Cathode Catalyst For Li-O2 Batteries Research Articles

Nanoengineering of Cathode Catalysts for Li-O2 Batteries.

Lithium-oxygen (Li-O2) batteries have obtained widespread attention as next-generation energy storage systems due to their extremely high energy density. However, the high charge overpotential, attributed to the insulating property of Li2O2, significantly limits the energy efficiency and triggers solvent degradation. The high electrochemical activities of oxygen reduction reactions (ORR) and oxygen evolution reactions (OER) on the cathode are crucial for alleviating the high charging polarizations and enhancing the lifetime of Li-O2 batteries, which are also top challenges of state-of-art research. In this review, the scientific challenges and the proposed solutions in the development of cathode catalysts have been summarized. The recent research advancements on the nanoengineering of cathode catalysts for Li-O2 batteries have been comprehensively discussed, and the perspectives on the structure optimization are presented. Meanwhile, we have elucidated the structure-performance relationship between the electronic state and performance of the cathode catalysts at the nanoscale level. This review intends to provide guidelines for the design and construction of cathode catalysts in advanced Li-O2 batteries.

Optimizing the adsorption of intermediates through modulating Mn d-band centers by the Mn-Ce heterojunction for high-performance lithium-oxygen batteries

Admitting that rare-earth (RE)-based transition metal oxides (TMO) are emerging as a promising catalyst for lithium-oxygen (Li-O2) batteries, the understanding of their electrocatalytic mechanism and active sites remains ambiguous. In this study, CeO2 nanoparticles modified MnOOH nanowires (CeO2@MnOOH NWs) is prepared by a simple solvothermal method as highly effective cathode catalysts for Li-O2 batteries. The incorporation of CeO2 nanoparticles into MnOOH facilitates a robust interaction between the 3d electronic state of MnOOH and the 4f electronic state of CeO2 at the Fermi level (Ef). The strong electron interaction at the heterogeneous interface between MnOOH and CeO2 promotes internal electron transfer. Compared to pristine MnOOH, the prepared CeO2@MnOOH NWs exhibits enhanced electrocatalytic activity and improved electrocatalytic stability. According to experimental analysis and density functional theory (DFT) results, it is demonstrated that there is a slight negative shift in the d-band center of the Mn site, resulting in faster electron transfer rates and higher conductivity. This acceleration of charge transfer optimizes the adsorption strength of the oxygen-containing intermediate (LiO2), thereby promoting the kinetics of the oxygen reduction/evolution reactions (ORR/OER) and reducting the reaction over-potential. As a result, the electrochemical performances of Li-O2 batteries are greatly enhanced.

First Principles Study of the Structure-Performance Relation of Pristine Wn+1Cn and Oxygen-Functionalized Wn+1CnO2 MXenes as Cathode Catalysts for Li-O2 Batteries.

Li-O2 batteries are considered a highly promising energy storage solution. However, their practical implementation is hindered by the sluggish kinetics of the oxygen reduction (ORR) and oxygen evolution (OER) reactions at cathodes during discharging and charging, respectively. In this work, we investigated the catalytic performance of Wn+1Cn and Wn+1CnO2 MXenes (n = 1, 2, and 3) as cathodes for Li-O2 batteries using first principles calculations. Both Wn+1Cn and Wn+1CnO2 MXenes show high conductivity, and their conductivity is further enhanced with increasing atomic layers, as reflected by the elevated density of states at the Fermi level. The oxygen functionalization can change the electronic properties of WC MXenes from the electrophilic W surface of Wn+1Cn to the nucleophilic O surface of Wn+1CnO2, which is beneficial for the activation of the Li-O bond, and thus promotes the Li+ deintercalation during the charge-discharge process. On both Wn+1Cn and Wn+1CnO2, the rate-determining step (RDS) of ORR is the formation of the (Li2O)2* product, while the RDS of OER is the LiO2* decomposition. The overpotentials of ORR and OER are positively linearly correlated with the adsorption energy of the RDS LixO2* intermediates. By lowering the energy band center, the oxygen functionalization and increasing atomic layers can effectively reduce the adsorption strength of the LixO2* intermediates, thereby reducing the ORR and OER overpotentials. The W4C3O2 MXene shows immense potential as a cathode catalyst for Li-O2 batteries due to its outstanding conductivity and super-low ORR, OER, and total overpotentials (0.25, 0.38, and 0.63 V).

