Search Results (124)

Rechargeable zinc–air batteries (ZABs) are promising candidates for sustainable energy storage owing to their high theoretical energy density, safety, and environmental compatibility. However, their practical application is hindered by sluggish oxygen evolution reaction (OER) kinetics and the high charging voltage required, which reduce energy efficiency and accelerate electrode degradation. Here, we report for the first time the beneficial role of potassium iodide (KI) as a reaction modifier in ZABs employing manganese dioxide (MnO₂) as a bifunctional catalyst. MnO₂ not only exhibits remarkable electrocatalytic activity toward the oxygen reduction reaction (ORR) but also catalyzes the iodide oxidation reaction (IOR), which proceeds at significantly lower potentials than the OER. As a result, KI-modified MnO₂ ZABs achieve a remarkably low charging voltage of ≈1.8 V and an energy efficiency of 69.9% at 5 mA/cm². Although the IOR is not fully reversible in alkaline media and its effectiveness depends on the iodide concentration in the electrolyte—which may decrease upon repeated discharge–charge cycling—the suppression of electrode degradation enables stable operation for more than 200 charge–discharge cycles. These findings demonstrate the synergistic effect of KI and MnO₂ in enabling an efficient ORR/IOR pathway, providing a sustainable and cost-effective alternative to noble metal catalysts and opening new perspectives for the practical development of high-performance ZABs. Full article

In this study, the Mg-8Y-0.8Al-xZn (x = 0.25, 0.45, 0.65 in wt.%) anode was selected as the research subject, and the relationship between its microstructural evolution and electrochemical performance was thoroughly investigated. The results indicate that an increasing zinc content leads to a distinct gradient change in the alloy phase composition. At a low zinc content (x = 0.25), the Al₂Y phase is uniformly distributed within the matrix. However, when the Zn content reaches 0.45 wt.% or higher, the Mg-Y phase and Mg-Y-Zn phase become the predominant phases. When applying 20 mA·cm⁻² current density, the investigated Mg-8Y-0.8Al-0.25Zn anode achieves a high specific capacity of 1030 mAh·g⁻¹ and an anode efficiency of 51%, providing a valuable experimental foundation for the advancement of new energy storage materials and offering significant theoretical guidance for advancing metal–air battery technology. Full article

The photo-assisted strategy is an effective technology that combines both photo and electrical energy conversion/storage, which represents the direction of the next generation of green energy utilization technologies. In particular, photo-assisted zinc–air batteries (PAZABs) are novel and innovative devices with the advantages of high efficiency and environmental friendliness. Thanks to the generation and effective separation of photo-generated carriers in photo-response air cathode catalysts, PAZABs possess significantly accelerated kinetics of oxygen reduction reaction and oxygen evolution reaction. Moreover, as a popular kind of newly developed two-electrode photoelectrochemical energy storage device, which could realize direct solar-to-electrochemical energy storage, PAZABs alleviate the limitations of the intermittent nature of solar energy in practical applications. In this study, the working mechanism of photoelectrochemical energy storage devices and PAZABs are thoroughly and systematically introduced; additionally, the design principles and types of photo-response electrode materials are reviewed. Interface engineering has been proven to be an effective strategy to improve the performance of the photo-response air cathode catalysts in PAZABs. Thus, the crucial role of the modulated interface chemistry of heterostructure air cathode catalysts is also summarized. Subsequently, the recent progress in the development of single-atom catalysts is outlined. Finally, this review presents several potential strategies for overcoming bottlenecks in the practical application of PAZABs. Full article

