Oxygen-Vacancy-Reinforced Vanadium Oxide/Graphene Heterojunction for Accelerated Zinc Storage with Long Life Span.

Vanadium trioxide (V6 O13 ) cathode has recently aroused intensive interest for aqueous zinc-ion batteries (AZIBs) due to their structural and electrochemical diversities. However, it undergoes sluggish reaction kinetics and significant capacity decay during prolonged cycling. Herein, an oxygen-vacancy-reinforced heterojunction in V6 O13- x /reduced graphene oxide (rGO) cathode is designed through electrostatic assembly and annealing strategy. The abundant oxygen vacancies existing in V6 O13- x weaken the electrostatic attraction with the inserted Zn2+ ; the external electric field constructed by the heterointerfaces between V6 O13- x and rGO provides additional built-in driving force for Zn2+ migration; the oxygen-vacancy-enriched V6 O13- x highly dispersed on rGO fabricates the interconnected conductive network, which achieves rapid Zn2+ migration from heterointerfaces to lattice. Consequently, the obtained 2D heterostructure exhibits a remarkable capacity of 424.5 mAh g-1 at 0.1 A g-1 , and a stable capacity retention (96% after 5800 cycles) at the fast discharge rate of 10 A g-1 . Besides, a flexible pouch-type AZIB with real-life practicability is fabricated, which can successfully power commercial products, and maintain stable zinc-ion storage performances even under bending, heavy strikes, and pressure condition. A series of quantitative investigation of pouch batteries demonstrates the possibility of pushing pouch-type AZIBs to realistic energy storage market.

Self-Assembled Layer of Organic Phosphonic Acid Enables Highly Stable MnO2 Cathode for Aqueous Znic Batteries.

Manganese dioxide (MnO2) is an attractive cathode material for aqueous zinc batteries (AZBs) owing to its environmental benignity, low cost, high operating voltage, and high theoretical capacity. However, the severe dissolution of Mn2+ leads to rapid capacity decay. Herein, a self-assembled layer of amino-propyl phosphonic acid (AEPA) on the MnO2 surface, which significantly improves its cycle performance is successfully modified. Specifically, AEPA can be firmly attached to MnO2 through a strong chemical bond, forming a hydrophobic, and uniform organic coating layer with a few nanometers thickness. This coating layer can significantly inhibit the dissolution of Mn2+ by avoiding the direct contact between the electrolyte and cathode, thus enhancing the structural integrity and redox reversibility of MnO2. As a result, the MnO2@AEPA cathode achieves a high reversible capacity of 223 mAh g-1 at 0.5 A g-1 and a high capacity retention of 97% after 1700 cycles at 1 A g-1. This work provides new insights in developing stable Mn-based cathodes for aqueous batteries.

N-Doped Ti3C2Tx Interfacial Layer Enabling Uniform Zn Deposition along (002) Plane for Stable Aqueous Zinc-Ion Battery.

Aqueous zinc-ion batteries hold great potentials for large-scale grid energy storage. However, the electrode corrosion, hydrogen evolution, and dendrite growth of Zn anode often lead to cell failure. Herein, N groups in Ti3C2Tx (NMXH) are introduced as interfacial layer through hydrothermal treatment of Ti3C2Tx with urea. The experimental analysis and density functional theory calculation indicate that N groups in Ti3C2Tx can homogenize electric field distribution, promote adsorption of Zn2+ on N groups, and strength interactions between N groups and Zn atoms on (002) plane. Thereby, the use of NMXH interfacial layer can effectively suppress the side reactions and realize uniform Zn deposition along the (002) plane. As a consequence, the NMXH─Zn//Zn cell exhibits an ultralow nucleation overpotential (1 mA cm-2, 18.9 mV) and can stably operate for 1400 h at 1 mA cm-2 (1 mAh cm-2) and 110 h at 40 mA cm-2 (1 mAh cm-2). A full battery with V2O5 nanowires as cathode displays a discharge capacity of 219 mAh g-1 (1.0 A g-1), along with a decent rate capability and cyclability. The significant role of N groups reported in this work offers a promising avenue to improve the cycling stability of Zn anodes of aqueous zinc batteries.

A High Capacity p-Type Organic Cathode Material for Aqueous Zinc Batteries.

