The slow oxygen reaction kinetics of air electrodes impair the performance of reversible protonic ceramic electrochemical cells(R-PCECs);hence,it is imperative to design novel air electrodes featuring excellent cataly...The slow oxygen reaction kinetics of air electrodes impair the performance of reversible protonic ceramic electrochemical cells(R-PCECs);hence,it is imperative to design novel air electrodes featuring excellent catalytic activity and endurance.Here,we report an Rb-doped double perovskite PrBa_(0.8)Ca_(0.1)Rb_(0.1)Co_(2)O_(5+δ)(denoted as PBCR_(0.1)C)as an air electrode for R-PCECs,displaying a low polarization resistance of 0.044Ωcm^(2) at 700℃ and excellent stability during exposure to humid air(3 vol%H_(2)O).The high performance is attributed to the high electrical conductivity,high concentration of oxygen vacancies,and fast surface exchange,as verified by the analyses of X-ray photoelectron spectroscopy,thermogravimetric testing,and conductivity tests.The R-PCECs with the PBCR_(0.1)C air electrode demonstrate an encouraging performance at 700℃:a peak power density of 2.32 W cm^(-2) in a fuel cell(FC)mode and an electrolysis current density of-3.55 A cm^(-2) at 1.3 V in an electrolysis(EL)mode.At 30 vol%steam concentration,a Faraday efficiency of 87.80%and a corresponding H_(2) production rate of 3.05 mL min^(-1) cm^(-2) at a current density of-0.5 A cm^(-2) at 650℃.Additionally,the durability of the cell in the FC mode(120 h),EL mode(120 h),and cycling FC/EL mode(100 h)at 650℃ suggests the great potential of PBCR_(0.1)C as the highly reactive and robust air electrodes of R-PCECs.展开更多
Flexible rechargeable Zn-air batteries are considered as one of the most promising battery systems to drive flexible and wearable electronic devices owing to their high safety,high gravimetric energy density,low self-...Flexible rechargeable Zn-air batteries are considered as one of the most promising battery systems to drive flexible and wearable electronic devices owing to their high safety,high gravimetric energy density,low self-discharge and low cost.One of the key challenges is to develop air electrodes with high performance and high mechanical flexibility.This minireview discusses the recent progress in the design and fabrication of flexible air electrodes.It focuses on the latest innovations in bifunctional oxygen reduction reaction and oxygen evolution reaction electrocatalysts,mainly including carbon-based materials(e.g.,heteroatom-doped carbon,metal-nitrogen moieties doped carbon),metal oxides(e.g.,spinel oxides,perovskite oxides)and their composites.It aims to provide an insight into the structureproperty relationship of bifunctional catalysts.We also discuss the challenges and future perspectives.展开更多
Smart wearable devices are regarded to be the next prevailing technology product after smartphones and smart homes,and thus there has recently been rapid development in flexible electronic energy storage devices.Among...Smart wearable devices are regarded to be the next prevailing technology product after smartphones and smart homes,and thus there has recently been rapid development in flexible electronic energy storage devices.Among them,flexible solid-state zinc-air batteries have received widespread attention because of their high energy density,good safety,and stability.Efficient bifunctional oxygen electrocatalysts are the primary consideration in the development of flexible solid-state zinc-air batteries,and self-supported air cathodes are strong candidates because of their advantages including simplified fabrication process,reduced interfacial resistance,accelerated electron transfer,and good flexibility.This review outlines the research progress in the design and construction of nanoarray bifunctional oxygen electrocatalysts.Starting from the configuration and basic principles of zinc-air batteries and the strategies for the design of bifunctional oxygen electrocatalysts,a detailed discussion of self-supported air cathodes on carbon and metal substrates and their uses in flexible zinc-air batteries will follow.Finally,the challenges and opportunities in the development of flexible zinc-air batteries will be discussed.展开更多
Recent advances in the preparation and application of perovskite-type oxides as bifunctional electrocatalysts for oxygen reaction and oxygen evolution reaction in rechargeable metal-air batteries are presented in this...Recent advances in the preparation and application of perovskite-type oxides as bifunctional electrocatalysts for oxygen reaction and oxygen evolution reaction in rechargeable metal-air batteries are presented in this review.Various fabrication methods of these oxides are introduced in detail,and their advantages and disadvantages are analyzed.Different preparation methods adopted have great influence on the morphologies and physicochemical properties of perovskite-type oxides.As a bifunctional electrocatalyst,perovskite-type oxides are widely used in rechargeable metal-air batteries.The relationship between the preparation methods and the performances of oxygen/air electrodes are summarized.This work is concentrated on the structural stability,the phase compositions,and catalytic performance of perovskite-type oxides in oxygen/air electrodes.The main problems existing in the practical application of perovskite-type oxides as bifunctional electrocatalysts are pointed out and possible research directions in the future are recommended.展开更多
Solid oxide cells(SOCs)are emerging devices for efficient energy storage and conversion.However,during SOC operation,gaseous chromium(Cr)species released from Fe-Cr alloy interconnect can lead to Cr deposition and poi...Solid oxide cells(SOCs)are emerging devices for efficient energy storage and conversion.However,during SOC operation,gaseous chromium(Cr)species released from Fe-Cr alloy interconnect can lead to Cr deposition and poisoning of air electrodes,causing substantial degradation in electrochemical performance and compromising the longterm stability of SOCs.This mini-review examines the mechanism of Cr deposition and poisoning in air electrodes under both fuel-cell and electrolysis modes.Furthermore,emphasis is placed on the recent advancements in strategies to mitigate Cr poisoning,offering insights into the rational design and development of active and Cr-tolerant air electrodes for SOCs.展开更多
