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1.
Freestanding bifunctional electrodes with outstanding oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) properties are of great significance for zinc–air batteries, attributed to the avoided use of organic binder and strong adhesion with substrates. Herein, a strategy is developed to fabricate freestanding bifunctional electrodes from the predeposited nickel nanoparticles (Ni‐NCNT) on carbon fiber paper. The steric effect of monodispersed SiO2 nanospheres limits the configuration of carbon atoms forming 3D interconnected nanotubes with uniformly distributed NiN2 active sites. The bifunctional electrodes (Ni‐NCNT) demonstrate ideal ORR and OER properties. The zinc–air batteries assembled with Ni‐NCNT directly exhibit extremely outstanding long term stability (2250 cycles with 10 mA cm?2 charge/discharge current density) along with high power density of 120 mV cm?2 and specific capacity of 834.1 mA h g?1. This work provides a new view to optimize the distribution of active sites and the electrode structure.  相似文献   

2.
Over the past decade, the surging interest for higher‐energy‐density, cheaper, and safer battery technology has spurred tremendous research efforts in the development of improved rechargeable zinc–air batteries. Current zinc–air batteries suffer from poor energy efficiency and cycle life, owing mainly to the poor rechargeability of zinc and air electrodes. To achieve high utilization and cyclability in the zinc anode, construction of conductive porous framework through elegant optimization strategies and adaptation of alternate active material are employed. Equally, there is a need to design new and improved bifunctional oxygen catalysts with high activity and stability to increase battery energy efficiency and lifetime. Efforts to engineer catalyst materials to increase the reactivity and/or number of bifunctional active sites are effective for improving air electrode performance. Here, recent key advances in material development for rechargeable zinc–air batteries are described. By improving fundamental understanding of materials properties relevant to the rechargeable zinc and air electrodes, zinc–air batteries will be able to make a significant impact on the future energy storage for electric vehicle application. To conclude, a brief discussion on noteworthy concepts of advanced electrode and electrolyte systems that are beyond the current state‐of‐the‐art zinc–air battery chemistry, is presented.  相似文献   

3.
Bromine‐based flow batteries are well suited for stationary energy storage due to attractive features of high energy density and low cost. However, the bromine‐based flow battery suffers from low power density and large materials consumption due to the relatively high polarization of the Br2/Br? couple on the electrodes. Herein, a self‐supporting 3D hierarchical composite electrode based on a TiN nanorod array is designed to improve the activity of the Br2/Br? couple and increase the power density of the bromine‐based flow battery. In this design, a carbon felt provides a composite electrode with a 3D electron conductive framework to guarantee high electronic conductivity, while the TiN nanorods possess excellent catalytic activity for the Br2/Br? electrochemical reaction to reduce the electrochemical polarization. Moreover, the 3D micro–nano hierarchical nanorod‐array alignment structure contributes to a high electrolyte penetration and a high ion‐transfer rate to reduce diffusion polarization. As a result, a zinc–bromine flow battery with the designed composite electrode can be operated at a current density of up to 160 mA cm?2, which is the highest current density ever reported. These results exhibit a promising strategy to fabricate electrodes for ultrahigh‐power‐density bromine‐based flow batteries and accelerate the development of bromine‐based flow batteries.  相似文献   

4.
Highly active and durable air cathodes to catalyze both the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) are urgently required for rechargeable metal–air batteries. In this work, an efficient bifunctional oxygen catalyst comprising hollow Co3O4 nanospheres embedded in nitrogen‐doped carbon nanowall arrays on flexible carbon cloth (NC‐Co3O4/CC) is reported. The hierarchical structure is facilely derived from a metal–organic framework precursor. A carbon onion coating constrains the Kirkendall effect to promote the conversion of the Co nanoparticles into irregular hollow oxide nanospheres with a fine scale nanograin structure, which enables promising catalytic properties toward both OER and ORR. The integrated NC‐Co3O4/CC can be used as an additive‐free air cathode for flexible all‐solid‐state zinc–air batteries, which present high open circuit potential (1.44 V), high capacity (387.2 mAh g?1, based on the total mass of Zn and catalysts), excellent cycling stability and mechanical flexibility, significantly outperforming Pt‐ and Ir‐based zinc–air batteries.  相似文献   

