Zn Batteries Research Articles

Highly reversible aqueous Zn battery based VS4 microcrystal cathode

Highly reversible aqueous Zn battery based VS4 microcrystal cathode

Zincophilic Interfacial Manipulation against Dendrite Growth and Side Reactions for Stable Zn Metal Anodes.

Constructing multifunctional interphases to suppress the rampant Zn dendrite growth and detrimental side reactions is crucial for Zn anodes. Herein, a phytic acid (PA)-ZnAl coordination compound is demonstrated as a versatile interphase layer to stabilize Zn anodes. The zincophilic PA-ZnAl layer can manipulate Zn2+ flux and promote rapid desolvation kinetics, ensuring the uniform Zn deposition with dendrite-free morphology. Moreover, the robust PA-ZnAl protective layer can effectively inhibit the hydrogen evolution reaction and formation of byproducts, further contributing to the reversible Zn plating/stripping with high Coulombic efficiency. As a result, the Zn@PA-ZnAl electrode shows a lower Zn nucleation overpotential and higher Zn2+ transference number compared with bare Zn. The Zn@PA-ZnAl symmetric cell exhibits a prolonged lifespan of 650 h tested at 5 mA cm-2 and 5 mAh cm-2 . Furthermore, the assembled Zn battery full cell based on this Zn@PA-ZnAl anode also delivers decent cycling stability even under harsh conditions.

Zincophilic Interfacial Manipulation against Dendrite Growth and Side Reactions for Stable Zn Metal Anodes

AbstractConstructing multifunctional interphases to suppress the rampant Zn dendrite growth and detrimental side reactions is crucial for Zn anodes. Herein, a phytic acid (PA)‐ZnAl coordination compound is demonstrated as a versatile interphase layer to stabilize Zn anodes. The zincophilic PA‐ZnAl layer can manipulate Zn2+ flux and promote rapid desolvation kinetics, ensuring the uniform Zn deposition with dendrite‐free morphology. Moreover, the robust PA‐ZnAl protective layer can effectively inhibit the hydrogen evolution reaction and formation of byproducts, further contributing to the reversible Zn plating/stripping with high Coulombic efficiency. As a result, the Zn@PA‐ZnAl electrode shows a lower Zn nucleation overpotential and higher Zn2+ transference number compared with bare Zn. The Zn@PA‐ZnAl symmetric cell exhibits a prolonged lifespan of 650 h tested at 5 mA cm−2 and 5 mAh cm−2. Furthermore, the assembled Zn battery full cell based on this Zn@PA‐ZnAl anode also delivers decent cycling stability even under harsh conditions.

A “Polymer‐in‐Salt” Solid Electrolyte Enabled by Fast Phase Transition Route for Stable Zn Batteries

AbstractSolid polymer electrolyte‐based batteries show great promise because of their safe operating properties, wide voltage window and suitable flexibility. However, low ionic conductivity, low cation transfer number, weak oxidation/reduction resistance and low mechanical strength limit their implementation in Zn ion batteries. Here, w e developed a “polymer‐in‐salt” Zn2+‐conductive solid electrolyte (denoted as 70% salt‐SPE) constructed by a simple and fast phase transition method. The room‐temperature ionic conductivity and the transfer number of the 70% salt‐SPE reaches 1.6 mS cm−1 and 0.78, respectively. Meanwhile, the ZnF2‐rich inorganic/organic hybrid solid electrolyte interface is formed, and the stable voltage window reaches 9.35 V. In consequence, the Zn||Zn symmetric cell continuously cycles over 700 hours at current density of 2 mA cm−2 and the Zn||Cu symmetric battery runs with Coulombic efficiency of >99%. The Zn||MnPBA full battery delivers a discharge specific capacity of 109 mAh g−1 at room temperature and 190 mAh g−1 at 60 °C. Meanwhile, impressive cyclic stability of 6000 cycles with capacity retention of 80% is achieved, which originates from the effectively optimized ion transport action and dendrite‐free Zn plating/stripping.

Self-Adaptive Liquid Film: Dynamic Realization of Dendrite-Free Zn Deposition Toward Ultralong-Life Aqueous Zn Battery.

