Zinc-air Research Articles

Internally connected porous PVA/PAA membrane with cross-aligned nanofiber network for facile and long-lasting ion transport in zinc–air batteries

In response to the growing interest in next-generation wearable devices, the demand for high-performance, safe, and flexible power sources has increased. Flexible zinc–air batteries (ZABs) based on gel polymer electrolytes (GPEs) have emerged as promising candidates for wearable power sources owing to their high energy density, safety, and cost efficiency. However, persistent electrolyte evaporation through the air cathode poses a significant challenge, resulting in poor lifespan characteristics that impede practical applications. In this study, we developed a polymer composite-type GPE composed of cross-aligned nanofibers (NFs) of a polyacrylic acid (PAA)-based framework embedded in a polyvinyl alcohol (PVA) matrix. Upon immersion in a liquid electrolyte (6 M KOH), the superabsorbent PAA spontaneously generated an internally connected porous (IP) structure adjacent to the aligned PAA NFs. These pores served as directional water channels, facilitating rapid hydroxide ion conduction and yielding a remarkable ionic conductivity of 235.7 mS cm−1. The PVA matrix acts as both a packaging material and the main body of the GPE, providing good dimensional stability and mitigating the swelling of PAA, even under conditions of high electrolyte uptake, while also ensuring high flexibility. The IP-PVA/PAA composite GPE demonstrated a high power output, rate performance, and excellent lifespan in flexible ZABs. Furthermore, successful operation at various bending angles provides empirical evidence supporting the viable application of flexible ZABs.

Modulating the Energy Barrier via the Synergism of Cu3P and CoP to Accelerate Kinetics for Bolstering Oxygen Electrocatalysis in Zn-Air Batteries.

Modulating the energy barrier of reaction intermediates to surmount sluggish kinetics is an utterly intriguing strategy for amplifying the oxygen reduction reaction. Herein, a Cu3P/CoP hybrid is incorporated on hollow porous N-doped carbon nanospheres via dopamine self-polymerization and high-temperature treatment. The resultant Cu3P/CoP@NC showcases a favorable mass activity of 4.41 mA mg-1 and a kinetic current density of 2.38 mA cm-2. Strikingly, the catalyst endows the aqueous Zn-air battery (ZAB) with a large power density of 209.0 mW cm-2, superb cyclability over 317 h, and promising application prospects in flexible ZAB. Theoretical simulations reveal that Cu functions as a modulator to modify the free energy of intermediates and adsorbs the O2 on the Co sites, hence rushing the reaction kinetics. The open and hydrophilic hollow spherical mesoporous structure provides unimpeded channels for reactant diffusion and electrolyte penetration, whereas the exposed inner and outer surfaces can confer a plethora of accessible actives sites. This research establishes a feasible design concept to tune catalytic activity for non-noble metal materials by construction of a rational nanoframework.

Enhanced Dendrite Resistance in Reversible Electrochemical Pneumatic Batteries with Nanoimprinted Nanowire Anodes for Jamming Robots

Traditional electric robots often rely on heavy gear units or expensive force–torque sensors, whereas pneumatic robots offer a cost-effective and simple alternative. However, their dependence on noisy and bulky pneumatic systems, such as compressed air technology, limits their portability and adaptability. To overcome these challenges, we have developed a reversible electrochemical pneumatic battery (REPB) that is compact, noise-free, energy-efficient, and portable. This innovative REPB, principled by the electrochemical redox reactions of zinc–air batteries, can simultaneously supply both electric and pneumatic power, either positive or negative pressure. Its modular, multi-stack structure allows for the easy customization of power output and capacity to suit various applications. We demonstrate the utility of REPB through its application in jamming robots, such as a novel soft yet robust gripper that merges the strengths of hard and soft grippers, enabling universal robotic gripping. This work presents a groundbreaking approach to powering devices that require pneumatic support.

Ar/NH3 Plasma Etching of Cobalt-Nickel Selenide Microspheres Rich in Selenium Vacancies Wrapped with Nitrogen Doped Carbon Nanotubes as Highly Efficient Air Cathode Catalysts for Zinc-Air Batteries.