P-type organic cathode materials typically exhibit high redox potentials and fast redox kinetics, presenting broad application prospects in aqueous zinc batteries (AZBs). However, most of the reported P-type organic cathode materials exhibit limited capacity (< 100 mAh g-1), which is attributable to the low mass content ratio of oxidation-reduction active functional groups in these materials. Herein, we report a high-capacity p-type organic material, 5,12-dihydro-5,6,11,12-tetraazatetracene (DHTAT), for aqueous zinc batteries. Both experiments and calculation indicate the charge storage of DHTAT involves the adsorption/ desorption of ClO4- on the -NH- group. Benefitting from the high mass content ratio of the -NH- group in DHATA molecule, the DHATA electrode demonstrates a remarkable capacity of 224 mAh g-1 at a current density of 50 mA g-1 with a stable voltage of 1.2 V. Notably, after 5000 cycles at a high current density of 5 A g-1, DHTAT retains 73% of its initial capacity, showing a promising cycling stability. In addition, DHTAT also has good low-temperature performance and can stably cycle at -40 °C for 4000 cycles at 1 A g-1, making it a competitive candidates cathode material for low-temperature batteries.

Electric Double Layer Regulator Design through a Functional Group Assembly Strategy towards Long-Lasting Zinc Metal Batteries.

Regulating the electric double layer (EDL) structure of the zinc metal anode by using electrolyte additives is an efficient way to suppress interface side reactions and facilitate uniform zinc deposition. Nevertheless, there are no reports investigating the proactive design of EDL-regulating additives before the start of experiments. Herein, a functional group assembly strategy is proposed to design electrolyte additives for modulating the EDL, thereby realizing a long-lasting zinc metal anode. Specifically, by screening ten common functional groups, N, N-dimethyl-1H-imidazole-1-sulfonamide (IS) is designed by assembling an imidazole group, characterized by its high adsorption capability on the zinc anode, and a sulfone group, which exhibits strong binding with Zn2+ ions. Benefiting from the adsorption functionalization of the imidazole group, the IS molecules occupy the position of H2O in the inner Helmholtz layer of the EDL, forming a molecular protective layer to inhibit H2O-induced side reactions. Meanwhile, the sulfone group in IS, acting as a binding site to Zn2+, promotes the de-solvation of Zn2+ ions, facilitating compact zinc deposition. Consequently, the utilization of IS significantly extending the cycling stability of Zn||Zn and Zn||NaV3O8 ⋅ 1.5H2O full cell. This study offers an innovative approach to the design of EDL regulators for high-performance zinc metal batteries.

Converting Commercial Zn Foils into Single (002)-Textured Zn with Millimeter-Sized Grains for Highly Reversible Aqueous Zinc Batteries.

Rechargeable aqueous zinc batteries are promising but hindered by unfavorable dendrite growth and side reactions on zinc anodes. In this study, we demonstrate a fast melting-solidification approach for effectively converting commercial Zn foils into single (002)-textured Zn featuring millimeter-sized grains. The melting process eliminates initial texture, residual stress, and grain size variations in diverse commercial Zn foils, guaranteeing the uniformity of commercial Zn foils into single (002)-textured Zn. The single (002)-texture ensures large-scale epitaxial and dense Zn deposition, while the reduction in grain boundaries significantly minimizes intergranular reactions. These features enable large grain single (002)-textured Zn shows planar and dense Zn deposition under harsh conditions (100 mA cm-2, 100 mAh cm-2), impressive reversibility in Zn||Zn symmetric cell (3280 h under 1 mA cm-2, 830 h under 10 mAh cm-2), and long cycling stability over 180 h with a high depth of discharge value of 75 %. This study successfully addresses the issue of uncontrollable texture formation in Zn foils following routine annealing treatments with temperatures below the Zn melting point. The findings of this study establish a highly efficient strategy for fabricating highly reversible single (002)-textured Zn anodes.

Aligned Dipoles Induced Electric-Field Promoting Zinc-Ion De-Solvation toward Highly Stable Dendrite-Free Zinc-Metal Batteries.