The poor reversibility and stability of Zn metal anode (ZMA) caused by uncontrolled Zn deposition behaviors and serious side reactions severely impeded the practical application of aqueous Zn metal battery. Herein, a liquid-dynamic and self-adaptive protective layer (LSPL) was constructed on the ZMA surface for inhibiting dendrites and by-products formation. Interestingly, the outer LSPL consists of liquid perfluoropolyether (PFPE), which can dynamically adapt volume change during repeat cycling and inhibit side reactions. Moreover, it can also decrease the de-solvation energy barrier of Zn2+ by strong interaction between C-F bond and foreign Zn2+ , improving Zn2+ transport kinetics. For the LSPL inner region, in-situ formed ZnF2 through the spontaneous chemical reaction between metallic Zn and part PFPE can establish an unimpeded Zn2+ migration pathway for accelerating ion transfer, thereby restricting Zn dendrites formation. Consequently, the LSPL-modified ZMA enables reversible Zn deposition/dissolution up to 2000h at 1mA cm-2 and high coulombic efficiency of 99.8% at 4mA cm-2 . Meanwhile, LSPL@Zn||NH4 V4 O10 full cells deliver an ultralong cycling lifespan of 100 00 cycles with 0.0056% per cycle decay rate at 10 A g-1 . This self-adaptive layer provides a new strategy to improve the interface stability for next-generation aqueous Zn battery.

Lithium Bis(oxalate)borate Additive for Self‐repairing Zincophilic Solid Electrolyte Interphases towards Ultrahigh‐rate and Ultra‐stable Zinc Anodes

AbstractThe artificial solid electrolyte interphase (SEI) plays a pivotal role in Zn anode stabilization but its long‐term effectiveness at high rates is still challenged. Herein, to achieve superior long‐life and high‐rate Zn anode, an exquisite electrolyte additive, lithium bis(oxalate)borate (LiBOB), is proposed to in situ derive a highly Zn2+‐conductive SEI and to dynamically patrol its cycling‐initiated defects. Profiting from the as‐constructed real‐time, automatic SEI repairing mechanism, the Zn anode can be cycled with distinct reversibility over 1800 h at an ultrahigh current density of 50 mA cm−2, presenting a record‐high cumulative capacity up to 45 Ah cm−2. The superiority of the formulated electrolyte is further demonstrated in the Zn||MnO2 and Zn||NaV3O8 full batteries, even when tested under harsh conditions (limited Zn supply (N/P≈3), 2500 cycles). This work brings inspiration for developing fast‐charging Zn batteries toward grid‐scale storage of renewable energy sources.

Synergistic effect of the co-solvent induced interfacial chemistries in aqueous Zn batteries

Aqueous zinc-ion batteries (ZIBs) have garnered significant attention due to their high energy, intrinsic safety, and environmental friendliness. NASICON-type compounds are promising cathode candidates in aqueous batteries due to their high ionic conductivity, and high operating voltage. However, these materials, e.g., Na3V2(PO4)3, suffer from inevitable structural degradation and dissolution in aqueous electrolytes, thus hampering their practical performance in aqueous batteries. Interfacial chemistry modulation by electrolyte engineering is beneficial for stabilizing Zn metal anode and high-voltage cathodes in ZIBs. Herein, the interfacial chemistries in an engineered non-concentrated aqueous electrolyte by co-solvent strategy are reported, which synergistically enables high reversibility of Zn anode and long cycling stability of Na3V2(PO4)3 cathode. Consequently, the Zn||Na3V2(PO4)3 full-cell exhibits high Coulombic efficiency (∼99.3% in average) with a prolonged cycling life, which can be ascribed to the synergistic-effect of the solid-electrolyte interphases with unique organic/inorganic hybrid structures on the electrodes. This work discloses the structures of the interphases formed on the electrodes induced by co-solvent strategy in aqueous electrolytes and their working mechanisms in stabilizing the aqueous Zn batteries, which will guide the future design of advanced aqueous electrolytes with unique interfacial chemistries for batteries.

Lithium Bis(oxalate)borate Additive for Self-repairing Zincophilic Solid Electrolyte Interphases towards Ultrahigh-rate and Ultra-stable Zinc Anodes.