This work utilizes defect engineering, heterostructure, pyridine N-doping, and carbon supporting to enhance cobalt-nickel selenide microspheres' performance in the oxygen electrode reaction. Specifically, microspheres mainly composed of CoNiSe2 and Co9Se8 heterojunction rich in selenium vacancies (VSe·) wrapped with nitrogen-doped carbon nanotubes (p-CoNiSe/NCNT@CC) are prepared by Ar/NH3 radio frequency plasma etching technique. The synthesized p-CoNiSe/NCNT@CC shows high oxygen reduction reaction (ORR) performance (half-wave potential (E1/2) = 0.878V and limiting current density (JL) = 21.88mA cm-2). The JL exceeds the 20wt% Pt/C (19.34mA cm-2) and the E1/2 is close to the 20wt% Pt/C (0.881V). It also possesses excellent oxygen evolution reaction (OER) performance (overpotential of 324 mV@10mA cm-2), which even exceeds that of the commercial RuO2 (427 mV@10mA cm-2). The density functional theorycalculation indicates that the enhancement of ORR performance is attributed to the synergistic effect of plasma-induced VSe· and the CoNiSe2-Co9Se8 heterojunction. The p-CoNiSe/NCNT@CC electrode assembled Zinc-air batteries (ZABs) show a peak power density of 138.29mW cm-2, outperforming the 20wt% Pt/C+RuO2 (73.9mW cm-2) and other recently reported catalysts. Furthermore, all-solid-state ZAB delivers a high peak power density of 64.83mW cm-2 and ultra-robust cycling stability even under bending.

Coupling of Fe-Nx sites and Fe nanoparticles on nitrogen-doped porous carbon for boosting oxygen electroreduction in Zn-air batteries

Fe and nitrogen co-doped carbon (Fe-N-C) catalysts have emerged as attractive materials to substitute Pt-based catalysts for the oxygen reduction reaction (ORR) in Zn-air batteries (ZABs). However, the Fe-N-C catalysts with monotypic active component usually endow suboptimal catalytic performance and stability under both acid and alkaline medium. Herein, a nano ZnO template and two-step pyrolysis co-assisted strategy is proposed to achieve the coupling of Fe-Nx sites and metallic Fe nanoparticles in hierarchically porous N-doped carbon for ORR. The nano ZnO template contributes to the formation of meso/macropores structure, while the secondary pyrolysis is beneficial to the creation of more micropores. Besides the advanced hierarchical porosity, the combination of dispersed Fe-Nx sites and dominated metallic Fe nanoparticles is also conducive to boost ORR activity in both acid and alkaline solution. Impressively, the prepared Fe@FeHPNC-P2 electrocatalyst exhibits an excellent half-wave potentials (E1/2) of 0.88 V and 0.79 V in alkaline and acidic electrolyte, respectively. Meanwhile, the assembled liquid Zn-air battery using Fe@FeHPNC-P2 delivers a peak power density of 149.3 mW cm−2 and a maximum energy density of 957.1 Wh kgZn−1 along with long-term stability for 1000 cycles.

Trifunctional phosphorus-doped cobalt molybdate catalyst in self-driven coupling systems for synchronized sulfur recovery and hydrogen evolution

This study introduces a self-driven system that effectively achieves synchronized sulfur recovery and hydrogen production using a Zn-air battery. The system ingeniously integrates the sulfur oxidation reaction (SOR) and the hydrogen evolution reaction (HER) into a single, efficient process. Central to this system is the trifunctional phosphorus-doped cobalt molybdate catalyst (P-CoMoO4/NF), which exhibits superior performance in both HER (ηj = 100 = 0.13 V) and SOR (ηj = 100 = 0.30 V) with remarkable stability (∼360 h), reaching 0.64 V at 100 mA cm−2 for simultaneous sulfur ion degradation and hydrogen production. Through density functional theory simulations and extensive characterizations, it has been shown that phosphorus doping in the cobalt molybdate catalyst facilitates electron redistribution, enhancing the catalyst's conductivity, generating more oxygen vacancies, and promoting improved mass and electron transfer. This modification also lowers the energy barrier for adsorbing reaction intermediates, thus increasing the hydrogen production rate and sulfur oxide conversion in this self-powered system. In summary, this research marks a substantial advancement in the development of trifunctional catalysts and proposes an eco-friendly, cost-effective strategy for integrated reaction systems, paving the way for sustainable energy solutions.

Prussian blue analogue derived phosphatized cobalt coupling N-doped carbon system as an efficient oxygen electrocatalyst for rechargeable zinc-air battery

Recently, CoP is considered as a very promising electrode material for rechargeable zinc-air battery (ZAB). In this study, a Prussian blue analogue (Co3[Co(CN)6]2, PBA) derived CoP coupling with N-doped carbon (NC) as an effective oxygen electrocatalyst PBA-CoP/NC was prepared. Notably, as-prepared PBA-CoP/NC has good oxygen reduction reaction (ORR) performance even comparable to Pt/C (0.855 V), with half wave potential reaching 0.847 V. While, it also has satisfactory performance for oxygen evolution reaction (OER). Importantly, the PBA-CoP/NC assembled ZAB exhibits an open circuit potential of 1.62 V, and a peak power density of 119.3 mW cm−2, as well as good stability. This PBA-CoP/NC catalyst would give good reference to developing advanced carbon-based electrocatalyst, also has great potential applied in other energy storage devices.