The insufficient stability and poor surface reaction kinetics(i.e.,oxygen reduction reaction(ORR)and oxygen evolution reaction(OER))of air electrodes are significant factors hindering the development of reversible sol...The insufficient stability and poor surface reaction kinetics(i.e.,oxygen reduction reaction(ORR)and oxygen evolution reaction(OER))of air electrodes are significant factors hindering the development of reversible solid oxide cells(R-SOCs).The high-entropy strategy offers a new direction to optimize air electrodes.We introduce a high-entropy air electrode,(La_(0.12)Pr_(0.12)Nd_(0.12)Sm_(0.12)Gd_(0.12))Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ)(LPNSGSrCF),demonstrating a low polarization resistance(0.15Ωcm^(2))and good durability(1.3×10^(-3)Ωcm^(2)h^(-1)),superior to those of La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ)(0.31Ωcm^(2),2.0×10^(-3)Ωcm^(2)h^(-1))at 650℃.The elevated activity may be a result of the substantial concentration of oxygen vacancies and rapid reaction kinetics,as verified by X-ray photoelectron spectroscopy,electrochemical impedance spectroscopy,and distribution of relaxation times studies.Specifically,an R-SOC with LPNSGSrCF air electrode achieves a peak power density of 1.05 W cm^(-2)in fuel cell mode and a current density of0.89 A cm^(-2)at 1.3 V in electrolysis cell mode(with 30%H_(2)O)at 700℃.Moreover,the cells with LPNSGSrCF electrode can be stably operated in both modes for over 100 h.展开更多
Reversible solid oxide cell(RSOC)is a new energy conversion device with significant applications,especially for power grid peaking shaving.However,the reversible conversion process of power generation/energy storage p...Reversible solid oxide cell(RSOC)is a new energy conversion device with significant applications,especially for power grid peaking shaving.However,the reversible conversion process of power generation/energy storage poses challenges for the performance and stability of air electrodes.In this work,a novel high-entropy perovskite oxide La_(0.2)Pr_(0.2)Gd_(0.2)Sm_(0.2)Sr_(0.2)Co_(0.8)Fe_(0.2)O_(3−δ)(HE-LSCF)is proposed and investigated as an air electrode in RSOC.The electrochemical behavior of HE-LSCF was studied as an air electrode in both fuel cell and electrolysis modes.The polarization impedance(Rp)of the HE-LSCF electrode is only 0.25Ω·cm^(2) at 800℃ in an air atmosphere.Notably,at an electrolytic voltage of 2 V and a temperature of 800℃,the current density reaches up to 1.68 A/cm^(2).The HE-LSCF air electrode exhibited excellent reversibility and stability,and its electrochemical performance remains stable after 100 h of reversible operation.With these advantages,HE-LSCF is shown to be an excellent air electrode for RSOC.展开更多
Developing highly active and stable air electrodes remains challenging for reversible solid oxide cells(R-SOCs).Herein,we re-port an A-site high-entropy engineered perovskite oxide,La_(0.2)Pr_(0.2)Nd_(0.2)Ba_(0.2)Sr_(...Developing highly active and stable air electrodes remains challenging for reversible solid oxide cells(R-SOCs).Herein,we re-port an A-site high-entropy engineered perovskite oxide,La_(0.2)Pr_(0.2)Nd_(0.2)Ba_(0.2)Sr_(0.2)Co_(0.8)Fe_(0.2)O_(3−δ)(HE-LSCF),and its electrocatalytic activity and stability property are systematically probed for tubular R-SOCs.The HE-LSCF air electrode exhibits excellent oxygen reduction reac-tion(ORR)activity with a low polarization resistance of 0.042Ω·cm^(2)at 700℃,which is much lower than that of La0.6Sr0.4Co_(0.8)Fe_(0.2)O_(3−δ)(LSCF),indicating the excellent catalytic activity of HE-LSCF.Meanwhile,the tubular R-SOCs with HE-LSCF shows a high peak power density of 1.18 W·cm^(−2)in the fuel cell mode and a promising electrolysis current density of−0.52 A·cm^(−2)at 1.5 V in the electrolysis mode with H_(2)(~10%H_(2)O)atmosphere at 700℃.More importantly,the tubular R-SOCs with HE-LSCF shows favorable stability under 180 h reversible cycling test.Our results show the high-entropy design can significantly enhance the activity and robustness of LSCF electrode for tubular R-SOCs.展开更多
The exploration of aqueous flexible metal-air batteries with high energy density and durability has attracted many research efforts with the demand for portable and wearable electronic devices.Aqueous flexible metal-a...The exploration of aqueous flexible metal-air batteries with high energy density and durability has attracted many research efforts with the demand for portable and wearable electronic devices.Aqueous flexible metal-air batteries feature Earth-abundant materials,environmental friendliness,and operational safety.Each part of one metal-air battery can significantly affect the overall performance.This review starts with the fundamental working principles and the basic battery configurations and then highlights on the common issues and the recent advances in designing high-performance metal electrodes,solid-state electrolytes,and air electrodes.Bifunctional oxygen electrocatalysts with high activity and long-term stability for constructing efficient air electrodes in flexible metal-air batteries are summarized including metal-free carbon-based materials and nonprecious Co/Fe-based materials(alloys,metal oxides,metal sulfites,metal phosphates,metal nitrates,single-site metal-nitrogen-carbon materials,and composites).Finally,a perspective is provided on the existing challenges and possible future research directions in optimizing the performance and lifetime of the flexible aqueous solid-state metal-air batteries.展开更多
Oxygen electrocatalysts are of great importance for the air electrode in zinc-air batteries(ZABs).Owing to the high specific surface area,controllable pore size and unsaturated metal active sites,metal-organic framewo...Oxygen electrocatalysts are of great importance for the air electrode in zinc-air batteries(ZABs).Owing to the high specific surface area,controllable pore size and unsaturated metal active sites,metal-organic frameworks(MOFs)derivatives have been widely studied as oxygen electrocatalysts in ZABs.To date,many strategies have been developed to generate efficient oxygen electrocatalysts from MOFs for improving the performance of ZABs.In this review,the latest progress of the MOF-derived non-noble metal-oxygen electrocatalysts in ZABs is reviewed.The performance of these MOF-derived catalysts toward oxygen reduction,and oxygen evolution reactions is discussed based on the categories of metal-free carbon materials,single-atom catalysts,metal cluster/carbon composites and metal compound/carbon composites.Moreover,we provide a comprehensive overview on the design strategies of various MOF-derived non-noble metal-oxygen electrocatalysts and their structure-performance relationship.Finally,the challenges and perspectives are provided for further advancing the MOF-derived oxygen electrocatalysts in ZABs.展开更多
Reversible proton ceramic electrochemical cell(R-PCEC)is regarded as the most promising energy conversion device,which can realize efficient mutual conversion of electrical and chemical energy and to solve the problem...Reversible proton ceramic electrochemical cell(R-PCEC)is regarded as the most promising energy conversion device,which can realize efficient mutual conversion of electrical and chemical energy and to solve the problem of large-scale energy storage.However,the development of robust electrodes with high catalytic activity is the main bottleneck for the commercialization of R-PCECs.Here,a novel type of high-entropy perovskite oxide consisting of six equimolar metals in the A-site,Pr_(1/6)La_(1/6)Nd_(1/6)Ba_(1/6)Sr_(1/6)Ca_(1/6)CoO_(3−δ)(PLN-BSCC),is reported as a high-performance bifunctional air electrode for R-PCEC.By harnessing the unique functionalities of multiple ele-ments,high-entropy perovskite oxide can be anticipated to accelerate reaction rates in both fuel cell and electrolysis modes.Especially,an R-PCEC utilizing the PLNBSCC air electrode achieves exceptional electrochemical performances,demonstrating a peak power density of 1.21 W cm^(−2)for the fuel cell,while simultaneously obtaining an astonishing current density of−1.95 A cm^(−2)at an electrolysis voltage of 1.3 V and a temperature of 600℃.The significantly enhanced electrochemical performance and durability of the PLNBSCC air electrode is attributed mainly to the high electrons/ions conductivity,fast hydration reactivity and high configurational entropy.This research explores to a new avenue to develop optimally active and stable air electrodes for R-PCECs.展开更多
