Efficient Catalysis of Ultrathin Two-Dimensional Fe2 O3 -CoP Heterostructure Nanosheets for Polysulfide Redox Reactions.

The "shuttle effect" and slow redox reactions of Li-S batteries limit their practical application. To solve these problems, a judicious catalyst design for improved battery cycle life and rate performance is essential. Herein, this issue is addressed by modifying the Li-S battery separator using a 2D Fe2 O3 -CoP heterostructure that combines the dual functions of polar Fe2 O3 and high-conductivity CoP. The synthesized ultrathin nanostructure exposes well-dispersed active sites and shortens the ion diffusion paths. Theoretical calculations, electrochemical tests, and in situ Raman spectroscopy measurements reveal that the heterostructure facilitates the inhibition of polysulfide shuttling and enhances the electrode kinetics. A sulfur cathode constructed using the Fe2 O3 -CoP-based separator provides an astonishing capacity of 1346 mAh g-1 at 0.2 C and a high capacity retention of ≈84.5%. Even at a high sulfur loading of 5.42 mg cm-2 , it shows an area capacity of 5.90 mAh cm-2 . This study provides useful insights into the design of new catalytic materials for Li-S batteries.

Freestanding Metal-Organic Frameworks and Their Derivatives: An Emerging Platform for Electrochemical Energy Storage and Conversion.

Metal-organic frameworks (MOFs) have recently emerged as ideal electrode materials and precursors for electrochemical energy storage and conversion (EESC) owing to their large specific surface areas, highly tunable porosities, abundant active sites, and diversified choices of metal nodes and organic linkers. Both MOF-based and MOF-derived materials in powder form have been widely investigated in relation to their synthesis methods, structure and morphology controls, and performance advantages in targeted applications. However, to engage them for energy applications, both binders and additives would be required to form postprocessed electrodes, fundamentally eliminating some of the active sites and thus degrading the superior effects of the MOF-based/derived materials. The advancement of freestanding electrodes provides a new promising platform for MOF-based/derived materials in EESC thanks to their apparent merits, including fast electron/charge transmission and seamless contact between active materials and current collectors. Benefiting from the synergistic effect of freestanding structures and MOF-based/derived materials, outstanding electrochemical performance in EESC can be achieved, stimulating the increasing enthusiasm in recent years. This review provides a timely and comprehensive overview on the structural features and fabrication techniques of freestanding MOF-based/derived electrodes. Then, the latest advances in freestanding MOF-based/derived electrodes are summarized from electrochemical energy storage devices to electrocatalysis. Finally, insights into the currently faced challenges and further perspectives on these feasible solutions of freestanding MOF-based/derived electrodes for EESC are discussed, aiming at providing a new set of guidance to promote their further development in scale-up production and commercial applications.

Construction of Medusa-Like Adhesive Carbon Nanotube Array Induced by Deformation of Alumina Sheets.

To change the binary structure of nanotube and nanotube array in vertically aligned carbon nanotube arrays, this work deposits regularly arranged amorphous alumina sheets on the classical array growth catalyst (10 nm-thick alumina and 2 nm-thick iron) and obtains an array similar to the Medusa head. Subsequent experiments revealed that these alumina sheets show both unstable and stable qualities during growth: unstable in that they thermally deform and change their newly discovered characteristics of blocking carbon source diffusion, which regulates the nanotube growth order in specific areas; stable in that they withstand the deformation caused by heat and sequential growth of nanotubes, serving as a substrate and buffer layer for Medusa's hair, i.e., nanotube bundles on the array surface. Their combination splits this binary structure into a tertiary architecture consisting of nanotubes, nanotube bundles, and the array spanning nano-, micro-, and milli-meter. Benefiting from this structure, this array exhibits a unique near-isotropic adhesion characteristic compared to existing reports and outperforms classical and patterned arrays with the same classical catalyst and growth conditions.

Self-Catalytic Ternary Compounds for Efficient Synthesis of High-Quality Boron Nitride Nanotubes.

