Flexible Zinc-air Batteries Research Articles

Biomimetic Nanostructure Engineering of Ultralow Ir-Loading Electrocatalysts for Oxygen Reduction Reaction.

Promoting the rate of the oxygen reduction reaction (ORR) is critical for boosting the overall energy efficiency of the flexible zinc-air batteries (FZABs). Inspired by nature, we designed "branch-leaf" like hierarchical porous carbon nanofibers with ultralow loadings of Ir nanoparticles (NPs) derived from covalent-organic framework/metal-organic framework (COF/MOF) core-shell hybrids. The as-obtained Ir/FeZn-hierarchical porous carbon nanofibers (HPCNFs) showcase enhanced ORR performance, and the ultralow Ir loading reduces the cost while maintaining catalytic capacity. Interestingly, the FZABs assembled with Ir/FeZn-HPCNFs deliver an impressive stable performance. This work provides a feasible approach for designing cost-effective and highly efficient electrocatalysts using in FZABs.

Biomass-templated strategy to synthesize Fe2P/Co2P heterojunction bifunctional electrocatalyst for high performance flexible zinc-air batteries

Biomass-templated strategy to synthesize Fe2P/Co2P heterojunction bifunctional electrocatalyst for high performance flexible zinc-air batteries

Tetramethylguanidine-Modified Graphene Oxide as a Gel Polymer Electrolyte Additive for Improving the Performance of Flexible Zinc-Air Batteries.

Flexible zinc-air batteries (FZABs) present a promising solution for the next generation of power sources in wearable electronics, owing to their high energy density, cost-effectiveness, and safety. However, solid-state electrolytes for FZABs continue to face challenges related to rapid water loss and low ionic conductivity. In this study, a hydrophilic and stable tetramethylguanidine-modified graphene oxide as an additive, which is incorporated into sodium polyacrylate to develop a high-performance gel polymer electrolyte (GPE), is designed. The addition of additives makes GPE more hydrophilic, allowing for a wider hydrogen bonding network and more efficient ion transport channels. Due to its stable structure, abundant water channels and fast OH- conductivity, GPE also offers excellent mechanical properties, long-lasting water retention, and high ionic conductivity (173.9 mS cm-1). FZABs assembled with this GPE exhibit a high open-circuit voltage of 1.558V, a cycle life of 230 h, a specific capacity of 810.3 mAh g-1, and a peak power density of 130.5mW cm-2, coupled with impressive flexibility. These characteristics underscore their significant potential for applications in wearable electronics.

Interfacial engineering of a MoS2–FeCoS2@NG nanocomposite: an efficient electrocatalyst for enhanced flexible zinc–air battery performance

MoS2–FeCoS2@NG materials are excellent electrocatalysts for ORR and (OER) pose a considerable obstacle in the development of future rechargeable zinc–air batteries.

Chlorine Axial Coordination Activated Lanthanum Single Atoms for Efficient Oxygen Electroreduction with Maximum Utilization.

Currently, there are still obstacles to rationally designing the ligand fields to activate rare-earth (RE) elements with satisfactory intrinsic electrocatalytic reactivity. Herein, axial coordination strategies and nanostructure design are applied for the construction of La single atoms (La-Cl SAs/NHPC) with satisfactory oxygen reduction reaction (ORR) activity. The nontrivial LaN4Cl2 motifs configuration and the hierarchical porous carbon substrate that facilitates maximized metal atom utilization ensure high half-wave potential (0.91V) and significant robustness in alkaline media. The aqueous and flexible Zinc-air battery (ZAB) integrating La-Cl SAs/NHPC as the cathode catalyst exhibits a maximum power density of 260.7 and 68.5mW cm-2, representing one of the most impressive RE-based ORR electrocatalysts to date. Theoretical calculations have demonstrated that the Cl coordination evidently modulate the electronic structures of La sites, which promoted electron transfer efficiency by d-p orbital couplings. With enhanced electroactivity of La sites, the adsorptions of key intermediates are optimized to alleviate the energy barriers of the potential-determining step. Importantly, this preparation strategy is also successfully applied to other REs. This work provides perspectives for near-range electronic structure modulation of RE-SAs based on a nonplanar coordination micro-environment for efficient electrocatalysis.