A lignocellulose-based hydrogel polymer electrolytes with high conductivity and stability for rechargeable flexible zinc-air batteries

Flexible Zinc-Air batteries (FZABs) have been extensively investigated by researchers due to their exceptional safety and high energy density. The sandwich structure employed in FZABs imposes stringent demands on the electrolyte, necessitating good electrical conductivity and alkali resistance. In this paper, a carboxylation@Lignocellulose-based hydrogel polymer electrolyte with high ionic conductivity and excellent alkali resistance has designed and applied in FZABs. The carboxylation@lignocellulose is dissolved in a sodium hydroxide/urea/water system, followed by the incorporation of acrylamide monomers into the lignocellulose solution to prepare the hydrogel polymer electrolyte. The results combined suggest that the solid electrolyte exhibits improved ion conductivity, liquid absorption capability, and alkali resistance. Therefore, it has been confirmed that carboxyl functional groups have a positive effect on the performance of solid electrolytes. These characteristics enable the lignocellulose-based hydrogel polymer electrolyte FZAB to have an open-circuit voltage (1.34 V), a peak power density (141.55 mW cm−2), and a cycle lifetime to 65 h (555 cycles). Compared to FZABs based polyacrylamide-KOH hydrogel polymer electrolyte-based, FZABs utilizing lignocellulose-based hydrogel polymer electrolyte prepared in this paper demonstrate excellent performance.

Research Progress and Future Expectations in Anode of Secondary Zinc-Air Batteries: A Review

Research Progress and Future Expectations in Anode of Secondary Zinc-Air Batteries: A Review

Enhanced Zinc–Air Batteries through the Fabrication of Structured Zinc Electrodes Using Freeze‐Casting

Ice‐templating, a versatile manufacturing process, is widely utilized to create porous materials by freezing aqueous solutions. Notably, this technique is material independent, allowing for the fabrication of microstructured bulk or sheet materials of ceramic, glass, metal, polymer, and composite materials. Herein, the influence of freeze‐cast zinc electrodes on zinc–air batteries is investigated. The analysis includes the charge and discharge cycling behavior of pure powder, gel matrix, and sintered freeze‐cast zinc electrodes, complemented by the study of the distribution of relaxation times. Remarkably, the best cycling performance is achieved with the combination of a gel electrolyte and a freeze‐cast zinc electrode, highlighting the potential significance of this microstructure–electrolyte pairing for enhancing the performance of zinc–air batteries.

PVDF-assisted pyrolysis strategy for corrugated plate oxygen electrocatalysis nanoreactor: Simultaneously realizing efficient active sites and rapid mass transfer

Though Zn-air batteries (ZABs) are one of the most promising system for energy storage and conversion, challenge still persists in its commercial application due to the sluggish kinetics of oxygen reduction/evolution reaction (ORR/OER). Hereby, a polyvinylidene fluoride (PVDF)-assisted pyrolysis strategy is proposed to develop a novel corrugated plate-like bifunctional electrocatalyst using two-dimensional zeolitic imidazolate frameworks (2D ZIF-67) as the precursor. The employed PVDF plays an important role in inheriting the original 2D structure of ZIF-67 and modulating the composition of the final products. As a result, a corrugated plate-like electrocatalyst, high-density Co nanoparticles decorated 2D Co, N, and F tri-doped carbon nanosheets, can be obtained. The acquired electrocatalyst enables efficient active sites and rapid mass transfer simultaneously, thus showing appreciable electrocatalytic performance for rechargeable Zn-air batteries. Undoubtedly, our proposed strategy offers a new perspective to the design of advanced oxygen electrocatalysts.

Inbuilt photoelectric field of heterostructured cobalt/iron oxides promotes oxygen electrocatalysis for high-energy-efficiency zinc-air batteries

The practical application of zinc-air batteries (ZABs) is limited by the large overpotentials generated by the sluggish kinetics of oxygen electrocatalysis at air electrodes. To address this challenge, we report a photocathode composed of Fe2O3/Co3O4 mixed metal oxides for photo-assisted rechargeable ZABs. Owing to the formation of Fe2O3/Co3O4 heterostructures with abundant oxygen vacancies (Vox), the air electrode exhibited a high surface photovoltage (SPV) of 220 mV based on the contact potential difference (CPD) recorded before and after light irradiation, corresponding to a very high specific SPV of 44 kV m−1. Consequently, the photo-rechargeable ZABs incorporating this Fe2O3/Co3O4 air photocathode exhibit a low charge potential of 1.6 V under light irradiation. Furthermore, these ZABs demonstrate a remarkable increase in energy efficiency, from 64 % to 78 %, coupled with a high specific capacity of 712.3 mAh g−1 and excellent stability over a span of 60 hours. This achievement underscores the potential for harnessing light energy in the next generation of ZABs, suggesting the promise of a brighter future for energy storage technologies.

