storage has gained extensive attention in recent research studies. However, the selection of the biomass and the electrochemical performance regulation of the derived biochar, as well as their interrelationship still remain challenging for practical application. Herein, corn wastes with high carbon content (>40%), corn cob and corn silk, were selected as precursors for the preparation of high value-added and high yield carbon materials via a modified synthetic process. Uniquely, this work put emphasis on the theoretical and experimental investigations of how the biomass properties influence the composition and nanostructure regulation, the electrolyte ion adsorption free energy, and the electrical conductivity of the derived carbon materials as well as their electrochemical performance optimization. Owing to the favorable specific surface area, the hierarchical porous structure, and the diverse elemental distribution, corn cob and corn silk derived carbon materials (CBC and SBC) present great potential as promising electrodes for alkaline aqueous zinc batteries and supercapacitors. The assembled CBC//Zn and SBC//Zn zinc batteries deliver high energy densities of 63.0 Wh kg-1 and 39.1 Wh kg-1 at a power density of 575 W kg-1, with excellent cycling performance of 91.1% and 84.3% capacitance retention after 10,000 cycles. As for the assembled symmetric supercapacitors, high energy densities of 14.9 Wh kg-1 and 13.6 Wh kg-1, and superior long-term cycling stability of 99.3% and 96.6% capacitance retention after 20,000 cycles could be achieved. This study highlights the advantages of utilizing corn cob and corn silk as carbon sources on the designed synthesis of carbon electrodes, and presents a meaningful perspective in the investigation of biomass-derived carbon materials and their potential applications in rechargeable devices.

Production of gas-releasing electrolyte-replenishing Ah-scale zinc metal pouch cells with aqueous gel electrolyte

Aqueous zinc batteries are ideal candidates for grid-scale energy storage because of their safety and low-cost aspects. However, the production of large-format aqueous Zn batteries is hindered by electrolyte consumption, hydrogen gas evolution and accumulation, and Zn dendrites growth. To circumvent these issues, here we propose an “open” pouch cell design for large-format production of aqueous Zn batteries, which can release hydrogen gas and allow the refilling of the electrolyte components consumed during cell cycling. The cell uses a gel electrolyte containing crosslinked kappa (k)-carrageenan and chitosan. It bonds water molecules and hinders their side reaction with Zn, preventing electrolyte leakage and fast evaporation. As a proof-of-concept, we report the assembly and testing of a Zn | |ZnxV2O5·nH2O multi-layer “open” pouch cell using the carrageenan/chitosan gel electrolyte, which delivers an initial discharge capacity of 0.9 Ah and 84% capacity retention after 200 cycles at 200 mA g‒1, 370 kPa and 25 °C.

Surface and interface regulation of cathode in aqueous zinc batteries

Surface and interface regulation of cathode in aqueous zinc batteries

A Dual Organic Solvent Zn-Ion Electrolyte Enables Highly Stable Zn Metal Batteries.

Aqueous zinc (Zn) batteries have been regarded as an alternative to lithium-ion batteries due to their high abundance, low cost, and higher intrinsic safety. However, the low Zn plating/stripping reversibility, Zn dendrite growth, and continuous water consumption have hindered the practical application of aqueous Zn anodes. Herein, a hydrous organic Zn-ion electrolyte based on a dual organic solvent, namely hydrated Zn(BF4)2 zinc salt dissolved in dimethyl carbonate (DMC) and vinyl carbonate (EC) solvents [denoted as Zn(BF4)2/DMC/EC], can address these problems, which not only inhibits the side reactions but also promotes uniform Zn plating/stripping through the formation of a stable solid state interface layer and Zn2+-EC/2DMC pairs. This electrolyte enables the Zn electrode to stably undergo >700 cycles at a rate of 1 mA cm-2 with a Coulombic efficiency of 99.71%. Moreover, the full cell paired with V2O5 also demonstrates excellent cycling stability without capacity decay at 1 A g-1 after 1600 cycles.