Constructing Built-In Electric Field in NiCo2O4-CeO2 Heterostructures to Regulate Li2O2 Formation Routes at High Current Densities.

Developing catalysts with suitable adsorption energy for oxygen-containing intermediates and elucidating their internal structure-performance relationships are essential for the commercialization of Li-O2 batteries (LOBs), especially under high current densities. Herein, NiCo2O4-CeO2 heterostructure with a spontaneous built-in electric field (BIEF) is designed and utilized as a cathode catalyst for LOBs at high current density. The driving mechanism of electron pumping/accumulation at heterointerface is studied via experiments and density functional theory (DFT) calculations, elucidating the growth mechanism of discharge products. The results show that BIEF induced by work function difference optimizes the affinity for LiO2 and promotes the formation of nano-flocculent Li2O2, thus improving LOBs performance at high current density. Specifically, NiCo2O4-CeO2 cathode exhibits a large discharge capacity (9546mAhg-1 at 4000mAg-1) and high stability (>430 cycles at 4000mAg-1), which are better than the majority of previously reported metal-based catalysts. This work provides a new method for tuning the nucleation and decomposition of Li2O2 and inspires the design of ideal catalysts for LOBs to operate at high current density.

Coupling MoSe2 with Non-Stoichiometry Ni0.85 Se in Carbon Hollow Nanoflowers for Efficient Electrocatalytic Synergistic Effect on Li-O2 Batteries.

Li-O2 batteries could deliver ultra-high theoretical energy density compared to current Li-ion batteries counterpart. The slow cathode reaction kinetics in Li-O2 batteries, however, limits their electrocatalytic performance. To this end, MoSe2 and Ni0.85 Se nanoflakeswere decorated in carbon hollow nanoflowers, whichwere served as the cathode catalysts for Li-O2 batteries. The hexagonal Ni0.85 Se and MoSe2 show good structural compatibility with the same space group, resulting in a stable heterogeneous structure. The synergistic interaction of the unsaturated atoms and the built-in electric fields on the heterogeneous structure exposes abundant catalytically active sites, accelerating ion and charge transport and imparting superior electrochemical activity, including high specific capacities and stable cycling performance. More importantly, the lattice distances of the Ni0.85 Se (101) plane and MoSe2 (100) plane at the heterogeneous interfaces are highly matched to that of Li2 O2 (100) plane, facilitating epitaxial growth of Li2 O2 , as well as the formation and decomposition of discharge products during the cycles. This strategy of employing nonstoichiometric compounds to build heterojunctions and improve Li-O2 battery performance is expected to be applied to other energy storage or conversion systems.

B-N Co-Doped Biphenylene as a Metal-Free Cathode Catalyst for Li-O2 Batteries: a Computational Study.

Lithium-oxygen batteries (LOBs) meet the growing demand for long-distance transportation over electric vehicles but face challenges because of the lack of high-performance cathode catalysts. Herein, using density functional theory calculations, we report a unique graphene allotrope, biphenylene, of which the doping structures exhibit great potential as metal-free catalysts for LOBs. Our modeling results demonstrate that the biphenylene nanosheets retain metallic properties after B doping, N doping, or B-N co-doping. Compared with the pristine biphenylene, the catalytic activity of the doped biphenylene is greatly improved due to charge redistributions. Notably, the overpotentials of the B-N co-doped biphenylene are as low as 0.19 and 0.18 V for the discharge and charge processes, respectively. Based on the electronic structure and bonding analysis, we identify two factors, i. e., Li-O bond strength and *Li2 O2 adsorption energy, that can influence the Li-O2 electrochemical reactions. This study not only proposes a promising cathode catalyst but also provides insights into optimizing cathode catalysts for LOBs.

La-based perovskites for capacity enhancement of Li-O2 batteries.

Li-O2 batteries are a promising technology for the upcoming energy storage requirements because of their high theoretical specific energy density of 11,680Wh kg-1. Currently, the actual capacity of Li-O2 batteries is much lower than this theoretical value. In many studies, perovskites have been applied as catalysts to improve the air electrode reactions in Li-O2 batteries. The effects of structure and doping on the catalytic activity of perovskites are still unclear. La1-xSrxCoO3-δ (x = 0.1, 0.3, and 0.5) and La0.9Sr0.1YbO3-δ mixed with carbon black (Vulcan XC500 or Super P) were used as air electrode catalysts. Electrochemical characterizations were conducted using a Swagelok-type cell. The charge-discharge capacity and cyclic voltammetry (CV) performance were investigated in this study. The La1-xSrxCoO3-δ (x = 0.1, 0.3, and 0.5) is a suitable cathode catalyst for Li-O2 batteries. In this study, the La0.5Sr0.5CoO3-δ/Super P cathode demonstrated the highest discharge capacity (6,032 mAh g-1). This excellent performance was attributed to the large reaction area and enhanced Li2CO3 generation.