Reversible protonic ceramic cells(RPCCs) show great potential as new-generation energy conversion and storage devices. However, the mature development of RPCCs is seriously hindered by the inactivity and poor stabilit...Reversible protonic ceramic cells(RPCCs) show great potential as new-generation energy conversion and storage devices. However, the mature development of RPCCs is seriously hindered by the inactivity and poor stability of air electrodes exposed to concentrated vapor under operating conditions. Herein, we report a high-entropy air electrode with the composition BaCo_(0.2)Fe_(0.2)Zr_(0.2)Sn_(0.2)Pr_(0.2)O_(3-δ)(BCFZSP), which shows integrated electronic, protonic and oxygenic conduction in a single perovskite phase and excellent structural stability in concentrated steam. Such triple conduction can spread the electrochemically active sites of the air electrode to the overall electrode surface, thus optimizing the kinetics of the oxygen reduction and evolution reactions(0.448 Ω cm^(2) of polarization resistance at 550℃). As-prepared RPCCs with a BCFZSP air electrode at 600℃ achieved a peak power density of 0.68 W/cm^(2) in fuel-cell mode and a current density of 0.92 A/cm^(2) under a 1.3 V applied voltage in electrolysis mode. More importantly, the RPCCs demonstrate an encouragingly high stability during 120 h of reversible switching between the fuelcell and electrolysis modes. Given their excellent performance, high-entropy perovskites can be promising electrode materials for RPCCs.展开更多
The effects of acetylene black powder surface free energy on air electrode electrochemical performance and lifetime were studied.The acetylene black was immersed in 30%H_(2)O_(2)at room temperature and the changes of ...The effects of acetylene black powder surface free energy on air electrode electrochemical performance and lifetime were studied.The acetylene black was immersed in 30%H_(2)O_(2)at room temperature and the changes of functional groups and surface free energy were investigated by X-ray Photoelectron Spectroscopy(XPS)and powder contact angle(CA).The air electrode performance was characterized by the potential polarization curves and the lifetime was measured by constant-current discharge.It shows that,its surface free energy is the lowest when the acetylene black is immersed in H_(2)O_(2)for 240 h.The polarization potential of the air electrode prepared by the pretreated acetylene black is 0.25 V(vs.Hg/HgO),0.21 V lower than the air electrode with untreated acetylene black when the working current density is 100 mA·cm^(-1).And its lifetime is over 800 h at 80 mA·cm^(-1).The pretreatment of acetylene black for proper time by H_(2)O_(2)is favorable for the stability of the tri-phase reaction interface of air electrode and improvement of its performance.展开更多
Reversible protonic ceramic cells(RePCCs)hold promise for efficient energy storage,but their practicality is hindered by a lack of high-performance air electrode materials.Ruddlesden-Popper perovskite Sr_(3)Fe_(2)O_(7...Reversible protonic ceramic cells(RePCCs)hold promise for efficient energy storage,but their practicality is hindered by a lack of high-performance air electrode materials.Ruddlesden-Popper perovskite Sr_(3)Fe_(2)O_(7−δ)(SF)exhibits superior proton uptake and rapid ionic conduction,boosting activity.However,excessive proton uptake during RePCC operation degrades SF’s crystal structure,impacting durability.This study introduces a novel A/B-sites co-substitution strategy for modifying air electrodes,incorporating Sr-deficiency and Nb-substitution to create Sr_(2.8)Fe_(1.8)Nb_(0.2)O_(7−δ)(D-SFN).Nb stabilizes SF’s crystal,curbing excessive phase formation,and Sr-deficiency boosts oxygen vacancy concentration,optimizing oxygen transport.The D-SFN electrode demonstrates outstanding activity and durability,achieving a peak power density of 596 mW cm^(−2)in fuel cell mode and a current density of−1.19 A cm^(−2)in electrolysis mode at 1.3 V,650℃,with excellent cycling durability.This approach holds the potential for advancing robust and efficient air electrodes in RePCCs for renewable energy storage.展开更多
Fabricating non-noble metal-based carbon air electrodes with highly efficient bifunctionality is big challenge owing to the sluggish kinetics of oxygen reduction/evolution reaction(ORR/OER).The efficient cathode catal...Fabricating non-noble metal-based carbon air electrodes with highly efficient bifunctionality is big challenge owing to the sluggish kinetics of oxygen reduction/evolution reaction(ORR/OER).The efficient cathode catalyst is urgently needed to further improve the performance of rechargeable zinc-air batteries.Herein,an activation-doping assisted interface modification strategy is demonstrated based on freestanding integrated carbon composite(CoNiLDH@NPC)composed of wood-based N and P doped active carbon(NPC)and CoNi layer double hydroxides(CoNiLDH).In the light of its large specific surface area and unique defective structure,CoNiLDH@NPC with strong interfacecoupling effect in 2D-3D micro-nanostructure exhibits outstanding bifunctionality.Such carbon composites show half-wave potential of 0.85 V for ORR,overpotential of 320 mV with current density of 10 mA cm^(-2) for OER,and ultra-low gap of 0.70 V.Furthermore,highly-ordered open channels of wood provide enormous space to form abundant triple-phase boundary for accelerating the catalytic process.Consequently,zinc-air batteries using CoNiLDH@NPC show high power density(aqueous:263 mW cm^(-2),quasi-solid-state:65.8 mW cm^(-2))and long-term stability(aqueous:500 h,quasi-solid-state:120 h).This integrated protocol opens a new avenue for the rational design of efficient freestanding air electrode from biomass resources.展开更多
