In-situ Construction of Poly(tetraisopentyl acrylate) based Gel Polymer Electrolytes with Lix La2-x TiO3 for High Energy Density Lithium-Metal Batteries.

As promising alternatives to liquid electrolytes, polymer electrolytes attract much research interest recently, but their widespread use is limited by the low ionic conductivity. In this study, we use electrostatic spinning to introduce particles of an ionic conductor into polyacrylonitrile (PAN) fibers to prepare a porous membrane as the host of gel polymer electrolytes (GPEs). The relevant in-situ produced GPE performs a high ionic conductivity of 6.0×10-3  S cm-1 , and a high lithium transfer number (tLi + ) of 0.85 at 30 °C, respectively. A symmetrical Li cell with this GPE can cycle stably for 550 h at a current density of 0.5 mA cm-2 . While the capacity retention of the NCM|GPE|Li cell is 79.84 % after 500 cycles at 2 C. Even with an increased cut-off voltage of 4.5 V, the 1st coulomb efficiency reaches 91.58 % with a specific discharge capacity of 213.4 mAh g-1 . This study provides a viable route for the practical application of high energy density lithium metal batteries.

Solid Electrolyte Interphase on Lithium Metal Anodes.

Lithium metal batteries (LMBs) represent the most promising next-generation high-energy density batteries. The solid electrolyte interphase (SEI) film on the lithium metal anode plays a crucial role in regulating lithium deposition and improving the cycling performance of LMBs. In this review, we comprehensively present the formation process of the SEI film, while elucidating the key properties such as electronic conductivity, ionic conductivity, and mechanical performance. Furthermore, various approaches for constructing the SEI film are discussed from both electrolyte regulation and artificial coating design perspectives. Lastly, future research directions along with development recommendations are also provided. This review aims to provide possible strategies for the further improvement of SEI film in LMBs and highlight their inspiration for future research directions.

New Quasi-Solid-State Li-SPAN Battery Enhanced by In Situ Thermally Polymerized Gel Polymer Electrolytes.

A lithium-sulfur (Li-S) battery is a promising candidate for an electrochemical energy-storage system. However, for a long time, it suffered from the "shuttle effect" of the intermediate products of soluble polysulfides and safety issues concerning the combustible liquid electrolyte and lithium anode. In this work, sulfide polyacrylonitrile (SPAN) is employed as a solid cycled cathode to resolve the "shuttle effect" fundamentally, a gel polymer electrolyte (GPE) based on poly(ethylene glycol) diacrylate (PEGDA) is matched to the SPAN cathode to minimize the safety concerns, and finally, a quasi-solid-state Li-SPAN battery is combined by an in situ thermal polymerization strategy to improve its adaptability to the existing battery assembly processes. The PEGDA-based GPE achieved at 60 °C for 40 min ensures little damage to the in situ battery, a good electrode-electrolyte interface, a high ionic conductivity of 6.87 × 10-3 S cm-1 at 30 °C, and a wide electrochemical window of 4.53 V. Ultimately, the as-prepared SPAN composite exerts a specific capacity of 1217.3 mAh g-1 after 250 cycles at 0.2 C with a high capacity retention rate of 89.9%. The combination of the SPAN cathode and in situ thermally polymerized PEGDA-based GPE provides a new inspiration for the design of Li-SPAN batteries with both high specific energy and high safety.

A NaCrO2@C free-standing cathode via electrospinning for sodium-ion batteries.

A flexible free-standing cathode is innovatively constructed with NaCrO2 as the electrochemical active substance via an electrospinning technique. The as constructed NaCrO2@C flexible free-standing cathode exhibits exceptional rate performance (106 mA h g-1 at 10C) and cyclability (retention rate of 87.5% after 300 cycles at 0.2C). This work provides a brand-new perspective to the development of flexible free-standing cathodes.

Catalytic Chemistry Derived Artificial Solid Electrolyte Interphase for Stable Lithium Metal Anodes Working at 20†mA cm-2 and 20†mAh cm-2.