5.
The recently emerging metal–air batteries equipped with advanced oxygen electrodes have provided enormous opportunities to develop the next generation of wearable and bio‐adaptable power sources. Theoretically, neutral electrolyte‐based Mg–air batteries possess potential advantages in electronics and biomedical applications over the other metal–air counterparts, especially the alkaline‐based Zn–air batteries. However, the rational design of advanced oxygen electrode for Mg–air batteries with high discharge voltage and capacity under neutral conditions still remains a major challenge. Inspired by fibrous string structures of bufo‐spawn, it is reported here that the scalable synthesis of atomic Fe–Nx coupled open‐mesoporous N‐doped‐carbon nanofibers (OM‐NCNF‐FeNx) as advanced oxygen electrode for Mg–air batteries. The fabricated OM‐NCNF‐FeNx electrodes present manifold advantages, including open‐mesoporous and interconnected structures, 3D hierarchically porous networks, good bio‐adaptability, homogeneously coupled atomic Fe–Nx sites, and high oxygen electrocatalytic performances. Most importantly, the assembled Mg–air batteries with neutral electrolytes reveal high open‐circuit voltage, stable discharge voltage plateaus, high capacity, long operating life, and good flexibility. Overall, the discovery on fabricating atomic OM‐NCNF‐FeNx electrode will not only create new pathways for achieving flexible, wearable, and bio‐adaptable power sources, but also take a step towards the scale‐up production of advanced nanofibrous carbon electrodes for a broad range of applications.  相似文献   

6.
Metal single‐atom materials with their high atom utilization efficiency and unique electronic structures usually show remarkable catalytic performances in many crucial chemical reactions. Herein, a facile and easily scalable “impregnation‐carbonization‐acidification” strategy for fabricating a class of single‐atom‐anchored (including cobalt and nickel single atoms) monolith as superior binder‐free electrocatalysts for developing high‐performance wearable Zn–air batteries is reported. The as‐prepared single atoms, supported by N‐doped carbon flake arrays grown on carbon nanofibers assembly (M SA@NCF/CNF), demonstrate the dual characteristics of excellent catalytic activity (reversible oxygen overpotential of 0.75 V) and high stability, owing to the greatly improved active sites' accessibility and optimized single‐sites/pore‐structures correlations. Furthermore, wearable Zn–air battery based on Co SA@NCF/CNF air electrode displays superior stability under deformation, satisfactory energy storage capacity, and good practicality to be utilized as an integrated battery system. Theoretical calculations reveal a mechanism for the promotion of the catalytic performances on single atomic sites by lowering the overall oxygen reduction/evolution reaction barriers comparing to metal cluster co‐existing configuration. These findings provide a facile strategy for constructing free‐standing single‐atom materials as well as the engineering of high‐performance binder‐free catalytic electrodes.  相似文献   

7.
Large‐scale application of renewable energy and rapid development of electric vehicles have brought unprecedented demand for advanced energy‐storage/conversion technologies and equipment. Rechargeable zinc (Zn)–air batteries represent one of the most promising candidates because of their high energy density, safety, environmental friendliness, and low cost. The air electrode plays a key role in managing the many complex physical and chemical processes occurring on it to achieve high performance of Zn–air batteries. Herein, recent advances of air electrodes from bifunctional catalysts to architectures are summarized, and their advantages and disadvantages are discussed to underline the importance of progress in the evolution of bifunctional air electrodes. Finally, some challenges and the direction of future research are provided for the optimized design of bifunctional air electrodes to achieve high performance of rechargeable Zn–air batteries.  相似文献   

8.
Bifunctional electrocatalysis for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) constitutes the bottleneck of various sustainable energy devices and systems like rechargeable metal–air batteries. Emerging catalyst materials are strongly requested toward superior electrocatalytic activities and practical applications. In this study, transition metal hydroxysulfides are presented as bifunctional OER/ORR electrocatalysts for Zn–air batteries. By simply immersing Co‐based hydroxide precursor into solution with high‐concentration S2?, transition metal hydroxides convert to hydroxysulfides with excellent morphology preservation at room temperature. The as‐obtained Co‐based metal hydroxysulfides are with high intrinsic reactivity and electrical conductivity. The electron structure of the active sites is adjusted by anion modulation. The potential for 10 mA cm?2 OER current density is 1.588 V versus reversible hydrogen electrode (RHE), and the ORR half‐wave potential is 0.721 V versus RHE, with a potential gap of 0.867 V for bifunctional oxygen electrocatalysis. The Co3FeS1.5(OH)6 hydroxysulfides are employed in the air electrode for a rechargeable Zn–air battery with a small overpotential of 0.86 V at 20.0 mA cm?2, a high specific capacity of 898 mAh g?1, and a long cycling life, which is much better than Pt and Ir‐based electrocatalyst in Zn–air batteries.  相似文献   