The artificial solid electrolyte interphase (SEI) plays a pivotal role in Zn anode stabilization but its long-term effectiveness at high rates is still challenged. Herein, to achieve superior long-life and high-rate Zn anode, an exquisite electrolyte additive, lithium bis(oxalate)borate (LiBOB), is proposed to in-situ derive a highly Zn2+-conductive SEI and to dynamically patrol its cycling-initiated defects. Profiting from the as-constructed real-time, automatic SEI repairing mechanism, the Zn anode can be cycled with distinct reversibility over 1800 h at an ultrahigh current density of 50 mA cm-2, presenting a record-high cumulative capacity up to 45 Ah cm-2. The superiority of the formulated electrolyte is further demonstrated in the Zn||MnO2 and Zn||NaV3O8 full batteries, even when tested under harsh conditions (limited Zn supply (N/P≈3), 2500 cycles). This work brings inspiration for developing fast-charging Zn batteries toward grid-scale storage of renewable energy sources.

Achieving stable Zn metal anode through novel interface design with multifunctional electrolyte additive

Rechargeable aqueous Zn batteries (RAZBs) are promising for energy storage systems as they are intrinsically safe, cost-effective and environmentally friendly. However, undesired dendrites and corrosion side reactions worsen at cycling, which limit the reversibility and scalable application of RAZBs. This issue arises from the undesired side reactions from corrosion of Zn in regular aqueous electrolytes, which lead to formation of side products, nonuniform Zn nucleation, finally dendrite formation. Here, we report nitrilotriacetic acid (NTA) as a highly efficient functional additive that can preferentially adsorbs on Zn surface, avoiding the direct contact between Zn and water molecules and significantly alleviating corrosion. This clean, protected Zn surface can thus promote uniform Zn plating/stripping. Furthermore, the adsorbed NTA molecules can attract water molecules to facilitate the desolvation of Zn2+ and promote Zn2+ fast transport, as verified both experimentally and computationally. Notably, we found that only a trace amount of NTA (0.15 wt%) is sufficient to form a stable electrode/electrolyte interface, reducing the corrosion rate from 3.63 mA cm−2 to merely 0.22 mA cm−2. This stable interface enabled highly reversible Zn stripping/plating at 5 mA cm−2 and 0.5 mAh cm−2 in symmetric cells, lasting about 2100 h. An outstanding average Coulombic efficiency of 99.40 % in 800 cycles was also achieved. This study provides new insights into realizing highly reversible Zn anodes for RAZBs via the addition of highly efficient, multifunctional electrolyte additive, whose design principle may be generalized to many rechargeable battery systems.

Highly reversible zinc metal anode enabled by zinc fluoroborate salt-based hydrous organic electrolyte

Although Zn(BF4)2 contains favorable ingredients of fluorine for the formation of ZnF2 rich-Zn2+ ion conducting solid electrolyte interface (SEI), the aqueous electrolyte based on inorganic Zn salt of Zn(BF4)2⋅xH2O shows high Hammett acidity with pH value <1, which gives rise to severe corrosion of metallic Zn electrode and thermodynamically spontaneous hydrogen evolution reaction (HER). Meanwhile, an uneven and arbitrarily aggregated SEI will result in uneven distribution of Zn2+ ion flux and electric field, leading to rampant dendrite growth. Here, we employ a hydrophilic organic solvent of vinylene carbonate (VC) and hydrate Zn(BF4)2⋅4H2O salt for a hydrous organic electrolyte, denoted as ZnBF-VC. With the ZnBF-VC electrolyte used, the VC molecules preferably adsorb on the Zn surface to block H2O molecules and Zn metals. Meanwhile, the unique Zn2+-solvation sheath of Zn(VC)2.89(H2O)1.28(BF4)1.83 is formed, which forms an organic/inorganic hybrid SEI in-situ with ZnF2 and ZnCO3 as inorganic species. The distinct SEI enables favorable Zn2+ ion transport and can effectively protect metallic Zn electrode from corrosion, side reactions and dendrite formation. Consequently, the ZnǀǀZn cells cycled over 2200 h at 0.5 mA cm−2 and the ZnǀǀCu asymmetric cells maintained an excellent Coulombic efficiency (CE) of ∼99.7% over 550 cycles at 1 mA cm−2. Whereas, the ZnǀǀZn cells broke after only 74 cycles in aqueous electrolyte. Additionally, the full cell we assembled with manganese hexacyanoferrate (MnHCF) in ZnBF-VC electrolyte demonstrates excellent cycling stability, achieving a high specific capacity of 146.2 mAh g − 1, and a high retention rate of 85.3% over 1300 cycles at 0.4 A g − 1, while the cell using the referred ZnBF-H2O electrolyte survived only ∼6 cycles. This work proposes a feasible direction for the study of Zn(BF4)2-based organic electrolyte for Zn batteries.