A stable solid electrolyte interphase (SEI) layer is crucial for lithium metal anode (LMA) to survive in long-term cycling. However, chaotic structures and chemical inhomogeneity of natural SEI make LMA suffering from exasperating dendrite growth and severe electrode pulverization, which hinder the practical application of LMAs. Here, we design a catalyst-derived artificial SEI layer with an ordered polyamide-lithium hydroxide (PA-LiOH) bi-phase structure to modulate ion transport and enable dendrite-free Li deposition. The PA-LiOH layer can substantially suppress the volume changes of LMA during Li plating/stripping cycles, as well as alleviate the parasitic reactions between LMA and electrolyte. The optimized LMAs demonstrate excellent stability in Li plating/stripping cycles for over 1000 hours at an ultra-high current density of 20 mA cm-2 in Li||Li symmetric cells. A high coulombic efficiency up to 99.2 % in Li half cells in additive-free electrolytes is achieved even after 500 cycles at a current density of 1 mA cm-2 with a capacity of 1 mAh cm-2 .

Interface engineering of Ni2P/MoOx decorated NiFeP nanosheets for enhanced alkaline hydrogen evolution reaction at high current densities.

The rational design of high-performance non-noble metal electrocatalysts at large current densities is important for the development of sustainable energy conversion devices such as alkaline water electrolyzers. However, improving the intrinsic activity of those non-noble metal electrocatalysts remains a great challenge. Therefore, Ni2P/MoOx decorated three-dimensional (3D) NiFeP nanosheets (NiFeP@Ni2P/MoOx) with abundant interfaces were synthesized using facile hydrothermal and phosphorization methods. NiFeP@Ni2P/MoOx exhibits excellent electrocatalytic activity for hydrogen evolution reaction (HER) at a high current density of -1000 mA cm-2 with a low overpotential of 390 mV. Surprisingly, it can operate steadily at a large current density of -500 mA cm-2 for 300 h, indicating its long-term durability under high current densities. The boosted electrocatalytic activity and stability can be ascribed to the as-fabricated heterostructures via interface engineering, leading to modifying the electronic structure, improving the active area, and enhancing the stability. Besides, the 3D nanostructure is also beneficial for exposing abundant accessible active sites. Therefore, this research proposes a considerable route for fabricating non-noble metal electrocatalysts by interface engineering and 3D nanostructure applied in large-scale hydrogen production facilities.

DFT Study on the Oxidation Mechanism of Common Cyclic Carbonates in the Presence of BF4- Anions.

Oxidative decomposition reactions of common cyclic carbonates in the presence of BF4- anions were investigated using density functional theory. A polarized continuum model was utilized to model solvent effects in the oxidation of ethylene carbonate (EC) and propylene carbonate (PC) clusters. We have found that the presence of BF4- significantly reduces EC and PC oxidation stability, from 7.11 to 6.17 and from 7.10 to 6.06 V (vs Li+/Li), respectively. The sequence of EC and PC oxidative decomposition paths and the oxidative products were affected by the BF4- anion. The decomposition products of the oxidized EC-BF4- contained CO2, vinyl alcohol, and acetaldehyde, while the decomposition products of the oxidized PC-BF4- contained CO2, acetone, and propanal, in agreement with the previous experimental studies. The oxidative decomposition reactions for PC-BF4- are compared with those for the isolated PC, PC2, PC-ClO4-, and PC-PF6-.

P-P Orbital Interaction Enables Single-Crystalline Semimetallic ß-MoTe2 Nanosheets as Efficient Electrocatalysts for Lithium-Sulfur Batteries.

The practical implementation of lithium-sulfur batteries (LSBs) has been impeded by the sluggish redox kinetics of lithium polysulfides (LiPSs) and shuttle effect of soluble LiPSs during charge/discharge. It is desirable to exploit materials combining superior electrical conductivity with excellent catalytic activity for use as electrocatalysts in LSBs. Herein, we report the employment of chemical vapor transport (CVT) method followed by an electrochemical intercalation process to fabricate high-quality single-crystalline semimetallic ß-MoTe2 nanosheets, which are utilized to manipulate the LiPSs conversion kinetics. The first-principles calculations prove that ß-MoTe2 could lower the Gibbs free-energy barrier for Li2S2 transformation to Li2S. The wavefunction analysis demonstrates that the p-p orbital interaction between Te p and S p orbitals accounts for the strong electronic interaction between the ß-MoTe2 surface and Li2S2/Li2S, making bonding and electron transfer more efficient. As a result, a ß-MoTe2/CNT@S-based LSB cell can deliver an excellent cycling performance with a low capacity fade rate of 0.11% per cycle over 300 cycles at 1C. Our work might not only provide a universal route to prepare high-quality single-crystalline transition-metal dichalcogenides (TMDs) nanosheets for use as electrocatalysts in LSBs, but also suggest a different viewpoint for the rational design of LiPSs conversion electrocatalysts.