Reversible protonic ceramic electrochemical cells(R-PCECs)demonstrate great feasibility for efficient energy storage and conversion.One critical challenge for the development of R-PCECs is the design of novel air elec...Reversible protonic ceramic electrochemical cells(R-PCECs)demonstrate great feasibility for efficient energy storage and conversion.One critical challenge for the development of R-PCECs is the design of novel air electrodes with the characteristics of high catalytic activity and acceptable durability.Here,we report a donor doping of Hf into the B-site of a cobalt-based double perovskite with a nominal formula of PrBa_(0.8)Ca_(0.2)Co_(1.9)Hf_(0.1)O_(5tδ)(PBCCHf_(0.1)),which is naturally reconfigured to a double perovskite PrBa_(0.8-x)Ca_(0.2)Co_(1.9)Hf_(0.1)-xO5tδ(PBCCHf_(0.1)-x)backbone and nano-sized BaHfO3(BHO)on the surface of PBCCHf_(0.1)x.The air electrode demonstrates enhanced catalytic activity and durability(a stable polarization resistance of 0.269Ωcm2 for~100 h at 600℃),due likely to the fast surface exchange process and bulk diffusion process.When employed as an air electrode of R-PCECs,a cell with PBCCHf_(0.1) air electrode demonstrates encouraging performances in modes of the fuel cell(FC)and electrolysis(EL)at 600℃:a peak power density of 0.998 W cm^(-2)and a current density of1.613 A cm^(-2)at 1.3 V(with acceptable Faradaic efficiencies).More importantly,the single-cell with PBCCHf_(0.1) air electrode demonstrates good cycling stability,switching back and forth from FC mode to EL mode0.5 A cm^(-2)for 200 h and 50 cycles.展开更多
X The catalysts of air electrode were prepared by sintering the active carbon loaded with manganese nitrate and potassium permanganate at 360 ℃ . The air electrode was made up of a catalyst layer, a waterproof and ga...X The catalysts of air electrode were prepared by sintering the active carbon loaded with manganese nitrate and potassium permanganate at 360 ℃ . The air electrode was made up of a catalyst layer, a waterproof and gas-permeable layer, a current collecting substrate and a second wa-terproof and gas-permeable layer. The cell was assembled by the air electrode, pure magnesium anode and 10% NaCl solution used as electrolyte. The microstructures of air electrodes before and after discharging were characterized by SEM. The electrochemical behaviors of the air electrodes were determined by means of polarization curves, volt-ampere curves and constant current discharge curves. The polarization voltage of air electrode is-173 mV （vs SCE） at the current density of 50 mA/cm2. The air electrodes exhibits good activity and stability in neutral electrolyte. The magnesium-air cell could work at 5 W for more than 7 h.展开更多
A gas diffusion electrode (air electrode) with a high current efficiency of electro\|synthesizing H 2 O 2 using O 2 in air was prepared. The several systems with air electrode as cathode of ele ctro\|s...A gas diffusion electrode (air electrode) with a high current efficiency of electro\|synthesizing H 2 O 2 using O 2 in air was prepared. The several systems with air electrode as cathode of ele ctro\|synthesizing H 2 O 2 on the reaction spot for degrading aniline in aqueous--electro\|Fenton system, photo\|excitation electro\|H 2 O 2 system and photo\|electro\|Fenton system, were developed. Th e rates of decomposition of H 2 O 2 and mineralization of anil ine were experimentally measured respectively under different conditions, and th e results indicated there has an excellent parallel relation between decompositi on rate of H 2 O 2 and mineralization rate of aniline. Especia lly, photo\|electro\|Fenton system, where H 2 O 2 is decompose d the fastest, is the best system of oxidizing and degrading organic toxicants. Compared photo\|electro\|Fenton system with photo\|Fenton system, important role is revealed in the interface of air electrode. In this paper, the mineralizatio n mechanism of aniline in the photo\|electro\|Fenton system was also discussed.展开更多
As global energy demand increases and environmental standards tighten,the development of efficient,eco-friendly energy conversion and storage technologies becomes crucial.Solid oxide cells(SOCs)show great promise beca...As global energy demand increases and environmental standards tighten,the development of efficient,eco-friendly energy conversion and storage technologies becomes crucial.Solid oxide cells(SOCs)show great promise because of their high energy conversion efficiency and wide range of applications.Highentropy materials(HEMs),a novel class of materials comprising several principal elements,have attracted significant interest within the materials science and energy sectors.Their distinctive structural features and adaptable functional properties offer immense potential for innovation across various applications.This review systematically covers the basic concepts,crystal structures,element selection,and major synthesis strategies of HEMs,and explores in detail the specific applications of these materials in SOCs,including its potential as air electrodes,fuel electrodes,electrolytes,and interconnects(including barrier coatings).By analyzing existing studies,this review reveals the significant advantages of HEMs in enhancing the performance,anti-poisoning,and stability of SOCs;highlights the key areas and challenges for future research;and looks into possible future directions.展开更多
During discharge, appropriately changing the development paths of electron avalanches and increasing the number of initial electrons can effectively inhibit the formation of filamentary discharge. Based on the aforeme...During discharge, appropriately changing the development paths of electron avalanches and increasing the number of initial electrons can effectively inhibit the formation of filamentary discharge. Based on the aforementioned phenomenon, we propose a method of using microdischarge electrodes to produce a macroscopic discharge phenomenon. In the form of an asymmetric structure composed of a carbon fiber electrode, an electrode structure of carbon fiber spiral-contact type is designed to achieve an atmospheric pressure glow discharge in air, which is characterized by low discharge voltage, low energy consumption, good diffusion and less ozone generation.展开更多
文摘The slow oxygen reaction kinetics of air electrodes impair the performance of reversible protonic ceramic electrochemical cells(R-PCECs);hence,it is imperative to design novel air electrodes featuring excellent catalytic activity and endurance.Here,we report an Rb-doped double perovskite PrBa_(0.8)Ca_(0.1)Rb_(0.1)Co_(2)O_(5+δ)(denoted as PBCR_(0.1)C)as an air electrode for R-PCECs,displaying a low polarization resistance of 0.044Ωcm^(2) at 700℃ and excellent stability during exposure to humid air(3 vol%H_(2)O).The high performance is attributed to the high electrical conductivity,high concentration of oxygen vacancies,and fast surface exchange,as verified by the analyses of X-ray photoelectron spectroscopy,thermogravimetric testing,and conductivity tests.The R-PCECs with the PBCR_(0.1)C air electrode demonstrate an encouraging performance at 700℃:a peak power density of 2.32 W cm^(-2) in a fuel cell(FC)mode and an electrolysis current density of-3.55 A cm^(-2) at 1.3 V in an electrolysis(EL)mode.At 30 vol%steam concentration,a Faraday efficiency of 87.80%and a corresponding H_(2) production rate of 3.05 mL min^(-1) cm^(-2) at a current density of-0.5 A cm^(-2) at 650℃.Additionally,the durability of the cell in the FC mode(120 h),EL mode(120 h),and cycling FC/EL mode(100 h)at 650℃ suggests the great potential of PBCR_(0.1)C as the highly reactive and robust air electrodes of R-PCECs.