Water-induced parasitic reactions and uncontrolled dendritic Zn growth are long-lasting tricky problems that severely hinder the development of aqueous zinc-metal batteries. Those notorious issues are closely related to electrolyte configuration and zinc-ion transport behavior. Herein, through constructing aligned dipoles induced electric-field on Zn surface, both the solvation structure and transport behavior of zinc-ions are fundamentally changed. The vertically ordered zinc-ion migration trajectory and gradually concentrated zinc-ion achieved inside the polarized electric-field remarkably eliminate water related side-reactions and Zn dendrites. Zn-metal under the polarized electric-field demonstrated significantly improve reversibility and a dendrite-free surface with strong (002) Zn deposition texturing. Zn||Zn symmetric cell delivers greatly prolonged lifespan up to 1400 h (17 times longer than that of the cell based on bare Zn) while the Zn||Cu half-cell demonstrate ultrahigh 99.9% coulombic efficiency. NH4 V4 O10 ||Zn half-cell delivered exceptional-high 132 mAh g-1 capacity after ultralong 2000 cycles (≈100% capacity retention). In addition, MnO2 ||Zn pouch-cell under aligned dipoles induced electric-field maintains 87.9% capacity retention after 150 cycles under practical condition of high MnO2 mass loading (≈10 mg cm-2 ) and limited N/P ratio. It is considered that this new strategy can also be implemented to other metallic batteries and spur the development of batteries with long-lifespan and high-energy-density.

Brønsted-Lowry Acid-Based Aqueous Eutectic Electrolyte for Practical Zinc Batteries.

Aqueous highly concentrated electrolytes (AHCEs) have recently emerged as an innovative strategy to enhance the cycling stability of aqueous Zinc (Zn) batteries (AZB). Particularly, thanks to high Zn Chloride (ZnCl2 ) solubility in water, AHCEs based on ZnCl2 feature remarkable Zn anode stability. However, due to their inherently acidic pH and Cl- anion reactivity, these electrolytes face compatibility challenges with other battery components. Here, an aqueous eutectic electrolyte (AEE) based on Brønsted-Lowry concept is reported-allowing the usage of cheap and abundant salts, ZnCl2, and sodium acetate (NaAc). The reported, pH buffered, AEE displays a higher coordination of water at an even lower salt concentration, by simply balancing the acceptor-donor H─bonding. This results in impressive improvement of electrolyte properties such as high electrochemical stability, high transport properties and low glass transition temperature. The developed AEE displays higher compatibility with vanadium oxide-based cathode with a 50% increase in capacity retention in comparison to sat. ZnCl2 . More importantly, the pH buffered AEE solves the incompatibility issues of ZnCl2 toward commonly used aluminium (Al) current collector as well as cellulose separator. This work presents an efficient, simple, and low-cost strategy for the development of aqueous electrolytes for the practical application of Zn batteries.

Oriented Zinc Metal Anode Based on Directional Recognition and Assembly.

The practical application of aqueous zinc batteries are highly limited by unsatisfied Zn anodes for the unavoidable dendrite growth and side reactions. Crystal orientation engineering is an effective way to overcome these inherent drawbacks. However, how to achieve Zn plating with manipulated crystallographic orientation is still a great challenge. Herein, a uniform (002)-oriented Zn metal anode is reported based on a directional cation recognition and crystal assembly strategy. The activated layered double hydroxide (Act-LDH) exhibits favorable adsorption energy with Zn2+ and high lattice matching with Zn (002) plane, which can be served as directional recognition layer to anchor Zn2+ and regulate crystallographic orientation of Zn as well. As demonstration, Zn crystals with ultrahigh ratio of (002)/(100) plane of 15.7 are assembled parallelly on horizontal Act-LDH, in which high CE of 99.85% maintains over 18 000 cycles. The symmetric battery with (002)-oriented Zn shows stable plating/stripping process over 1650 and 420 h at 1 mA cm-2 /0.5 mA h cm-2 and 10 mA cm-2 /5 mA h cm-2 , respectively, which is 9 and 12 times higher than unoriented polycrystalline Zn. Moreover, as-assembled full battery displays high specific capacity of 120 mA h g-1 at 2 A g-1 over 1800 cycles.

Low-Concentration Redox-Electrolytes for High-Rate and Long-Life Zinc Metal Batteries.

The uncontrolled zinc electrodeposition and side reactions severely limit the power density and lifespan of Zn metal batteries. Herein, the multi-level interface adjustment effect is realized with low-concentration redox-electrolytes (0.2 m KI) additives. The iodide ions adsorbed on the zinc surface significantly suppress water-induced side reactions and by-product formation and enhance the kinetics of zinc deposition. The distribution of relaxation times results reveal that iodide ions can reduce the desolvation energy of hydrated zinc ions and guide the deposition of zinc ions due to their strong nucleophilicity. As a consequence, the Zn||Zn symmetric cell achieves superior cycling stability (>3000 h at 1 mA cm-2 , 1 mAh cm-2 ) accompanied by a uniform deposition and a fast reaction kinetics with a low voltage hysteresis (<30 mV). Additionally, coupled with an activated carbon (AC) cathode, the assembled Zn||AC cell delivers a high-capacity retention of 81.64% after 2000 cycles at 4 A g-1 . More importantly, the operando electrochemical UV-vis spectroscopies show that a small number of I3 - can spontaneously react with the dead zinc as well as basic zinc saltsand regenerate iodide ions and zinc ions; thus, the Coulombic efficiency of each charge-discharge process is close to 100%.

