Rechargeable Zn-based Batteries Research Articles

Open-framework indium hexacyanoferrate for high-voltage and coaxially-fibrous aqueous K//Zn battery

The design of eco-friendly fibrous aqueous rechargeable Zn-based batteries is important for the advancement of flexible electronics. But it is still remains extremely difficult to develop high-voltage fibrous Zn-based batteries on a single-fiber architecture that directly influence their energy density. Furthermore, the sluggish Zn2+ diffusion kinetics and tough electrostatic interaction seriously astrict to further move ahead for the Zn-based batteries. Herein, we demonstrate a high-voltage coaxially-fibrous aqueous rechargeable (CFAR) K//Zn battery based on open-framework indium hexacyanoferrate (InHCF) cathode. The resultant assembled CFAR K//Zn battery provides an eminent voltage of 1.70 V and a superhigh energy density of 197.88 mWh cm-3 at 170.4 mW cm-3. More importantly, our assembled CFAR K//Zn battery exhibits excellent mechanical steadiness with the capacity retention of 92.7 % by following bending at 90° for 4000 times. Therefore, the design of the new-style architecture in high-voltage CFAR K//Zn batteries provides a fresh strategy for economic, reliable, and high-energy-density wearable energy-storage devices.

Crystal engineering of bimetallic cobalt-based metal–organic framework nanosheets for high-performance aqueous rechargeable cobalt-zinc batteries

Aqueous rechargeable Zn-based batteries (ARZBs) have attracted increasing attention as favorable candidates for energy storage systems due to their high security, environmental friendliness, and abundance of electrode materials. At present, the most widely reported materials used in cobalt-zinc (Co-Zn) batteries are cobalt-based oxides and their derivatives, however, they still exhibit low actual capacities and unsatisfactory cycle lives. Metal-organic frameworks (MOFs), as a new class of porous materials with high specific surface area and adjustable pore size, have attracted considerable attention in the field of energy storage. Currently, pristine MOFs have currently few applications in Co-Zn batteries, and their performance is not ideal. Herein, we report a series of two-dimensional (2D) bimetallic CoM-MOF (M = Ni, Mn, Mg and Cu) nanosheets based on trimesic acid (H3BTC) ligand as cathodes for alkaline Co-Zn batteries via a simple one-pot hydrothermal synthesis. Among the synthesized MOFs, the CoNi-MOF nanosheets have the best performance, exhibiting a high reversible capacity of 344 mA h g−1 and demonstrating a good cycling life with 90 % capacity retention at 20 A g−1 after 1500 cycles. The energy storage mechanism is studied through a series of ex-situ characterizations. This study is of great importance in advancing the application of 2D pristine MOFs for high-performance Co-Zn batteries.

Constructing Crystalline NiCoP@Amorphous Nickel–Cobalt Boride Core–Shell Nanospheres with Enhanced Rate Capability for Aqueous Supercapacitors and Rechargeable Zn-Based Batteries

Constructing Crystalline NiCoP@Amorphous Nickel–Cobalt Boride Core–Shell Nanospheres with Enhanced Rate Capability for Aqueous Supercapacitors and Rechargeable Zn-Based Batteries

Zn-induced formation of polymetallic carbonate hydroxide cathodes with high mass loading for high performance aqueous alkaline Zn-based batteries

Developing high mass loading cathodes with high capacity and durable life cycles is greatly worthwhile and challenging for alkaline aqueous rechargeable Zn-based batteries (AAZBs). Herein, we demonstrate an efficient zinc-induced strategy to rationally develop Zn-Ni-Co carbonate hydroxides/hydroxides heterostructure nanosheet array with an extremely high mass loading of 9.2 mg cm−2 on Ni foam (ZNC/NF) as such a superior cathode for AAZBs. It is discovered that Ni-Co hydroxide nanowires can be transformed into Zn-Ni-Co carbonate hydroxides/hydroxides heterostructure nanosheet with rich defect structures after the introduction of Zn during the synthetic process. The formed heterostructures and rich defect structures can enhance ion and electron transfer efficiency, thus ensuring the excellent electrochemical performance under high loading condition. Consequently, the ZNC/NF//Zn battery shows an outstanding areal capacity of 2.1 mAh cm−2 at 5 mA cm−2, with an ultrahigh energy density of 3.6 mWh cm−2. Moreover, the battery can still retain a high capacity of 0.42 mAh cm−2 after 5000 cycles at 50 mA cm−2, suggesting strong long-term cycling stability. This research enables pave the way for the rational design and manufacture of advanced electrode materials with large mass loadings.

