Stable Zinc Research Articles

Polycation-Regulated Electrolyte and Interfacial Electric Fields for Stable Zinc Metal Batteries.

Zn metal as one of promising anode materials for aqueous batteries but suffers from disreputable dendrite growth, grievous hydrogen evolution and corrosion. Here, a polycation additive, polydiallyl dimethylammonium chloride (PDD), is introduced to achieve long-term and highly reversible Zn plating/stripping. Specifically, the PDD can simultaneously regulate the electric fields of electrolyte and Zn/electrolyte interface to improve Zn2+ migration behaviors and guide dominant Zn (002) deposition, which is veritably detected by Zeta potential, Kelvin probe force microscopy and scanning electrochemical microscopy. Moreover, PDD also creates a positive charge-rich protective outer layer and a N-rich hybrid inner layer, which accelerates the Zn2+ desolvation during plating process and blocks the direct contact between water molecules and Zn anode. Thereby, the reversibility and long-term stability of Zn anodes are substantially improved, as certified by a higher average coulombic efficiency of 99.7% for Zn//Cu cells and 22 times longer life for Zn//Zn cells compared with that of PDD-free electrolyte.

Low cost carboxymethyl cellulose additive toward stable zinc anodes in aqueous zinc ion battery

Aqueous zinc ion batteries (AZIBs) have got increasingly worldwide attention in virtue of the excellent advantages of cheap price, safety and high specific capacity. Nevertheless, the formation of dendrites and the hydrogen evolution reaction on the Zn anode leads to low cycle life and restrict their commercial application. In this paper, an inexpensive, safe, eco-friendly and effective electrolyte additive, carboxymethyl cellulose (CMC), which can guide a uniform Zn deposition during the plating and stripping process and further inhibit the growth of dendrite, has been proposed. The experimental results indicate that the Zn//Zn symmetric cells show remarkable cycling performance for >600 h at a current density of 5 mA cm−2 with 1 mAh cm−2 and 1000 h at a current density of 1 mA cm−2 with 1 mAh cm−2, respectively. In addition, the Zn//V2O5 full cells with addition of CMC can obtain a desirable specific capacity for 173 mAh g−1 and keep a high-capacity retention of 54.2 % (19.5 % for without CMC additive) after 1000 cycles at 2A g−1. A reasonable improved mechanism of electrochemical performance by addition of CMC electrolyte additive has been proposed. This work demonstrates that addition of CMC in electrolyte is a promising strategy for inhibiting Zn dendrite and corrosion in AZIBs.

N‐CNTs‐Based Composite Membrane Engineered By A Partially Embedded Strategy: A Facile Route To High‐Performing Zinc‐Based Flow Batteries

AbstractZinc‐based flow batteries are promising for distributed energy storage due to their low‐cost and high‐energy density advantages. One of the most critical issues for their practical application is the reliability that results from the heterogeneous zinc deposition and dead zinc from falling off the electrode. Herein, nitrogen‐doped carbon nanotubes (N‐CNTs)‐based composite membrane through a facilely partially embedded method is reported to enable a dendrite‐free alkaline zinc‐based flow battery. The results indicate that the electrically conductive N‐CNTs functional layer can enhance the transport dynamics of charge carriers and homogenize electric field distribution in membrane–electrode interface, which induces the initial nucleation of metallic zinc from the carbon felt electrode to N‐CNTs functional layer and further achieve a uniform and dense plating of metallic zinc in alkaline media. Thus, the engineered membrane enables a stable alkaline zinc–iron flow battery performance for more than 350 h at a current density of 80 mA cm−2. Moreover, an energy efficiency of over 80% can be afforded at a current density of 200 mA cm−2. The scientific finding of this study provides a new strategy on composite membranes design and their capability to adjust the plating of metallic zinc in alkaline media.