Electrolyte Modulation Strategies for Low-Temperature Zn Batteries.

Aqueous rechargeable Zn metal batteries (ARZBs) are extensively studied recently because of their low-cost, high-safety, long lifespan, and other unique merits. However, the terrible ion conductivity and insufficient interfacial redox dynamics at low temperatures restrict their extended applications under harsh environments such as polar inspections, deep sea exploration, and daily use in cold regions. Electrolyte modulation is considered to be an effective way to achieve low-temperature operation for ARZBs. In this review, first, the fundamentals of the liquid-solid transition of water at low temperatures are revealed, and an in-depth understanding of the critical factors for inferior performance at low temperatures is given. Furthermore, the electrolyte modulation strategies are categorized into anion/concentration regulation, organic co-solvent/additive introduction, anti-freezing hydrogels construction, and eutectic mixture design strategies, and emphasize the recent progress of these strategies in low-temperature Zn batteries. Finally, promising design principles for better electrolytes are recommended and future research directions about high-performance ARZBs at low temperatures are provided.

Mediating Triple Ions Migration Behavior via a Fluorinated Separator Interface toward Highly Reversible Aqueous Zn Batteries.

Rampant dendrite growth, electrode passivation and severe corrosion originate from the uncontrolled ions migration behavior of Zn2+ , SO4 2- , and H+ , which are largely compromising the aqueous zinc ion batteries (AZIBs) performance. Exploring the ultimate strategy to eliminate all the Zn anode issues is challenging but urgent at present. Herein, a fluorinated separator interface (PVDF@GF) is constructed simply by grafting the polyvinylidene difluoride (PVDF) on the GF surface to realize high-performance AZIBs. Experimental and theoretical studies reveal that the strong interaction between C─F bonds in the PVDF and Zn2+ ions enables evenly redistributed Zn2+ ions concentration at the electrode interface and accelerates the Zn transportation kinetics, leading to homogeneous and fast Zn deposition. Furthermore, the electronegative separator interface can spontaneously repel the SO4 2- and anchor H+ ions to alleviate the passivation and corrosion. Accordingly, the Zn|Zn symmetric cell with PVDF@GF harvests a superior cycling stability of 500h at 10 mAh cm-2 , and the Zn|VOX full cell delivers 76.8% capacity retention after 1000 cycles at 2 A g-1 . This work offers an all-round solution and provides new insights for the design of advanced separators with ionic sieve function toward stable and reversible Zn metal anode chemistry.

Anchoring Polar Organic Molecules in Defective Ammonium Vanadate for High-Performance Flexible Aqueous Zinc-Ion Battery.

Ammonium vanadate (NVO) often has unsatisfactory electrochemical performance due to the irreversible removal of NH4 + during the reaction. Herein, layered DMF-NVO nanoflake arrays (NFAs) grown on highly conductive carbon cloth (CC) are employed as the binder-free cathode (DMF-NVO NFAs/CC), which produces an enlarged interlayer spacing of 12.6Å (against 9.5 Å for NH4 V4 O10 ) by effective N, N-dimethylformamide (DMF) intercalation. Furthermore, the strong attraction of highly polar carbonyl and ammonium ions in DMF can stabilize the lattice structure, and low-polar alkyl groups can interact with the weak electrostatic generated by Zn2+ , which allows Zn2+ to be freely intercalated. The DMF-NVO NFAs/CC//Zn battery exhibits an impressive high capacity of 536 mAh g-1 at 0.5Ag-1 , excellent rate capability, and cycling performance. The results of density functional theory simulation demonstrate that the intercalation of DMF can significantly reduce the band gap and the diffusion barrier of Zn2+ , and can also accommodate more Zn2+ . The assembled flexible aqueous rechargeable zinc ion batteries (FARZIBs) exhibit outstanding energy density and power density, up to 436Wh kg-1 at 400W kg-1 , and still remains 180Wh kg-1 at 4000W kg-1 . This work can provide a reference for the design of cathode materials for high-performance FARZIBs.