Integration of Fe2N Nanoparticles and FeCo Alloys into N-Doped Carbon Nanotubes as Efficient Oxygen Catalysts for Rechargeable Zn–air Batteries

Integration of Fe₂N Nanoparticles and FeCo Alloys into N-Doped Carbon Nanotubes as Efficient Oxygen Catalysts for Rechargeable Zn–air Batteries

Precise construction of RuPt dual single-atomic sites to optimize oxygen electrocatalytic behaviors for high-performance Zn-air batteries

The development of redox bifunctional electrocatalysts with high performance, low cost, and long lifetimes is essential for achieving clean energy goals. This study proposed an atom capture strategy for anchoring dual single atoms (DSAs) in a zinc–zeolitic imidazolate framework (Zn–ZIF), followed by calcination under an N2 atmosphere to synthesize ruthenium–platinum DSAs supported on a nitrogen-doped carbon substrate (RuPt DSAs-NC). Theoretical calculations showed that the degree of Ru 5dxz − *O 2px orbital hybridization was high when *O was adsorbed at the Ru site, indicating enhanced covalent hybridization of metal sites and oxygen ligands, which benefited the adsorption of intermediate species. The presence of the RuPtN6 active center optimized the absorption–desorption behavior of intermediates, improving the electrocatalytic performance of the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). RuPt DSAs-NC exhibited a 0.87 V high half-wave potential and a 268 mV low overpotential at 10 mA cm−2 in an alkaline environment. Furthermore, rechargeable zinc–air batteries (ZABs) achieved a peak power density of 171 mW cm−2. The RuPt DSAs-NC demonstrated long-term cycling for up to 500 h with superior round-trip efficiency. This study provided an effective structural design strategy to construct DSAs active sites for enhanced electrocatalytic performance.

Formation of core-shell structure MnCo2O4 microspheres and as a bifunctional catalyst for zinc-air batteries

Efficient and stable bifunctional catalysts, facilitating oxygen reduction and oxygen evolution, play a pivotal role in energy conversion and storage fields. In this paper, four core-shell MnCo2O4 catalyst samples are prepared by controlling different solvent heating time, which are 0.5 h, 2 h, 6 h, and 12 h, respectively. The subsequent tests indicate that the sample with a 6 h not only has an ideal core-shell structure, but also exhibits favorable performance. The unique core-shell structure and favorable electrochemical performance are mainly attributed to the prepared precursor spheres. The microspheres have an inherent core-shell structure. Detailed studies of the morphological variations of MnCo2O4 catalysts with the different solvent heating time are performed using transmission electron microscopy and field emission scanning electron microscopy. Furthermore, we analyze the potential formation mechanism of the core-shell structure MnCo2O4 catalyst. The obtained core-shell structured MnCo2O4 catalysts provide a new way for the preparation of cathode catalyst for zinc-air batteries.

Co-doped hollow nanospheres with low Pt loading for electrocatalytic oxygen reduction and zinc-air batteries

Preparing high-performance catalysts for oxygen reduction reaction (ORR) with low Pt loading is crucial to promote the development of clean energy storage devices such as metal air batteries. Herein, Co/N-HCMs support material with isolated Co atoms and hollow flower-like structure could be prepared by a self-sacrificing template strategy. Co/N-HCMs are then used to anchor Pt to obtain PtCo/N-HCMs catalyst with low Pt loading. Thanks to its improved specific surface area, hierarchical porous structure, and reinforced metal-support interactions, the obtained PtCo/N-HCMs deliver high onset potential of 0.99 V and half-wave potential of 0.82 V, and an excellent durability. When used as air cathode catalyst, PtCo/N-HCMs-based Zinc-air battery (ZAB) exhibits a power density of up to 202 mW cm−2, which is significantly better than ZAB assembled with commercial Pt/C. This study provides an effective strategy for preparing high-performance electrocatalysts with low precious metal content for use as the cathode of metal-air batteries.

