Atomically Thin Mesoporous Co3O4 Layers Strongly Coupled with N‐rGO Nanosheets as High‐Performance Bifunctional Catalysts for 1D Knittable Zinc–Air Batteries

Under development for next‐generation wearable electronics are flexible, knittable, and wearable energy‐storage devices with high energy density that can be integrated into textiles. Herein, knittable fiber‐shaped zinc–air batteries with high volumetric energy density (36.1 mWh cm^?3) are fabricated via a facile and continuous method with low‐cost materials. Furthermore, a high‐yield method is developed to prepare the key component of the fiber‐shaped zinc–air battery, i.e., a bifunctional catalyst composed of atomically thin layer‐by‐layer mesoporous Co₃O₄/nitrogen‐doped reduced graphene oxide (N‐rGO) nanosheets. Benefiting from the high surface area, mesoporous structure, and strong synergetic effect between the Co₃O₄ and N‐rGO nanosheets, the bifunctional catalyst exhibits high activity and superior durability for oxygen reduction and evolution reactions. Compared to a fiber‐shaped zinc–air battery using state‐of‐the‐art Pt/C + RuO₂ catalysts, the battery based on these Co₃O₄/N‐rGO nanosheets demonstrates enhanced and stable electrochemical performance, even under severe deformation. Such batteries, for the first time, can be successfully knitted into clothes without short circuits under external forces and can power various electronic devices and even charge a cellphone.     

Boosting the Cycling Stability of Aqueous Flexible Zn Batteries via F Doping in Nickel–Cobalt Carbonate Hydroxide Cathode

Cathodes of rechargeable Zn batteries typically face the issues of irreversible phase transformation, structure collapse, and volume expansion during repeated charge/discharge cycles, which result in an increased transfer resistance and poor long‐term cycling stability. Herein, a facile F doping strategy is developed to boost the cycling stability of nickel cobalt carbonate hydroxide (NiCo–CH) cathode. Benefiting from the extremely high electronegativity, the phase and morphology stabilities as well as the electrical conductivity of NiCo–CH are remarkably enhanced by F incorporation (NiCo–CH–F). Phase interface and amorphous microdomains are also introduced, which are favorable for the electrochemical performance of cathode. Benefiting from these features, NiCo–CH–F delivers a high capacity (245 mA h g^?1), excellent rate capability (64% retention at 8 A g^?1), and outstanding cycling stability (maintains 90% after 10 000 cycles). Moreover, the quasi‐solid‐state battery also manifests superior cycling stability (maintains 90% after 7200 cycles) and desirable flexibility. This work offers a general strategy to boost the cycling stability of cathode materials for aqueous Zn batteries.     

Au Nanowires Decorated Ultrathin Co3O4 Nanosheets toward Light-Enhanced Nitrate Electroreduction

Nitrate is a reasonable alternative instead of nitrogen for ammonia production due to the low bond energy, large water-solubility, and high chemical polarity for good absorption. Nitrate electroreduction reaction (NO₃RR) is an effective and green strategy for both nitrate treatment and ammonia production. As an electrochemical reaction, the NO₃RR requires an efficient electrocatalyst for achieving high activity and selectivity. Inspired by the enhancement effect of heterostructure on electrocatalysis, Au nanowires decorated ultrathin Co₃O₄ nanosheets (Co₃O₄-NS/Au-NWs) nanohybrids are proposed for improving the efficiency of nitrate-to-ammonia electroreduction. Theoretical calculation reveals that Au heteroatoms can effectively adjust the electron structure of Co active centers and reduce the energy barrier of the determining step (*NO → *NOH) during NO₃RR. As the result, the Co₃O₄-NS/Au-NWs nanohybrids achieve an outstanding catalytic performance with high yield rate (2.661 mg h⁻¹ mg_cat⁻¹) toward nitrate-to-ammonia. Importantly, the Co₃O₄-NS/Au-NWs nanohybrids show an obviously plasmon-promoted activity for NO₃RR due to the localized surface plasmon resonance (LSPR) property of Au-NWs, which can achieve an enhanced NH₃ yield rate of 4.045 mg h⁻¹ mg_cat⁻¹. This study reveals the structure–activity relationship of heterostructure and LSPR-promotion effect toward NO₃RR, which provide an efficient nitrate-to-ammonia reduction with high efficiency.     