Nickel-Iron Interfacial Alloy Nanoparticles Encapsulated By Pyridinic-N Enriched CNT on Carbon Fiber Cloth for Bifunctional Oxygen Catalysts and Biaxially Flexible Zinc-Air Batteries

Low-price, high-performance, and long-term stability electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are highly significant in the application of rechargeable zinc air batteries. In this study, we report a highly reversible bifunctional electrocatalyst for flexible Zn air batteries featuring pyridinic-N exclusively enriched carbon-nanotube-encased nickel-iron (NiFe) interfacial alloy nanoparticles derived from an LDH template on knitted carbon fiber cloth. NiFe nanoparticles are catalytically released from the NiFe-MOF to form CNT tentacles when pyrolyzed in an inert atmosphere. XPS and XAS studies revealed the dominating presence of pyridinic-N, which reduces electron localization around NiFe centers and improves the interaction with oxygenated species. As a result, the NiFe-N-CNT-KCC catalysts exhibited a low operating overpotential (η10) of 173 mV for the OER and a half-wave potential (E1/2) of 0.87 V for the ORR, superior to benchmark electrocatalysts. As an air cathode for zinc-air batteries, the NiFe-N-CNT-KCC-based battery showed excellent electrochemical performance, with an open circuit voltage (OCV) of 1.55 V, high power density (153 mW cm-2), excellent specific capacity of 793.2 mA h g-1, and long-term stability. Most impressively, the solid-state flexible zinc-air battery with the NiFe-N-CNT-KCC cathode showed admirable rate performance and exceptional mechanical stability under arbitrary bending and twisting conditions, holding great potential in practical implementation in next-generation high-power and high-energy-density batteries, even with the potential for wearable applications.

Advanced Eutectogel Electrolyte for High‐Performance and Wide‐Temperature Flexible Zinc‐Air Batteries

AbstractDespite ongoing challenges, achieving further breakthroughs in the development of gel polymer electrolytes with a wide temperature range, excellent liquid retention capability and enhanced anode compatibility in flexible zinc‐air batteries (FZABs) remains a significant objective. This study presents a significant advancement in the development of choline chloride/ethylene glycol‐polyvinyl alcohol (ChCl/EG‐PVA) eutectogel electrolyte, tailored for high‐performance operation across a wide temperature range. Systematic in‐situ and ex‐situ characterizations and theoretical simulations confirm the formation of robust hydrogen bonding and denser polymer cross‐linked networks within the prepared eutectogel, leading to enhanced liquid retention ability (93.7 % after 96 h exposure to air) and ion transport capacity (ionic conductivity of 171.3 mS cm−1). Additionally, the zincophilicity nature of the choline cation in eutectogel effectively suppresses dendrites growth. The assembled FZAB utilizing this eutectogel electrolyte achieves a peak power density of 109.3 mW cm−2 and a cycle life of 90 h. Notably, the power density of FZAB is maintained as high as 38.2 mW cm−2 at −40 °C and 63.2 mW cm−2 at 50 °C, demonstrating its prominent suitability for applications in extreme temperature conditions. The design of eutectogel provides a novel way to achieve the high‐performance FZAB.

Advanced Eutectogel Electrolyte for High-Performance and Wide-Temperature Flexible Zinc-Air Batteries.