Co nanoparticles embedded into leaf-like porous carbon as a promising cathode catalyst for Li-O2 batteries

Rechargeable Li-O2 batteries show great potential due to their superior high energy density. However, the practical application is still limited by the sluggish kinetics, resulting in poor cycling performance and high overpotentials. Herein, highly dispersed Co nanoparticles embedded into porous N-doped carbon matrix (DCo-NC) with carbon nanotubes is explored through the pyrolysis of a bimetallic leaf-shaped ZnCo-ZIFs. The evaporation of Zn species and porous carbon matrix derived from ZIFs prevents the Co nanoparticles aggregation, exposes more Co-N active sites and provides abundant pores. They facilitate Li+ and electron transfer, prevent Co nanoparticles from deactivation and provide enough space for Li2O2, thereby accelerating oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) kinetics. Accordingly, the Li-O2 batteries with DCo-NC cathode exhibit reduced overpotential, high discharge capacity (10,490 mA h g−1 at 100 mA g−1 current density) and improved cycling performance (258 cycles at 500 mA g−1 with a limited capacity of 500 mA h g−1, 103 cycles at 500 mA g−1 with a limited capacity of 1000 mA h g−1).

MOF-Derived Mn2 O3 Nanocage with Oxygen Vacancies as Efficient Cathode Catalysts for Li-O2 Batteries.

Designing efficient and cost-effective electrocatalysts is the primary imperative for addressing the pivotal concerns confronting lithium-oxygen batteries (LOBs). The microstructure of the catalyst is one of the key factors that influence the catalytic performance. This study proceeds to the advantage of metal-organic frameworks (MOFs) derivatives by annealing manganese 1,2,3-triazolate (MET-2) at different temperatures to optimize Mn2 O3 crystals for special microstructures. It is found that at 350 °C annealing temperature, the derived Mn2 O3 nanocage maintains the structure of MOF, the inherited high porosity and large specific surface area provide more channels for Li+ and O2 diffusion, beside the oxygen vacancies on the surface of Mn2 O3 nanocages enhance the electrocatalytic activity. With the synergy of unique structure and rich oxygen vacancies, the Mn2 O3 nanocage exhibits ultrahigh discharge capacity (21 070.6 mAh g-1 at 500mA g-1 ) and excellent cycling stability (180 cycles at the limited capacity of 600 mAh g-1 with a current of 500mA g-1 ). This study demonstrates that the Mn2 O3 nanocage structure containing oxygen vacancies can significantly enhance catalytic performance for LOBs, which provide a simple method for structurally designed transition metal oxide electrocatalysts.

Modulating Electronic Structure with Copper Doping to Promote the Electrocatalytic Performance of Cobalt Disulfide in Li-O2 Batteries.

Introducing heteroatom into catalyst lattice to modulate its intrinsic electronic structure is an efficient strategy to improve the electrocatalytic performance in Li-O2 batteries. Herein, Cu-doped CoS2 (Cu-CoS2 ) nanoparticles are fabricated by a solvothermal method and evaluated as promising cathode catalysts for Li-O2 batteries. Based on physicochemical analysis as well as density functional theory calculations, it is revealed that doping Cu heteroatom in CoS2 lattice can increase the covalency of the CoS bond with more electron transfer from Co 3d to S 3p orbitals, thereby resulting in less electron transfer from Co 3d to O 2p orbitals of Li-O species, which can weaken the adsorption strength toward Li-O intermediates, decrease the reaction barrier, and thus improve the catalytic performance in Li-O2 batteries. As a result, the battery using Cu-CoS2 nanoparticles in the cathode exhibits superior kinetics, reversibility, capacity, and cycling performance, as compared to the battery based on CoS2 catalyst. This work provides an atomic-level insight into the rational design of transition-metal dichalcogenide catalysts via regulating the electronic structure for high-performance Li-O2 batteries.