Epitaxial deposition of Zn (0 0 2) for stable zinc metal anodes

The prosperity of aqueous rechargeable Zn-based batteries is largely confined by the discontent performance of zinc anodes. Uncontrollable Zn dendrite is the first to be ascribed, however, the control of deposited crystal phase and crystallography is one effective solution. Here, aimed at the close-packed growth of Zn (002) plane parallel to anode surface, we propose a zincophilic and lattice-matched texture on Zn foil surface, MgO (111), to regulating Zn deposition behavior. The strong binding energy between Zn atom and MgO (111) plane along with the good lattice match of Zn (002) and MgO (111) plane lead to the good heterogenous epitaxial alignment. And then the layer-by-layer growth of Zn (002) has been achieved to obtain dendrite-free Zn anode. The specific anode surface can not only afford stable dissolution/deposition for 1250 h at 1 mA h cm−2 with high voltage tolerance (25 mV) in symmetric cells, but also is compatible to V2O5 cathode in full cells. The conception of lattice-matched crystal orientation texture could be the intrinsic solution to metal anodes.

Tailoring the Electrochemical Deposition of Zn by Tuning the Viscosity of the Liquid Electrolyte

The issues during Zn deposition in rechargeable Zn-based batteries greatly hinder cycling stability. In this work, a simple and inexpensive approach to tailor the Zn electrodeposition is proposed by tuning the viscosity of the liquid electrolyte (LE). First, the growth mechanisms of Zn deposition under different electrolyte properties are investigated by numerical simulation, from which the bottom deposition tends to fuse with each other when there are more deposition sites, and the mass-transfer coefficient is lower, thus achieving uniform deposition. Besides, the whole process of Zn deposition in charging-discharging cycling is in situ observed by an optical microscope. It is found that the cause of the poor stability in the LE is due to the uneven Zn deposition, resulting in weak bonding between the deposition and the electrode surface, which is also the reason for the formation of dead Zn. In contrast, when an appropriate amount of the polymer is added to the LE to increase the viscosity, an appropriate overpotential can be created, generating more deposition sites. In addition, the viscosity reduces the mass-transfer coefficient, making the distance from the ion to the deposition sites the main controlling factor. The Zn ions are more inclined to move in the direction of electric field lines, which results in a uniform and dense deposition layer. Furthermore, the effectiveness of this method is demonstrated in a Zn-LiFePO4 battery, from which the battery with the modified electrolyte condition still works properly even in the Zn utilization of 100% and shows a capacity retention rate (35%) of nearly twice that in the original LE condition (18%) after 10 cycles. This work provides a theoretical basis for Zn deposition and provides ideas for the future development of high-performance Zn-based batteries.

Facile electrochemically induced vacancy modulation of NiCo2O4 cathode toward high-performance aqueous Zn-based battery