This work introduces a novel approach to enhancing the performance of zinc anodes in zinc–air batteries through a photopolymerizable organic–inorganic hybrid coating. Electrochemical tests were conducted in a neutral NaCl electrolyte, selected to minimize electrolyte carbonation, anode corrosion, and zinc dendrite formation. The behavior of bare and coated zinc electrodes was investigated using linear sweep voltammetry, electrochemical impedance spectroscopy (EIS), potentiostatic measurements, galvanostatic discharge tests, and charge-discharge tests, while morphological and structural characterizations were carried out by Atomic Force Microscopy (AFM), Raman spectroscopy, and X-ray Diffraction (XRD). The results confirmed that the hybrid coating acts as a corrosion-resistant barrier, enhancing the reversibility and stability of zinc electrodes through a barrier mechanism. Charge–discharge tests further confirmed the improved performance of the coated electrode, obtaining at a current density of 1 mA/cm², a coulombic efficiency of 92.61% and a capacity retention of 90.18%, respectively, after 16 cycles. These findings highlight the effectiveness of the photopolymerizable hybrid coating in improving the durability and rechargeability of zinc–air batteries. Full article

The commercialization of rechargeable alkaline zinc–air batteries has been constrained by critical challenges associated with the zinc electrode, including passivation, dendrite growth, and hydrogen evolution reaction. These issues severely limit the cycle life and pose a major barrier to large-scale industrial deployment. Integration of porous anode structures and electrode additives—two widely investigated approaches for mitigating challenges related to zinc anode—shows significant promise. However, effectively combining these approaches remains challenging. This study introduces a method for fabricating zinc anodes that can combine the benefits of a porous structure and electrode additive. The polytetrafluoroethylene (PTFE) polymer binder used in fabricating the anode material resulted in a stable scaffold, providing the desired anode porosity of approximately 60% and effectively anchoring ZnO nanoparticles. The zinc anodes prepared using a nickel mesh current collector without any electrode additives demonstrated stable cycling performance, sustaining 350 cycles at a current density of 60 mA g_Zn⁻¹ with a coulombic efficiency of approximately 95%. Incorporating 2 wt.% Bi₂O₃ as an electrode additive further enhanced the cycling performance, achieving 200 stable cycles with 100% coulombic efficiency under an increased current density of 120 mA g_Zn⁻¹, signifying the effectiveness of the proposed fabrication strategy. Full article

Developing cost-effective, sustainable, and high-performance air electrode catalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) remains a significant challenge in the advancement of rechargeable zinc–air batteries (ZABs). Herein, we successfully construct a vacancy-rich heterogeneous perovskite La_0.85Y_0.15Ni_0.7Fe_0.3O₃ (LYNF) hybridized with Co₃O₄ spinel nanoparticles using a simple chemical bath-assisted method. The Co₃O₄ composite LYNF material is systematically evaluated as the bifunctional catalyst for ZABs in the proportion of 25 wt%, 50w t%, and 75 wt% (denoted as LYNF-xCo₃O₄, x = 0.25, 0.5, 0.75). The results confirm an intimate coupling between the perovskite and spinel phases, along with a significant increase in oxygen vacancy concentration. Among the composites, LYNF-0.5Co₃O₄ exhibits the best performance, achieving an ORR onset potential of 0.813 V vs. RHE at −0.1 mA cm⁻² and a lower OER overpotential of 441 mV at 10 mA cm⁻². When applied as the air electrode catalyst in ZABs, LYNF-0.5Co₃O₄ displays the highest discharge voltage and a peak power density of 115 mW cm⁻², representing a 20% improvement over pristine LYNF. The enhanced performance of the LYNF-0.5Co₃O₄ composite is attributed to the accumulation of Co₃O₄ nanoparticles within the LYNF matrix, which introduces numerous electrochemically active sites and facilitates the charge and mass transport during the catalytic process in ZABs. Full article