Exploratory construction of Co/Co3O4-Ni/NiO heterointerface modified macroporous interconnected hollow carbon nanofibers towards efficient and flexible electrocatalysis

Developing high-porosity, flexible non-noble metal oxygen electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) involving proton coupled electron transfer reaction is of essential importance for improving the efficiency of electrocatalysts. Herein, we propose a novel multilevel structure of Co/Co3O4-Ni/NiO doped macroporous interconnected hollow carbon nanofibers (Co/Co3O4-Ni/NiO@MHCNFs) as a self-standing and binder-free cathode catalyst for Li-O2 batteries. We employed poly(styrene-co-acrylonitrile) (SAN) as a self-sacrificial template to fabricate hollow nanofibers by coaxial electrospinning and pyrolysis. Furthermore, macroporous interconnected hollow carbon nanofibers were achieved by fine-tuning the particle size of ZIF-8 and electrospinning parameters. Remarkably, as a proof-of-concept application, the Co/Co3O4-Ni/NiO decorated self-standing macroporous interconnected hollow carbon nanofibers (MHCNFs) electrodes exhibited significantly electrochemical performance, including a long-term cyclability (163 cycles) and maximum capacity (16623 mAh/g). This work rationally designs a scalable preparation of Co/Co3O4-Ni/NiO doped macroporous interconnected hollow carbon nanofibers, which provides a new idea for the design of self-supporting and binder-free oxygen electrocatalysts.

Low-carbon CeOx/Ru@RuO2 nanosheets as bifunctional catalysts for lithium-oxygen batteries

Lithium-oxygen (Li-O2) batteries are facing challenges in capacity, cycling stability, and kinetics for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Advanced catalysts should have a high and bifunctional catalytic activity for ORR and OER. Moreover, the trade-off carbon in catalysts should have good oxidation resistance and high electronic conductivity and be used in a tiny amount. Up to now, it is still a challenge. Therefore, this work introduces a low-carbon CeOx/Ru@RuO2 nanosheet as efficient cathode catalysts for Li-O2 batteries and studies the preparation and working mechanisms using a variety of characterization and electrochemical techniques. The air oxidation treatment oxidizes Ru into Ru@RuO2 and simultaneously removes unstable C into CO2, leaving a tiny amount of stable carbon. CeOx/Ru@RuO2 has enormous mesopores, well-distributed sub-5 nm CeOx and Ru@RuO2 nanocrystals, a tiny amount of anti-oxidation carbon (1.2 %), and a high specific surface area of 159.3 m² g−1. These aspects optimize the Li-O reaction and regulate the Li2O2 nucleation to form uniform and ultrathin Li2O2 nanoflakes. As a result, the ORR and OER overpotentials are only 0.17 V and 0.45 V, respectively. This work provides a novel material combination and structure design for developing bifunctional catalyst materials in Li-O2 batteries.

Metal atom-doped Co3O4 nanosheets for Li-O2 battery catalyst: Study on the difference of catalytic activity

As a new star in catalysts, single atom catalysts (SACs) show excellent catalytic activity for Li-O2 battery. However, the mechanism of SACs in Li-O2 battery remains a vague but crucial challenge. Hence, we synthesized a series of Co3O4 nanosheet array-supported single atom catalysts grown on carbon cloth (marked as MSA-Co3O4/CC, M = Ti, V, Cr, Mn, Fe, Ni, Cu, Zn), whose (MSA-Co3O4/CC) structural and physicochemical properties are similar, and used them as cathode catalysts for Li-O2 batteries. Experimental results show that the catalytic activity of MSA-Co3O4/CC doped with different metal atoms is different for Li-O2 battery. Compared with the original Co3O4/CC cathode, the catalytic activity of some MSA-Co3O4/CC is improved while that of others is decreased. Among them, NiSA-Co3O4/CC has the best catalytic activity for Li-O2 battery, while VSA-Co3O4/CC has the worst. Density functional theory (DFT) calculation revealed that the reaction barrier on the active sites and the interaction (adsorption energy and electron transfer) between the doped metal atoms and the key reactants are the main factors affecting the catalytic activity of different metal atoms doped MSA-Co3O4/CC. We believe that this universal preparation method is of great significance for the development of novel SACs. In addition, this work also provides an atomic-scale understanding of fundamental catalytic trends and mechanisms for studying SACs.