Integrated electrolyte regulation strategy: Trace trifunctional tranexamic acid additive for highly reversible Zn metal anode and stable aqueous zinc ion battery

Aqueous zinc ion batteries (AZIBs) are appealing increasing attention for large-scale energy storage systems (ESS) due to their intrinsic safety, low cost, and scalability. Unfortunately, the Zn metal anode suffers from chaotic side reactions, rampant dendrite growth and continuous hydrogen evolution, severely hampering the application of AZIBs. Herein, the trifunctional tranexamic acid (TXA) is introduced into aqueous electrolyte to form unique anode/electrolyte interface, enhance steric effect and regulate Zn2+ solvation structure. Theoretical calculations first illustrate the mechanism of TXA additive on Zn metal anode and electrolyte. Experimental results and molecular dynamic simulations further demonstrate the vital role of TXA in simultaneously regulating the anode interface chemistry and electrolyte environment. Consequently, Zn//Zn symmetric cells deliver a durable lifespan of over 2000 h at 1 mA cm–2, and a high cumulative capacity at 5 mA cm–2. A highly reversible Zn plating/stripping processes for over 1000 cycles in Zn//Cu asymmetric cells are also achieved. Moreover, the assembled Zn//NiCo-MnO2 and Zn//NH4V4O10 full cells exhibit stable cycling performance and high capacity retentions. This work proposes a novel and facile integrated electrolyte regulation strategy to realize dendrite-free Zn anodes and stable full cells, which is favorable for advanced AZIBs and beyond.

Zn3V3O8@ZnO@NC heterostructure for stable zinc ion storage from assembling nanodisks into cross-stacked architecture

Zn3V3O8@ZnO@NC heterostructure for stable zinc ion storage from assembling nanodisks into cross-stacked architecture

Refining the Grain Size of Zinc Electrodeposit by Pb2+ Ion Grinding for Compact and Stable Zinc Anode

AbstractRecently, aqueous zinc‐based batteries (AZBs) have become a promising candidate for energy storage devices due to the high safety of aqueous electrolytes and the appealing features of Zn anodes, for example, low cost and high theoretical capacity. However, the excessive growth of Zn electrodeposits as well as the uneven stacking of large hexagonal Zn crystal units always render loose and irregular electrodeposition or even dendritic growth, which seriously deteriorates the actual performance of AZBs. Herein, to refine the grain size of Zn electrodeposits, a trace of Pb2+ ions as a novel electrolyte additive is performed to inhibit the growth of Zn grain during the Zn electrodeposition. Owing to the higher adsorption energy of Pb2+ ions on Zn crystal when compared with Zn2+ ions, the strongly positively‐charged Pb2+ ions are tightly absorbed on the typical crystal planes of initially‐formed Zn nuclei, which block the way for the subsequent absorption and electroreduction of Zn2+ ions. As a result, the Pb2+ ions‐containing electrolyte refines the grain size of Zn electrodeposits from 7.43–7.87 μm to 0.88–2.26 μm, and affords a high reversibility of Zn plating/stripping behavior with a high Coulombic efficiency of 99.9 % over 1000 cycles.

Hydrated solvation suppression of zinc ions for highly reversible zinc anodes

Low-cost and high-safety aqueous zinc batteries are promising for large-scale energy storage applications. However, the actual performance of aqueous zinc batteries is hampered by the irreversibility of the zinc metal anode originating from the dendrite growth and side reactions, which are associated closely with the hydrated solvation sheath of Zn2+ ions in aqueous electrolytes. Here, dimethylacetamide is employed as a water dragger agent in low-concentration ZnSO4 electrolytes to reshape the solvation structure of Zn2+ ions. Theoretical calculations and experimental investigations reveal that a low fractional addition of dimethylacetamide in aqueous ZnSO4 electrolytes performs strong interactions with water molecules and Zn2+ ions, which inhibits hydrated Zn2+–H2O solvation, facilitates Zn2+-SO42- association and captures free water molecules via H-bonds formation. The coulombic efficiency of Zn plating/stripping is improved from 94.3% to 98.1% and can be stabilized at 99.5% over 200 cycles with the hybrid electrolyte. The cycle lifespan of the Zn symmetric cell is prolonged over 1000 h at 1 mA cm−2 and over 450 h at 5 mA cm−2 with the dimethylacetamide -hybrid electrolyte, which are over fourfold higher than that of the pristine ZnSO4 electrolyte. Moreover, when the designed electrolyte is incorporated in full cells, the Zn-MnO2 cell exhibits an improved rate performance and an excellent long-term cyclability with a capacity-retention rate of 81% over 2,000 cycles at 1 A g−1. This work provides a feasible strategy for the development of highly stable aqueous zinc batteries.