Elucidating the Reaction Mechanism of Mn2+ Electrolyte Additives in Aqueous Zinc Batteries.

Aqueous zinc batteries (ZIBs) have attracted considerable attention in recent years because of their high safety and eco-friendly features. Numerous studies have shown that adding Mn2+ salts to ZnSO4 electrolytes enhanced overall energy densities and extended the cycling life of Zn/MnO2 batteries. It is commonly believed that Mn2+ additives in the electrolyte inhibit the dissolution of MnO2 cathode. To better understand the role of Mn2+ electrolyte additives, the ZIB using a Co3 O4 cathode instead of MnO2 in 0.3 m MnSO4 + 3 m ZnSO4 electrolyte is built to avoid interference from MnO2 cathode. As expected, the Zn/Co3 O4 battery exhibits electrochemical characteristics nearly identical to those of Zn/MnO2 batteries. Operando synchrotron X-ray diffraction (XRD), ex situ X-ray absorption spectroscopy (XAS), and electrochemical analyses are carried out to determine the reaction mechanism and pathway. This work demonstrates that the electrochemical reaction occurring at cathode involves a reversible Mn2+ /MnO2 deposition/dissolution process, while a chemical reaction of Zn2+ /Zn4 SO4 (OH)6 ∙5H2 O deposition/dissolution is involved during part of the charge/discharge cycle due to the change in the electrolyte environment. The reversible Zn2+ /Zn4 SO4 (OH)6 ∙5H2 O reaction contributes no capacity and lowers the diffusion kinetics of the Mn2+ /MnO2 reaction, which prevents the operation of ZIBs at high current densities.

Manipulating Coulombic Efficiency of Cathodes in Aqueous Zinc Batteries by Anion Chemistry.

Electrolyte environments, including cations, anions, and solvents are critical for the performance delivery of cathodes of batteries. Most works focused on interactions between cations and cathode materials, in contrast, there is a lack of in-depth research on the correlation between anions and cathodes. Here, we systematically investigated how anions manipulate the coulombic efficiency (CE) of cathodes of zinc batteries. We take intercalation-type V2 O5 and conversion-type I2 cathodes as typical cases for profound studies. It was found that electronic properties of anions, including charge density and its distribution, can tune conversion or intercalation reactions, leading to significant CE differences. Using operando visual Raman microscopy and theoretical simulations, we confirm that competitive coordination between anions and I- can regulate CEs by modulating polyiodide diffusion rates in Zn-I2 cells. In Zn-V2 O5 cells, anion-tuned solvation structures vastly affect CEs through varying Zn2+ intercalation kinetics. Conversion I2 cathode achieves a 99 % CE with highly electron-donating anions, while anions with preferable charge structures that interact strongly with Zn2+ afford an intercalation V2 O5 a nearly 100 % CE. Understanding the mechanism of anion-governed CEs will help us evaluate compatibility of electrolytes with electrodes, thus providing a guideline for anion selection and electrolyte design for high-energy, long-cycling zinc batteries.

A Reversible Six-Electron Transfer Cathode for Advanced Aqueous Zinc Batteries.

The electrochemical reactions for the storage of Zn2+ while embracing more electron transfer is a foundation of the future high-energy aqueous zinc batteries. Herein, we report a six-electron transfer electrochemistry of nano-sized TeO2 /C (n-TeO2 /C) cathode by facilitating the reversible conversion of TeO2 ↔Te and Te↔ZnTe. Benefitting from the integrated conductive nanostructure and the proton-rich environment in providing optimized electrochemical kinetics (facilitated Zn2+ uptake and high electronic conductivity) and feasible thermodynamic process (low Gibbs free energy change), the as-prepared n-TeO2 /C with stable cycling performance exhibits a superior reversible capacity of over 800 mAh g-1 at 0.1 A g-1 . A precise understanding of the reaction mechanism via ex situ and in situ characterizations presents that the reversible six-electron transfer reaction is proton-dependent, and a proton generating and consuming mechanism of three-phase conversion n-TeO2 /C in the weakly acidic electrolyte is thoroughly revealed.