Bimetallic ZIF-derived cobalt nanoparticles anchored on N- and S-codoped porous carbon nanofibers as cathode catalyst for Li-O2 batteries

Metal-organic frameworks (MOFs) have shown great application potential for improving Lithium-oxygen (Li-O2) batteries performance with high O2 affinity and accessible active centers. Herein, a novel type of cobalt nanoparticles embedded in porous nitrogen (N)- and sulfur (S)-codoped carbon nanofiber (Co@N/S-CNF) structure is developed by employing electrospinning technology and bimetallic zeolitic imidazole framework (ZIF-8/ZIF-67, a kind of MOF) precursor with the following annealing and hydrothermal treatment route. When utilized as cathode catalysts for Li-O2 batteries, the Co@N/S-CNF sample exhibits higher discharge capacity (9290.7 mAh g−1 at 50 mA g−1) and better cycling stability (42 cycles at 100 mA g−1 under a curtailing capacity of 500 mAh g−1) compared to Co@N-CNF electrode. The enhanced performance can be attributed to the 1D porous morphology and N/S doping effect, which can effectively improve mass transport, increase exposed active sites, and induce structural defect, thereby accelerating the formation and decomposition progress of discharge products. This simple synthetic strategy may provide a new insight for designing and developing MOFs-based multifunctional catalysts in the field of energy and electrocatalysis.

Metal-organic framework-derived ZrO2/NiCo2O4/graphene mesoporous cake-like structure as enhanced bifunctional electrocatalytic cathodes for long life Li-O2 batteries

Metal-organic frameworks (2D MOFs) have great potential to improve the electrochemical performance of Li-O2 batteries with high O2 accessibility, the catalytic activity of the open active metal sites, and large specific surface areas. Herein, we prepared a 3D hierarchical ZrO2@NiCo2O4/GNS (ZNCO) framework as cathode catalysts in Li-O2 batteries that have been developed to synthesize with Zr/Ni to Co molar ratio of 0.1:1:2 by a facile hydrothermal method. The coating of foreign Zr4+ ions into the nickel cobaltite matrix, have superior oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) bifunctional activity, and allowed the formation of 3D dimensional networks for oxygen diffusion, electrolyte impregnation, and has very ORR/OER low overpotential due to Zr insertion. Moreover, the ZrO2 coated shell increases the electronic conductivity, porosity, specific surface area, and protects the core and interstitial decoration against lithium peroxide passivation (Li2O2). The electrochemical performance of the 3D hierarchical ZrO2@NiCo2O4/GNS nanocomposite delivers a higher discharge capacity of 9034 mAh g–1 at 50 mA g–1 and a superior cycling performance up to 100 cycles with a limited capacity of 1000 mAh g−1 at 100 mA g−1. An ORR/OER mechanism was suggested to illustrate the interesting growth of spherical-like particle and film-like Li2O2 deposits at the different cycles for the ZrO2@NiCo2O4/GNS cathodes. Such MOF-derived; hierarchical porous nanocomposites can lead to high-performance efficient bifunctional electrocatalysts and enables the formation and decomposition of discharge products (Li2O2) during the discharge-charge process.

CoS2 Nanoparticles Anchored on MoS2 Nanorods As a Superior Bifunctional Electrocatalyst Boosting Li2 O2 Heteroepitaxial Growth for Rechargeable Li-O2 Batteries.

Developing an excellent bifunctional catalyst is essential for the commercial application of Li-O2 batteries. Heterostructures exhibit great application potential in the field of energy catalysis because of the accelerated charge transfer and increased active sites on their surfaces. In this work, CoS2 nanoparticles decorated on MoS2 nanorods are constructed and act as a superior cathode catalyst for Li-O2 batteries. Coupling MoS2 and CoS2 can not only synergistically enhance their electrical conductivity and electrochemical activity, but also promote the heteroepitaxial growth of discharge products on the heterojunction interfaces, thus delivering high discharge capacity, stable cycle performance, and good rate capability.