Colloid Electrolyte with Weakly Solvated Structure and Optimized Electrode/Electrolyte Interface for Zinc Metal Batteries

Aqueous zinc batteries are considered as a viable candidate for cost-effective and environmentally sustainable energy storage technology but are severely hampered by the notorious dendrite growth and parasitic reactions at the zinc anode side. Herein, we propose a bifunctional colloidal electrolyte design that utilizes upconversion nanocrystals, i.e., NaErF4@NaYF4, as a solid additive to provide the sustained release of functional metal and fluoride ions, which can effectively improve the reversibility of the Zn anode to inhibit dendrite growth and hydrogen evolution through forming an electrostatic shielding layer and in situ constructing a ZnF2-enriched protective interface. Experimental characterization and molecular dynamics simulation jointly confirm that the NaErF4@NaYF4 additive could modify the Zn2+ solvation environment in the vicinity of the NaErF4@NaYF4 surface via the strong electrostatic coupling with Zn2+ ions. As a consequence, the modified electrolyte enables stable zinc plating/stripping over 2100 h at a current density of 3 mA cm–2 and a capacity of 1 mAh cm–2 in symmetric cells. The assembled Zn||MnO2 full cells with a modified electrolyte can operate stably for 1600 cycles at 2 A g–1. This work thereby has great potential for the exploration of multifunctional electrolyte additives toward long-lasting aqueous Zn metal batteries.

Circumventing the zinc dendrites via contact-actuated aspectant growth

Aqueous zinc batteries (AZBs) are long deemed as one of the most promising high-safe energy storage devices. However, the Zn anode still suffers severe dendrite growth, which greatly hinders the practical deployment of AZBs. Here, a functionalized separator with pre-embedded nucleation seeds was designed to intentionally tune the Zn deposition direction. Upon plating, the pre-stored Zn@In particles could induce the Zn deposition from separator toward anode, and hence, an aspectant Zn growth simultaneously from the anode and the functional layer of separator is conduced. Once the growth frontiers of the deposited Zn from the two aspects contact with each other, the contact-actuated equipotential within these areas would eliminate the vertically-distributed electric field and drive the dendrite growth along transverse direction, finally leading to a dense Zn deposition. Such a regulation of deposition direction thereby rendered a vastly enhanced cycling life of Zn//Zn symmetric cell from 72 h to 2100 h (1 mA cm−2 and 1 mAh cm−2). This strategy was also proved viable in other types of separators and cell configurations, providing a new methodology to improve the performance of AZBs via smartly regulating the Zn deposition direction.

Electrolyte and Additive Engineering for Zn Anode Interfacial Regulation in Aqueous Zinc Batteries.

Aqueous Zn-metal batteries (AZMBs) have gained great interest due to their low cost, eco-friendliness, and inherent safety, which serve as a promising complement to the existing metal-based batteries, e.g., lithium-metal batteries and sodium-metal batteries. Although the utilization of aqueous electrolytes and Zn metal anode in AZMBs ensures their improved safety over other metal batteries meanwhile guaranteeing their decent energy density at the cell level, plenty of challenges involved with metallic Zn anode still await to be addressed, including dendrite growth, hydrogen evolution reaction, and zinc corrosion and passivation. In the past years, several attempts have been adopted to address these problems, among which engineering the aqueous electrolytes and additives is regarded as a facile and promising approach. In this review, a comprehensive summary of aqueous electrolytes and electrolyte additives will be given based on the recent literature, aiming at providing a fundamental understanding of the challenges associated with the metallic Zn anode in aqueous electrolytes, meanwhile offering a guideline for the electrolytes and additives engineering strategies toward stable AZMBsin the future.

Metal–Organic Framework‐Derived MnO Nanocrystals Embedded in a Spindle Carbon for Rechargeable Aqueous Zinc Battery with a Molten Hydrate Electrolyte

Rechargeable aqueous zinc batteries (RAZBs) are emerging candidates for large‐scale energy storage. However, the lack of high‐capacity cathodes because of the electrostatic interactions between Zn2+ and cathode and the inferior electronic conductivity restricts their performance. The operating voltage limitation imposed by water is another barrier for RAZBs. Herein, manganese oxide (MnO) nanocrystals embedded in a spindle carbon matrix (MnO@C) synthesized from a metal–organic framework are used as a cathode. The uniform distribution of fine‐sized MnO (≈100 nm) in the carbonized matrix (≈5 μm) and the intimate connection between them not only increase the utilization of electroactive material but also eliminate the use of conductive additive. By utilizing the molten hydrate electrolyte, ZnCl2·2.33H2O, a discharge voltage plateau approaching 1.60 V and a high reversible capacity of 106 mAh g−1 after 200 cycles are achieved. This research proposes an approach for affordable RAZBs to fulfill large‐scale energy storage.