基金financial supports from the Science and Technology Program of Longyan(No.2018LYF8010)the NaturalScience Foundation of Fujian Province(No.2019J01800)+1 种基金the Qimai Natural Science Foundation of Shanghang County(No.2018SHQM01)the funding from the Australian Research Council Centre of Excellence Scheme(No.CE 140100012)。
文摘Flexible rechargeable Zn-air batteries are considered as one of the most promising battery systems to drive flexible and wearable electronic devices owing to their high safety,high gravimetric energy density,low self-discharge and low cost.One of the key challenges is to develop air electrodes with high performance and high mechanical flexibility.This minireview discusses the recent progress in the design and fabrication of flexible air electrodes.It focuses on the latest innovations in bifunctional oxygen reduction reaction and oxygen evolution reaction electrocatalysts,mainly including carbon-based materials(e.g.,heteroatom-doped carbon,metal-nitrogen moieties doped carbon),metal oxides(e.g.,spinel oxides,perovskite oxides)and their composites.It aims to provide an insight into the structureproperty relationship of bifunctional catalysts.We also discuss the challenges and future perspectives.
基金supported by the National Natural Science Foundation of China(22072107,21872105)the Natural Science Foundation of Shanghai(23ZR1464800)+1 种基金the Fundamental Research Funds for the Central Universitiesthe Science&Technology Commission of Shanghai Municipality(19DZ2271500)。
文摘Smart wearable devices are regarded to be the next prevailing technology product after smartphones and smart homes,and thus there has recently been rapid development in flexible electronic energy storage devices.Among them,flexible solid-state zinc-air batteries have received widespread attention because of their high energy density,good safety,and stability.Efficient bifunctional oxygen electrocatalysts are the primary consideration in the development of flexible solid-state zinc-air batteries,and self-supported air cathodes are strong candidates because of their advantages including simplified fabrication process,reduced interfacial resistance,accelerated electron transfer,and good flexibility.This review outlines the research progress in the design and construction of nanoarray bifunctional oxygen electrocatalysts.Starting from the configuration and basic principles of zinc-air batteries and the strategies for the design of bifunctional oxygen electrocatalysts,a detailed discussion of self-supported air cathodes on carbon and metal substrates and their uses in flexible zinc-air batteries will follow.Finally,the challenges and opportunities in the development of flexible zinc-air batteries will be discussed.
基金Projects(51504212,21573184,51703061)supported by the National Natural Science Foundation of ChinaProject(2018J01521)supported by the Natural Science Foundation of Fujian Province,ChinaProject(fma2017202)supported by the Open Fund of Fujian Provincial Key Laboratory of Functional Materials and Applications(Xiamen University of Technology),China
文摘Recent advances in the preparation and application of perovskite-type oxides as bifunctional electrocatalysts for oxygen reaction and oxygen evolution reaction in rechargeable metal-air batteries are presented in this review.Various fabrication methods of these oxides are introduced in detail,and their advantages and disadvantages are analyzed.Different preparation methods adopted have great influence on the morphologies and physicochemical properties of perovskite-type oxides.As a bifunctional electrocatalyst,perovskite-type oxides are widely used in rechargeable metal-air batteries.The relationship between the preparation methods and the performances of oxygen/air electrodes are summarized.This work is concentrated on the structural stability,the phase compositions,and catalytic performance of perovskite-type oxides in oxygen/air electrodes.The main problems existing in the practical application of perovskite-type oxides as bifunctional electrocatalysts are pointed out and possible research directions in the future are recommended.
基金supported by National Natural Science Foundation of China(22279018)National Natural Science Foundation of China(22005055)Natural Science Foundation of Fujian Province(2022J01085).
文摘Solid oxide cells(SOCs)are emerging devices for efficient energy storage and conversion.However,during SOC operation,gaseous chromium(Cr)species released from Fe-Cr alloy interconnect can lead to Cr deposition and poisoning of air electrodes,causing substantial degradation in electrochemical performance and compromising the longterm stability of SOCs.This mini-review examines the mechanism of Cr deposition and poisoning in air electrodes under both fuel-cell and electrolysis modes.Furthermore,emphasis is placed on the recent advancements in strategies to mitigate Cr poisoning,offering insights into the rational design and development of active and Cr-tolerant air electrodes for SOCs.
基金supported by the National Key R&D Program of China(2022YFB4003601)the National Natural Science Foundation of China(22179039)+4 种基金the Introduced Innovative R&D Team of Guangdong(2021ZT09L392)the Guangzhou Science and Technology Project(2024A04J3079)the Guangdong Basic and Applied Basic Research Foundation(2024A1515010448)the Pearl River Talent Recruitment Program(2019QN01C693)Zijin Mining Group Co.,Ltd(5405-ZC-2023-00008).