The large-scale synthesis of high-quality boron nitride nanotubes (BNNTs) has attracted considerable interests due to their applications in nanocomposites, thermal management, and so on. Despite decades of development, efficient preparation of high-quality BNNTs, which relies on the effective design of precursors and catalysts and deep insights into the catalytic mechanisms, is still urgently needed. Here, a self-catalytic process is designed to grow high-quality BNNTs using ternary W-B-Li compounds. W-B-Li compounds provide boron source and catalyst for BNNTs growth. High-quality BNNTs are successfully obtained via this approach. Density functional theory-based molecular dynamics (DFT-MD) simulations demonstrate that the Li intercalation into the lattice of W2 B5 promotes the formation of W-B-Li liquid and facilitates the compound evaporation for efficient BNNTs growth. This work demonstrates a high-efficient self-catalytic growth of high-quality BNNTs via ternary W-B-Li compounds, providing a new understanding of high-quality BNNTs growth.

Interface Engineering of Aqueous Zinc/Manganese Dioxide Batteries with High Areal Capacity and Energy Density.

Commercialization of aqueous batteries is mainly hampered by their low energy density, owing to the low mass loading of active cathode materials. In this work, a MnO2 cathode structure (MnO2 /CTF) is designed to modify the MnO2 /collector interface for enhanced ion transportation properties. Such a cathode can achieve ultrahigh mass loading of MnO2 , large areal capacity, and high energy density, with excellent cycling stability and rate performance. Specifically, a 0.15 mm thick MnO2 /CTF cathode can realize a mass loading of 20 mg cm-2 with almost 100% electrochemical conversion of MnO2 , providing the maximum areal capacity of 12.08 mA h cm-2 and energy density of 191 W h kg-1 for Zn-MnO2 /CTF batteries when considering both cathode and anode. Besides the conventional low energy demonstrations, such a Zn-MnO2 /CTF battery is capable of realistic applications, such as mobile phones in our daily life, which is a promising alternative for wearable electronics.

Nanomaterials enhancing the solid-state storage and decomposition of ammonia.

Hydrogen is ideal for producing carbon-free and clean-green energy with which to save the world from climate change. Proton exchange membrane fuel cells use to hydrogen to produce 100% clean energy, with water the only by-product. Apart from generating electricity, hydrogen plays a crucial role in hydrogen-powered vehicles. Unfortunately, the practical uses of hydrogen energy face many technical and safety barriers. Research into hydrogen generation and storage and reversibility transportation are still in its very early stages. Ammonia (NH3) has several attractive attributes, with a high gravimetric hydrogen density of 17.8 wt% and theoretical hydrogen conversion efficiency of 89.3%. Ammonia storage and transport are well-established technologies, making the decomposition of ammonia to hydrogen the safest and most carbon-free option for using hydrogen in various real-time applications. However, several key challenges must be addressed to ensure its feasibility. Current ammonia decomposition technologies require high temperatures, pressures and non-recyclable catalysts, and a sustainable decomposition mechanism is urgently needed. This review article comprehensively summarises current knowledge about and challenges facing solid-state storage of ammonia and decomposition. It provides potential strategic solutions for developing a scalable process with which to produce clean hydrogen by eliminating possible economic and technical barriers.

The exceptionally high thermal conductivity after 'alloying' two-dimensional gallium nitride (GaN) and aluminum nitride (AlN).

Alloying is a widely employed approach for tuning properties of materials, especially for thermal conductivity which plays a key role in the working liability of electronic devices and the energy conversion efficiency of thermoelectric devices. Commonly, the thermal conductivity of an alloy is acknowledged to be the smallest compared to the parent materials. However, the findings in this study bring some different points of view on the modulation of thermal transport by alloying. The thermal transport properties of monolayer GaN, AlN, and their alloys of Ga x Al1-x N are comparatively investigated by solving the Boltzmann transport equation (BTE) based on first-principles calculations. The thermal conductivity of Ga0.25Al0.75N alloy (29.57 Wm-1 K-1) and Ga0.5Al0.5N alloy (21.49 Wm-1 K-1) are found exceptionally high to be between AlN (74.42 Wm-1 K-1) and GaN (14.92 Wm-1 K-1), which violates the traditional knowledge that alloying usually lowers thermal conductivity. The mechanism resides in that, the existence of Al atoms reduces the difference in atomic radius and masses of the Ga0.25Al0.75N alloy, which also induces an isolated optical phonon branch around 18 THz. As a result, the scattering phase space of Ga0.25Al0.75N is largely suppressed compared to GaN. The microscopic analysis from the orbital projected electronic density of states and the electron localization function further provides insight that the alloying process weakens the polarization of bonding in Ga0.25Al0.75N alloy and leads to the increased thermal conductivity. The exceptionally high thermal conductivity of the Ga x Al1-x N alloys and the underlying mechanism as revealed in this study would bring valuable insight for the future research of materials with applications in high-performance thermal management.