Despite ongoing challenges, achieving further breakthroughs in the development of gel polymer electrolytes with a wide temperature range, excellent liquid retention capability and enhanced anode compatibility in flexible zinc-air batteries (FZABs) remains a significant objective. This study presents a significant advancement in the development of choline chloride/ethylene glycol-polyvinyl alcohol (ChCl/EG-PVA) eutectogel electrolyte, tailored for high-performance operation across a wide temperature range. Systematic in-situ and ex-situ characterizations and theoretical simulations confirm the formation of robust hydrogen bonding and denser polymer cross-linked networks within the prepared eutectogel, leading to enhanced liquid retention ability (93.7 % after 96 h exposure to air) and ion transport capacity (ionic conductivity of 171.3 mS cm-1). Additionally, the zincophilicity nature of the choline cation in eutectogel effectively suppresses dendrites growth. The assembled FZAB utilizing this eutectogel electrolyte achieves a peak power density of 109.3 mW cm-2 and a cycle life of 90 h. Notably, the power density of FZAB is maintained as high as 38.2 mW cm-2 at -40 °C and 63.2 mW cm-2 at 50 °C, demonstrating its prominent suitability for applications in extreme temperature conditions. The design of eutectogel provides a novel way to achieve the high-performance FZAB.

Composite Gel Polymer Electrolyte for High-Performance Flexible Zinc-Air Batteries.

Enhancing ionic conductivity and electrolyte uptake is of significance for gel polymer electrolytes (GPEs) for flexible zinc-air batteries (FZABs). Herein, a composite mesoporous silica/polyacrylamide (5 wt.% mPAM) GPE is constructed with comparable ionic conductivity to aqueous electrolytes, where the ionic conductivity is up to 337 mS cm-1, and the weight loss after exposing in air 72h is less than 18%, owing to the excellent electrolyte uptake and continuous ion migration network provided by the mesoporous silica fillers. When used as a quasi-solid-electrolyte, the rechargeable FZAB exhibited high electrochemical performance and structural stability, where the peak power density is up to 162.8mW cm-2, and the initial charge-discharge potential gap is as low as 0.62V, resulting in a long lifespan exceeding 110h, showcasing the combination of high durability, cost-effectiveness and easy production for practical applications.

Consolidating the Oxygen Reduction with Sub-Polarized Graphitic Fe-N4 Atomic Sites for an Efficient Flexible Zinc-Air Battery.

The effectuation of the Zn-air battery (ZAB) is appealing for active and durable catalysts to kinetically drive the sluggish cathodic oxygen reduction reaction (ORR). Atomic metal-Nx-C sites are widely witnessed with Pt-like activity, but their demetalations still severely restrict the durability in ORR. Here we have profiled an ordered hierarchical porous carbon supported Fe-N4 single-atom (FeNC) catalyst by a template derivation method for efficient ORR and flexible ZAB studies. The FeNC structure is observed with a sub-polarized graphitic Fe-N4 coordination with a shortened Fe-N bond for potentially consolidating the ORR, together with the hierarchical porous matrix for kinetical mass transfer. Resultantly, the optimized FeNC catalyst showcases Pt-beyond alkaline ORR activity (E1/2 = 0.95 V) with long-term durability for 100 h, delivering the flexible ZAB device with high power density (251 mW cm-2) and durable cycle life (80 h). This research underscores the criterion in rationalizing active and robust ORR catalysts through metal-nitrogen bond modulation.

Deep Eutectic Solvent and Molten Salt-Assisted Construction of Wheat Straw-Derived N/O Co-Doped Porous Carbon for Flexible Zinc-Air Batteries.

As a common biomass resource, wheat straw is gradually being derived as carbon materials for oxygen reduction reaction (ORR) in zinc-air batteries (ZABs). Herein, the wheat straw-derived carbon was prepared by ball milling and pyrolysis using deep eutectic solvent (DES) as the medium, which avoided the cumbersome procedures. The hydrogen bond of DES was utilized to reconstructed into a hydrogen bond network structure between DES and lignin/cellulose/hemicellulose of wheat straw. The hydrogen bond network structure was converted into N/O co-doped porous carbon (N/O-WSPC) with abundant N/O co-doped sites after high-temperature pyrolysis. Meanwhile, KHCO3 was employed to further generate hierarchical pore structures and increase the specific surface area of the N/O-WSPC. The N/O co-doped sites provided intrinsic ORR activity, while the porous structure facilitates the mass transfer effect. Therefore, the N/O-WSPC exhibited a half-wave potential of 0.87 V (vs. RHE) and a limiting current density of 5.98 mA cm-2 for ORR. The N/O-WSPC-based flexible ZAB displayed an energy density of 652.23 Wh kg-1 and a charging-discharging cycle duration for over 19 h. The DES-assisted strategy facilitates the sustainable and efficient application of wheat straw-derived carbon materials in energy storage and conversion devices.