文摘The insufficient stability and poor surface reaction kinetics(i.e.,oxygen reduction reaction(ORR)and oxygen evolution reaction(OER))of air electrodes are significant factors hindering the development of reversible solid oxide cells(R-SOCs).The high-entropy strategy offers a new direction to optimize air electrodes.We introduce a high-entropy air electrode,(La_(0.12)Pr_(0.12)Nd_(0.12)Sm_(0.12)Gd_(0.12))Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ)(LPNSGSrCF),demonstrating a low polarization resistance(0.15Ωcm^(2))and good durability(1.3×10^(-3)Ωcm^(2)h^(-1)),superior to those of La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ)(0.31Ωcm^(2),2.0×10^(-3)Ωcm^(2)h^(-1))at 650℃.The elevated activity may be a result of the substantial concentration of oxygen vacancies and rapid reaction kinetics,as verified by X-ray photoelectron spectroscopy,electrochemical impedance spectroscopy,and distribution of relaxation times studies.Specifically,an R-SOC with LPNSGSrCF air electrode achieves a peak power density of 1.05 W cm^(-2)in fuel cell mode and a current density of0.89 A cm^(-2)at 1.3 V in electrolysis cell mode(with 30%H_(2)O)at 700℃.Moreover,the cells with LPNSGSrCF electrode can be stably operated in both modes for over 100 h.
基金supported by Fundamental Research Funds for the Central Universities(2023KYJD1008)the Science Research Projects of the Anhui Higher Education Institutions of China(2022AH051582).
文摘Reversible solid oxide cell(RSOC)is a new energy conversion device with significant applications,especially for power grid peaking shaving.However,the reversible conversion process of power generation/energy storage poses challenges for the performance and stability of air electrodes.In this work,a novel high-entropy perovskite oxide La_(0.2)Pr_(0.2)Gd_(0.2)Sm_(0.2)Sr_(0.2)Co_(0.8)Fe_(0.2)O_(3−δ)(HE-LSCF)is proposed and investigated as an air electrode in RSOC.The electrochemical behavior of HE-LSCF was studied as an air electrode in both fuel cell and electrolysis modes.The polarization impedance(Rp)of the HE-LSCF electrode is only 0.25Ω·cm^(2) at 800℃ in an air atmosphere.Notably,at an electrolytic voltage of 2 V and a temperature of 800℃,the current density reaches up to 1.68 A/cm^(2).The HE-LSCF air electrode exhibited excellent reversibility and stability,and its electrochemical performance remains stable after 100 h of reversible operation.With these advantages,HE-LSCF is shown to be an excellent air electrode for RSOC.
基金support provided by the National Key R&D Program of China(No.2024YFE0101500)the National Natural Science Foundation of China(No.52272257)the Natural Science Foundation of Jiangsu Province(No.BK20240109).
文摘Developing highly active and stable air electrodes remains challenging for reversible solid oxide cells(R-SOCs).Herein,we re-port an A-site high-entropy engineered perovskite oxide,La_(0.2)Pr_(0.2)Nd_(0.2)Ba_(0.2)Sr_(0.2)Co_(0.8)Fe_(0.2)O_(3−δ)(HE-LSCF),and its electrocatalytic activity and stability property are systematically probed for tubular R-SOCs.The HE-LSCF air electrode exhibits excellent oxygen reduction reac-tion(ORR)activity with a low polarization resistance of 0.042Ω·cm^(2)at 700℃,which is much lower than that of La0.6Sr0.4Co_(0.8)Fe_(0.2)O_(3−δ)(LSCF),indicating the excellent catalytic activity of HE-LSCF.Meanwhile,the tubular R-SOCs with HE-LSCF shows a high peak power density of 1.18 W·cm^(−2)in the fuel cell mode and a promising electrolysis current density of−0.52 A·cm^(−2)at 1.5 V in the electrolysis mode with H_(2)(~10%H_(2)O)atmosphere at 700℃.More importantly,the tubular R-SOCs with HE-LSCF shows favorable stability under 180 h reversible cycling test.Our results show the high-entropy design can significantly enhance the activity and robustness of LSCF electrode for tubular R-SOCs.
基金Australian Research Council,Grant/Award Numbers:DP190101008,FT190100058。
文摘The exploration of aqueous flexible metal-air batteries with high energy density and durability has attracted many research efforts with the demand for portable and wearable electronic devices.Aqueous flexible metal-air batteries feature Earth-abundant materials,environmental friendliness,and operational safety.Each part of one metal-air battery can significantly affect the overall performance.This review starts with the fundamental working principles and the basic battery configurations and then highlights on the common issues and the recent advances in designing high-performance metal electrodes,solid-state electrolytes,and air electrodes.Bifunctional oxygen electrocatalysts with high activity and long-term stability for constructing efficient air electrodes in flexible metal-air batteries are summarized including metal-free carbon-based materials and nonprecious Co/Fe-based materials(alloys,metal oxides,metal sulfites,metal phosphates,metal nitrates,single-site metal-nitrogen-carbon materials,and composites).Finally,a perspective is provided on the existing challenges and possible future research directions in optimizing the performance and lifetime of the flexible aqueous solid-state metal-air batteries.
基金This work is supported by the National Natural Science Foundation of China(22075092)the Program for HUST Academic Frontier Youth Team(2018QYTD15).
文摘Oxygen electrocatalysts are of great importance for the air electrode in zinc-air batteries(ZABs).Owing to the high specific surface area,controllable pore size and unsaturated metal active sites,metal-organic frameworks(MOFs)derivatives have been widely studied as oxygen electrocatalysts in ZABs.To date,many strategies have been developed to generate efficient oxygen electrocatalysts from MOFs for improving the performance of ZABs.In this review,the latest progress of the MOF-derived non-noble metal-oxygen electrocatalysts in ZABs is reviewed.The performance of these MOF-derived catalysts toward oxygen reduction,and oxygen evolution reactions is discussed based on the categories of metal-free carbon materials,single-atom catalysts,metal cluster/carbon composites and metal compound/carbon composites.Moreover,we provide a comprehensive overview on the design strategies of various MOF-derived non-noble metal-oxygen electrocatalysts and their structure-performance relationship.Finally,the challenges and perspectives are provided for further advancing the MOF-derived oxygen electrocatalysts in ZABs.
基金The work was supported by National Natural Science Foundation of China(21878158 and 21706129)State Key Laboratory of Clean Energy Utilization(Open Fund Project No.ZJUCEU2021001)Natural Science Foundation of Jiangsu Province(BK20221312).