Tailored Heterojunction Active Sites for Oxygen Electrocatalyst Promotion in Zinc-Air Batteries

Rechargeable zinc-air batteries (ZABs) are promising energy storage systems due to their low-cost and safety. However, the working principle of ZABs is based on oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), which display sluggish kinetic and low stability. Herein, this work proposes a novel method to design a heterogeneous CoP/CoO electrocatalyst on mesopore nanobox carbon/carbon nanotube (CoP/CoO@MNC-CNT) that enriched active sites and synergistic effect. Moreover, the well-defined heterointerfaces could lower the energy barrier for intermediate species adsorption and promote OER and ORR electrochemical performances. The CoP/CoO@MNC-CNT electrocatalyst presents a high half-wave potential of 0.838 V for ORR and a small overpotential of 270 mV for OER. The ZABs-based CoP/CoO@MNC-CNT air-cathode shows an open-circuit voltage of 1.409 V, the long-term cycle life of 500 h with a small voltage difference change of 7.7%. Additionally, the flexible ZABs exhibit highly mechanical stability, demonstrating their application potential in wearable electronic devices.     

锂离子电池正极材料LiV3O8的低温合成研究

以ＬｉＮＯ_３和ＮＨ_４ＶＯ_３为原料,通过溶胶－凝胶法制备了层状锂钒氧化物ＬｉＶ_３Ｏ_８锂离子电池正极材料,通过ＴＧ－ＤＴＧ、ＸＲＤ等考察了合成条件对产物首次放电比容量的影响．实验结果表明,在４５０℃左右热分解２０ｈ可得到单一相产物ＬｉＶ_３Ｏ_８,其层状结构较为完整,电化学性能好,首次放电比容量可达３５０ｍＡｈ·ｇ－１,作为高能锂离子电池正极材料较为理想．     

A Laser-Induced Mo2CTx MXene Hybrid Anode for High-Performance Li-Ion Batteries

MXenes, a fast-growing family of two-dimensional (2D) transition metal carbides/nitrides, are promising for electronics and energy storage applications. Mo₂CT_x MXene, in particular, has demonstrated a higher capacity than other MXenes as an anode for Li-ion batteries. Yet, such enhanced capacity is accompanied by slow kinetics and poor cycling stability. Herein, it is revealed that the unstable cycling performance of Mo₂CT_x is attributed to the partial oxidation into MoO_x with structural degradation. A laser-induced Mo₂CT_x/Mo₂C (LS-Mo₂CT_x) hybrid anode has been developed, of which the Mo₂C nanodots boost redox kinetics, and the laser-reduced oxygen content prevents the structural degradation caused by oxidation. Meanwhile, the strong connections between the laser-induced Mo₂C nanodots and Mo₂CT_x nanosheets enhance conductivity and stabilize the structure during charge–discharge cycling. The as-prepared LS-Mo₂CT_x anode exhibits an enhanced capacity of 340 mAh g⁻¹ vs 83 mAh g⁻¹ (for pristine) and an improved cycling stability (capacity retention of 106.2% vs 80.6% for pristine) over 1000 cycles. The laser-induced synthesis approach underlines the potential of MXene-based hybrid materials for high-performance energy storage applications.     

Synthesis of Co/SiO2 hybrid nanocatalyst via twisted Co3Si2O5(OH)4 nanosheets for high-temperature Fischer-Tropsch reaction

A cobalt-silica hybrid nanocatalyst bearing small cobalt particles of diameter ～5 nm was prepared through a hydrothermal reaction and hydrogen reduction.The resulting material showed very high CO conversion (＞82％) and high hydrocarbon productivity (～1.0 gHc·g-1cat,·h-11) with high activity (～8.5 x 10-5 molco·g-1Co·S-1) in the Fischer-Tropsch synthesis reaction.     