Zn Ionophores to Suppress Hydrogen Evolution and Promote Uniform Zn Deposition in Aqueous Zn Batteries

AbstractUncontrolled Zn dendrites and undesirable side reactions such as Zn self‐corrosion and hydrogen evolution reaction (HER) remain major challenges for the further development of aqueous Zn batteries (AZBs). In this study, macrolide antibiotics are proposed to be added to aqueous electrolyte, serving as Zn ionophores to modulate Zn2+ solvation structure, regulate Zn electrodeposition, and suppress undesirable parasitic reactions. Azithromycin (Azi), a representative macrolide antibiotic, is demonstrated to undergo bidentate coordination with Zn ions and remodel the solvation structure into [ZnAzi(H2O)4]2+. Meanwhile, the self‐corrosion and HER at the Zn anode side are significantly suppressed, evidenced quantitatively by the on‐line hydrogen production monitoring. Furthermore, the promotion of dense and uniform Zn electrodeposition by the ionophores is also confirmed. The repeated Zn plating/stripping test with 0.1 m Azi in electrolyte reaches a high cumulative capacity of 10 Ah cm−2 at a current density of 10 mA cm−2 and an area capacity of 10 mAh cm−2. Moreover, the corresponding Zn‐V2O5 pouch cell achieves stable operation for 100 cycles without bulging caused by gas evolution. Thus, the electrolyte engineering approach presents a practically viable strategy for the development of AZBs.

Linking Interfacial Hydrogen‐Bond Network to Electrochemical Performance of Zinc Anode in Aqueous Solution

AbstractWater‐induced parasitic reaction, e.g., spontaneous corrosion and hydrogen evolution reaction, has been widely recognized as a culprit of the poor electrochemical performance of Zn anode in aqueous electrolyte. Nevertheless, how the interfacial water, the pertinent participant of the Zn electrochemistry, affects the parasitic reaction occurring on Zn anode remains incompletely understood. Herein, a step forward toward understanding the relationship of the hydrogen‐bond network of interfacial water and the electrochemical performance of Zn anode is reported, where the structure of interfacial water can be regulated by (aminomethyl)phosphonic acid (AMPA), a molecular additive that can specifically adsorb on Zn surface. Direct spectral evidence coupled with theoretical calculation reveals that the AMPA preferentially adsorbs on the Zn anode surface that serves as a shield for water dissociation (i.e., spontaneous corrosion). Moreover, AMPA can promote interfacial water toward ordered H‐bond network with high electrochemical stability at electrified interface. As a result, water‐induced parasitic reaction has been significantly suppressed, enabling a dendrite‐free Zn2+ deposition, an exceptional high coulombic efficiency, prolonged longevity of model Zn/Zn cells, and improved Zn//NH4V4O10 full battery. The results presented here underscore the ramifications of interfacial water structure and provide design criteria for versatile electrolytes of rechargeable Zn batteries.

Progress Towards the Development and Understanding of Energy Dense Rechargeable Batteries Utilizing Zn and Cu