9.
A critical bottleneck limiting the performance of rechargeable zinc–air batteries lies in the inefficient bifunctional electrocatalysts for the oxygen reduction and evolution reactions at the air electrodes. Hybridizing transition‐metal oxides with functional graphene materials has shown great advantages due to their catalytic synergism. However, both the mediocre catalytic activity of metal oxides and the restricted 2D mass/charge transfer of graphene render these hybrid catalysts inefficient. Here, an effective strategy combining anion substitution, defect engineering, and the dopant effect to address the above two critical issues is shown. This strategy is demonstrated on a hybrid catalyst consisting of sulfur‐deficient cobalt oxysulfide single crystals and nitrogen‐doped graphene nanomeshes (CoO0.87S0.13/GN). The defect chemistries of both oxygen‐vacancy‐rich, nonstoichiometric cobalt oxysulfides and edge‐nitrogen‐rich graphene nanomeshes lead to a remarkable improvement in electrocatalytic performance, where CoO0.87S0.13/GN exhibits strongly comparable catalytic activity to and much better stability than the best‐known benchmark noble‐metal catalysts. In application to quasi‐solid‐state zinc–air batteries, CoO0.87S0.13/GN as a freestanding catalyst assembly benefits from both structural integrity and enhanced charge transfer to achieve efficient and very stable cycling operation over 300 cycles with a low discharge–charge voltage gap of 0.77 V at 20 mA cm?2 under ambient conditions.  相似文献   

10.
Porous carbon electrodes have emerged as important cathode materials for metal–air battery systems. However, most approaches for fabricating porous carbon electrodes from biomass are highly energy inefficient as they require the breaking down of the biomass and its subsequent reconstitution into powder‐like carbon. Here, enzymes are explored to effectively hydrolyze the partial cellulose in bulk raw wood to form a large number of nanopores, which helps to maximally expose the inner parts of the raw wood to sufficiently dope nitrogen onto the carbon skeletons during the subsequent pyrolysis process. The resulting carbons exhibit excellent catalytic activity with respect to the oxygen reduction and oxygen evolution reactions. As‐fabricated cellulose‐digested, carbonized wood plates are mechanically strong, have high conductivity, and contain a crosslinked network and natural ion‐transport channels and can be employed directly as metal‐free electrodes without carbon paper, polymer binders, or carbon black. When used as metal‐free cathodes in zinc–air batteries, they result in a specific capacity of 801 mA h g?1 and an energy density of 955 W h kg?1 with the long‐term stability of the batteries being as high as 110 h. This work paves the way for the ready conversion of abundant biomass into high‐value engineering products for energy‐related applications.  相似文献   

11.
Zinc–air batteries with high‐density energy are promising energy storage devices for the next generation of energy storage technologies. However, the battery performance is highly dependent on the efficiency of oxygen electrocatalyst in the air electrode. Herein, the N, F, and B ternary doped carbon fibers (TD‐CFs) are prepared and exhibited higher catalytic properties via the efficient 4e transfer mechanism for oxygen reduction in comparison with the single nitrogen doped CFs. More importantly, the primary and rechargeable Zn–air batteries using TD‐CFs as air–cathode catalysts are constructed. When compared to batteries with Pt/C + RuO2 and Vulcan XC‐72 carbon black catalysts, the TD‐CFs catalyzed batteries exhibit remarkable battery reversibility and stability over long charging/discharging cycles.  相似文献   

12.
Portable water splitting devices driven by rechargeable metal–air batteries or solar cells are promising, however, their scalable usages are still hindered by lack of suitable multifunctional electrocatalysts. Here, a highly efficient multifunctional electrocatalyst is demonstrated, i.e., 2D nanosheet array of Mo‐doped NiCo2O4/Co5.47N heterostructure deposited on nickel foam (Mo‐NiCo2O4/Co5.47N/NF). The successful doping of non‐3d high‐valence metal into a heterostructured nanosheet array, which is directly grown on a conductive substrate endows the resultant catalyst with balanced electronic structure, highly exposed active sites, and binder‐free electrode architecture. As a result, the Mo‐NiCo2O4/Co5.47N/NF exhibits remarkable catalytic activity toward the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), affording high current densities of 50 mA cm?2 at low overpotentials of 310 mV for OER, and 170 mV for HER, respectively. Moreover, a low voltage of 1.56 V is achieved for the Mo‐NiCo2O4/Co5.47N/NF‐based water splitting cell to reach 10 mA cm?2. More importantly, a portable overall water splitting device is demonstrated through the integration of a water‐splitting cell and two Zn–air batteries (open‐circuit voltage of 1.43 V), which are all fabricated based on Mo‐NiCo2O4/Co5.47N/NF, demonstrating a low‐cost way to generate fuel energy. This work offers an effective strategy to develop high‐performance metal‐doped heterostructured electrode.  相似文献   