Co Nanoislands Rooted on Co–N–C Nanosheets as Efficient Oxygen Electrocatalyst for Zn–Air Batteries

Developing non‐precious‐metal bifunctional oxygen reduction and evolution reaction (ORR/OER) catalysts is a major task for promoting the reaction efficiency of Zn–air batteries. Co‐based catalysts have been regarded as promising ORR and OER catalysts owing to the multivalence characteristic of cobalt element. Herein, the synthesis of Co nanoislands rooted on Co–N–C nanosheets supported by carbon felts (Co/Co–N–C) is reported. Co nanosheets rooted on the carbon felt derived from electrodeposition are applied as the self‐template and cobalt source. The synergistic effect of metal Co islands with OER activity and Co–N–C nanosheets with superior ORR performance leads to good bifuctional catalytic performances. Wavelet transform extended X‐ray absorption fine spectroscopy and X‐ray photoelectron spectroscopy certify the formation of Co (mainly Co⁰) and the Co–N–C (mainly Co²⁺ and Co³⁺) structure. As the air‐cathode, the assembled aqueous Zn–air battery exhibits a small charge–discharge voltage gap (0.82 V@10 mA cm^?2) and high power density of 132 mW cm^?2, outperforming the commercial Pt/C catalyst. Additionally, the cable flexible rechargeable Zn–air battery exhibits excellent bendable and durability. Density functional theory calculation is combined with operando X‐ray absorption spectroscopy to further elucidate the active sites of oxygen reactions at the Co/Co–N–C cathode in Zn–air battery.     

Triggering High Capacity and Superior Reversibility of Manganese Oxides Cathode via Magnesium Modulation for Zn//MnO2 Batteries

Aqueous zinc-ion batteries (ZIBs) have attracted extensive attention in recent years because of its high volumetric energy density, the abundance of zinc resources, and safety. However, ZIBs still suffer from poor reversibility and sluggish kinetics derived from the unstable cathodic structure and the strong electrostatic interactions between bivalent Zn²⁺ and cathodes. Herein, magnesium doping into layered manganese dioxide (Mg–MnO₂) via a simple hydrothermal method as cathode materials for ZIBs is proposed. The interconnected nanoflakes of Mg–MnO₂ possess a larger specific surface area compared to pristine δ-MnO₂, providing more electroactive sites and boosting the capacity of batteries. The ion diffusion coefficients of Mg–MnO₂ can be enhanced due to the improved electrical conductivity by doped cations and oxygen vacancies in MnO₂ lattices. The assembled Zn//Mg–MnO₂ battery delivers a high specific capacity of 370 mAh g⁻¹ at a current density of 0.6 A g⁻¹. Furthermore, the reaction mechanism confirms that Zn²⁺ insertion occurred after a few cycles of activation reactions. Most important, the reversible redox reaction between Zn²⁺ and MnOOH is found after several charge–discharge processes, promoting capacity and stability. It believes that this systematic research enlightens the design of high-performance of ZIBs and facilitates the practical application of Zn//MnO₂ batteries.     

Carbon Nanotube–CoF2 Multifunctional Cathode for Lithium Ion Batteries: Effect of Electrolyte on Cycle Stability

Transition metal fluorides (MF_x) offer remarkably high theoretical energy density. However, the low cycling stability, low electrical and ionic conductivity of metal fluorides have severely limited their applications as conversion‐type cathode materials for lithium ion batteries. Here, a scalable and low‐cost strategy is reported on the fabrication of multifunctional cobalt fluoride/carbon nanotube nonwoven fabric nanocomposite, which demonstrates a combination of high capacity (near‐theoretical, ) and excellent mechanical properties. Its strength and modulus of toughness exceed that of many aluminum alloys, cast iron, and other structural materials, fulfilling the use of MF_x‐based materials in batteries with load‐bearing capabilities. In the course of this study, cathode dissolution in conventional electrolytes has been discovered as the main reason that leads to the rapid growth of the solid electrolyte interphase layer and attributes to rapid cell degradation. And such largely overlooked degradation mechanism is overcome by utilizing electrolyte comprising a fluorinated solvent, which forms a protective ionically conductive layer on the cathode and anode surfaces. With this approach, 93% capacity retention is achieved after 200 cycles at the current density of 100 mA g⁻¹ and over 50% after 10 000 cycles at the current density of 1000 mA g⁻¹.     