Batteries are easy to use, remotely monitorable, not fuel dependent, easily permitted and installed, and start automatically and reliably during an electrical outage. This makes them optimal for stationary storage and power assurance applications. Within battery-based grid storage, as of mid-2017, lithium-ion, sodium-ion, and lead-acid systems are the leaders, comprising 59% (~1.1 GW), 8% (0.15 GW), and 3% (0.06 GW) of global operational electrochemical storage, respectively.However, these batteries suffer from low energy density, high cost, poor safety, environmental concerns, and/or cycle life. Existing battery options on the market also do not meet the required market needs for long-duration backup power. For example, lead-acid batteries require too much space, are heavy, and contain toxic materials. Lithium-ion batteries, while compact and capable of excellent cycle life, are too expensive to serve long outages and have notable flammability and environmental risks.Alkaline Zn batteries are a strong candidate for electrical grid storage applications due to Zn’s high capacity (820 mAh/g), established materials supply chain and low cost. To realize the highest energy dense batteries, Zn needs to be coupled with a similarly low cost, abundant and high-capacity cathode. CuO (674 mAh/g) is an intriguing high-capacity cathode when paired with Zn in alkaline electrolyte, a battery that until recently has been relegated to the history books as a primary system. In 2021 Schorr et al. reported a rechargeable Zn/CuO battery that utilized a Bi additive to help facilitate the electrochemical reversibility of the Cu conversion electrode. Bi2O3, a species with comparable redox potentials to Cu2O, promoted reversibility and minimized passivation in the historically non-reversible system. The battery cycled without any observable Cu and Bi mixed oxide phases, cycling between metallic Cu and Bi and Cu2O/Cu(OH)2 and Bi2O3, respectively. Although the Bi additive did not eliminate capacity fade completely, limiting the cells to a 30% depth of discharge (relative to CuO) enabled 250 cycles at > 124 Wh/L. Alternatively, compensating for capacity loss with additional Cu metal provided for very high areal capacities (∼40 mA h/cm2) and energy densities (∼260 W h/L), despite only 65% active material cathode loadings and ∼10% Zn anode utilization; preliminary tests indicated these batteries were prone to shorting.Seeking to improve performance and minimize the spatial segregation of Cu- and Bi-phases observed upon cycling in the prior system, D. Arnot et al. prepared nanoscale carbon coated (Cu/Bi) particles, where the coating partially minimized dissolution and diffusion of soluble cuprate and bismuthate complexes, where ~ 200 cycles at 300 mAh/g was demonstrated (@ ~ 100 Wh/L). CuBi2O4 and CuO phases were formed upon oxidation, indicating carbon coatings can affect the battery cycling mechanism and may have future roles increasing performance. Data collected from a variety of experimental techniques, including cyclic voltammetry, rotating ring-disk electrode voltammetry, electrochemical impedance spectroscopy, electron microscopy, transmission electron microscopy, Raman spectroscopy, operando energy-dispersive X-ray diffraction measurements, battery cycling along with recent DFT modeling will be presented to help elucidate the role of additives, carbon coatings, and ion selective polymers in enabling reversible Zn/Cu based batteries. In addition, the general challenges of achieving a highly reversible energy dense battery based on two conversion electrodes operating in highly alkaline environment will be discussed.The goal is to demonstrate a Zn/CuO battery with long lifetime, at appreciable energy densities (> 200 Wh/L), with excellent safety, lower toxicity and sufficiently low cost to be manufactured and installed on the grid. While the laboratory scale Zn/CuO battery builds have very promising characteristics to date they have not been optimized or adapted for consumer or market-based needs in terms of power performance, energy density, cycle life or stability in terms of shelf life and the ability to tolerate partial state of charge. Progress towards these goals may also be discussed.N. B. Schorr et al. Rechargeable Alkaline Zinc/Copper Oxide Batteries. ACS Applied Energy Mater. 2021, 4, 7, 7073–7082. https://doi.org/10.1021/acsaem.1c01133.D. J. Arnot et al. Rechargeable Alkaline Zn-Cu Batteries Enabled by Carbon Coated Cu/Bi Particles. J. Power Sources 2022, 529, 231168. https://doi.org/10.1016/j.jpowsour.2022.231168.This work was supported by the U.S. Department of Energy, Office of Electricity, and the Laboratory Directed Research and Development program at Sandia National Laboratories. Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA-0003525. The views expressed herein do not necessarily represent the views of the U.S. Department of Energy or the United States Government.

