Co/CoO heterojunction rich in oxygen vacancies introduced by O_(2) plasma embedded in mesoporous walls of carbon nanoboxes covered with carbon nanotubes for rechargeable zinc-air battery

Herein,Co/CoO heterojunction nanoparticles(NPs)rich in oxygen vacancies embedded in mesoporous walls of nitrogen-doped hollow carbon nanoboxes coupled with nitrogen-doped carbon nanotubes(P-Co/CoOV@NHCNB@NCNT)are well designed through zeolite-imidazole framework(ZIF-67)carbonization,chemical vapor deposition,and O_(2) plasma treatment.As a result,the threedimensional NHCNBs coupled with NCNTs and unique heterojunction with rich oxygen vacancies reduce the charge transport resistance and accelerate the catalytic reaction rate of the P-Co/CoOV@NHCNB@NCNT,and they display exceedingly good electrocatalytic performance for oxygen reduction reaction(ORR,halfwave potential[EORR,1/2=0.855 V vs.reversible hydrogen electrode])and oxygen evolution reaction(OER,overpotential(η_(OER,10)=377mV@10mA cm^(−2)),which exceeds that of the commercial Pt/C+RuO_(2) and most of the formerly reported electrocatalysts.Impressively,both the aqueous and flexible foldable all-solid-state rechargeable zinc-air batteries(ZABs)assembled with the P-Co/CoOV@NHCNB@NCNT catalyst reveal a large maximum power density and outstanding long-term cycling stability.First-principles density functional theory calculations show that the formation of heterojunctions and oxygen vacancies enhances conductivity,reduces reaction energy barriers,and accelerates reaction kinetics rates.This work opens up a new avenue for the facile construction of highly active,structurally stable,and cost-effective bifunctional catalysts for ZABs.

Defect Engineering:Can it Mitigate Strong Coulomb Effect of Mg^(2+)in Cathode Materials for Rechargeable Magnesium Batteries?

Rechargeable magnesium batteries(RMBs)have been considered a promising“post lithium-ion battery”system to meet the rapidly increasing demand of the emerging electric vehicle and grid energy storage market.However,the sluggish diffusion kinetics of bivalent Mg^(2+)in the host material,related to the strong Coulomb effect between Mg^(2+)and host anion lattices,hinders their further development toward practical applications.Defect engineering,regarded as an effective strategy to break through the slow migration puzzle,has been validated in various cathode materials for RMBs.In this review,we first thoroughly understand the intrinsic mechanism of Mg^(2+)diffusion in cathode materials,from which the key factors affecting ion diffusion are further presented.Then,the positive effects of purposely introduced defects,including vacancy and doping,and the corresponding strategies for introducing various defects are discussed.The applications of defect engineering in cathode materials for RMBs with advanced electrochemical properties are also summarized.Finally,the existing challenges and future perspectives of defect engineering in cathode materials for the overall high-performance RMBs are described.

Bayesian framework for satellite rechargeable lithium battery synthesizing bivariate degradation and lifetime data

Reliability and remaining useful life(RUL)estimation for a satellite rechargeable lithium battery(RLB)are significant for prognostic and health management(PHM).A novel Bayesian framework is proposed to do reliability analysis by synthesizing multisource data,including bivariate degradation data and lifetime data.Bivariate degradation means that there are two degraded performance characteristics leading to the failure of the system.First,linear Wiener process and Frank Copula function are used to model the dependent degradation processes of the RLB's temperature and discharge voltage.Next,the Bayesian method,in combination with Markov Chain Monte Carlo(MCMC)simulations,is provided to integrate limited bivariate degradation data with other congeneric RLBs'lifetime data.Then reliability evaluation and RUL prediction are carried out for PHM.A simulation study demonstrates that due to the data fusion,parameter estimations and predicted RUL obtained from our model are more precise than models only using degradation data or ignoring the dependency of different degradation processes.Finally,a practical case study of a satellite RLB verifies the usability of the model.