13.
The kinetically sluggish rate of oxygen reduction reaction (ORR) on the cathode side is one of the main bottlenecks of zinc‐air batteries (ZABs), and thus the search for an efficient and cost‐effective catalyst for ORR is highly pursued. Co3O4 has received ever‐growing interest as a promising ORR catalyst due to the unique advantages of low‐cost, earth abundance and decent catalytic activity. However, owing to the poor conductivity as a result of its semiconducting nature, the ORR activity of the Co3O4 catalyst is still far below the expectation. Herein, we report a controllable N‐doping strategy to significantly improve the catalytic activity of Co3O4 for ORR and demonstrate these N doped Co3O4 nanowires as an additive‐free air‐cathode for flexible solid‐state zinc‐air batteries. The results of experiments and DFT calculations reveal that the catalytic activity is promoted by the N dopant through a combined set of factors, including enhanced electronic conductivity, increased O2 adsorption strength and improved reaction kinetics. Finally, the assembly of all‐solid‐state ZABs based on the optimized cathode exhibit a high volumetric capacity of 98.1 mAh cm‐3 and outstanding flexibility. The demonstration of such flexible ZABs provides valuable insights that point the way to the redesign of emerging portable electronics.  相似文献   

14.
Driven by the intensified demand for energy storage systems with high‐power density and safety, all‐solid‐state zinc–air batteries have drawn extensive attention. However, the electrocatalyst active sites and the underlying mechanisms occurring in zinc–air batteries remain confusing due to the lack of in situ analytical techniques. In this work, the in situ observations, including X‐ray diffraction and Raman spectroscopy, of a heteroatom‐doped carbon air cathode are reported, in which the chemisorption of oxygen molecules and oxygen‐containing intermediates on the carbon material can be facilitated by the electron deficiency caused by heteroatom doping, thus improving the oxygen reaction activity for zinc–air batteries. As expected, solid‐state zinc–air batteries equipped with such air cathodes exhibit superior reversibility and durability. This work thus provides a profound understanding of the reaction principles of heteroatom‐doped carbon materials in zinc–air batteries.  相似文献   

15.
An efficient and low‐cost electrocatalyst for reversible oxygen electrocatalysis is crucial for improving the performance of rechargeable metal?air batteries. Herein, a novel oxygen vacancy–rich 2D porous In‐doped CoO/CoP heterostructure (In‐CoO/CoP FNS) is designed and developed by a facile free radicals–induced strategy as an effective bifunctional electrocatalyst for rechargeable Zn–air batteries. The electron spin resonance and X‐ray absorption near edge spectroscopy provide clear evidence that abundant oxygen vacancies are formed in the interface of In‐CoO/CoP FNS. Owing to abundant oxygen vacancies, porous heterostructure, and multiple components, In‐CoO/CoP FNS exhibits excellent oxygen reduction reaction activity with a positive half‐wave potential of 0.81 V and superior oxygen evolution reaction activity with a low overpotential of 365 mV at 10 mA cm?2. Moreover, a home‐made Zn–air battery with In‐CoO/CoP FNS as an air cathode delivers a large power density of 139.4 mW cm?2, a high energy density of 938 Wh kgZn?1, and can be steadily cycled over 130 h at 10 mA cm?2, demonstrating great application potential in rechargeable metal–air batteries.  相似文献   

16.
The development of robust and efficient trifunctional catalysts for oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen reaction (HER) is central to regenerative metal–air batteries and overall water splitting. It is still a big challenge to achieve an efficient integration of three functions in one freestanding electrode. Herein, a facile and upscalable strategy is demonstrated, to construct cobalt nanoparticle‐encapsulated 3D conductive films (Co/CNFs), which were induced by in situ solid diffusion from bulk cobalt metal. Under high‐temperature, volatile cobalt species from bulk cobalt foil are trapped by the contacted nitrogen‐rich carbons, followed by catalytic growth of interconnected carbon tubes, forming the 3D structured film. This resulting film can be directly preformed as self‐supporting and binder‐free electrode, which simultaneously facilitates the ORR, OER, and HER with excellent activities and superior stability. Furthermore, such “all‐in‐one” film also exhibits remarkable performance for Zn–air batteries and overall water splitting, demonstrating its feasibility for practical applications.  相似文献   