Hydrogel-Derived Co3ZnC/Co Nanoparticles with Heterojunctions Supported on N-Doped Porous Carbon and Carbon Nanotubes for the Highly Efficient Oxygen Reduction Reaction in Zn-Air Batteries.

It is crucial for metal-air batteries and fuel cells to design non-precious-metal catalysts instead of platinum-based materials to boost the sluggish oxygen reduction reaction (ORR). Herein, Co3ZnC/Co nanoparticles with heterojunctions supported on N-doped porous carbon and carbon nanotubes (CNTs) are fabricated by pyrolyzing the hydrogel prepared from melamine and citric acid chelated with Co2+/Zn2+ ions. This hybrid shows strong ORR catalytic activity as its half-wave potential reaches 0.88 V (vs reversible hydrogen electrode (RHE)) in 0.1 M KOH and Zn-air batteries with the catalyst have higher discharge plateaus and capacity than those employing Pt/C. The hybrid mixed with RuO2 can also be used as an efficient bifunctional catalyst for rechargeable Zn-air batteries. The excellent performance is primarily derived from the Co3ZnC/Co heterojunctions, the electron transfer of which boosts the ORR catalysis. Moreover, the suitable ratio of Co/Zn in precursors results in the epitaxial growth of hollow CNTs and abundant mesopores, hence promoting the adsorption of oxygen and the transport of ORR-related species.

Polyacrylonitrile Porous Membrane-Based Gel Polymer Electrolyte by In Situ Free-Radical Polymerization for Stable Li Metal Batteries.

Because of their high ionic conductivity, utilizing gel polymer electrolytes (GPEs) is thought to be an effective way to accomplish high-energy-density batteries. Nevertheless, most GPEs have poor adaptability to Ni-rich cathodes to alleviate the problem of inevitable rapid capacity decay during cycling. Therefore, to match LiNi0.8Co0.1Mn0.1O2 (NCM811), we applied pentaerythritol tetraacrylate (PETEA) monomers to polymerize in situ in a polyacrylonitrile (PAN) membrane to obtain GPEs (PETEA-TCGG-PAN). The impedance variations and key groups during the in situ polymerization of PETEA-TCGG-PAN are investigated in detail. PETEA-TCGG-PAN with a high lithium-ion transference number (0.77) exhibits an electrochemical decomposition voltage of 5.15 V. Noticeably, the NCM811|PETEA-TCGG-PAN|Li battery can cycle at 2C for 120 cycles with a capacity retention rate of 89%. Even at 6C, the discharge specific capacity is able to reach 101.47 mAh g-1. The combination of LiF and Li2CO3 at the CEI interface is the reason for the improved rate performance. Moreover, when commercialized LFP is used as the cathode, the battery can also cycle stably for 150 cycles at 0.5C. PETEA and PAN can together foster the transportation of Li+ with the construction of a fast ion transport channel, making a contribution to stable charge-discharge of the above batteries. This study provides an innovative design philosophy for designing in situ GPEs in high-energy-density lithium metal batteries.

Rechargeable Aqueous Mn-Metal Battery Enabled by Inorganic-Organic Interfaces.

Aqueous batteries that use metal anodes exhibit maximum anodic capacity, whereas the energy density is still unsatisfactory partially due to the high redox potential of the metal anode. Current metal anodes are plagued by the dilemma that the redox potential of Zn is not low enough, whereas Al, Mg, and others with excessively low redox potential cannot work properly in aqueous electrolytes. Mn metal with a suitably low redox potential is a promising candidate, which was rarely explored before. Here, we report a rechargeable aqueous Mn-metal battery enabled by a well-designed electrolyte and robust inorganic-organic interfaces. The inorganic Sn-based interface with a bottom-up microstructure was constructed to preliminarily suppress water decomposition. With this bubble-free interface, the organic interface can be formed via an esterification reaction of sucrose triggered by acyl chloride in the electrolyte, generating a dense physical shield that isolates water while permitting Mn2+ diffusion. Hence, a Mn symmetric cell achieves a superior plating/stripping stability for 200 hours, and a Mn||V2 O5 battery maintains approximately 100 % capacity after 200 cycles. Moreover, the Mn||V2 O5 battery realizes a much higher output voltage than that of the Zn||V2 O5 battery, evidencing the possibility of increasing the energy density through using a Mn anode. This work develops a systematic strategy to stabilize a Mn-metal anode for Mn-metal batteries, opening a new door towards enhanced voltage of aqueous batteries.

Interface Engineering of NixSy@MnOxHy Nanorods to Efficiently Enhance Overall-Water-Splitting Activity and Stability.