文摘Reversible proton ceramic electrochemical cell(R-PCEC)is regarded as the most promising energy conversion device,which can realize efficient mutual conversion of electrical and chemical energy and to solve the problem of large-scale energy storage.However,the development of robust electrodes with high catalytic activity is the main bottleneck for the commercialization of R-PCECs.Here,a novel type of high-entropy perovskite oxide consisting of six equimolar metals in the A-site,Pr_(1/6)La_(1/6)Nd_(1/6)Ba_(1/6)Sr_(1/6)Ca_(1/6)CoO_(3−δ)(PLN-BSCC),is reported as a high-performance bifunctional air electrode for R-PCEC.By harnessing the unique functionalities of multiple ele-ments,high-entropy perovskite oxide can be anticipated to accelerate reaction rates in both fuel cell and electrolysis modes.Especially,an R-PCEC utilizing the PLNBSCC air electrode achieves exceptional electrochemical performances,demonstrating a peak power density of 1.21 W cm^(−2)for the fuel cell,while simultaneously obtaining an astonishing current density of−1.95 A cm^(−2)at an electrolysis voltage of 1.3 V and a temperature of 600℃.The significantly enhanced electrochemical performance and durability of the PLNBSCC air electrode is attributed mainly to the high electrons/ions conductivity,fast hydration reactivity and high configurational entropy.This research explores to a new avenue to develop optimally active and stable air electrodes for R-PCECs.
基金financially supported by the National Natural Science Foundation of China (Nos. 22078022, 22178023, 22179007)China Postdoctoral Science Foundation (No. 2021M690379)。
文摘Reversible protonic ceramic cells(RPCCs) show great potential as new-generation energy conversion and storage devices. However, the mature development of RPCCs is seriously hindered by the inactivity and poor stability of air electrodes exposed to concentrated vapor under operating conditions. Herein, we report a high-entropy air electrode with the composition BaCo_(0.2)Fe_(0.2)Zr_(0.2)Sn_(0.2)Pr_(0.2)O_(3-δ)(BCFZSP), which shows integrated electronic, protonic and oxygenic conduction in a single perovskite phase and excellent structural stability in concentrated steam. Such triple conduction can spread the electrochemically active sites of the air electrode to the overall electrode surface, thus optimizing the kinetics of the oxygen reduction and evolution reactions(0.448 Ω cm^(2) of polarization resistance at 550℃). As-prepared RPCCs with a BCFZSP air electrode at 600℃ achieved a peak power density of 0.68 W/cm^(2) in fuel-cell mode and a current density of 0.92 A/cm^(2) under a 1.3 V applied voltage in electrolysis mode. More importantly, the RPCCs demonstrate an encouragingly high stability during 120 h of reversible switching between the fuelcell and electrolysis modes. Given their excellent performance, high-entropy perovskites can be promising electrode materials for RPCCs.
基金This work was financially supported by the Key Technologies R&D Programme of Hebei Province(401073).
文摘The effects of acetylene black powder surface free energy on air electrode electrochemical performance and lifetime were studied.The acetylene black was immersed in 30%H_(2)O_(2)at room temperature and the changes of functional groups and surface free energy were investigated by X-ray Photoelectron Spectroscopy(XPS)and powder contact angle(CA).The air electrode performance was characterized by the potential polarization curves and the lifetime was measured by constant-current discharge.It shows that,its surface free energy is the lowest when the acetylene black is immersed in H_(2)O_(2)for 240 h.The polarization potential of the air electrode prepared by the pretreated acetylene black is 0.25 V(vs.Hg/HgO),0.21 V lower than the air electrode with untreated acetylene black when the working current density is 100 mA·cm^(-1).And its lifetime is over 800 h at 80 mA·cm^(-1).The pretreatment of acetylene black for proper time by H_(2)O_(2)is favorable for the stability of the tri-phase reaction interface of air electrode and improvement of its performance.
基金supported by the Research Grants Council,University Grants Committee,Hong Kong SAR(Project Number:N_PolyU552/20)supported by the National Nature Science Foundation of China(22209138)Guangdong Basic and Applied Basic Research Foundation(2021A1515110464).
文摘Reversible protonic ceramic cells(RePCCs)hold promise for efficient energy storage,but their practicality is hindered by a lack of high-performance air electrode materials.Ruddlesden-Popper perovskite Sr_(3)Fe_(2)O_(7−δ)(SF)exhibits superior proton uptake and rapid ionic conduction,boosting activity.However,excessive proton uptake during RePCC operation degrades SF’s crystal structure,impacting durability.This study introduces a novel A/B-sites co-substitution strategy for modifying air electrodes,incorporating Sr-deficiency and Nb-substitution to create Sr_(2.8)Fe_(1.8)Nb_(0.2)O_(7−δ)(D-SFN).Nb stabilizes SF’s crystal,curbing excessive phase formation,and Sr-deficiency boosts oxygen vacancy concentration,optimizing oxygen transport.The D-SFN electrode demonstrates outstanding activity and durability,achieving a peak power density of 596 mW cm^(−2)in fuel cell mode and a current density of−1.19 A cm^(−2)in electrolysis mode at 1.3 V,650℃,with excellent cycling durability.This approach holds the potential for advancing robust and efficient air electrodes in RePCCs for renewable energy storage.
基金financially supported by the National Key Research and Development Program of China(2022YF E0138900)National Natural Science Foundation of China(21972017)+2 种基金the Fundamental Research Funds for the Central Universities(2232022D-18)Shanghai Sailing Program(22YF1400700)the Chenguang Program of Shanghai Education Development Foundation and Shanghai Municipal Education Commission(22CGA37).
文摘Fabricating non-noble metal-based carbon air electrodes with highly efficient bifunctionality is big challenge owing to the sluggish kinetics of oxygen reduction/evolution reaction(ORR/OER).The efficient cathode catalyst is urgently needed to further improve the performance of rechargeable zinc-air batteries.Herein,an activation-doping assisted interface modification strategy is demonstrated based on freestanding integrated carbon composite(CoNiLDH@NPC)composed of wood-based N and P doped active carbon(NPC)and CoNi layer double hydroxides(CoNiLDH).In the light of its large specific surface area and unique defective structure,CoNiLDH@NPC with strong interfacecoupling effect in 2D-3D micro-nanostructure exhibits outstanding bifunctionality.Such carbon composites show half-wave potential of 0.85 V for ORR,overpotential of 320 mV with current density of 10 mA cm^(-2) for OER,and ultra-low gap of 0.70 V.Furthermore,highly-ordered open channels of wood provide enormous space to form abundant triple-phase boundary for accelerating the catalytic process.Consequently,zinc-air batteries using CoNiLDH@NPC show high power density(aqueous:263 mW cm^(-2),quasi-solid-state:65.8 mW cm^(-2))and long-term stability(aqueous:500 h,quasi-solid-state:120 h).This integrated protocol opens a new avenue for the rational design of efficient freestanding air electrode from biomass resources.