Regional banks, financing constraints and manufacturing enterprises' total factor productivity: A quasi-natural experiment of China's city commercial banks

The literature shows that the financial system dominated by large national banks restricts enterprises' financing channels, leading to efficiency losses. In response, governments introduce different types of banks to address this issue. However, the literature overlooks the relationships among regional banks, financing constraints and manufacturing enterprises' productivity. We fill this gap by exploiting the China's unique policy of staggered rollout of city commercial banks across cities and using data from Chinese listed manufacturing enterprises over the period 1992 to 2022 to explore how regional banks affect productivity. We find that regional banks represented by city commercial banks in China significantly increase the manufacturing enterprises' total factor productivity by alleviating financing constraints, especially pronounced for state-owned enterprises, large enterprises, and well-established enterprises. Our research results emphasize the effectiveness of regional banks in promoting the development of the manufacturing industry and offer insights for sustainable economic development policies.

Fe3Co nanoparticles embedded carbon nanotube complex as effective bifunctional electrocatalysts for rechargeable zinc-air batteries

Fe3Co nanoparticles have been successfully embedded within ZIF-8 derived carbon nanotube complex using a simple solvent-heated self-assembly-pyrolysis strategy, it acts as an efficient ORR/OER bifunctional electrocatalyst and showed outstanding performance of excellent catalytic activity for ORR (E1/2 = 0.87 V at 0.1 M KOH) and OER (the overpotential at 10 mA cm−2 is 390 mV at 1 M KOH). Density functional theory (DFT) demonstrates that the introduction of iron and cobalt atoms significantly impacted on the adsorption energies of the reactive intermediates. In particular, the combination of cobalt and iron exhibited significantly enhanced ORR/OER activities, revealing an enhanced effect of synergistic interaction of FeCo site for bifunctional properties. It is used as Fe3Co1−NC in aqueous zinc-air battery (ZAB) and exhibited a high open-circuit voltage of 1.52 V, power density of 189.8 mW cm−2, and long cycle durability of 400 h. Flexible ZABs assembled exhibit high power density (81.59 mW cm−2) and long cycling durability (90 h).

Hierarchical MoO2@MoS2 heterojunction nanosheets anchored with metal-organic framework-derived CoFe alloy as bifunctional catalysts for flexible zinc-air batteries

Crafting a robust, high-performance, non-precious metal-based flexible air electrode is crucial for realizing flexible zinc-air batteries (ZABs). Herein, hierarchical MoO2 and MoS2 heterojunction nanosheets grown on carbon cloth (CC) are prepared through a simple hydrothermal reaction followed by calcination. Afterward, through self-assembly and high-temperature carbonization of zeolitic imidazolate framework-67 (ZIF-67) and Materials of Institute Lavoisier-101 (MIL-101) on the heterojunction nanosheets, a hierarchical structure of nitrogen-doped carbon (NC) encapsulated CoFe alloy nanoparticles (NPs) supported on MoO2@MoS2 heterojunction nanosheets (CC/MoS2@MoO2@CoFe) is obtained. It exhibits remarkable activity and durability for both bifunctional oxygen evolution and reduction reactions (OER/ORR), attributed to the ternary heterojunction formed by NC-coated CoFe alloy NPs uniformly dispersed among the MoO2@MoS2 nanosheets, along with oxygen vacancies at heterogeneous interfaces between MoS2, MoO2, and Co0.72Fe0.28 alloy. As a binder-less self-supporting electrode, the assembled aqueous ZAB demonstrates a maximum power density of 113.6 mW cm–2, surpassing that of Pt/C + RuO2 (75.2 mW cm–2), along with excellent cycling stability. Furthermore, the CC/MoS2@MoO2@CoFe-based flexible ZABs achieve a maximum power density of 54.1 mW cm–2, exhibit good cycling stability for up to 120 cycles, and show outstanding flexibility. This study paves the way for the practical integration of flexible ZABs into wearable electronic devices, heralding a new era of portable power solutions.