In Situ Construction of Anode–Molecule Interface via Lone‐Pair Electrons in Trace Organic Molecules Additives to Achieve Stable Zinc Metal Anodes

AbstractThe practical application of aqueous zinc batteries (AZBs) is significantly limited by the poor reversibility of the zinc anodes, including rampant dendrite growth and severe interfacial side‐reactions. Herein, trace hexamethylenetetramine (HMTA) additive with a lone‐pair‐electron containing heterocycle is introduced for Zn metal anode protection. Specifically, the trace added HMTA can change the solvated structure by strong interaction with zinc ions, and preferentially absorb on the anode surface to in situ establish an unique anode–molecule interface. Such an interface not only shows strong affinity to promote the dynamic transmission and deposition of Zn2+ ions but also displays a role in suppressing parasitic reactions. Consequently, a zinc anode in an electrolyte with trace HMTA achieves a high Coulombic efficiency of 99.75%, and delivers a remarkable lifespan over 4000 h at 5 mA cm−2 and 1 mAh cm−2 in a Zn//Zn symmetric cell. Even under a deep plating/stripping condition (5 mA cm−2 and 5 mAh cm−2), it can still run almost for 600 h. Additionally, the Zn//V2O5 full cell with HMTA retains a high capacity retention of 61.7% after 4000 cycles at 5 A g−1. Such an innovative strategy is expected to be of immediate benefit to design low‐cost AZBs with ultra‐long lifespan.

Regulating the Water Molecular in the Solvation Structure for Stable Zinc Metal Batteries

AbstractRechargeable aqueous zinc batteries are promising energy storage devices because of their low cost, high safety, and high energy density. However, their performance is plagued by the unsatisfied cyclability due to the dendrite growth and hydrogen evolution reaction (HER) at the Zn anode. Herein, it is demonstrated that the concentrated hybrid aqueous/non‐aqueous ZnCl2 electrolytes constitute a peculiar chemical environment for not only the Zn‐ions but also water molecules. The high concentration of chloride ions substitutes the H2O molecular in the solvation structure of Zn2+, while the acetonitrile further interacts with H2O to decrease its activity. The hybrid electrolytes both inhibit the dendrite formation and HER, enabling an ultrahigh average Coulombic efficiency of 99.9% in the Zn||Cu half‐cell and a highly reversible Zn plating/stripping with a low overpotential of 21 mV. Using this hybrid electrolyte, the Zn||polytriphenylamine (PTPAn) full cell deliveres a high discharge capacity of 110 mAh g−1, a high power density of 9200 W kg−1 at 100 °C and maintains 85% of the capacity for over 6000 cycles at 10 °C. This study provides a deep understanding between the solvation structure and columbic efficiency of Zn anode, thus inspiring the development for stable Zn batteries.

Strategically Constructing a Hydrophilic Interface toward Ultrastable Zinc Metal Anodes.

Aqueous zinc-ion storage devices have received increasing attention due to their inherent safety, high capacity, and cost-effectiveness. However, problems such as uneven Zn deposition, limited diffusion kinetics, and corrosion greatly reduce the cycling performance of zinc anodes. Here, a sulfonate-functionalized boron nitride/graphene oxide (F-BG) buffer layer is designed and utilized to modulate the plating/stripping behavior and mitigate the side reactions with the electrolyte. Benefiting from the synergistic effect of high electronegativity and abundant surface functional groups, the F-BG protective layer accelerates the ordered migration of Zn2+, homogenizes the Zn2+ flux, and effectively improves the reversibility of plating and nucleation with strong zincphilicity and dendrite-inhibiting capabilities. Further, electrochemical measurements and cryo-EM observations reveal the mechanism by which the interfacial wettability of the zinc negative electrode acts on capacity and cycling stability. Our work provides deeper insight into the influence of wettability on the energy storage properties and brings forward a facile and instructive way to construct stable zinc anodes for zinc-ion hybrid capacitors.