基金the financial support from the National Natural Science Foundation of China(Nos.22179039)the Introduced Innovative R&D Team of Guangdong(No.2021ZT09L392)+3 种基金the Fundamental Research Funds for the Central Universities(2022ZYGXZR002)Zijin Mining Group Co.,Ltd(5405-ZC-2023-00008)the Pearl River Talent Recruitment Program(2019QN01C693)the Natural Science Foundation of Guangdong Province(No.2022A1515011785).
文摘Reversible protonic ceramic electrochemical cells(R-PCECs)demonstrate great feasibility for efficient energy storage and conversion.One critical challenge for the development of R-PCECs is the design of novel air electrodes with the characteristics of high catalytic activity and acceptable durability.Here,we report a donor doping of Hf into the B-site of a cobalt-based double perovskite with a nominal formula of PrBa_(0.8)Ca_(0.2)Co_(1.9)Hf_(0.1)O_(5tδ)(PBCCHf_(0.1)),which is naturally reconfigured to a double perovskite PrBa_(0.8-x)Ca_(0.2)Co_(1.9)Hf_(0.1)-xO5tδ(PBCCHf_(0.1)-x)backbone and nano-sized BaHfO3(BHO)on the surface of PBCCHf_(0.1)x.The air electrode demonstrates enhanced catalytic activity and durability(a stable polarization resistance of 0.269Ωcm2 for~100 h at 600℃),due likely to the fast surface exchange process and bulk diffusion process.When employed as an air electrode of R-PCECs,a cell with PBCCHf_(0.1) air electrode demonstrates encouraging performances in modes of the fuel cell(FC)and electrolysis(EL)at 600℃:a peak power density of 0.998 W cm^(-2)and a current density of1.613 A cm^(-2)at 1.3 V(with acceptable Faradaic efficiencies).More importantly,the single-cell with PBCCHf_(0.1) air electrode demonstrates good cycling stability,switching back and forth from FC mode to EL mode0.5 A cm^(-2)for 200 h and 50 cycles.
文摘X The catalysts of air electrode were prepared by sintering the active carbon loaded with manganese nitrate and potassium permanganate at 360 ℃ . The air electrode was made up of a catalyst layer, a waterproof and gas-permeable layer, a current collecting substrate and a second wa-terproof and gas-permeable layer. The cell was assembled by the air electrode, pure magnesium anode and 10% NaCl solution used as electrolyte. The microstructures of air electrodes before and after discharging were characterized by SEM. The electrochemical behaviors of the air electrodes were determined by means of polarization curves, volt-ampere curves and constant current discharge curves. The polarization voltage of air electrode is-173 mV （vs SCE） at the current density of 50 mA/cm2. The air electrodes exhibits good activity and stability in neutral electrolyte. The magnesium-air cell could work at 5 W for more than 7 h.
文摘A gas diffusion electrode (air electrode) with a high current efficiency of electro\|synthesizing H 2 O 2 using O 2 in air was prepared. The several systems with air electrode as cathode of ele ctro\|synthesizing H 2 O 2 on the reaction spot for degrading aniline in aqueous--electro\|Fenton system, photo\|excitation electro\|H 2 O 2 system and photo\|electro\|Fenton system, were developed. Th e rates of decomposition of H 2 O 2 and mineralization of anil ine were experimentally measured respectively under different conditions, and th e results indicated there has an excellent parallel relation between decompositi on rate of H 2 O 2 and mineralization rate of aniline. Especia lly, photo\|electro\|Fenton system, where H 2 O 2 is decompose d the fastest, is the best system of oxidizing and degrading organic toxicants. Compared photo\|electro\|Fenton system with photo\|Fenton system, important role is revealed in the interface of air electrode. In this paper, the mineralizatio n mechanism of aniline in the photo\|electro\|Fenton system was also discussed.
基金supported by the National Key R&D Program of China(2022YFB4004000)National Natural Science Foundation of China(U24A20542,52472210,22279057)+3 种基金Natural Science Foundation of Jiangsu Province(BK20221312)Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX23_1465)Cultivation Program for the Excellent Doctoral Dissertation of Nanjing Tech University(2023-09)the grant of Hydrogen Energy Laboratory(No.FEUZ-2024-0009)。
文摘As global energy demand increases and environmental standards tighten,the development of efficient,eco-friendly energy conversion and storage technologies becomes crucial.Solid oxide cells(SOCs)show great promise because of their high energy conversion efficiency and wide range of applications.Highentropy materials(HEMs),a novel class of materials comprising several principal elements,have attracted significant interest within the materials science and energy sectors.Their distinctive structural features and adaptable functional properties offer immense potential for innovation across various applications.This review systematically covers the basic concepts,crystal structures,element selection,and major synthesis strategies of HEMs,and explores in detail the specific applications of these materials in SOCs,including its potential as air electrodes,fuel electrodes,electrolytes,and interconnects(including barrier coatings).By analyzing existing studies,this review reveals the significant advantages of HEMs in enhancing the performance,anti-poisoning,and stability of SOCs;highlights the key areas and challenges for future research;and looks into possible future directions.
基金Supported by the National Natural Science Foundation of China under Grant No 51577011
文摘During discharge, appropriately changing the development paths of electron avalanches and increasing the number of initial electrons can effectively inhibit the formation of filamentary discharge. Based on the aforementioned phenomenon, we propose a method of using microdischarge electrodes to produce a macroscopic discharge phenomenon. In the form of an asymmetric structure composed of a carbon fiber electrode, an electrode structure of carbon fiber spiral-contact type is designed to achieve an atmospheric pressure glow discharge in air, which is characterized by low discharge voltage, low energy consumption, good diffusion and less ozone generation.