HIGHLIGHTS: Three-dimensional (3D) core-shell heterostructured NixSy@MnOxHy nanorods grown on nickel foam (NixSy@MnOxHy/NF) were successfully fabricated via a simple hydrothermal reaction and a subsequent electrodeposition process. The fabricated NixSy@MnOxHy/NF shows outstanding bifunctional activity and stability for hydrogen evolution reaction and oxygen evolution reaction, as well as overall-water-splitting performance. The main origins are the interface engineering of NixSy@MnOxHy, the shell-protection characteristic of MnOxHy, and the 3D open nanorod structure, which remarkably endow the electrocatalyst with high activity and stability. Exploring highly active and stable transition metal-based bifunctional electrocatalysts has recently attracted extensive research interests for achieving high inherent activity, abundant exposed active sites, rapid mass transfer, and strong structure stability for overall water splitting. Herein, an interface engineering coupled with shell-protection strategy was applied to construct three-dimensional (3D) core-shell NixSy@MnOxHy heterostructure nanorods grown on nickel foam (NixSy@MnOxHy/NF) as a bifunctional electrocatalyst. NixSy@MnOxHy/NF was synthesized via a facile hydrothermal reaction followed by an electrodeposition process. The X-ray absorption fine structure spectra reveal that abundant Mn-S bonds connect the heterostructure interfaces of NixSy@MnOxHy, leading to a strong electronic interaction, which improves the intrinsic activities of hydrogen evolution reaction and oxygen evolution reaction (OER). Besides, as an efficient protective shell, the MnOxHy dramatically inhibits the electrochemical corrosion of the electrocatalyst at high current densities, which remarkably enhances the stability at high potentials. Furthermore, the 3D nanorod structure not only exposes enriched active sites, but also accelerates the electrolyte diffusion and bubble desorption. Therefore, NixSy@MnOxHy/NF exhibits exceptional bifunctional activity and stability for overall water splitting, with low overpotentials of 326 and 356 mV for OER at 100 and 500 mA cm-2, respectively, along with high stability of 150 h at 100 mA cm-2. Furthermore, for overall water splitting, it presents a low cell voltage of 1.529 V at 10 mA cm-2, accompanied by excellent stability at 100 mA cm-2 for 100 h. This work sheds a light on exploring highly active and stable bifunctional electrocatalysts by the interface engineering coupled with shell-protection strategy.

Heterogeneous Bimetallic Organic Coordination Polymer-Derived Co/Fe@NC Bifunctional Catalysts for Rechargeable Li-O2 Batteries.

The Li-O2 battery has attracted substantial attention due to its high theoretical energy density. In particular, high-efficiency oxygen catalysts are very important for the design of practical Li-O2 batteries. Herein, we have synthesized heterogeneous crystalline-coated partially crystalline bimetallic organic coordination polymers (PC@C-BMOCPs), which are further pyrolyzed to obtain Co- and Fe-based nanoparticles embedded within rodlike N-doped carbon (Co/Fe@NC) as a bifunctional oxygen reduction reaction/oxygen evolution reaction (ORR/OER) catalyst used in the Li-O2 battery. Owing to excellent ORR/OER catalytic ability, the Co/Fe@NC bifunctional catalyst exhibits an efficient reversible reaction between O2 and Li2O2. Additionally, a large number of mesoporous channels are present in the core-shell Co/Fe@NC nanoparticles. These channels not only promote the diffusion of Li+ and O2, but also create ample room to store insoluble discharge product Li2O2. The Li-O2 batteries utilizing the bifunctional Co/Fe@NC oxygen electrode exhibit a large capacity of 17,326 mAh g-1, a long cycling life of more than 250 cycles, and excellent reversibility. This work provides a universally applicable strategy for designing nonnoble metal ORR/OER catalysts with excellent electrochemical performance for metal-air batteries.

MnOx -Decorated Nickel-Iron Phosphides Nanosheets: Interface Modifications for Robust Overall Water Splitting at Ultra-High Current Densities.