N-doped porous carbon hollow microspheres encapsulated with iron-based nanocomposites as advanced bifunctional catalysts for rechargeable Zn-air battery

The design and development of low-cost,efficient,and stable bifunctional electrocatalysts for the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)are desirable for rechargeable metal-air batteries.In this work,N-doped porous hollow carbon spheres encapsulated with ultrafine Fe/Fe3O4 nanoparticles(FeOx@N-PHCS)were fabricated by impregnation and subsequent pyrolysis,using melamine-formaldehyde resin spheres as self-sacrifice templates and polydopamine as N and C sources.The sufficient adsorption of Fe3+on the polydopamine endowed the formation of Fe-Nx species upon high-temperature carbonization.The prepared FeOx@N-PHCS has advanced features of large specific surface area,porous hollow structure,high content of N dopants,sufficient Fe-Nx species and ultrafine FeOx nanoparticles.These features endow FeOx@N-PHCS with enhanced mass transfer and considerable active sites,leading to high activity and stability in catalyzing ORR and OER in alkaline electrolyte.Furthermore,the rechargeable Zn-air battery with FeOx@N-PHCS as air cathode catalyst exhibits a large peak power density,narrow charge-discharge potential gap and robust cycling stability,demonstrating the potential of the fabricated FeOx@N-PHCS as a promising electrode material for metal-air batteries.This new finding may open an avenue for rational design of bifunctional catalysts by integrating different active components within all-in-one catalyst for different electrochemical reactions.

Fundamentals,recent developments and prospects of lithium and non-lithium electrochemical rechargeable battery systems

The present and future energy requirements of mankind can be fulfilled with sustained research and development efforts by global scientists.The purpose of this review paper is to provide an overview of the fundamentals,recent advancements on Lithium and non-Lithium electrochemical rechargeable battery systems,and their future prospects.The initial part of this review paper is dedicated to the advancement and challenges faced by the conventional rechargeable batteries,such as lead-acid,Ni-Cd and Ni-MH batteries.The subsequent section of this review focuses on an in-depth analysis of two major categories of rechargeable batteries,namely lithium-based rechargeable battery systems and alternative non-Lithium rechargeable battery systems.The working principle,construction,and a few important research progress on Li-ion,Li-O_(2),Li-CO_(2) and Li-S batteries have been highlighted.The recent progress and challenges of the alternate batteries such as Na-ion,Na-S,Mg-ion,K-ion,Al-ion,Al-air,Zn-ion and Zn-air are also discussed in this review.The large gap between theoretical and practical electrochemical values for the alternate battery system must be filled by adopting a series of design architectures followed by modern instrumentation for developing next-generation batteries in a sustainable and efficient way.

An interface-reconstruction effect for rechargeable aluminum battery in ionic liquid electrolyte to enhance cycling performances

Aluminum(Al) metal has been regarded as a promising anode for rechargeable batteries because of its natural abundance and high theoretical specific capacity. However, rechargeable aluminum batteries(RABs) using A1 metal as anode display poor cycling performances owing to interface problems between anode and electrolyte. The solid-electrolyte interphase(SEI) layer on the anode has been confirmed to be essential for improving cycling performances of rechargeable batteries. Therefore, we immerse the Al metal in ionic liquid electrolyte for some time before it is used as anode to remove the passive film and expose fresh Al to the electrolyte. Then the reactions of exposed Al, acid, oxygen and water in electrolyte are occurred to form an SEI layer in the cycle. Al/electrolyte/V_2 O_5 full batteries with the thin, uniform and stable SEI layer on Al metal anode perform high discharge capacity and coulombic efficiency(CE). This work illustrates that an SEI layer is formed on Al metal anode in the cycle using a simple and effective pretreatment process and results in superior cycling performances for RABs.

3D hollow sphere Co_3O_4/MnO_2-CNTs:Its high-performance bi-functional cathode catalysis and application in rechargeable zinc-air battery

There has been a continuous need for high active, excellently durable and low-cost electrocatalysts for rechargeable zinc-air batteries. Among many low-cost metal based candidates, transition metal oxides with the CNTs composite have gained increasing attention. In this paper, the 3-D hollow sphere MnO_2 nanotube-supported Co_3O_4 nanoparticles and its carbon nanotubes hybrid material(Co_3 O_4/MnO_2-CNTs) have been synthesized via a simple co-precipitation method combined with post-heat treatment. The morphology and composition of the catalysts are thoroughly analyzed through SEM, TEM, TEM-mapping, XRD, EDX and XPS. In comparison with the commercial 20% Pt/C, Co_3O_4/MnO_2,bare MnO_2 nanotubes and CNTs, the hybrid Co_3O_4/MnO_2-CNTs-350 exhibits perfect bi-functional catalytic activity toward oxygen reduction reaction and oxygen evolution reaction under alkaline condition(0.1 M KOH). Therefore, high cell performances are achieved which result in an appropriate open circuit voltage(～1.47 V),a high discharge peak power density(340 mW cm^(-2)) and a large specific capacity(775 mAh g^(-1) at 10 mA cm^(-2)) for the primary Zn-air battery, a small charge-discharge voltage gap and a high cycle-life(504 cycles at 10 mA cm^(-2) with 10 min per cycle) for the rechargeable Zn-air battery. In particular, the simple synthesis method is suitable for a large-scale production of this bifunctional material due to a green, cost effective and readily available process.