A Bio-Inspired Trehalose Additive for Reversible Zinc Anodes with Improved Stability and Kinetics.

The moderate reversibility of Zn anodes, as a long-standing challenge in aqueous zinc-ion batteries, promotes the exploration of suitable electrolyte additives continuously. It is crucial to establish the absolute predominance of smooth deposition within multiple interfacial reactions for stable zinc anodes, including suppressing side parasitic reactions and facilitating Zn plating process. Trehalose catches our attention due to the reported mechanisms in sustaining biological stabilization. In this work, the inter-disciplinary application of trehalose is reported in the electrolyte modification for the first time. The pivotal roles of trehalose in suppressed hydrogen evolution and accelerated Zn deposition have been investigated based on the principles of thermodynamics as well as reaction kinetics. The electrodeposit changes from random accumulation of flakes to dense bulk with (002)-plane exposure due to the unlocked crystal-face oriented deposition with trehalose addition. As a result, the highly reversible Zn anode is obtained, exhibiting a high average CE of 99.8 % in the Zn/Cu cell and stable cycling over 1500 h under 9.0 % depth of discharge in the Zn symmetric cell. The designing principles and mechanism analysis in this study could serve as a source of inspiration in exploring novel additives for advanced Zn anodes.

Fine-Tuning Electrolyte Concentration and Metal-Organic Framework Surface toward Actuating Fast Zn2+ Dehydration for Aqueous Zn-Ion Batteries.

Functional porous coating on zinc electrode is emerging as a powerful ionic sieve to suppress dendrite growth and side reactions, thereby improving highly reversible aqueous zinc ion batteries. However, the ultrafast charge rate is limited by the substantial cation transmission strongly associated with dehydration efficiency. Here, we unveil the entire dynamic process of solvated Zn2+ ions' continuous dehydration from electrolyte across the MOF-electrolyte interface into channels with the aid of molecular simulations, taking zeolitic imidazolate framework ZIF-7 as proof-of-concept. The moderate concentration of 2 M ZnSO4 electrolyte being advantageous over other concentrations possesses the homogeneous water-mediated ion pairing distribution, resulting in the lowest dehydration energy, which elucidates the molecular mechanism underlying such concentration adopted by numerous experimental studies. Furthermore, we show that modifying linkers on the ZIF-7 surface with hydrophilic groups such as -OH or -NH2 can weaken the solvation shell of Zn2+ ions to lower the dehydration free energy by approximately 1 eV, and may improve the electrical conductivity of MOF. These results shed light on the ions delivery mechanism and pave way to achieve long-term stable zinc anodes at high capacities through atomic-scale modification of functional porous materials.

Bifunctional Interphase with Target-Distributed Desolvation Sites and Directionally Depositional Ion Flux for Sustainable Zinc Anode.

Aqueous zinc batteries (AZBs) feature high safety and low cost, but intricate anodic side reactions and dendrite growth severely restrict their commercialization. Herein, ethylenediaminetetraacetic acid (EDTA) grafted metal organic framework (MOF-E) is proposed as a dually-functional anodic interphase for sustainable Zn anode. Specifically, the target-distributed EDTA serves as an ion-trapped tentacle to accelerate the desolvation and ionic transport by powerful chemical coordination, while the MOFs offer suitable ionic channels to induce oriented deposition. As a result, MOF-E interphase fundamentally suppresses side reactions and guides horizontally arranged Zn deposition with (002) preferred orientations. The Zn|MOF-E@Cu cell exhibits a markedly improved Coulombic efficiency of 99.7 % over 2500 cycles, and the MOF-E@Zn|KVOH (KV12 O30-y ⋅ nH2 O) cell yields a steady circulation of 5000 cycles@90.47 % at 8 A g-1 .

Decavanadate Doped Polyaniline for Aqueous Zinc Batteries.