Exploring highly active and stable bifunctional water-splitting electrocatalysts at ultra-high current densities is remarkably desirable. Herein, 3D nickel-iron phosphides nanosheets modified by MnOx nanoparticles are grown on nickel foam (MnOx /NiFeP/NF). Resulting from the electronic coupling effect enabled by interface modifications, the intrinsic activities of the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are improved. Meanwhile, 3D nanosheets provide abundant active sites for HER and OER, leading to accelerating the reaction kinetics. Besides, the shell-protection characteristic of MnOx improves the durability of MnOx /NiFeP/NF. Therefore, MnOx /NiFeP/NF shows exceptional bifunctional electrocatalytic activities toward HER (an overpotential of 255 mV at 500 mA cm-2 ), OER (overpotentials of 296 and 346 mV at 500 and 1000 mA cm-2 , respectively), and overall water splitting (cell voltages of 1.796 and 1.828 V at 500 and 1000 mA cm-2 , respectively). Furthermore, it owns remarkably outstanding stability for overall water splitting at ultra-high current densities (120 and 70 h at 500 and 1000 mA cm-2 , respectively), which outperforms almost all of the non-noble metal electrocatalysts. This work presents efficient strategies of interface modifications, 3D nanostructures, and shell protection to afford ultra-high current densities.

Mixed ionic/electronic conducting nanosheet arrays for stable lithium storage.

Lithium metal batteries (LMBs) have received extensive attention and research interest as high specific energy systems. However, the issues of Li dendrites growth in LMBs restrict their practical applications. The development of lithiophilic collectors can effectively solve the issues of Li dendrites growth. This study reports excellent lithium storage performance of lithiophilic nanosheet arrays which consist of electronic conductor Ni and ionic conductor Li2O (Ni-LONSs) on Ni foil (NF) fabricated via a simple preparation method for LMBs. The ionic conductor Li2O of the Ni-LONSs layer is lithiophilic and can induce uniform Li deposition on the Ni-LONSs collector. In addition, the nanosheet array structure of the Ni-LONSs collector is beneficial to slow down the volume change of the Li plating/stripping. In comparison with the NF collector, due to the specific nanosheet array structure of Ni-LONSs collector, the Ni-LONSs collector demonstrates excellent coulombic efficiency of 97.2% after 280 cycles (95.7% after 100 cycles of NF collector) and satisfactory cycling lifespan of 340 h (about 120 h of NF collector) at 0.5 mA cm-2with 1.0 mAh cm-2. Furthermore, the Ni-LONSs collector shows superior electrochemical performance in Ni-LONS/Li∣LiFePO4full cells. The excellent lithium storage performance of Ni-LONSs collector with mixed ionic/electronic conductor is conducive to the development and practical applications of LMBs.

Ultrasonic Plasma Engineering Toward Facile Synthesis of Single-Atom M-N4/N-Doped Carbon (M = Fe, Co) as Superior Oxygen Electrocatalyst in Rechargeable Zinc-Air Batteries.

As bifunctional oxygen evolution/reduction electrocatalysts, transition-metal-based single-atom-doped nitrogen-carbon (NC) matrices are promising successors of the corresponding noble-metal-based catalysts, offering the advantages of ultrahigh atom utilization efficiency and surface active energy. However, the fabrication of such matrices (e.g., well-dispersed single-atom-doped M-N4/NCs) often requires numerous steps and tedious processes. Herein, ultrasonic plasma engineering allows direct carbonization in a precursor solution containing metal phthalocyanine and aniline. When combining with the dispersion effect of ultrasonic waves, we successfully fabricated uniform single-atom M-N4 (M = Fe, Co) carbon catalysts with a production rate as high as 10 mg min-1. The Co-N4/NC presented a bifunctional potential drop of ΔE = 0.79 V, outperforming the benchmark Pt/C-Ru/C catalyst (ΔE = 0.88 V) at the same catalyst loading. Theoretical calculations revealed that Co-N4 was the major active site with superior O2 adsorption-desorption mechanisms. In a practical Zn-air battery test, the air electrode coated with Co-N4/NC exhibited a specific capacity (762.8 mAh g-1) and power density (101.62 mW cm-2), exceeding those of Pt/C-Ru/C (700.8 mAh g-1 and 89.16 mW cm-2, respectively) at the same catalyst loading. Moreover, for Co-N4/NC, the potential difference increased from 1.16 to 1.47 V after 100 charge-discharge cycles. The proposed innovative and scalable strategy was concluded to be well suited for the fabrication of single-atom-doped carbons as promising bifunctional oxygen evolution/reduction electrocatalysts for metal-air batteries.

A P3-Type K1/2Mn5/6Mg1/12Ni1/12O2 Cathode Material for Potassium-Ion Batteries with High Structural Reversibility Secured by the Mg-Ni Pinning Effect.