In-situ growth of CoNi bimetal anchored on carbon nanoparticle/nanotube hybrid for boosting rechargeable Zn-air battery

Exploring highly efficient non-precious metal based catalysts for bifunctional oxygen electrode is crucial for rechargeable metal-air batteries.In this study,with MOFs as precursors,a facile coprecipitation method is designed to realize in-situ growth of the CoNi anchored carbon nanoparticle/nanotube(CoNi/N-CNN)hybrid,which can achieve the simultaneous maximum exposure of both oxygen evolution reaction(OER)and oxygen reduction reaction(ORR)active centers.Benefiting from the unique structure,the CoNi/N-CNN catalyst exhibits excellent electrocatalytic performance for ORR(E_(onset)=1.183 V,E_(1/2)=0.819 V)and a low operating voltage of 1.718 V at 10 mA cm^(−2)(Ej=10)for OER.Delightfully,the home-made rechargeable Zn-air battery with CoNi/N-CNN delivers a high discharge power density up to 209 mW cm^(−2),and an outstanding charge–discharge cycling stability.The boosted bifunctional electrocatalytic activity can be ascribed to the strong coupling effect between Co/Ni center sites and defect-rich N-anchored carbon featured with porous and nanotube structure,which can introduce uniformly dispersed active sites,tailored electronic configuration,superb conductivity and convenient charge transfer process.The hybrid non-precious bimetal based electrocatalyst provides the possibility to develop the low-cost and high-efficient ORR/OER bifunctional electrocatalysts in rechargeable metal-air battery.

Superior oxygen electrocatalyst derived from metal organic coordination polymers by instantaneous nucleation and epitaxial growth for rechargeable Li-O_(2) battery

Rechargeable aprotic Li-O_(2)batteries have attractea increasing attention due to their extremely high capacity,and it is very important to design appropriate strategies to synthesize efficient catalysts used as oxygen cathode.In present work,we present an expedient "instantaneous nucleation and epitaxial growth"(INEG) synthesis strategy for convenient and large-scale synthesis of ultrafine MOCPs nanoparticles(size 50-100 nm) with obvious advantages such as fast synthesis,high yields,low costs and reduced synthetic steps.The bimetallic Ru/Co-MOCPs are further pyrolyzed to obtain bimetallic Coand low content of Ru-based nanoparticles embedded within nitrogen-doped carbon(Ru/Co@N-C) as an efficient catalyst used in Li-O_(2)battery.The Ru/Co@N-C provides porous carbon framework for the ion transportation and O_(2)diffusion,and has large amounts of metal/nonmetal sites as active site to promote the oxygen reduction reaction(ORR)/oxygen evolution reaction(OER) in Li-O_(2)batteries.As a consequence,a high discharge specific capacity of 15246 mA h g^(-1)at 250 mA g^(-1), excellent rate capability at different current densities,and stable overpotential during cycling,are achieved.This work opened up a new understanding for the industrialized synthesis of ultrafine catalysts for Li-O_(2)batteries with excellent structural characteristics and electrochemical performance.

Dual-Defect Engineering Strategy Enables High-Durability Rechargeable Magnesium-Metal Batteries