Zinc-Contained Alloy as a Robustly Adhered Interfacial Lattice Locking Layer for Planar and Stable Zinc Electrodeposition.

Stable zinc (Zn)/electrolyte interface is critical for developing rechargeable aqueous Zn-metal batteries with long-term stability, which requires the dense and stable Zn electrodeposition. Herein, an interfacial lattice locking (ILL) layer is constructed via the electro-codeposition of Zn and Cu onto the Zn electrodes. The ILL layer shows a low lattice misfit (δ= 0.036) with Zn(002) plane and selectively locks the lattice orientation of Zn deposits, enabling the epitaxial growth of Zn deposits layer by layer. Benefiting from the unique orientation-guiding and robustly adhered properties, the ILL layer enables the symmetric Zn||Zn cells to achieve an ultralong life span of >6000h at 1mA cm-2 and 1 mAh cm-2 , a low overpotential (65mV) at 10 mAh cm-2 , and a stable Zn plating/stripping for >90h at an ultrahigh Zn depth of discharge (≈85%). Even with a limited Zn supply and a high current density (8.58mA cm-2 ), the ILL@Zn||Ni-doped MnO2 cells can still survive for >2300 cycles.

A dendrite-free Ga-In-Sn-Zn solid-liquid composite anode for rechargeable zinc batteries

Rechargeable zinc batteries (RZBs) have been considered as promising candidates for next-generation large-scale energy storage systems due to the high theoretical capacity (820 mAh g−1), environmental friendliness and sustainability of zinc metal anode. Nevertheless, the practical realization of secondary zinc batteries were impeded by the dendrite issues and consequent poor cycle stability. Here, the Ga-In-Sn-Zn solid-liquid composite (SLC) was proposed to construct SLC-2 electrode by a facile and easily scalable painting strategy. The experimental results and theoretical calculations validated that the solid phase InSn4 in the designed electrode shows good adsorbing ability and lower migration energy barrier of Zn ions, and the electrochemically inert Ga-In liquid component can release the stress changes of the composite electrode, realizing a smooth and dendrite-free Zn deposition. The SLC-2 anode having a areal capacity of 1 mAh cm−2 with excellent stability for 600 h at a current density of 3 mA cm−2 was demonstrated in a symmetric cell, and the SLC-2/PANI battery delivered a reversible capacity of 61.2 mAh g − 1 after 3000 cycles at 1A g − 1. The printing strategy for SLC electrode may open up a new way to obtain highly stable and dendrite-free zinc metal anodes.

Stable zinc metal anode with an ultrathin carbon coating for zinc-ion batteries

Owing to the good safety, low cost, environmentally friendliness, and relatively high energy density, aqueous zinc-ion batteries (ZIBs) are promising alternatives to lithium-ion batteries. However, the zinc metal anode in aqueous ZIBs is prone to dendrite growth and side reactions. Herein, an ultrathin carbon coating is fabricated on the Zn metal anode to suppress dendrite growth and alleviate side reactions. The symmetrical cell containing the modified Zn electrode shows a long cycling life of 3500 h at 0.5, 1 and 2 mA cm−2 with areal capacities of 0.5, 1 and 2 mAh cm−2, respectively. The cycling life is superior to those of previously reported Zn metal anodes with carbon-based coatings. Meanwhile, the full ZIB using Zn anode with ultrathin carbon coating deliver enhanced rate performance and cycling stability compared to that of using bare Zn anode.

A facile finger-paint physical modification for bilateral electrode/electrolyte interface towards a stable aqueous Zn battery

Since the electrode/electrolyte interface (EEI) is the main redox center of electrochemical processes, proper manipulation of the EEI microenvironment is crucial to stabilize interfacial behaviors. Here, a finger–paint method is proposed to enable quick physical modification of glass–fiber separator without complicated chemical technology to modulate EEI of bilateral electrodes for aqueous zinc–ion batteries (ZIBs). An elaborate biochar derived from Aspergillus Niger is exploited as the modification agent of EEI, in which the multi–functional groups assist to accelerate Zn2+ desolvation and create a hydrophobic environment to homogenize the deposition behavior of Zn anode. Importantly, the finger–paint interface on separator can effectively protect cathodes from abnormal capacity fluctuation and/or rapid attenuation induced by H2O molecular on the interface, which is demonstrated in modified MnO2, V2O5, and KMnHCF–based cells. The as–proposed finger–paint method opens a new idea of bilateral interface engineering to facilitate the access to the practical application of the stable zinc electrochemistry.