Mn-based layered oxides are very attractive as cathodes for potassium-ion batteries (PIBs) due to their low-cost and environmentally friendly precursors. Their transfer to practical application, however, is inhibited by some issues including consecutive phase transitions, sluggish K+ deintercalation/intercalation, and serious capacity loss. Herein, Mg-Ni co-substituted K1/2Mn5/6Mg1/12Ni1/12O2 is designed as a promising cathode material for PIBs, with suppressed phase transitions that occurred in K1/2MnO2 and improved K+ storage performance. Part of Mg2+ and Ni2+ occupies the K+ layer, playing the role of a "nailed pillar", which restrains metal oxide layer gliding during the K+ (de)intercalation. The "Mg-Ni pinning effect" not only suppresses the phase transitions but also reduces the cell volume variation, leading to the improved cycle performance. Moreover, K1/2Mn5/6Mg1/12Ni1/12O2 has low activation barrier energy for K+ diffusion and high electron conductivity as demonstrated by first-principles calculations, resulting in better rate capability. In addition, K1/2Mn5/6Mg1/12Ni1/12O2 also delivers a higher reversible capacity owing to the participation of the Ni element in electrochemical reactions and the pseudocapacitive contribution. This study provides a basic understanding of structural evolution in layered Mn-based oxides and broadens the strategic design of cathode materials for PIBs.

O3-Type NaCrO2 as a Superior Cathode Material for Sodium/Potassium-Ion Batteries Ensured by High Structural Reversibility.

O3-type NaCrO2 is attracting increasing attention as potential cathode material for sodium-ion batteries (SIBs). Bare NaCrO2 is usually synthesized by a solid-state reaction and suffers from serious capacity decay and poor power capability. Modification by coating is an effective method to improve the electrochemical properties, but it inevitably reduces the energy density. To avoid the decrease of energy density and optimize the electrochemical performance, a specific route, i.e., a freeze-drying-assisted sol-gel method, has been adopted to synthesize bare NaCrO2 in this work. Three-phase coexistence during charging is confirmed for the first time, which contributes to delaying the disappearance of the O3 phase and then improving the structural reversibility, resulting in superior cycle stability (∼50% capacity retention after 3000 cycles at 5C). Meanwhile, as-synthesized NaCrO2 delivers an outstanding rate capability (82.1 mAh g-1 at 50C), which is attributed to the fast Na+ diffusivity and high electronic conductivity proved by density functional theory (DFT) calculations. It is worth mentioning that NaCrO2 also exhibits excellent electrochemical properties when used as a cathode for potassium-ion batteries (PIBs). This work provides new perspectives on the structural evolution of NaCrO2, and the results are expected to contribute to the development of SIBs and PIBs.

Enhancing ORR/OER active sites through lattice distortion of Fe-enriched FeNi3 intermetallic nanoparticles doped N-doped carbon for high-performance rechargeable Zn-air battery.

Low-cost, high-activity, non-precious metal electrocatalysts are needed to enhance the bifunctional oxygen activities of rechargeable Zn-Air batteries. In this study, a Fe-enriched FeNi3 inter-metallic nanoparticle/nitrogen-doped carbon (Fe-enriched-FeNi3/NC) electrocatalyst was designed and prepared using a facile method based on plasma engineering. The excess Fe-ions in the Fe-enriched FeNi3 nanoparticles led to a high degree of lattice distortion that produced abundant oxygen-active sites. The electrocatalyst exhibited excellent oxygen evolution reaction (OER) activity as well as favorable oxygen reduction reaction (ORR) activity in an alkaline electrolyte. In addition, the electrocatalyst revealed a lower potential difference (ΔE = 0.80 V vs. RHE) in a bifunctional oxygen reaction compared to that of the benchmark 20 wt% Pt/C + Ir/C (ΔE = 0.84 V vs. RHE), and most of the reported FeNi3 alloy-doped carbon catalysts. Based on DFT calculations, the lattice distortion in Fe-enriched-FeNi3/NC promoted a higher density of active electrons around the Fermi level. Owing to its great bifunctional oxygen activities, Fe-enriched FeNi3/NC was applied as an ORR/OER catalyst in the air cathode in a homemade zinc-air battery and exhibited an excellent discharge-charge voltage gap (0.89 V), peak power density (89 mW/cm2), and high specific capacity of 734 mAh/g at 20 mA/cm2, which outperformed the benchmark 20 wt% Pt/C + Ir/C electrocatalyst. In summary, this research provides a novel strategy to enhance the OER/ORR activities of transition metal-based alloys through lattice distortion defects. In addition, it provides a new pathway for achieving noble metal-free air cathode materials for the next generation Zn-air battery.