Rechargeable magnesium-metal batteries(RMMBs)are promising next-generation secondary batteries;however,their development is inhibited by the low capacity and short cycle lifespan of cathodes.Although various strategies have been devised to enhance the Mg^(2+)migration kinetics and structural stability of cathodes,they fail to improve electronic conductivity,rendering the cathodes incompatible with magnesium-metal anodes.Herein,we propose a dual-defect engineering strategy,namely,the incorporation of Mg^(2+)pre-intercalation defect(P-Mgd)and oxygen defect(Od),to simultaneously improve the Mg^(2+)migration kinetics,structural stability,and electronic conductivity of the cathodes of RMMBs.Using lamellar V_(2)O_(5)·nH_(2)O as a demo cathode material,we prepare a cathode comprising Mg_(0.07)V_(2)O_(5)·1.4H_(2)O nanobelts composited with reduced graphene oxide(MVOH/rGO)with P-Mgd and Od.The Od enlarges interlayer spacing,accelerates Mg^(2+)migration kinetics,and prevents structural collapse,while the P-Mgd stabilizes the lamellar structure and increases electronic conductivity.Consequently,the MVOH/rGO cathode exhibits a high capacity of 197 mAh g^(−1),and the developed Mg foil//MVOH/rGO full cell demonstrates an incredible lifespan of 850 cycles at 0.1 A g^(−1),capable of powering a light-emitting diode.The proposed dual-defect engineering strategy provides new insights into developing high-durability,high-capacity cathodes,advancing the practical application of RMMBs,and other new secondary batteries.

A novel Zn-PANI dry rechargeable battery

Conducting polyaniline (PANI) powder was well mixed with graphite and acetylene black to obtain the optimum conductivity and porosity. The mixed powder was compressed into a pellet for cathode. Zinc powder was mixed with some metal powder, and compressed into a pellet used as the anode. The electrolyte comprised ZnCl2, NH4Cl, Triton-X100 and PVA at pH 3. The battery has an open-circuit voltage of 1.44 V. The battery underwent charge-discharge cycle with a constant current density of 3 mA·cm-2, within the voltage range of 0.40-1.68 V. It is found that the capacity of the battery is related to the charge-discharge cycles, the maximum capacity is 67.9 mAh·g-1, and Coulombic efficiency is between 95% and 100%. The battery stability was also investigated after 78 d of standing without use. It is found that the battery experiences a self-discharge of less than 0.29% per day.

Bi-salt electrolyte for aqueous rechargeable aluminum battery

The exertion of superior high-energy density based on multivalent ions transfer of rechargeable aluminum batteries is greatly hindered by limited electrochemical stability window of typical water in salt electrolyte(Wi SE). Recently, it is reported that a second salt addition to the Wi SE can offer further suppression of water activities, and achieves a much wider electrochemical window compared with aqueous Wi SE electrolytes. Hence, we demonstrate a class of water in bi-salt electrolyte containing the trifluoromethanesulfonate(OTF), which exhibits an ultra-wide electrochemical window of 4.35 V and a very low overpotential of 14.6 m V. Moreover, the interface chemistry between cathode and electrolyte is also confirmed via kinetic analysis. Surprisingly, we find the electrolyte can effectively suppress Mn dissolution from the cathode, alleviate self-discharge behavior, and ensure a stable electrode–electrolyte interface based on the interface concentrated-confinement effect. Owing to these unique merits of water in bi-salt electrolyte, the AlxMnO_(2)·nH_(2)O material delivers a high capacity of 364 m Ah g;and superb long-term cycling performance > 150 cycles with a capacity decay rate of 0.37% per cycle with coulombic efficiency at ca. 95%.

Comments on “An ultrafast rechargeable aluminum ion battery”

Nature published an article'An ultrafast rechargeable aluminum ion battery'On April 6,2015.The authors used many new materials to compose the cell,such as three-dimensional graphitic-foam as the cathode,an ionic liquid electrolyte.The experimental cell has shown well-defined discharge voltage plateaus near 2 V.The cell is mechanically bendable and foldable without affecting its operation.

Understanding the catalysis of chromium trioxide added magnesium hydride for hydrogen storage and Li ion battery applications

This study explores how the chemical interaction between magnesium hydride(MgH_(2))and the additive CrO_(3) influences the hydrogen/lithium storage characteristics of MgH_(2).We have observed that a 5 wt.%CrO_(3) additive reduces the dehydrogenation activation energy of MgH_(2) by 68 kJ/mol and lowers the required dehydrogenation temperature by 80℃.CrO_(3) added MgH_(2) was also tested as an anode in an Li ion battery,and it is possible to deliver over 90%of the total theoretical capacity(2038 mAh/g).Evidence for improved reversibility in the battery reaction is found only after the incorporation of additives with MgH_(2).In depth characterization study by X-ray diffraction(XRD)technique provides convincing evidence that the CrO_(3) additive interacts with MgH_(2) and produces Cr/MgO byproducts.Gibbs free energy analyses confirm the thermodynamic feasibility of conversion from MgH_(2)/CrO_(3) to MgO/Cr,which is well supported by the identification of Cr(0)in the powder by X ray photoelectron spectroscopy(XPS)technique.Through high resolution transmission electron microscopy(HRTEM)and energy dispersive spectroscopy(EDS)we found evidence for the presence of 5 nm size Cr nanocrystals on the surface of MgO rock salt nanoparticles.There is also convincing ground to consider that MgO rock salt accommodates Cr in the lattice.These observations support the argument that creation of active metal–metal dissolved rock salt oxide interface may be vital for improving the reactivity of MgH_(2),both for the improved storage of hydrogen and lithium.