2D PbS Nanosheets with Zigzag Edges for Efficient CO2 Photoconversion.

The rational design of transition-metal sulfide with two-dimensional (2D) structure and tunable edges on the nanoscale can effectively improve their activity for variously catalytic reactions. Herein, the 2D PbS nanosheets with abundant zigzag edges (e-PbS NS), which exhibited an excellent performance for CO2 photoconversion to CO, were constructed. The zigzag edges on the PbS NS are beneficial for exposing more active sites and promoting charge separation, thereby accelerating the kinetics process of CO2 photoreduction. This study provides a strategy to regulate structure with effective edge sites for the CO2 reduction.

Flexible and High-Voltage Coaxial-Fiber Aqueous Rechargeable Zinc-Ion Battery.

Extensive efforts have been devoted to construct a fiber-shaped energy-storage device to fulfill the increasing demand for power consumption of textile-based wearable electronics. Despite the myriad of available material selections and device architectures, it is still fundamentally challenging to develop eco-friendly fiber-shaped aqueous rechargeable batteries (FARBs) on a single-fiber architecture with high energy density and long-term stability. Here, we demonstrate flexible and high-voltage coaxial-fiber aqueous rechargeable zinc-ion batteries (CARZIBs). By utilizing a novel spherical zinc hexacyanoferrate with prominent electrochemical performance as cathode material, the assembled CARZIB offers a large capacity of 100.2 mAh cm-3 and a high energy density of 195.39 mWh cm-3, outperforming the state-of-the-art FARBs. Moreover, the resulting CARZIB delivers outstanding flexibility with the capacity retention of 93.2% after bending 3000 times. Last, high operating voltage and output current are achieved by the serial and parallel connection of CARZIBs woven into the flexible textile to power high-energy-consuming devices. Thus, this work provides proof-of-concept design for next-generation wearable energy-storage devices.

Conversion Synthesis of Self-Standing Potassium Zinc Hexacyanoferrate Arrays as Cathodes for High-Voltage Flexible Aqueous Rechargeable Sodium-Ion Batteries.

Prussian blue analogs exhibit great promise for applications in aqueous rechargeable sodium-ion batteries (ARSIBs) due to their unique open framework and well-defined discharge voltage plateau. However, traditional coprecipitation methods cannot prepare self-standing electrodes to meet the needs of wearable energy storage devices. In this work, a water bath method is reported to grow microcube-like K2 Zn3 (Fe(CN)6 )2 ·9H2 O on carbon cloth (CC) using Zn nanosheet arrays as the zinc source and reducing agent, directly serving as a self-standing cathode. Benefiting from fast ion diffusion and high conductivity, the cathode delivers a high areal capacity of 0.76 mAh cm-2 at 0.5 mA cm-2 and excellent capacity retention of 57.9% as the current density increases to 20 mA cm-2 . By coupling with NaTi2 (PO4 )3 grown on CC as an anode, a quasi-solid-state flexible ARSIB with a high output voltage plateau of 1.6 V is successfully assembled, exhibiting a superior areal capacity of 0.56 mAh cm-2 and energy density of 0.92 mWh cm-2 . In particular, the device shows admirable mechanical flexibility, maintaining 90.3% of initial capacity after 3000 bending cycles. This work is anticipated to open a new avenue for the rational design of self-standing electrodes used in high-voltage flexible ARSIBs.

Ammonium-tungstate-promoted growth of boron nitride nanotubes.

Ammonium tungstate ((NH4)10W12O41 · xH2O) is a kind of oxygen-containing ammonium salt. The following study proves that it can be successfully used as a metal oxide alternative to produce boron oxide (B2O2) by oxidizing boron (B) in a traditional boron oxide chemical vapor deposition (BOCVD) process. This special oxidant promotes the simplistic fabrication of boron nitride nanotubes (BNNTs) in a conventional horizontal tube furnace, an outcome which may have resulted from its strong oxidizability. The experimental results demonstrate that the mole ratio of B and (NH4)10W12O41 · xH2O is a key parameter in determining the formation, quality and quantity of BNNTs when stainless steel is employed as a catalyst. We also found that Mg(NO3)2 and MgO nanoparticles (NPs) can be used as catalysts to grow BNNTs with the same precursor. The BNNTs obtained from the Mg(NO3)2 catalyst were straighter than those obtained from the MgO NP catalyst. This could have been due to the different physical forms of the catalysts that were used.