Transition metal oxides are highly promising cathode materials in rechargeable Zn-based batteries owing to their low cost, high theoretical capacity and good reversibility. Nevertheless, intrinsically low conductivity and sluggish redox reaction kinetics normally result in their inferior specific capacity and poor rate capability, which critically constrains the practical performance of Zn-based batteries. Herein, an ultrafast and controllable electrochemical activation (EA) process is developed to effectively enhance the electrochemical performance of NiCo2O4 cathode. Systematic studies reveal EA process triggers in situ reconstruction of NiCo2O4 lattice by weakening the coordination of Co-O bonds, resulting in the formation of abundant oxygen vacancies (octahedral Co2+). These oxygen vacancies increase the charge carrier density and endow the superficial metallic active sites with higher electrochemical activity, which synergistically accelerates the electrochemical reaction kinetics. The oxygen-deficient NiCo2O4 exhibits a remarkable capacity of 418.9 mAh/g at 1 A/g, which is nearly 5-fold higher than that of pristine NiCo2O4. Furthermore, the oxygen-deficient NiCo2O4//Zn battery presents an extremely high energy density (682.4 Wh kg−1) and excellent power density (50.8 kW kg−1), surpassing most of the reported aqueous rechargeable batteries. This work provides a facile and effective vacancy modulation strategy for the development of advanced materials utilized in energy and catalysis fields.

Engineering techniques to dendrite free Zinc-based rechargeable batteries.

Rechargeable Zn-based batteries (RZBs) have garnered a great interest and are thought to be among the most promising options for next-generation energy storage technologies due to their low price, high levels of safety, adequate energy density and environmental friendliness. However, dendrite formation during stripping/plating prevents rechargeable zinc-based batteries from being used in real-world applications. Dendrite formation is still a concern, despite the fact that inhibitory strategies have been put up recently to eliminate the harmful effects of zinc dendrites. Thus, in order to direct the strategies for inhibiting zinc dendrite growth, it is vital to understand the formation mechanism of zinc dendrites. Hence, for the practical application of zinc-based batteries, is essential to use techniques that effectively prevent the creation and growth of zinc dendrites. The development and growth principles of zinc dendrites are first made clear in this review. The recent advances of solutions to the zinc dendrite problem are then discussed, including strategies to prevent dendrite growth and subsequent creation as much as possible, reduce the negative impacts of dendrites, and create dendrite-free deposition processes. Finally, the challenges and perspective for the development of zinc-based batteries are discussed.

Dendrite Issues for Zinc Anodes in a Flexible Cell Configuration for Zinc-Based Wearable Energy-Storage Devices.

A key application of aqueous rechargeable Zn-based batteries (RZBs) is flexible and wearable energy storage devices (FESDs). Current studies and optimizations of Zn anodes have not considered the special flexible working modes needed. In this study, we present the Zn accumulation on the folded line and curve areas of flexible anodes. The correlation between the bending radius and the lifespan of symmetric cells is proposed. The interface contact of hydrogel electrolytes when working in a bending mode is another key factor affecting cell lifespan. After detailed analysis, the ideal cell configuration is shown to be hydrogel electrolytes with suitable chemistry, satisfactory mechanical properties, and high adhesivity. Thus a water in salt (WIS) hydrogel is proposed that demonstrates a highly stable cell performance. This work provides a new perspective in Zn anode research for the development of FESDs.

Dendrite Issues for Zinc Anodes in a Flexible Cell Configuration for Zinc‐Based Wearable Energy‐Storage Devices

AbstractA key application of aqueous rechargeable Zn‐based batteries (RZBs) is flexible and wearable energy storage devices (FESDs). Current studies and optimizations of Zn anodes have not considered the special flexible working modes needed. In this study, we present the Zn accumulation on the folded line and curve areas of flexible anodes. The correlation between the bending radius and the lifespan of symmetric cells is proposed. The interface contact of hydrogel electrolytes when working in a bending mode is another key factor affecting cell lifespan. After detailed analysis, the ideal cell configuration is shown to be hydrogel electrolytes with suitable chemistry, satisfactory mechanical properties, and high adhesivity. Thus a water in salt (WIS) hydrogel is proposed that demonstrates a highly stable cell performance. This work provides a new perspective in Zn anode research for the development of FESDs.

Unveiling the Synergistic Effect of Ferroelectric Polarization and Domain Configuration for Reversible Zinc Metal Anodes.