A self-assembled nanoporous polyelectrolytic interlayer for highly stable zinc metal anodes

Aqueous zinc-ion batteries (AZIBs) based on Zn metal anodes are promising candidates for next-generation energy storage due to their high performance, environmental friendliness, low cost, and high abundance. However, the excessive dendrite growth and continuous hydrogen evolution of Zn metal anodes in aqueous electrolytes severely deteriorate the electrochemical performance of AZIBs. Here, a highly stable Zn metal anode is designed by reconstructing its surface with a self-assembled nanoporous polyelectrolytic interlayer. This unique protective layer consisting of polyacrylic acid-zinc (PAAZn) nanospheres is highly hydrophilic and can act as a physical barrier to reduce the contact between Zn metal and water molecules, thus suppressing hydrogen evolution and Zn corrosion. Meanwhile, the unique nanostructures and chemical compositions of the PAAZn interlayer ensure fast Zn plating/stripping kinetics and facilitate the homogeneous growth of Zn deposits by redistributing Zn ion flux and local electric field at Zn/electrolyte interfaces. Therefore, symmetric cells based on the PAAZn-modified Zn metal anode (PAAZn@Zn) exhibited a significantly prolonged cycle life of 2,850 h and low voltage hysteresis. This work reports a uniquely designed nanoporous polyelectrolytic interlayer for highly reversible Zn metal anodes and provides a new strategy to enhance the electrochemical performance of AZIBs.

Recent progress of dendrite‐free stable zinc anodes for advanced zinc‐based rechargeable batteries: Fundamentals, challenges, and perspectives

AbstractZinc‐based batteries are a very promising class of next‐generation electrochemical energy storage systems, with high safety, eco‐friendliness, abundant resources, and the absence of rigorous manufacturing conditions. However, practical applications of zinc‐based rechargeable batteries are impeded by the low Coulombic efficiency, inferior cyclability, and poor rate capability, due to the instability of zinc anode. Herein, effective strategies for dendrite‐free zinc anode are symmetrically reviewed, especially highlighting specific mechanisms, delicate design of electrode and current collectors, controlled electrode|electrolyte interface, ameliorative electrolytes, and advanced separators design. First, the particular mechanisms of dendrites formation and the associated fundamentals of the stable Zn metal anodes are presented elaborately. Then, recent key strategies for dendrites prevention and hydrogen evolution reaction suppression are categorized, discussed, and analyzed in detail in view of the electrodes, electrolytes, and separators. Finally, the challenging perspectives and major directions of stable zinc anodes are briefly discussed for further industrialization and commercialization of zinc‐based rechargeable batteries.

Discovering the Intrinsic Causes of Dendrite Formation in Zinc Metal Anodes: Lattice Defects and Residual Stress.

Developing a highly stable and dendrite-free zinc anode is essential to the commercial application of zinc metal batteries. However, the understanding of zinc dendrites formation mechanism is still insufficient. Herein, for the first time, we discover that the interfacial heterogeneous deposition induced by lattice defects and epitaxial growth limited by residual stress are intrinsic and critical causes for zinc dendrite formation. Therefore, an annealing reconstruction strategy was proposed to eliminate lattice defects and stresses in zinc crystals, which achieve dense epitaxial electrodeposition of zinc anode. The as-prepared annealed zinc anodes exhibit dendrite-free morphology and enhanced electrochemical cycling stability. This work first proves that lattice defects and residual stresses are also very important factors for epitaxial electrodeposition of zinc in addition to crystal orientation, which can provide a new mechanism for future researches on zinc anode modification.