Fulfilling the High Capacity of Zn Anodes in Rechargeable Alkaline Zn Batteries

A Zn anode in an alkaline electrolyte is often discharged to a shallow depth for an adequate cycle life. It limits the overall cell energy density and undermines its competitiveness against ever-improving lithium-ion cells. Our lab has been pushing the capacity limit of the alkaline Zn anode by understanding its failure mechanism and designing electrode microstructures and electrolyte alkalinity. I will discuss how we can revamp the paths of phase transition between Zn and ZnO by building a bi-continuous porous Zn anode and how a super-alkaline electrolyte can stabilize the anode at 60% depth of discharge. The mechanisms underlying the designs, including the interface-controlled structural evolution and the structural diffusion of alkaline electrolytes, will be explained to shed light on the future development of rechargeable Zn batteries.

Role of Acetonitrile Additive in Enhanced Performances of Aqueous Zn Anodes

Zinc-ion batteries have been proposed as promising candidates to address ever-growing demands for energy storage and limited resources available for the currently used lithium-battery systems. Despite their promise, the apparent advantages of aqueous zinc-ion batteries (low cost and high energy density) are still overshadowed by uncontrolled water interactions at the zinc metal-electrolyte interface, such as the hydrogen evolution reaction and electrode corrosion. A number of different strategies – e.g., water-in-salt, addition of chelating agents and/or co-solvents – have been proposed to overcome the aforementioned interfacial problems. Among them, the addition of acetonitrile to aqueous ZnSO4-based electrolytes has shown great promise, with reports of improved Coulombic efficiencies and increased cycle life. However, the actual role of this additive remains unclear. In this work, we determine the mechanistic principles behind the participation of acetonitrile in enhancing the performance of aqueous Zn batteries. For this purpose, we utilized a combination of X-ray absorption and Raman spectroscopies, cyclic voltammetry, and galvanostatic coin cell cycling. Our results indicate that the addition of acetonitrile perturbs the interfacial solvation structure, rather than the bulk. Specifically, acetonitrile does not penetrate the first solvation shell of the Zn2+ ion, but does modify interfacial solvation behavior, likely by physisorption to the electrode surface. The Coulombic efficiency of half cells was found to depend on electrode material, employed current density and capacity, and only moderately on acetonitrile concentration. Overall, this works points strongly to the need for systematic evaluation of battery performance in co-solvent systems, and provides a new framework for future efforts to optimize ion transport and performance in zinc-ion batteries._______________________The submitted manuscript has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory (“Argonne”). Argonne, a U.S. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357. The U.S. Government retains for itself, and others acting on its behalf, a paid-up nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan. http://energy.gov/downloads/doe-public-access-plan

Hemimorphite /C interface layer with dual-effect methodically redistricted Zn2+ deposition behavior for dendrite-free zinc metal anodes

The uneven distribution of Zn2+ gradient and electric fields at the electrolyte–anode interface are the two “pain points” that seriously limit the lifespan of AZIBs. Traditional artificial SEI layers targeted one single “pain points” cannot simultaneously balance the Zn2+ gradient and electric fields. Herein, hemimorphite/C interface layer, sandwich structure Zn4(Si2O7)(OH)2·H2O@rGO@Zn4(Si2O7)(OH)2·H2O (rGO@ZnSi) prepared by in-situ growth strategy is provided as “dual-effect” to modulate Zn2+ gradient and electric fields regulation. The rGO@ZnSi is demonstrated with the zincophilicity due to Zn-ion-conducive transport channel about 5Å and boosted electroconductibility properties by in situ growth rGO. The internal rGO acts as conductive core, facilitating the rapid transfer of electrons along the two-dimensional plane, thus significantly enhancing the conductivity of hemimorphite. Additionally, it opens up a new territory for Zn2+ reduction process, which would enhance the reversibility of Zn anode, mitigate the polarization and promote electrochemical performance. The Zn//Zn battery with the modified rGO@ZnSi SEI exhibits an ultra-long and outstanding cycling stability of up to 170 days. Benefitting from the rGO@ZnSi SEI, the rGO@ZnSi-Zn//V2O5 full battery delivers a high discharge capacity and long cycle performance. The “dual-effect” rGO@ZnSi SEI escorts for the dendrite-free zinc metal anodes with lifetime extension, ultra-high rate performance and cost-effectiveness.

Colossal Capacity Loss during Calendar Aging of Zn Battery Chemistries

Colossal Capacity Loss during Calendar Aging of Zn Battery Chemistries