17.
Developing a scalable approach to construct efficient and multifunctional electrodes for the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR) is an urgent need for overall water splitting and zinc–air batteries. In this work, a freestanding 3D heterostructure film is synthesized from a Ni-centered metal−organic framework (MOF)/graphene oxide. During the pyrolysis process, 1D carbon nanotubes formed from the MOF link with the 2D reduced graphene oxide sheets to stitch the 3D freestanding film. The results of the experiments and theoretical calculations show that the synergistic effect of the N-doped carbon shell and Ni nanoparticles leads to an optimized film with excellent electrocatalytic activity. Low overpotentials of 95 and 260 mV are merely needed for HER and OER, respectively, to reach a current density of 10 mA cm−2. In addition, a high half-wave potential of 0.875 V is obtained for the ORR, which is comparable to that of Pt/RuO2 and ranks among the top of non-noble-metal catalysts. The use of an “all-in-one” film as the electrode leads to excellent performance of the homemade water electrolyzer and zinc–air battery, indicating the potential of the film for practical applications.  相似文献   

18.
This study presents a novel metal‐organic‐framework‐engaged synthesis route based on porous tellurium nanotubes as a sacrificial template for hierarchically porous 1D carbon nanotubes. Furthermore, an ultrathin Fe‐ion‐containing polydopamine layer has been introduced to generate highly effective FeNxC active sites into the carbon framework and to induce a high degree of graphitization. The synergistic effects between the hierarchically porous 1D carbon structure and the embedded FeNxC active sites in the carbon framework manifest in superior catalytic activity toward oxygen reduction reaction (ORR) compared to Pt/C catalyst in both alkaline and acidic media. A rechargeable zinc‐air battery assembled in a decoupled configuration with the nonprecious pCNT@Fe@GL/CNF ORR electrode and Ni‐Fe LDH/NiF oxygen evolution reaction (OER) electrode exhibits charge–discharge overpotentials similar to the counterparts of Pt/C ORR electrode and IrO2 OER electrode.  相似文献   

19.
Pt‐Gd alloy polycrystalline thin film is deposited on 3D nickel foam by pulsed laser deposition method serving as a whole binder/carbon‐free air electrode, showing great catalytic activity enhancement as an efficient bifunctional catalyst for the oxygen reduction and evolution reactions in lithium oxygen batteries. The porous structure can facilitate rapid O2 and electrolyte diffusion, as well as forming a continuous conductive network throughout the whole energy conversion process. It shows a favorable cycle performance in the full discharge/charge model, owing to the high catalytic activity of the Pt‐Gd alloy composite and 3D porous nickel foam structure. Specially, excellent cycling performance under capacity limited mode is also demonstrated, in which the terminal discharge voltage is higher than 2.5 V and the terminal charge voltage is lower than 3.7 V after 100 cycles at a current density of 0.1 mA cm?2. Therefore, this electrocatalyst is a promising bifunctional electrocatalyst for lithium oxygen batteries and this depositing high‐efficient electrocatalyst on porous substrate with polycrystalline thin film by pulsed laser deposition is also a promising technique in the future lithium oxygen batteries research.  相似文献   

20.
The nonaqueous lithium oxygen battery is a promising candidate as a next‐generation energy storage system because of its potentially high energy density (up to 2–3 kW kg?1), exceeding that of any other existing energy storage system for storing sustainable and clean energy to reduce greenhouse gas emissions and the consumption of nonrenewable fossil fuels. To achieve high energy density, long cycling stability, and low cost, the air electrode structure and the electrocatalysts play important roles. Here, a metal‐free, free‐standing macroporous graphene@graphitic carbon nitride (g‐C3N4) composite air cathode is first reported, in which the g‐C3N4 nanosheets can act as efficient electrocatalysts, and the macroporous graphene nanosheets can provide space for Li2O2 to deposit and also promote the electron transfer. The electrochemical results on the graphene@g‐C3N4 composite air electrode show a 0.48 V lower charging plateau and a 0.13 V higher discharging plateau than those of pure graphene air electrode, with a discharge capacity of nearly 17300 mA h g?1 (composite). Excellent cycling performance, with terminal voltage higher than 2.4 V after 105 cycles at 1000 mA h g?1 (composite) capacity, can also be achieved. Therefore, this hybrid material is a promising candidate for use as a high energy, long‐cycle‐life, and low‐cost cathode material for lithium oxygen batteries.  相似文献   

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