Constructing Ultrahigh-Capacity Zinc-Nickel-Cobalt Oxide@Ni(OH)2 Core-Shell Nanowire Arrays for High-Performance Coaxial Fiber-Shaped Asymmetric Supercapacitors.

Increased efforts have recently been devoted to developing high-energy-density flexible supercapacitors for their practical applications in portable and wearable electronics. Although high operating voltages have been achieved in fiber-shaped asymmetric supercapacitors (FASCs), low specific capacitance still restricts the further enhancement of their energy density. This article specifies a facile and cost-effective method to directly grow three-dimensionally well-aligned zinc-nickel-cobalt oxide (ZNCO)@Ni(OH)2 nanowire arrays (NWAs) on a carbon nanotube fiber (CNTF) with an ultrahigh specific capacitance of 2847.5 F/cm3 (10.678 F/cm2) at a current density of 1 mA/cm2, These levels are approximately five times higher than those of ZNCO NWAs/CNTF electrodes (2.10 F/cm2) and four times higher than Ni(OH)2/CNTF electrodes (2.55 F/cm2). Benefiting from their unique features, we successfully fabricated a prototype coaxial FASC (CFASC) with a maximum operating voltage of 1.6 V, which was assembled by adopting ZNCO@Ni(OH)2 NWAs/CNTF as the core electrode and a thin layer of carbon coated vanadium nitride (VN@C) NWAs on a carbon nanotube strip (CNTS) as the outer electrode with KOH poly(vinyl alcohol) (PVA) as the gel electrolyte. A high specific capacitance of 94.67 F/cm3 (573.75 mF/cm2) and an exceptional energy density of 33.66 mWh/cm3 (204.02 µWh/cm2) were achieved for our CFASC device, which represent the highest levels of fiber-shaped supercapacitors to date. More importantly, the fiber-shaped ZnO-based photodetector is powered by the integrated CFASC, and it demonstrates excellent sensitivity in detecting UV light. Thus, this work paves the way to the construction of ultrahigh-capacity electrode materials for next-generation wearable energy-storage devices.

Wrapping Aligned Carbon Nanotube Composite Sheets around Vanadium Nitride Nanowire Arrays for Asymmetric Coaxial Fiber-Shaped Supercapacitors with Ultrahigh Energy Density.

The emergence of fiber-shaped supercapacitors (FSSs) has led to a revolution in portable and wearable electronic devices. However, obtaining high energy density FSSs for practical applications is still a key challenge. This article exhibits a facile and effective approach to directly grow well-aligned three-dimensional vanadium nitride (VN) nanowire arrays (NWAs) on carbon nanotube (CNT) fiber with an ultrahigh specific capacitance of 715 mF/cm2 in a three-electrode system. Benefiting from their intriguing structural features, we successfully fabricated a prototype asymmetric coaxial FSS (ACFSS) with a maximum operating voltage of 1.8 V. From core to shell, this ACFSS consists of a CNT fiber core coated with VN@C NWAs as the negative electrode, Na2SO4 poly(vinyl alcohol) (PVA) as the solid electrolyte, and MnO2/conducting polymer/CNT sheets as the positive electrode. The novel coaxial architecture not only fully enables utilization of the effective surface area and decreases the contact resistance between the two electrodes but also, more importantly, provides a short pathway for the ultrafast transport of axial electrons and ions. The electrochemical results show that the optimized ACFSS exhibits a remarkable specific capacitance of 213.5 mF/cm2 and an exceptional energy density of 96.07 µWh/cm2, the highest areal capacitance and areal energy density yet reported in FSSs. Furthermore, the device possesses excellent flexibility in that its capacitance retention reaches 96.8% after bending 5000 times, which further allows it to be woven into flexible electronic clothes with conventional weaving techniques. Therefore, the asymmetric coaxial architectural design allows new opportunities to fabricate high-performance flexible FSSs for future portable and wearable electronic devices.

Freestanding Boron Nitride Nanosheet Films for Ultrafast Oil/Water Separation.