Electrocatalytic Oxygen Reduction Using Metastable Zirconium Suboxide

AbstractStrategies for discovery of high‐performance electrocatalysts are important to advance clean energy technologies. Metastable phases such as low temperature or interfacial structures that are difficult to access in bulk may offer such catalytically active surfaces. We report here that the suboxide Zr3O, which is formed at Zr−ZrO2 interfaces but does not appear in the experimental Zr−O phase diagram exhibits outstanding oxygen reduction reaction (ORR) performance surpassing that of benchmark Pt/C and most transition metal‐based catalysts. Addition of Fe3C nanoparticles to give a Zr−Zr3O−Fe3C/NC catalyst (NC=nitrogen‐doped carbon) gives a half‐wave potential (E1/2) of 0.914 V, outperforming Pt/C and showing only a 3 mV decrease after 20,000 electrochemical cycles. A zinc‐air battery (ZAB) using this cathode material has a high power density of 241.1 mW cm−2 and remains stable for over 50 days of continuous cycling, demonstrating potential for practical applications. Zr3O demonstrates that interfacial or other phases that are difficult to stabilize may offer new directions for the discovery of high‐performance electrocatalysts.

Electrocatalytic Oxygen Reduction Using Metastable Zirconium Suboxide.

Strategies for discovery of high-performance electrocatalysts are important to advance clean energy technologies. Metastable phases such as low temperature or interfacial structures that are difficult to access in bulk may offer such catalytically active surfaces. We report here that the suboxide Zr3O, which is formed at Zr-ZrO2 interfaces but does not appear in the experimental Zr-O phase diagram exhibits outstanding oxygen reduction reaction (ORR) performance surpassing that of benchmark Pt/C and most transition metal-based catalysts. Addition of Fe3C nanoparticles to give a Zr-Zr3O-Fe3C/NC catalyst (NC=nitrogen-doped carbon) gives a half-wave potential (E1/2) of 0.914 V, outperforming Pt/C and showing only a 3 mV decrease after 20,000 electrochemical cycles. A zinc-air battery (ZAB) using this cathode material has a high power density of 241.1 mW cm-2 and remains stable for over 50 days of continuous cycling, demonstrating potential for practical applications. Zr3O demonstrates that interfacial or other phases that are difficult to stabilize may offer new directions for the discovery of high-performance electrocatalysts.

FeNx/ZnSe/Fe Heterojunctions Embedded in Leafy N-Doped Carbon as Efficient Bifunctional Oxygen Electrocatalysts for Flexible Rechargeable Zn–Air Batteries

FeN_<i>x</i>/ZnSe/Fe Heterojunctions Embedded in Leafy N-Doped Carbon as Efficient Bifunctional Oxygen Electrocatalysts for Flexible Rechargeable Zn–Air Batteries

Study of the Suitability of Corncob Biochar as Electrocatalyst for Zn–Air Batteries

There has been a recent increasing interest in Zn–air batteries as an alternative to Li-ion batteries. Zn–air batteries possess some significant advantages; however, there are still problems to solve, especially related to the tuning of the properties of the air–cathode which should carry an inexpensive but efficient bifunctional oxygen reduction (ORR) and oxygen evolution (OER) reaction electrocatalyst. Biochar can be an alternative, since it is a material of low cost, it exhibits electric conductivity, and it can be used as support for transition metal ions. Although there is a significant number of publications on biochars, there is a lack of data about biochar from raw biomass rich in hemicellulose, and biochar with a small number of heteroatoms, in order to report the pristine activity of the carbon phase. In this work, activated biochar has been made by using corncobs. The biomass was first dried and minced into small pieces and pyrolyzed. Then, it was mixed with KOH and pyrolyzed for a second time. The final product was characterized by various techniques and its electroactivity as a cathode was determined. Physicochemical characterization revealed that the biochar had a hierarchical pore structure, moderate surface area of 92 m2 g−1, carbon phase with a relatively low sp2/sp3 ratio close to one, and a limited amount of N and S, but a high number of oxygen groups. The graphitization was not complete while the biochar had an ordered structure and contained significant O species. This biochar was used as an electrocatalyst for ORR and OER in Zn–air batteries where it demonstrated a satisfactory performance. More specifically, it reached an open-circuit voltage of about 1.4 V, which was stable over a period of several hours, with a short-circuit current density of 142 mA cm−2 and a maximum power density of 55 mW cm−2. Charge–discharge cycling of the battery was achieved between 1.2 and 2.1 V for a constant current of 10 mA. These data show that corncob biochar demonstrated good performance as an electrocatalyst in Zn–air batteries, despite its low specific surface and low sp2/sp3 ratio, owing to its rich oxygen sites, thus showing that electrocatalysis is a complex phenomenon and can be served by biochars of various origins.