Facilely synthesized honeycomb-like NiCo2O4 nanoflakes with an increased content of oxygen vacancies as an efficient cathode catalyst for Li-O2 batteries

The development of high energy density Li-O2 batteries is restricted by the sluggish kinetics of both the oxygen reduction reaction and the oxygen evolution reaction, and developing an efficient cathode catalyst is the key to resolving this issue. In present study, interconnected honeycomb-like NiCo2O4 nanoflakes are synthesized by facile electrochemical deposition on carbon cloth (CC) and subsequent heat treatment. Compared with NiO and Co3O4, suitably sized NiCo2O4 nanoflakes benefit from a vital synergistic effect of components Co and Ni and are expected to show superior OER/ORR performance. The presence of redox couples Co3+/Co2+ and Ni2+/Ni3+ and abundant oxygen vacancies in NiCo2O4 allow Li-O2 batteries deliver satisfactory cycle durability and high discharge/recharge capacities. Li-O2 batteries that use the NiCo2O4/CC cathodes exhibit high specific discharge capacities of 8388 mA h g−1 and 5238 mA h g−1 at 200 mA g−1 and 400 mA g−1, respectively, and deliver a long lifetime of 102 cycles with a capacity limit of 500 mA h g−1 at 340 mA g−1, thereby suggesting that honeycomb-like NiCo2O4 nanoflakes are a promising cathode catalyst.

Two-dimensional Mo-based compounds for the Li-O2 batteries: Catalytic performance and electronic structure studies

Rechargeable Li-O2 batteries have captured increasing attention owing to their ultra-high theoretical specific energy. However, this promising system is confronted with the large overpotential, limited discharge capacity and low cyclic life. Herein, three two-dimensional (2D) molybdenum-based compounds of MoN, MoO3 and MoS2 are used as cathode catalysts in Li-O2 batteries. The catalytic performance and electronic structures of these catalysts are compared comprehensively. Electrochemical test results reveal the superior battery performance of MoN cathodes, which deliver the highest specific discharge capacity of approximately 7400 mAh g−1 and the lowest discharge/charge overpotential of 0.19/0.72 V. Density functional theory (DFT) calculations demonstrate the metallic property of MoN whereas MoO3 and MoS2 are poor conductive. Besides, interface properties between MoN and Li2O2 products as well as reaction pathways of the Li-O2 battery with MoN cathode are also investigated detailedly by DFT calculations, explaining the excellent catalytic properties of MoN at the atomic level. The present work provides intrinsic insights into designing high-performance cathode catalysts for Li-O2 batteries with fine-tuned morphology and electronic characteristics.

Ti3C2Tx MXene cathode catalyst with efficient decomposition Li2O2 and high-rate cycle stability for Li-O2 batteries

MXenes have been theoretical predicted as one of the most promising materials for catalytic cathode materials in Li-O2 batteries (LOBs). Herein, we demonstrated the outstanding electrocatalytic performance of Ti3C2Tx MXene as cathode catalyst for LOBs. The Ti3C2Tx MXene exhibited highly efficient catalytic capability for the formation/decomposition of discharge product, large specific capacity and high-rate cycle stability. The Ti3C2Tx MXene provided a heterogeneous surface condition and dominated the discharge/charge products evolution with multi-formation kinetics of Li2O2 and Li2-xO2 at high-rate conditions. Furthermore, the porous structure of discharge products composed by the vertical growing Li2O2 nanoflakes favored the mass transport between the electrode/electrolyte interfaces. As a consequence, the Ti3C2Tx MXene cathode delivered a large capacity of 15468 mAh g−1 and an excellent high rate cyclability of 155/80 cycles at a high current of 500/1000 mA g−1. This work provides intrinsic insights into designing high-performance MXene based electrocatalysts for LOBs.

Nitrogen-Coordinated CoS2@NC Yolk-Shell Polyhedrons Catalysts Derived from a Metal-Organic Framework for a Highly Reversible Li-O2 Battery.

Transition-metal sulfides (TMS) are one of the most promising cathode catalysts for Li-O2 batteries (LOBs) owing to their excellent stabilities and inherent metallicity. In this work, a highly efficient mode has been used to synthesize Co@CNTs [pyrolysis products of metal-organic frameworks (MOFs)]-derived CoS2(CoS)@NC. Benefiting from the special yolk-shell hierarchical porous morphology, the existence of Co-N bonds, and dual-function catalytic activity (ORR/OER) of the open metal sites contributed by MOFs, the CoS2@NC-400/AB electrode illustrated excellent charge-discharge cycling for up to nearly 100 times at a current density of 0.1 mA cm-2 under a limited capacity of 500 mA h g-1 (based on the total weight of CoS2@NC and AB) with a high discharge voltage plateau and a low charge cut-off voltage. Meanwhile, the average transferred electron number (n) is around 3.7 per O2 molecule for CoS2@NC-400, which is the chief approach for a four-electron pathway of the ORR under alkaline media. Therefore, we believe that the novel CoS2@NC-400/AB electrode could serve as an excellent catalyst in the LOBs.