Polyaniline (PANI) is a promising cathode material for aqueous rechargeable zinc batteries (ARZBs), mainly benefitting from its good electrical conductivity. The high conductivity of PANI requires high doping level, yet the introduced nonactive dopants (e.g., SO4 2- ) limit the gravimetric capacity of PANI (usually < 180 mAh g-1 ). Herein, an electro-active dopant (decavanadate anion, V10 O28 6- ) is employed to fabricate the PANI cathode (PANI-V10 O28 ) for ARZBs. The doped decavanadate anion with the sub-nanometer structure can fully expose the V-based active sites, exhibiting good electrochemical activity. Due to the steric hindrance effect as well as the strong interaction between decavanadate anions and PANI chains, the active dopants are trapped in the polymer chains, demonstrating good structural and electrochemical stability. PANI-V10 O28 achieves a record-high gravimetric capacity of 355 mAh g-1 at 0.1 A g-1 , which is significantly higher than other reported PANI cathodes. Experimental results suggest that the charge storage mechanism of PANI-V10 O28 includes reversible injection/extraction of Zn(H2 O)2 Cl4 2- ions in PANI, as well as the protonation/deprotonation of V10 O28 6- . This work enriches the doping chemistry of conducting polymer and pushes the development of organic cathodes for ARZBs to a new stage.

Hierarchical Heterostructure Engineering of Layered Double Hydroxides on Nickel Sulfides Heteronanowire Arrays as Efficient Cathode for Alkaline Aqueous Zinc Batteries.

Aqueous alkaline rechargeable nickel-zinc (Ni-Zn) batteries possess great potential for large-scale energy storage systems because of their high output voltage, cheap cost, and intrinsic safety. However, the practical applicability of Ni-Zn batteries has been limited by traditional Ni-based cathodes with low capacity and poor cycle stability. Rational design of electrode structure and composition is highly desired but still significantly challenging. Herein, uniform self-supported hierarchical heterostructure composites interacting NiCo-layered double hydroxide with 1D nickel sulfides heteronanowire rooted on Ni foam (NF\Ni3 S2 /NiS@NiCo-LDH) are successfully developed by a hydrothermal sulfurization-electrodeposition process. The self-supported 3D hierarchical heterostructured composites nanoarray provides abundant reactive sites, rapid ion diffusion channels, and fast electron transfer routes, as well as strong structural stability. More significantly, the strong interfacial charge transfer between Ni3 S2 /NiS heteronanowire and NiCo-LDH effectively modifies the electronic structure of the composites and thereby improving the reaction kinetics. Consequently, the NF\Ni3 S2 /NiS@NiCo-LDH electrode presents a superior capacity of 434.5 mAh g-1 (1.73 mAh cm-2 ) at 3 mA cm-2 . In addition, the fabricated NF\Ni3 S2 /NiS@NiCo-LDH//Zn battery can offer a maximal energy density and power density as large as 556.3 Wh kg-1 and 26.3 kW kg-1 , respectively, as well as an exceptional cycling performance.

Regulating Surface Reaction Kinetics through Ligand Field Effects for Fast and Reversible Aqueous Zinc Batteries.

Designing water-deficient solvation sheath of Zn2+ by ligand substitution is a widely used strategy to protect Zn metal anode, yet the intrinsic tradeoff between Zn nucleation/dissolution kinetics and the side hydrogen evolution reaction (HER) remains a huge challenge. Herein, we find boric acid (BA) with moderate ligand field interaction can partially replace H2 O molecules in the solvation sheath of Zn2+ , forming a stable water-deficient solvation sheath. It enables fast Zn nucleation/dissolution kinetics and substantially suppressed HER. Crucially, by systematically comparing the ligand field strength and solvation energies between BA and the ever-reported electrolyte additives, we also find that the solvation energy has a strong correlation with Zn nucleation/dissolution kinetics and HER inhibition ability, displaying a classic volcano behavior. The modulation map could provide valuable insights for solvation sheath design of zinc batteries and beyond.

Regulating Exposed Facets of Metal-Organic Frameworks for High-rate Alkaline Aqueous Zinc Batteries.

Metal-organic frameworks (MOFs) have drawn growing attention as promising electrode candidates for rechargeable batteries. However, most studies focus on the direct use of MOF electrodes without any modification. Post-synthetic modification, a judicious tool to modify targeted properties of MOFs, has been long-neglected in the field of batteries. Herein, crystal-facet engineering is proposed to design MOF-based electrodes with high capacity and fast electrochemical kinetics. We found that a thermally-modified strategy can regulate the dominant exposed facet of Ni-based MOF (PFC-8). With the optimally exposed facets, the battery exhibited admirable rate capability (139.4 mAh g-1 at 2.5 A g-1 and 110.0 mAh g-1 at 30 A g-1 ) and long-term stability. Furthermore, density functional theory calculations demonstrate that stronger OH- adsorption behaviors and optimized electronic structures induced by the regulated exposed facets boost the electrochemical performance.