Functionally gradient materials for sustainable and high-energy rechargeable lithium batteries:Design principles,progress,and perspectives

Rechargeable lithium batteries with high-capacity cathodes/anodes promise high energy densities for nextgeneration electrochemical energy storage.However,the associated limitations at various scales greatly hinder their practical applications.Functional gradient material(FGM)design endows the electrode materials with property gradient,thus providing great opportunities to address the kinetics and stability obstacles.To date,still no review or perspective has covered recent advancements in gradient design at multiple scales for boosting lithium battery performances.To fill this void,this work provides a timely and comprehensive overview of this exciting and sustainable research field.We begin by overviewing the fundamental features of FGM and the rationales of gradient design for improved electrochemical performance.Then,we comprehensively review FGM design for rechargeable lithium batteries at various scales,including natural or artificial solid electrolyte interphase(SEI)at the nanoscale,micrometer-scale electrode particles,and macroscale electrode films.The link between gradient structure design and improved electrochemical performance is particularly highlighted.The most recent research into constructing novel functional gradients,such as valence and temperature gradients,has also been explored.Finally,we discussed the current constraints and future scope of FGM in rechargeable lithium batteries,aiming to inspire the development of novel FGM for next-generation high-performance lithium batteries.

A non-nucleophilic electrolyte based on all-inorganic salts with conditioning-free characteristic for rechargeable magnesium batteries

Conditioning-free electrolytes with high reversibility of Mg plating/stripping are of vital importance for the commercialization of the superior rechargeable magnesium batteries(RMBs).In the present work,a non-nucleophilic electrolyte(denoted as MLCH)based on all-inorganic salts of MgCl_(2),LiCl and CrCl_(3) for RMBs is prepared by a straightforward one-step reaction.As a result,the MLCH electrolyte shows the noticeable performance of high ionic conductivity(3.40 mS cm^(−1)),low overpotential(∼46 mV vs Mg/Mg^(2+)),high Coulombic efficiency(∼93%),high anodic stability(SS,∼2.56 V vs Mg/Mg^(2+))and long-term(more than 500 h)cycling stability,especially the conditioning-free characteristic.The main equilibrium species in the MLCH electrolyte are confirmed to be the tetracoordinated anions of[LiCl2(THF)2]−and solvated dimers of[Mg_(2)(μ-Cl)3(THF)6]+.The addition of LiCl can assist the dissolution of MgCl_(2) and activation of the electrode/electrolyte interface,resulting in a superior Mg plating/stripping efficiency.The synergistic effect of LiCl,CrCl_(3),a small amount of HpMS and the absence of polymerization THF enable the conditioning-free characteristic of the MLCH electrolyte.Moreover,the MLCH electrolyte exhibits decent compatibility with the cathodic materials of CuS.The Mg/CuS full cell using the MLCH electrolyte presents a discharge specific capacity of 215 mAh g^(−1)at 0.1 C and the capacity can retain∼72%after 40 cycles.Notably,the MLCH electrolyte has other superiorities such as the broad sources of materials,low-cost and easy-preparation,leading to the potential prospect of commercial application.

Interfacial chemistry of anode/electrolyte interface for rechargeable magnesium batteries

Rechargeable magnesium batteries(RMBs),as a low-cost,high-safety and high-energy storage technology,have attracted tremendous attention in large-scale energy storage applications.However,the key anode/electrolyte interfacial issues,including surface passivation,uneven Mg plating/stripping,and pulverization after cycling still result in a large overpotential,short cycling life,poor power density,and possible safety hazards of cells,severely impeding the commercial development of RMBs.In this review,a concise overview of recently advanced strategies to address these anode/electroyte interfacial issues is systematically classified and summarized.The design of magnesiophilic substrates,construction of artificial SEI layers,and modification of electrolyte are important and effective strategies to improve the uniformity/kinetics of Mg plating/stripping and achieve the stable anode/electrolyte interface.The key opportunities and challenges in this field are advisedly put forward,and the insights into future directions for stabilizing Mg metal anodes and the anode/electrolyte interface are highlighted.This review provides important references fordeveloping the high-performance and high-safety RMBs.