Prussian Blue-Derived Atomic Fe/Fe3C@N-Doped C Catalysts Supported by Carbon Cloth as Integrated Air Cathode for Flexible Zn-Air Batteries.

The development of an integrated air cathode with superior oxygen reduction reaction (ORR) performance is fundamental to flexible zinc-air batteries (ZABs) for wearable electronics. Herein, a self-assembled metal-organic framework (MOF)-derived strategy is proposed to prepare a atomic Fe/Fe3C@N-doped C catalysts supported by carbon cloth (CC) catalyst for use as an air cathode of flexible ZABs. The Prussian Blue precursor, which self-assembles on the surface of the carbon cloth due to electrostatic attraction, is critical in achieving the uniform dispersion of catalysts with high density loading on carbon cloth substrates. The hollow cubic structure, N-doped carbon layer coating, and the integrated electrode design can provide more accessible active sites and facilitate a rapid electron transfer and mass transport. Density functional theory (DFT) calculation reveals that the electronic interactions between the Fe-N4 and Fe3C dual active sites can optimize the adsorption-desorption behavior of oxygen intermediates formed during the ORR. Consequently, the Fe/Fe3C@N-doped C/CC exhibits an excellent half wave potential (E1/2 = 0.903V) and superior long-term cycling stability in alkaline environments. With excellent ORR performance, ZABs and flexible ZABs based on Fe/Fe3C@N-doped C/CC air cathode demonstrate excellent overall electrochemical performance in terms of open circuit voltage, maximum power density, flexibility, and cycling stability.

Study on the enhancement of flexible zinc-air battery performance with polyethylene glycol and nano SiO2 composite hydrogel

Flexible zinc-air batteries have garnered significant attention due to their high energy density, low cost, and environmental friendliness. However, issues such as poor cycle life and anode dendrite growth severely hinder their practical application. This study introduces polyethylene glycol (PEG) as a pore-forming agent and incorporates nano SiO2 into a polyacrylamide/carboxymethyl cellulose (PAM/CMC) composite hydrogel, resulting in a PAM/CMC/PEG/SiO2 (PCPS) composite hydrogel. Phase analysis and electrochemical characterization of PCPS were conducted. The hydrogel electrolyte formed in an alkaline KI environment, when assembled into a battery, achieved a capacity of 494.6 mAh/g and maintained a low potential range of 0.36 V for over 40 h, with an energy efficiency of 86.3 % for the first 60 cycles. To address the issue of dendrite growth in alkaline environments, this study also explores the performance of PCPS composite hydrogel in near-neutral environments.

Bionic Leaf: Ultrahigh energy efficiency in a defect Engineered MoS2 based photo induced charging of flexible Zn-Air battery

Introducing solar energy directly into flexible energy storage systems is an environmentally friendly, efficient, and low-cost strategy. Herein, we constructed a photoelectrode based on flexible carbon cloth (CC) to promote the oxygen evolution reaction (OER) and effectively reduce the charging voltage of flexible zinc-air batteries (ZABs), inspired by the photosynthesis process in leaves. The implementation of sulfur vacancies (VS) and oxygen doping in nanoscale molybdenum disulfide (MoS2) effectively enhances the separation efficiency of photo-generated electron-hole pairs, and adjusts its band structure to improve the oxidation capability. The constructed photocathode with defect-rich MoS2 (D-MoS2) exhibits a low overpotential of 235 mV at 10 mA cm−2 for OER. The sandwich flexible ZABs based on D-MoS2 achieve a low charge voltage around 1.3 V and an ultra-high energy efficiency greater than 90 % under illumination at 0.1 mA cm−2. This strategy provides a new insight for the application of light energy in smart wearable energy storage devices.