The tendency of zinc (Zn) anodes to form uncontrolled Zn electrodeposits and the occurrence of side‐reactions at Zn‐electrolyte interfaces are a fundamental barrier hampering broad applications of aqueous rechargeable Zn‐based batteries. Herein, a ferroelectric domain‐mediated strategy is proposed to manipulate the Zn plating behavior and achieve controllable Zn growth orientation by coating Zn foil with a ferroelectric tetragonal KTN (t‐KTN) layer. The ferroelectric domain of t‐KTN single crystals exhibits periodic distribution of upward and downward polarizations, corresponding to alternating positively and negatively charged surfaces. The charged ferroelectric surfaces can manipulate the transfer kinetics of Zn ions and the concentration distribution of anions via the interplay between ferroelectric dipoles and adsorbed ions. With the synergistic effect of the ferroelectric polarization and domain configurations, the well‐aligned interlamellar arrays composed of electrodeposited Zn are formed in the initial deposition process, which enable selective deposition within interlamellar arrays and eliminate the dendrite growth during the following plating process. As a result, the t‐KTN layer‐modified Zn anode enables reversible Zn plating/stripping with low voltage hysteresis for over 1200 h at 1 mA cm−2 in symmetric cells, and the assembled full cell exhibits a significantly enhanced cycling stability of over 5500 cycles at 5 A g−1.

Strategies for Stabilization of Zn Anodes for Aqueous Zn-Based Batteries: A Mini Review.

In recent years, thanks to the investigation of the in-depth mechanism, novel cathode material exploitation, and electrolyte optimization, the electrochemical performance of rechargeable Zn-based batteries (RZBs) has been significantly improved. Nevertheless, there are still some persistent challenges locating the instability of the Zn anodes that hinder the commercialization and industrialization of RZBs, especially the obstinate dendrites and hydrogen evolution reaction (HER) on Zn anodes, which will dramatically compromise the cycle stability and Coulombic efficiency. Therefore, various strategies with fundamental design principles focusing on the suppression of dendrite and the HER have been carefully summarized and categorized in this review, which are critically dissected according to the intrinsic mechanisms. Finally, pertinent insights into the challenges and perspectives on the future development of Zn anodes are also emphasized, expecting to supply potential research directions to promote the practical applications of RZBs.

Fe-decorated-NiCo layered double hydroxide nanoflakes via corrosion engineering for high-energy rechargeable Zn-based batteries

A reliable and cost-effective corrosion engineering approach is proposed to prepare highly active Fe-decorated-NiCo layered double hydroxide nanoflakes for alkaline Zn-based batteries.

Corrosion engineering towards a high-energy Mn doped Co3O4 nanoflake cathode for rechargeable Zn-based batteries

A facile surface corrosion strategy is proposed to synthesize Mn-doped Co3O4 nanoflakes with remarkable electrochemical performance for Zn-based batteries.

Optimizing the charging protocol to address the self-discharge issues in rechargeable alkaline Zn-Co batteries

Aqueous rechargeable Zn-Co batteries feature intrinsic safety and excellent electrochemical performance, and zinc metal is cheap with abundant reserves. However, a key issue, self-discharge, which may be fatal to the application, is always overlooked. Herein, the self-discharge performance is investigated systematically for the first time, and in-depth charge–discharge mechanisms are analyzed. Based on a free-standing Co3O4 electrode, the insufficient utilization of the active material is found under a conventional galvanostatic charging process. Additionally, a dramatic attenuation in the open-circuit voltage is exhibited during the delay, leading to poor capacity retention. Through electrochemical tests and ex-situ characterization, the limited capacity and the severe self-discharge behavior are ascribed to the low amount and poor stability of the high valence state, respectively. Aiming at suppressing the self-discharge behavior, a novel charging protocol is proposed based on a new mechanism, which uses a time-controlling potentiostatic charging after the galvanostatic charging process. Using this strategy, the discharge capacity increases effectively by about 31.8% from 220 to 290 mA h g−1, and the capacity retention ratio after 10 h delay lifts from 72% to 90%. More importantly, the discharge capacity remains 100% after even 2500 cycles. This work puts forward a practical method for the operation of Zn-Co batteries, addresses the limiting issues for application, and greatly facilitates the improvement of this technology. Further, the results also inspire the research of other rechargeable Zn-based batteries.