Silicon carbide (SiC) and silicon nanoparticle-decorated carbon (Si/C) materials are electrodes that can potentially be used in various rechargeable batteries, owing to their inimitable merits, including non-flammability, stability, eco-friendly nature, low cost, outstanding theoretical capacity, and earth abundance. However, SiC has inferior electrical conductivity, volume expansion, a low Li⁺ diffusion rate during charge–discharge, and inevitable repeated formation of a solid–electrolyte interface layer, which hinders its commercial utilization. To address these issues, extensive research has focused on optimizing preparation methods, engineering morphology, doping, and creating composites with other additives (such as carbon materials, metal oxides, nitrides, chalcogenides, polymers, and alloys). Owing to the upsurge in this research arena, providing timely updates on the use of SiC and Si/C for batteries is of great importance. This review summarizes the controlled design of SiC-based and Si/C composites using various methods for rechargeable metal-ion batteries like lithium-ion (LIBs), sodium-ion (SIBs), zinc-air (ZnBs), and potassium-ion batteries (PIBs). The experimental and predicted theoretical performance of SiC composites that incorporate various carbon materials, nanocrystals, and non-metal dopants are summarized. In addition, a brief synopsis of the current challenges and prospects is provided to highlight potential research directions for SiC composites in batteries. Full article

The development of robust oxygen reduction reaction (ORR) catalyst with fast kinetics and good durability is significant for rechargeable zinc–air batteries (ZABs) but still remains a great challenge. Herein, inspired by the chain-like interconnective porous structure of plant luffa, an ORR catalyst of Co/CoCr₂O₄@ IPCF is fabricated, with Co and CoCr₂O₄ hybrid nanoparticles (NPs) embedding into interconnective porous carbon nanofibers (IPCF). Contributing to CoCr₂O₄ NPs stabilized Co active sites, the resulting ZABs assembled with Co/CoCr₂O₄@IPCF as an air cathode catalyst delivering sustainable cycling stability of 550 h, surpassing that of Co@IPCF based on ZABs (215 h). Also, the Co/CoCr₂O₄@IPCF has a high ORR performance with a half-wave potential (E_1/2) of 0.866 V in alkaline medium. The cycling stability originates from the IPCF carrier and the synergistic effect of Co NPs and CoCr₂O₄ NPs. The chain-like interconnective porous structure of the fibers provides more active sites and facilitates mass transfer to avoid the accumulation of OH⁻ and the exposure of H₂O₂, while the CoCr₂O₄ NPs can serve as a regulator for stabilizing the Co NPs electrochemical performance. Full article

Zinc–air batteries (ZABs) are crucial for renewable energy conversion and storage due to their cost-effectiveness, excellent safety, and superior cycling stability. However, developing efficient and affordable bifunctional electrocatalysts for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) at the air cathode remains a significant challenge. Manganese (Mn)-based materials, known for their tunable oxidation states, adaptable crystal structures, and environmental friendliness, are regarded as the most promising candidates. This review systematically summarizes recent advances in Mn-based bifunctional catalysts, concentrating on four primary categories: Mn–N–C electrocatalysts, manganese oxides, manganates, and other Mn-based compounds. By examining the intrinsic merits and limitations of each category, we provide a comprehensive discussion of optimization strategies, which include morphological modulation, structural engineering, carbon hybridization, heterointerface construction, heteroatom doping, and defect engineering, aimed at enhancing catalytic performance. Additionally, we critically address existing challenges and propose future research directions for Mn-based materials in rechargeable ZABs, offering theoretical insights and design principles to advance the development of next-generation energy storage systems. Full article