Freestanding boron nitride nanosheet (BNNS) films with designed structures are first fabricated by chemical vapor deposition (CVD) methods. As-prepared freestanding BNNS films exhibit outstanding hydrophobicity and lipophilicity properties. Such brilliant behaviors make them applicable in oil/water separation with very high fluxes up to 1 200 000 L m-2 h-1 bar-1 and excellent separation efficiencies (ppm level in terms of the water content in the filtrate).

Wafer-scale transfer of vertically aligned carbon nanotube arrays.

The first critical step in making vertically aligned carbon nanotube (VACNT)-based thermal interface materials is to transfer the VACNTs on a large scale. Although VACNTs have been transferred by several methods, they were only transferred inadvertently in most cases. Here we report well-controlled weak-oxidation-assisted transfer of VACNTs. Specifically, after a short time of weak oxidation, we found that VACNTs could be easily detached from the native growth substrates, and thus, a freestanding VACNT film was obtained. Then the VACNTs could be assembled onto specific substrates for its real applications. More importantly, the repeated growth-transfer synthesis of VACNT arrays can be realized in one batch by introducing an additional process of weak oxidation in chemical vapor deposition, which makes the strategy more effective. Surprisingly, no degradation in the quality was observed before and after the weak oxidation according to thermogravimetric analysis and Raman spectra of VACNTs. Enhanced thermal and mechanical properties were achieved after reactive ion etching (RIE) and subsequent metallization of the surfaces of the VACNTs, and this might be due to the removal of impurities such as amorphous carbon and entangled CNTs by RIE. These findings provide an efficient approach for transferring VACNTs, which is important for the application of VACNTs in thermal management.

Ti-B-O System for Catalyzing Boron Nitride Nanotube Growth.

Chemical vapor deposition (CVD) stands out as the most promising method for cost-effective production of high-quality boron nitride nanotubes (BNNTs). Catalysts play a crucial role in BNNT synthesis. This work delves into the impact of oxygen (O) on Ti-based catalysts during the CVD growth of BNNTs. In contrast to the B/TiB2 nanoparticles (NPs) and B/TiN NPs systems, the oxygen-containing precursor B/TiO2 NPs remarkably catalyzes the growth of high-quality and high-purity BNNTs across a wider range of synthesis parameters. Subsequent analyses reveal that TiBO3 acts as an active catalyst, facilitating BNNT growth in Ti-based catalyst systems. Moreover, the nanocomposite film synthesized from BNNTs and PVDF-HFP exhibits excellent mechanical properties and heat dissipation capabilities. Utilizing the nanocomposite film as a thermal interface material effectively enhances the heat dissipation for a 5 W light-emitting diode (LED) chip. Consequently, our research confirms the effectiveness of the Ti-B-O system in catalyzing BNNT growth.

3D Porous Fibers with Spatial Traps and Excellent Zn2+ Transport Kinetics Enable Stable Zn-Based Aqueous Battery.

Adverse side reactions and uncontrolled Zn dendrites growth are the dominant factors that have restricted the application of Zn ion batteries. Herein, a 3D self-supporting porous carbon fibers (denoted as PCFs) host is developed with "trap" effect to adjust the Zn deposition. The unique open structural design of N-doped carbon can act as the zincophilic sites to induce uniform deposition and inhibit adverse side reactions. More importantly, the porous hollow PCFs host with "trap" effect can induce Zn deposition in the fiber by adjusting the local electric field and current density, thereby increasing the specific energy density of the battery and inhibiting dendrite growth. In addition, the 3D open frameworks can regulate Zn2+ flux to enable outstanding cycling performance at ultra-high current densities. As expected, the PCFs framework guarantees the uniform Zn plating and stripping with an outstanding stability over 6000 cycles at the current density of 40 mA cm-2. And the Zn@PCFs||MnO2 full battery shows an excellent lifespan over 1300 cycles at 2000 mA g-1.

In Situ Self-Reconfiguration Induced Multifunctional Triple-Gradient Artificial Interfacial Layer toward Long-Life Zn-Metal Anodes.