An Overview and Future Perspectives of Rechargeable Zinc Batteries.

Aqueous rechargeable zinc-based batteries have sparked a lot of enthusiasm in the energy storage field recently due to their inherent safety, low cost, and environmental friendliness. Although remarkable progress has been made in the exploration of performance so far, there are still many challenges such as low working voltage and dissolution of electrode materials at the material and system level. Herein, the central tenet is to establish a systematic summary for the construction and mechanism of different aqueous zinc-based batteries. Details for three major zinc-based battery systems, including alkaline rechargeable Zn-based batteries (ARZBs), aqueous Zn ion batteries (AZIBs), and dual-ion hybrid Zn batteries (DHZBs) are given. First, the electrode materials and energy storage mechanism of the three types of zinc-based batteries are discussed to provide universal guidance for these batteries. Then, the electrode behavior of zinc anodes and strategies to deal with problems such as dendrite and passivation are recommended. Finally, some challenge-oriented solutions are provided to facilitate the next development of zinc-based batteries. Combining the characteristics of zinc-based batteries with good use of concepts and ideas from other disciplines will surely pave the way for its commercialization.

Morphological Evolution of Zn-Sponge Electrodes Monitored by In Situ X-ray Computed Microtomography

Use of Zn sponges has been recently proposed as an effective means of limiting the shape change and dendrite formation issues, affecting the anodes of electrically rechargeable Zn-based batteries. This paper contributes to this field of research with in situ X-ray computed microtomography (XCMT) monitoring of the morphological and chemical changes undergone by Zn-sponge anodes during electrochemical cycling. Starting from a pristine anode, fabricated in the discharged state, this was first charged and then subjected to a representative series of charge–discharge sequences and, in correspondence, it was studied by XCMT in order to determine (i) the volume fractions of Zn and ZnO, porosity, and their space arrangement and (ii) the degree of connectivity of the elemental Zn framework. Good stability of the metal framework, reversibility of the Zn and ZnO phases, and their space distribution, with a limited alteration of the pore structure, were observed over more than 60 charge–discharge cycles.

Zinc Anode Design for Rechargeable Aqueous High-Energy Zn Batteries

As an energy storage system, Li-ion batteries are not safe because they use flammable organic electrolytes. A safer alternative is rechargeable Zn-based batteries with aqueous electrolytes. Among them, Zn-air batteries have high theoretical volumetric energy density (4400 Wh/L), which can even compete with lithium-sulfur batteries. Alkaline electrolyte is preferable for Zn-air batteries. However, the performance of Zn anodes in alkaline electrolyte is limited by passivation, dissolution and hydrogen evolution. Through SEM investigation, critical passivation size was found to be ~ 2 µm. Sub-micron-sized Zn anodes won’t have passivation problem. As a result, we focus our research on nanoscale. However, Zn dissolution of nanosized anodes will be accelerated because of large electrode-electrolyte surface area. Thus, anode modification and protection are needed to alleviate the dissolution. We designed a (1) Zn mesh@GO anode (Fig. 1a): graphene oxide (GO) layers on the Zn mesh surface deliver electrons across insulating ZnO and can slow down the Zn dissolution; (2) lasagna-inspired ZnO@GO anode (Fig. 1b): ZnO nanoparticles encapsulated by GO can solve simultaneously the passivation and dissolution problems; (3) core-shell ZnO@TiN nanorod anode (Fig. 1c): thin and conformal TiN coating mitigates Zn dissolution, mechanically maintains the nanostructure, and delivers electron to nanorods. These coatings are ion selective, which allow permeation of OH- and water, and prevents loss of Zn active material through blocking bigger Zn(OH)4 2-. Hydrogen evolution is a competitive side reaction on the zinc anodes, which causes low efficiency of Zn based batteries. Two approaches are investigated to suppress hydrogen evolution, including (1) modify the anode with a hydrogen suppressive material: core-shell ZnO@TiO2 nanorod anode was made with hydrogen suppressive TiO2 coating, which solves hydrogen evolution, passivation and dissolution problems at the same time; (2) design a hydrogen evolution suppressive nanostructured alloy anode: Zn-Ag alloy with increased standard reduction potential was used, which is more competitive compared with hydrogen evolution and more stable in aqueous electrolyte. All of these anodes show superior performance compared with unmodified anodes. These anodes can be paired with air cathodes to make high energy Zn-air batteries. The nanoscale design principles here can potentially be applied to overcome intrinsic limitations of other battery materials. Figure 1