Interfacial Engineering of Co3O4/Fe2O3 Nano-Heterostructure Toward Superior Li-O2 Batteries

A major issue with Li-O₂ batteries is their slow oxygen reduction and evolution kinetics, necessitating catalysts with high catalytic activity to improve reaction kinetics and cycle stability. Herein, a nano-heterostructured catalyst composed of Co₃O₄ and Fe₂O₃ (Co₃O₄/Fe₂O₃) with a porous rod morphology is achieved through an interfacial engineering strategy by constructing Fe₂O₃ on the Co₃O₄ surface, which can function as a high-performance cathode in order to efficiently encourage the oxygen reduction and evolution while also reduce the battery polarization during charging and discharging. The density functional theory (DFT) calculations show the differences in charge density at the interface of nano-heterostructures, demonstrating the occurrence of an electron transfer process in the interface region of Co₃O₄ and Fe₂O₃, implying a strong electronic coupling transfer, and in turn changing the electronic structure of the Co₃O₄. This significantly reduces the adsorption energy of LiO₂ intermediates, thereby effectively lowering the overpotential. The resultant Li-O₂ battery has larger discharge specific capacity, lower overpotential for the efficient oxygen evolution/reduction, as well as good cycling stability of 280 cycles. This work demonstrates an effective method to fabricate the nano-heterostrucutred materials with enhanced catalytic efficiency for advanced energy applications.     

Hierarchical 3D Oxygenated Cobalt Molybdenum Selenide Nanosheets as Robust Trifunctional Catalyst for Water Splitting and Zinc–Air Batteries

The development of hierarchical nanostructures with highly active and durable multifunctional catalysts has a new significance in the context of new energy technologies of water splitting and metal–air batteries. Herein, a strategy is demonstrated to construct a 3D hierarchical oxygenated cobalt molybdenum selenide (O‐Co_1?xMo_xSe₂) series with attractive nanoarchitectures, which are fabricated by a simple and cost‐effective hydrothermal process followed by an exclusive ion‐exchange process. Owing to its highly electroactive sites with numerous nanoporous networks and plentiful oxygen vacancies, the optimal O‐Co_0.5Mo_0.5Se₂ could catalyze the hydrogen evolution reaction and oxygen evolution reaction effectively with a low overpotential of ≈102 and 189 mV, at a current density of 10 mA cm^?2, respectively, and exceptional durability. Most importantly, the O‐Co_0.5Mo_0.5Se₂||O‐Co_0.5Mo_0.5Se₂ water splitting device only entails a voltage of ≈1.53 V at a current density of 10 mA cm^?2, which is much better than benchmark Pt/C||RuO₂ (≈1.56 V). Furthermore, O‐Co_0.5Mo_0.5Se₂ air cathode‐based zinc–air batteries exhibit an excellent power density of 120.28 mW cm^?2 and exceptional cycling stability for 60 h, superior to those of state‐of‐art Pt/C+RuO₂ pair‐based zinc–air batteries. The present study provides a strategy to design hierarchical 3D oxygenated bimetallic selenide‐based multifunctional catalysts for energy conversion and storage systems.     

Co@Co3O4@PPD Core@bishell Nanoparticle‐Based Composite as an Efficient Electrocatalyst for Oxygen Reduction Reaction

Durable electrocatalysts with high catalytic activity toward oxygen reduction reaction (ORR) are crucial to high‐performance primary zinc‐air batteries (ZnABs) and direct methanol fuel cells (DMFCs). An efficient composite electrocatalyst, Co@Co₃O₄ core@shell nanoparticles (NPs) embedded in pyrolyzed polydopamine (PPD) is reported, i.e., in Co@Co₃O₄@PPD core@bishell structure, obtained via a three‐step sequential process involving hydrothermal synthesis, high temperature calcination under nitrogen atmosphere, and gentle heating in air. With Co@Co₃O₄ NPs encapsulated by ultrathin highly graphitized N‐doped carbon, the catalyst exhibits excellent stability in aqueous alkaline solution over extended period and good tolerance to methanol crossover effect. The integration of N‐doped graphitic carbon outer shell and ultrathin nanocrystalline Co₃O₄ inner shell enable high ORR activity of the core@bishell NPs, as evidenced by ZnABs using catalyst of Co@Co₃O₄@PPD in air‐cathode which delivers a stable voltage profile over 40 h at a discharge current density of as high as 20 mA cm^?2.     