Zinc Absorption Estimated by Fecal Monitoring of Zinc Stable Isotopes Validated by Comparison with Whole-Body Retention of Zinc Radioisotopes in Humans

Knowledge about zinc availability from human diets is limited due to methodological difficulties. Recently developed stable isotope techniques for estimating dietary zinc abosrption were compared with radioisotope techniques in five men and three women. Stable and radioactive zinc isotopes were simultaneously administered. Fecal excretion of the isotopes as well as whole-body retention of the radioactive zinc isotope was monitored. Concentration of stable zinc isotope label in fecal samples was determined by inductively coupled plasma mass spectrometry by fully quantitative measurements and from inductively coupled plasma mass spectrometry isotope ratios combined with analysis of total zinc content using atomic absorption spectrometry. Zinc absorption estimated from whole-body retention was 27 ± 6% (x̄ ± SD), estimated zinc absorption obtained by fecal monitoring of radioisotope was 26 ± 9%, and the two stable zinc measurements resulted in values of 29 ± 12 and 33 ± 12%, respectively. There was no signfiicant difference in zinc absorption estimated from whole-body retention and with the fecal monitoring methods. Recovered stable zinc isotope label was significantly lower than recovered radiolsotope. For individual fecal samples, systematic differences of 16% and 12%, respectively (P < 0.05), between the radioisotope recovery and the recovery of stable isotopes with the two methods for measurement was observed. The stable zinc isotope technique for measurement of zinc absorption resulted in mean results similar to those of the radioisotope technique, but with a larger variation in the measurements.

Constructing an ion‐oriented channel on a zinc electrode through surface engineering

AbstractThe inherent shortcomings of a zinc anode in aqueous zinc‐ion batteries (ZIBs) such as zinc dendrites and side reactions severely limit their practical application. Herein, to address these issues, an ion‐oriented transport channel constructed by graphdiyne (GDY) nanowalls is designed and grown in situ on the surface of a zinc electrode. The vertically stacked GDY nanowalls with a unique hierarchical porous structure and mechanical properties form a nanomesh‐like interface on the zinc electrode, acting as an ion‐oriented channel, which can efficiently confine the segmented growth of zinc metal in microscopic regions of hundreds of nanometers. In those microscopic regions, the uniform domain current density is effortlessly maintained compared with a large surface area, thereby inhibiting zinc dendrites effectively. Besides, due to the presence of the ion‐oriented channel, the modified zinc anode demonstrates long‐term stable zinc plating/stripping performance for more than 600 h at 1 mAh cm−2 in an aqueous electrolyte. In addition, full‐cells coupled with MnO2 show high specific capacity and power density, as well as excellent cycling stability with a capacity retention of 82% after 5000 cycles at 1 A g−1. This work provides a feasible and accessible surface engineering approach to modify the electrode interface for confined and dendrite‐free zinc deposition in aqueous ZIBs.

Melamine Foam-Derived Carbon Scaffold for Dendrite-Free and Stable Zinc Metal Anode

Aqueous Zn-ion batteries (AZIBs) are one of the most promising large-scale energy storage devices due to the excellent characteristics of zinc metal anode, including high theoretical capacity, high safety and low cost. Nevertheless, the large-scale applications of AZIBs are mainly limited by uncontrollable Zn deposition and notorious Zn dendritic growth, resulting in low plating/stripping coulombic efficiency and unsatisfactory cyclic stability. To address these issues, herein, a carbon foam (CF) was fabricated via melamine-foam carbonization as a scaffold for a dendrite-free and stable Zn anode. Results showed that the abundant zincophilicity functional groups and conductive three-dimensional network of this carbon foam could effectively regulate Zn deposition and alleviate the Zn anode's volume expansion during cycling. Consequently, the symmetric cell with CF@Zn electrode exhibited lower voltage hysteresis (32.4 mV) and longer cycling performance (750 h) than the pure Zn symmetric cell at 1 mA cm-2 and 1 mAh cm-2. Furthermore, the full battery coupling CF@Zn anode with MnO2 cathode can exhibit a higher initial capacity and better cyclic performance than the one with the bare Zn anode. This work brings a new idea for the design of three-dimensional (3D) current collectors for stable zinc metal anode toward high-performance AZIBs.