Ultrafast Rechargeable Zinc Battery Based on High-Voltage Graphite Cathode and Stable Nonaqueous Electrolyte.

Zinc-based battery chemistries have lately drawn great attention for grid-scale energy storage due to their material abundance and high safety. However, the low Coulombic efficiency (CE) and dendrite growth of zinc (Zn) anodes and the limited working voltage of current oxide cathodes are the major barriers hindering the development of rechargeable Zn-based batteries (RZBs). Here, we report an ultrafast and high-voltage Zn battery in a new cell configuration employinga graphite cathode, a Zn anode, and nonaqueous 1 M zinc bis(trifluoromethylsulfonyl)imide (Zn(TFSI)2) in acetonitrile (AN) electrolyte. This RZB operates through the (de)intercalation of TFSI- anions into the graphite and the electrochemical Zn2+ plating/stripping at the anode. The optimized Zn(TFSI)2/AN electrolyte features high reductive/oxidative stability, good ionic conductivity (∼28 mS cm-1), and low viscosity (∼0.4 mPa·s), enabling the unprecedented cycling stability (over 1000 h) of the Zn anode with a dendrite-free morphology, the ultrafast Zn plating/stripping with a high CE (>99%), and the good compatibility with the graphite cathode. Consequently, this RZB exhibits a high average output voltage (2.2 V), a high energy/power density (86.5 Wh kg-1 at 4400 W kg-1), and a long cycle life (97.3% capacity retention after 1000 cycles). The present work offers new insights and opportunities to the Zn-based electrochemistry.

Sealing ZnO nanorods for deeply rechargeable high-energy aqueous battery anodes

Rechargeable Zn-based batteries are a safe alternative to Li-ion for compatibility with aqueous electrolyte. Also, theoretical volumetric energy density of Zn-based batteries (e.g. Zn-air) is ~85% of lithium-sulfur battery. However, the rechargeability and specific capacity of Zn anodes are limited by passivation and dissolution. Here we report a ZnO@TiNxOy core/shell nanorod structure for deeply rechargeable Zn anodes. The small diameter (<500 nm) of ZnO prevents passivation and allows full utilization of active materials, while the thin and conformal TiNxOy coating mitigates Zn dissolution in alkaline electrolyte, mechanically maintains the nanostructure, and delivers electron to nanorods. As a result, the ZnO@TiNxOy core/shell nanorod anode achieves superior specific capacity and cycle life compared with bulk Zn foil and uncoated ZnO nanorod anodes. The discharge capacity of this anode is twice as large as that of the uncoated ZnO nanorod anode. Remarkably, our ZnO@TiNxOy nanorod anode achieves a much higher specific discharge capacity of 508 mA h/g(Zn) than that of many previously reported zinc anodes. It can deeply cycle >640 times (64 days) in a beaker cell and deliver excellent long-term electrochemical performance (more than 7500 cycles) when cycled under start-stop conditions. The nanoscale design principles reported here is an important step towards practical deeply rechargeable Zn anodes, and can potentially be applied to overcome intrinsic limitations of other battery materials that involve soluble intermediates or insulating discharge products.