Efficient electrocatalysts for the oxygen reduction reaction (ORR) are essential for numerous energy storage and conversion systems, including zinc–air batteries and fuel cells. Cutting-edge Pt/C catalysts remain the most efficient ORR catalysts to date; however, their high cost and inadequate stability impede their use in commercial devices. Recently, transition metal-based electrocatalysts are being pursued as ideal alternatives for cost-effective and efficient materials with a promising future. This review provides an in-depth analysis of the principles, synthesis, and electrocatalytic assessment of noble metal and transition metal-based catalysts derived from diverse gel precursors, including hydrogels, aerogels, xerogels, metal–organic gels, and metal aerogels. Electrocatalysts derived from gel precursors have garnered significant interest due to their superior physicochemical properties, including an exceptionally high surface area, adjustable porosity, adaptability, and scalability. Catalysts obtained from gel precursors offer numerous advantages over conventional catalyst synthesis methods, including the complete utilization of precursors, precise control over surface area and porosity, and uniform distribution of ORR active sites. Among the various types, metal aerogels are distinguished as the superior catalysts, exceeding the Department of Energy’s (DoE) 2025 targets for the mass and specific activities of ORR catalysts. In contrast, hydrogel- and aerogel-derived catalysts excel in terms of ORR activity, specific surface area, and the potential to incorporate high loadings of single-atom catalysts composed of transition metals. Ultimately, we unequivocally categorized the electrocatalysts into high-, moderate-, and low-performance tiers, identifying the most promising catalyst candidate within each gel classification. Concluding insights, future outlooks, and recommendations were provided for the advancement of cost-effective, scalable electrocatalysts derived from gels for fuel cells and zinc–air batteries. Full article

In this work, the effect of the palladium precursor on the Oxygen Reduction Reaction (ORR) performance of lignin-based electrospun carbon fibers was studied. The fibers were spun from a lignin-ethanol solution free of any binder, where different Pd salts were added at two concentration levels. The system implemented to perform the spinning was a coaxial setup in which the internal flow contains the precursor dispersion with the metallic precursor, and ethanol was used as external flow to help fiber formation and prevent drying before generating the Taylor cone. The obtained cloths were thermostabilized in air at 200 °C and carbonized in nitrogen at 900 °C. The resulting carbon fibers were characterized by physicochemical and electrochemical techniques. The palladium precursor significantly affects nanoparticle distribution and size, fiber diameter, pore distribution, surface area and electrochemical behavior. The fibers prepared with palladium acetylacetonate at high Pd loading and carbonized at 900 °C under a CO₂ atmosphere showed high mechanical stability and the best ORR activity, showing near total selectivity towards the 4-electron path. These features are comparable to those of the commercial Pt/C catalyst but much lower metal loading (10.6 wt.% vs. 20 wt.%). The most promising fibers have been evaluated as cathodes in a zinc–air battery, delivering astonishing stability results that surpassed the performance of commercial Pt/C materials in both charging and discharging processes. Full article

Layered double hydroxides (LDHs), notable for their unique two-dimensional layered structures, have attracted significant research attention due to their exceptional versatility and promising performance in energy storage and conversion applications. This comprehensive review systematically addresses the fundamentals and diverse synthesis strategies for LDHs, including co-precipitation, hydrothermal synthesis, electrochemical deposition, sol-gel processes, ultrasonication, and exfoliation techniques. The synthesis methods profoundly influence the physicochemical properties, morphology, and electrochemical performance of LDHs, necessitating a detailed understanding to optimize their applications. In this paper, the role of LDHs in batteries, supercapacitors, and hydrogen production is critically evaluated. We discuss their incorporation in various battery systems, such as lithium-ion, lithium–sulfur, sodium-ion, chloride-ion, zinc-ion, and zinc–air batteries, highlighting their structural and electrochemical advantages. Additionally, the superior pseudocapacitive behavior and high energy densities offered by LDHs in supercapacitors are elucidated. The effectiveness of LDHs in hydrogen production, particularly through electrocatalytic water splitting, underscores their significance in renewable energy systems. This review paper uniquely integrates these three pivotal energy technologies, outlining current innovations and challenges, thus fulfilling a critical need for the scientific community by providing consolidated insights and guiding future research directions. Full article