Synergistic Vertical Graphene‐Exsolved Perovskite to Boost Reaction Kinetics for Flexible Zinc–Air Batteries

AbstractZinc–air batteries (ZABs) hold significant promise for flexible electronics due to their high energy density and low cost. However, their practical application is hindered by the sluggish kinetics of the oxygen evolution and oxygen reduction reactions (OER/ORR). This study highlights a novel design of vertical graphene arrays (VGs) anchored on PrBa0.5Sr0.5Co1.8Ru0.2O5+δ (PBSCRu) perovskite nanofibers, fabricated via plasma‐enhanced chemical vapor deposition. Notably, the VG growth induces the exsolution of Co nanoparticles from the PBSCRu perovskite, resulting in a unique PBSCRu‐Co‐VG heterostructure. Theoretical calculations demonstrate that constructing PBSCRu‐Co‐VG heterojunction regulates interfacial electronic redistribution, thereby lowering energy barriers for both OER and ORR. As a result, the PBSCRu@VG‐5 electrocatalyst exhibits superior stability and higher peak power density in both liquid and flexible solid‐state ZABs compared to the pristine PBSCRu electrocatalyst. This protocol advances the integration of synergetic perovskite/metal/graphene composites, offering considerable potential for next‐generation energy conversion technologies.

MnO2/rGO bifunctional catalyst and support materials for gel polymer electrolyte based Zn-air batteries

A high-performance and long-lasting, rechargeable Zn-air battery requires a reliable and effective bifunctional catalyst material to facilitate the oxygen reduction and oxygen evolution reactions during the battery operation. Manganese oxide (MnO2) is a promising non-precious perspective due to its multivalency and various polymorphic structures that effectively catalyze oxygen evolution and reduction. In the present work, MnO2 nanowires (NWs) have been integrated with over-reduced graphene oxide (rGO) in various concentrations via a facile hydrothermal route. The synthesized materials, tested in lab-made zinc-air battery devices fabricated using gel polymer electrolyte, exhibit a significant enhancement in the performance and 2–3 times the cycle life compared to the bare MnO2. The ZAB device was tested for galvanostatic charge-discharge technique, and results exhibit a cycle life of 165 h (495 cycles@20 min per cycle) when discharged up to 1.0 V at a current density of 5.2 mA/cm2 and displayed a capacity of 731 mAh/gZn. Reduced graphene oxide acts as a support material that enhances the conductivity and surface area of the active material and also provides active sites for catalysis. This work signifies the importance of the engineering of the catalyst, support material, and additives, as slight changes may result in a significant enhancement in the cycle life.The appropriate composition of catalyst and support material and a compatible gel polymer electrolyte facilitates the fabrication of flexible zinc-air batteries for various applications.

Enhanced Zinc-air battery performance and local electrochemical evaluation of atomically dispersed Co and Ni in S, N-codoped carbon nanofibers via scanning electrochemical microscopy

This study reports the successful synthesis of a novel electrocatalyst for oxygen reduction reactions (ORR), comprising S,N dual-doped carbon nanofibers with atomically dispersed Co/Ni species (denoted as Co,Ni-SAs/S,N-CNFs), leveraging electrostatic spinning to achieve a unique spatial architecture that maximizes both active site density and mass transport efficiency. Density functional theory (DFT) analysis identified the initial proton-electron transfer to adsorbed O2 as the rate-limiting step, with CoN3S1-NiN3S1 emerging as the pivotal active site structure catalyzing this critical reaction. The fabricated Co,Ni-SAs/S,N-CNFs electrocatalyst exhibited remarkable ORR performance, characterized by a high half-wave potential of 0.84 V and a low Tafel slope of 57.9 mV dec-1. To gain a comprehensive understanding of its catalytic behavior, a tailored temperature-controlled scanning electrochemical microscopy (SECM) was employed, enabling the mapping of reactivity distribution under simulated operating conditions while preserving structural integrity. Liquid zinc-air batteries (ZABs) with this electrocatalyst excelled, reaching 175 mW/cm2 power density and enduring 1240 cycles. The electrospun membrane catalyst enabled both button and flexible ZABs, adaptable to diverse environments. This study advances non-precious metal electrocatalyst design and offers insights for ZAB applications, fostering green energy prospects.