Aqueous Zn-ion batteries featuring with intrinsic safety and low cost are highly desirable for large-scale energy storage, but the unstable Zn-metal anode resulting from uncontrollable dendrite growth and grievous hydrogen evolution reaction (HER) shortens their cycle life. Herein, a feasible in situ self-reconfiguration strategy is developed to generate triple-gradient poly(diallyldimethylammonium) bis(trifluoromethanesulfonyl)imide (PDDA-TFSI)-Zn5(OH)8Cl2·H2O-Sn (PT-ZHC-Sn) artificial layer. The resulting triple-gradient interface consists of the spherical top layer PT with cation confinement and H2O inhibition, the dense intermediate layer ZHC nanosheet with Zn2+ conduction and electron shielding, and the bottom layer Znophilic Sn metal. The well-designed triple-gradient artificial interfacial layer synergistically facilitates rapid Zn2+ diffusion to regulate uniform Zn deposition and accelerates the desolvation process while suppressing HER. Consequently, the PT-ZHC-Sn@Zn symmetric cell achieves an ultralong lifespan over 6500 h at 0.5 mA cm-2 for 0.5 mAh cm-2. Furthermore, a full battery coupling with MnO2 cathode exhibits a 17.2% increase in capacity retention compared with bare Zn anode after 1000 cycles. The in situ self-reconfiguration strategy is also applied to prepare triple-gradient PT-ZHC-In, and the assembled Zn//Cu cell operates steadily for over 8400 h while maintaining Coulombic efficiency of 99.6%. This work paves the way to designing multicomponent gradient interface for stable Zn-metal anodes.

High-Fluidity/High-Strength Dual-Layer Gel Electrolytes Enable Ultra-Flexible and Dendrite-Free Fiber-Shaped Aqueous Zinc Metal Battery.

Fiber-shaped aqueous zinc-ion batteries (FAZIBs) with intrinsic safety, highcapacity, and superb omnidirectional flexibility hold promise for wearable energy-supply devices. However, the interfacial separation of fiber-shaped electrodes and electrolytes caused by Zinc (Zn) stripping process and severe Zn dendrites occurring at the folded area under bending condition seriously restricts FAZIBs' practical application. Here, an advanced confinement encapsulation strategy is originally reported to construct dual-layer gel electrolyte consisting of high-fluidity polyvinyl alcohol-Zn acetate inner layer and high-strength Zn alginate outer layer for fiber-shaped Zn anode. Benefiting from the synergistic effect of inner-outer gel electrolyte and the formation of solid electrolyte interphase on Zn anode surface by lysine additive, the resulting fiber-shaped Zn-Zn symmetric cell delivers long cycling life over 800 h at 1 mA cm-2 with dynamic bending frequency of 0.1 Hz. The finite element simulation further confirms that dual-layer gel electrolyte can effectively suppress the interfacial separation arising from the Zn stripping and bending process. More importantly, a robust twisted fiber-shaped Zn/zinc hexacyanoferrate battery based on dual-layer gel electrolyte is successfully assembled, achieving a remarkable capacity retention of 97.7% after bending 500 cycles. Therefore, such novel dual-layer gel electrolyte design paves the way for the development of long-life fiber-shaped aqueous metal batteries.

Molecular Engineering Enables Hydrogel Electrolyte with Ionic Hopping Migration and Self-Healability toward Dendrite-Free Zinc-Metal Anodes.

Hydrogel electrolytes (HEs), characterized by intrinsic safety, mechanical stability, and biocompatibility, can promote the development of flexible aqueous zinc-ion batteries (FAZIBs). However, current FAZIB technology is severely restricted by the uncontrollable dendrite growth arising from undesirable reactions between the HEs with sluggish ionic conductivity and Zn metal. To overcome this challenge, this work proposes a molecular engineering strategy, which involves the introduction of oxygen-rich poly(urea-urethane) (OR-PUU) into polyacrylamide (PAM)-based HEs. The OR-PUU/PAM HEs facilitate rapid ion transfer through their ionic hopping migration mechanism, resulting in uniform and orderly Zn2+ deposition. The abundant polar groups on the OR-PUU molecules in OR-PUU/PAM HEs break the inherent H-bond network, tune the solvation structure of hydrated Zn2+, and inhibit the occurrence of side reactions. Moreover, the interaction of hierarchical H-bonds in the OR-PUU/PAM HEs endows them with self-healability, enabling in situ repair of cracks induced by plating/stripping. Consequently, Zn symmetric cells incorporating the novel OR-PUU/PAM HEs exhibit a long cycling life of 2000 h. The resulting Zn-MnO2 battery displays a low capacity decay rate of 0.009% over 2000 cycles at 2000 mA g-1. Overall, this work provides valuable insights to facilitate the realization of dendrite-free Zn-metal anodes through the molecular engineering of HEs.