Developing efficient and durable non-precious metal catalysts for oxygen electrocatalysis in fuel cells and zinc–air batteries remains an urgent issue to be addressed. Herein, a bimetallic CoCe-NC catalyst is synthesized through pyrolysis of Co/Ce co-doped metal–organic frameworks (MOFs), retaining the inherently high surface area of MOFs to maximize the exposure of Co-N and Ce-N active sites. The electronic interaction between Co and Ce atoms effectively modulates the adsorption/desorption behavior of oxygen-containing intermediates, thereby enhancing intrinsic catalytic activity. In alkaline media, the CoCe-NC catalyst exhibits E_1/2 = 0.854 V electrocatalytic capability comparable to commercial Pt/C, along with superior methanol resistance and durability. Notably, CoCe-NC demonstrates an overpotential 84 mV lower than Pt/C at 300 mA cm⁻² in a GDE half-cell. When the catalyst is employed as a cathode in zinc–air batteries, it demonstrates an open-circuit voltage of 1.47 V, a peak power density of 202 mW cm⁻², and exceptional cycling durability. Full article

Manganese-based oxides, particularly β-MnO₂, have emerged as promising cathode materials for aqueous zinc-ion batteries (ZIBs) due to their high theoretical capacity, low cost, and intrinsic safety. However, their sluggish reaction kinetics, limited active sites, and poor conductivity often lead to suboptimal electrochemical performance. To address these limitations, we propose a facile ethanol-mediated hydrothermal strategy to engineer rod-like β-MnO₂ nanostructures with tailored oxygen vacancies. By precisely adjusting ethanol addition (3–5 mL) during synthesis, oxygen vacancy concentrations were optimized to enhance electronic conductivity and active site exposure. The experimental results demonstrate that β-MnOx-2-5 synthesized with 5 mL of ethanol delivers an exceptional areal capacity of 4.87 mAh cm⁻² (348 mAh g⁻¹, 469.8 Wh kg⁻¹) at 200 mA cm⁻² under a high mass loading of 14 mg cm⁻². Further, a hybrid electrode combining oxygen-deficient β-MnO₂-x-3 (air-calcined) and structurally stable β-Mn₅O₈-y-3 (Ar-calcined) achieves a retained capacity of 3.9 mAh cm⁻² with stable cycling performance, achieving an optimal equilibrium between high capacity and long-term operational durability. Systematic characterizations (XPS, ESR, XANES, FT-EXAFS) confirm vacancy-induced electronic structure modulation, accelerating ion diffusion and redox kinetics. This scalable vacancy engineering approach, requiring only ethanol dosage control, presents a viable pathway toward industrial-scale ZIB applications. Full article

Realistic applications of zinc–air batteries are hindered by the high cost of Pt/C cathode catalysts, necessitating the search for alternative, sustainable electrocatalysts. In this work, we developed a sustainable Fe₃C/Fe-N_x-C cathode catalyst from waste coffee biomass for an oxygen reduction reaction (ORR) in alkaline electrolytes and zinc–air battery applications. The Fe₃C/Fe-N_x-C cathode catalyst was synthesized via a mechanochemical synthesis strategy by using melamine and an EDTA–Fe chelate complex, followed by pyrolysis at 900 °C. The obtained Fe₃C/Fe-N_x-C catalyst was evaluated for detailed ORR activity and stability. The ORR results show that Fe₃C/Fe-N_x-C displayed excellent ORR activity with an E_1/2 of 0.93 V vs. RHE, a Tafel slope of 68 mV dec⁻¹, 3.95 e⁻ transfer for the O₂ molecule, and high ECSA values. In addition, the Fe₃C/Fe-N_x-C catalyst exhibited excellent stability with a loss of 75 mV for 10,000 potential cycles, and a loss of ~14% of relative currents in the chronoamperometric test. When applied as a cathode catalyst in zinc–air battery, the Fe₃C/Fe-N_x-C catalyst delivered a power density of 81 mW cm⁻² and admirable electrochemical stability under galvanostatic discharge conditions. Furthermore, the practical application of the Fe₃C/Fe-N_x-C catalyst was demonstrated by a panel of LEDs illuminated with a dual-cell zinc–air battery connected in a series, clearly validating the practically developed catalysts for use in various energy storage and electronic devices. Full article