A perspective on the key factors of safety for rechargeable magnesium batteries

Rechargeable Mg batteries(RMBs)have become one of the best subsitutes for lithium-ion batteries due to the high volumetric capacity,abundant resources,and uniform plating behavior of Mg metal anode.However,the safety hazard induced by the formation of high-modulue Mg dendrites under a high current density(10 mA cm^(-1))was still revealed in recent years.It has forced researchers to re-examine the safety of RMBs.In this review,the intrinsic safety factors of key components in RMBs,such as uneven plating,pitting and flammability of Mg anode,heat release and crystalline water decomposition of cathode,strong corrosion,low oxidition stability and flammability of electrolytes,and soforth,are systematacially summarized.Their origins,formation mechanisms,and possible safety hazards are deeply discussed.To develop high-performance Mg anode,current strategies including designing artificial SEI,three-dimensional substrates,and Mg alloys are summarized.For practical electrolytes,the configurations of boron-centered anions and simple Mg salts and the functionalized solvent with high boiling point and low flammability are suggested to comprehensively design.In addition,the future study should more focus on the investigation on the thermal runaway and decomposition of cathode materials and separa-tors.This review aims to provide fundamental insights into the relationship between electrochemistry and safety,further promoting the sustainable development of RMBs.

Novel medium entropy perovskite oxide Sr(FeCoNiMo)_(1/4)O_(3−δ)for zinc-air battery cathode

It is widely recognized that the development of ZABs is impeded by the kinetic bottleneck of oxygen evolution reaction(OER)and oxygen reduction reaction(ORR).The application of conformational entropy strategy to oxides often involves introducing multiple elements with different properties,thereby providing outstanding bifunctional catalytic activity for OER/ORR.Nevertheless,the possible underlying catalytic pathways and potential interactions between various components are still poorly understood.This paper presents an excellent medium-entropy perovskite oxide,Sr(FeCoNiMo)_(1/4)O_(3−δ)(lower overpotential of 301 mV at 10 mA cm^(−2)).Zinc-air batteries employing it as a cathode catalyst demonstrate excellent round-trip efficiency(62%).By combining theoretical calculation with experiments,we aim to establish the link between the electronic structure of perovskite oxides with different elemental compositions and their OER mechanism.Research reveals that the conformational entropy strategy can simultaneously shift the O 2p-band center and metal d-band center of perovskite oxide towards the vicinity of the Fermi energy level,thereby triggering a more favorable lattice oxygen-participated mechanism(LOM)during the OER process.The outcomes of this work provide crucial insights into the role of conformational entropy strategies in oxygen catalysis and offer potential avenues for constructing efficient and stable electrocatalysts.

Heteroatom anchors Fe-Mn dual-atom catalysts with bi-functional oxygen catalytic activity for low-temperature rechargeable flexible Zn-air batteries

M-N-C(M=Fe,Co,Ni,etc.) catalyst owns high catalytic activity in the oxygen catalytic reaction which is the most likely to replace the Pt-based catalysts.But it is still a challenge to further increase the active site density.This article constructs the high-efficiency FeMn-N/S-C-1000 catalyst to realize ORR/OER bifunctional catalysis by hetero-atom,bimetal(Fe,Mn) doped simultaneously strategy.When evaluated it as bi-functional electro-catalysts,FeMn-N/S-C-1000 exhibits excellent catalytic activity(E_(1/2)=0.924 V,E_(j=10)=1.617 V) in alkaline media,outperforms conventional Pt/C,RuO_(2) and most non-precious-metal catalysts reported recently,Such outstanding performance is owing to N,S co-coordinated with metal to form multi-types of single atom,dual atom active sites to carry out bi-catalysis.Importantly,nitrite poison test provides the proof that the active sites of FeMn-N/S-C are more than that of single-atom catalysts to promote catalytic reactions directly.To better understand the local structure of Fe and Mn active sites,XAS and DFT were employed to reveal that FeMn-N_5/S-C site plays the key role during catalysis.Notably,the FeMn-N/S-C-1000 based low-temperature rechargeable flexible Zn-air also exhibits superior discharge performance and extraordinary durability at-40℃.This work will provide a new idea to design diatomic catalysts applied in low-temperature rechargeable batteries.