Biomass-Derived Bifunctional Cathode Electrocatalyst and Multiadaptive Gel Electrolyte for High-Performance Flexible Zn–Air Batteries in Wide Temperature Range

High-efficiency and low-cost bifunctional electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), as well as gel electrolytes with high thermal and mechanical adaptability are required for the development of flexible batteries. Herein, abundant Setaria Viridis (SV) biomass is selected as the precursor to prepare porous N-doped carbon tubes with high specific surface area and the 900 °C calcination product of SV (SV-900) shows the optimum ORR/OER activities with a small E_OER–E_ORR of 0.734 V. Meanwhile, a new multifunctional gel electrolyte named C20E2G5 is prepared using cellulose extracted from another widely distributed biomass named flax as the skeleton, epichlorohydrin as the cross-linker and glycerol as the antifreezing agent. C20E2G5 possesses high ionic conductivity from −40 to + 60 °C, excellent tensile and compressive resistance, high adhesion, strong freezing and heat resistance. Moreover, the symmetrical cell assembled with C20E2G5 can significantly inhibit Zn dendrite growth. Finally, flexible solid-state Zn–air batteries assembled with SV-900 and C20E2G5 show high open circuit voltage, large energy density, and long-term operation stability between −40 and + 60 °C. This biomass-based approach is generic and can be used for the development of diverse next-generation electrochemical energy conversion and storage devices.     

High‐Performance Two‐Ply Yarn Supercapacitors Based on Carbon Nanotube Yarns Dotted with Co3O4 and NiO Nanoparticles

Yarn supercapacitors are promising power sources for flexible electronic applications that require conventional fabric‐like durability and wearer comfort. Carbon nanotube (CNT) yarn is an attractive choice for constructing yarn supercapacitors used in wearable textiles because of its high strength and flexibility. However, low capacitance and energy density limits the use of pure CNT yarn in wearable high‐energy density devices. Here, transitional metal oxide pseudocapacitive materials NiO and Co₃O₄ are deposited on as‐spun CNT yarn surface using a simple electrodeposition process. The Co₃O₄ deposited on the CNT yarn surface forms a uniform hybridized CNT@Co₃O₄ layer. The two‐ply supercapacitors formed from the CNT@Co₃O₄ composite yarns display excellent electrochemical properties with very high capacitance of 52.6 mF cm^?2 and energy density of 1.10 μWh cm^?2. The high performance two‐ply CNT@Co₃O₄ yarn supercapacitors are mechanically and electrochemically robust to meet the high performance requirements of power sources for wearable electronics.     

锂离子电池正极材料LiV3O8的低温合成研究

以LiNO3和NH4VO3的原料，通过溶胶－凝胶法制备了层状锂钒氧化物LiV3O8锂离子电池正极材料，通过TG－DTG、XRD等考察了合成条件对产物首次放电比容量的影响，实验结果表明，在450℃左右热分解20h可能得到单一相产物LiV3O8，其层状结构较为完整，电化学性能好，首次放电比容量可达350mAh.g^-1，作为高能锂离子电池正极材料较为理想。     

Microwave-Assisted Rational Designed CNT-Mn3O4/CoWO4 Hybrid Nanocomposites for High Performance Battery-Supercapacitor Hybrid Device

Extensive research interest in hybrid battery-supercapacitor (BSH) devices have led to the development of cathode materials with excellent comprehensive electrochemical properties. In this work, carbon nanotube (CNT)-Mn₃O₄/CoWO₄ triple-segment hybrid electrode is synthesized by using a two-step microwave-assisted hydrothermal route. Systematic physical characterization revealed that, with the assistance of microwave, granular Mn₃O₄ and spheroid-like CoWO₄ with preferred orientation, and oxygen vacancies are stacked or arranged on CNTs skeletons to construct a rational designed hybrid nanocomposite with abundant heterointerfaces and interfacial chemical bonds. Electrochemical evaluations show that the synergistic cooperation in CNT-Mn₃O₄/CoWO₄ resulted in an ultra-high specific capacity (1907.5 C g⁻¹/529.8 mA h g⁻¹ at 1 A g⁻¹), a wide operating voltage window (1.15 V), the satisfactory rate capability (capacity maintained at 1016.5 C g⁻¹/282.3 mA h g⁻¹ at 15 A g⁻¹), and excellent cycling stability (117.2% initial capacity retention after 13000 cycles at 15 A g⁻¹). In addition, the assembled CNT-Mn₃O₄/CoWO₄//N doped porous carbon (N C) BSH device delivered a stable working voltage of 2.05 V and superior energy density of 67.5 Wh kg⁻¹ at power density of 1025 W kg⁻¹, as well as excellent stability (92.2% capacity retained at 5 A g⁻¹ for 12600 cycles). This work provides a new and feasible tactic to develop high-performance transition metal oxide-based cathodes for advanced BSH devices.