Fiber‐in‐Tube Design of Co 9 S 8 ‐Carbon/Co 9 S 8 : Enabling Efficient Sodium Storage

Macroscale preparation of CoS2 nanoparticles for ultra-high fast-charging performance in sodium-ion batteries

Improving the fast-charging capabilities and energy storage capacity of electric vehicles presents a feasible strategy for mitigating the prevalent concern of range anxiety in the market. Nanostructure electrode materials play a crucial role in this process. However, the current method of preparation is arduous and yields restricted quantities. In view of this, we have devised an innovative approach that provides convenience and efficacy, facilitating the large-scale synthesis of CoS2 nanoparticles, which exhibited exceptional performance. When the current density was 1000 mA g-1, the discharging capacity reached 760 mAh g-1 after 400 cycles. Remarkably, even at an increased current density of 5000 mA g-1, the discharging capacity of CoS2 remained at 685.5 mAh g-1. The ultra-high performance could be attributed to the specific surface area, which minimized the diffusion distance of sodium-ions during the charging and discharging processes and mitigated the extent of structural damage. Our straightforward preparation techniques facilitate the mass production and present a novel approach for the development of cost-effective and high-performing anode materials for sodium-ion batteries.

Confined WS2 Nanosheets Tubular Nanohybrid as High-Kinetic and Durable Anode for Sodium-Based Dual Ion Batteries

Sodium based dual-ion battery (SDIB) has been regarded as one of the promising batteries technologies thanks to its high working voltage and natural abundance of sodium source, its practical application yet faces critical issues of low capacity and sluggish kinetics of intercalation-type graphite anode. Here, a tubular nanohybrid composed of building blocks of carbon-film wrapped WS₂ nanosheets on carbon nanotube (WS₂ /C@CNTs) was reported. The expanded (002) interlayer and dual-carbon confined structure endowed WS₂ nanosheets with fast charge transportation and excellent structural stability, and thus WS₂ /C@CNTs showed highly attractive electrochemical properties for Na⁺ storage with high reversible capacity, fast kinetic, and robust durability. The full sodium-based dual ion batteries by coupling WS₂ /C@CNTs anode with graphite cathode full cell presented a high reversible capacity (210 mAh g^-1 at 0.1 A g^-1 ), and excellent rate performance with a high capacity of 137 mAh g^-1 at 5.0 A g^-1 .

Ultrahigh Rate Capability and Lifespan MnCo2 O4 /Ni-MOF Electrode for High Performance Battery-Type Supercapacitor

MnCo₂ O₄ is derived from a Co/Mn bimetallic metal-organic framework (MOF). Then Ni-MOF is directly grown on the surface of the obtained MnCo₂ O₄ to form a nano-flower structure with small balls. A large surface area, abundant active sites of MnCo₂ O₄ and porosity of Ni-MOF allow the prepared MnCo₂ O₄ /Ni-MOF composite material to deliver an excellent electrochemical performance. At the same time, an appropriate thermal treatment temperature of the MnCo₂ O₄ precursor is also very important for controlling the morphology of the obtained MnCo₂ O₄ and electrochemical performances of the resulted composite material including electric conductivity, specific capacitance and rate performance. The prepared MnCo₂ O₄ -600/Ni-MOF shows an ultrahigh rate performance (when the current density increases from 1 to 10 A g^-1 , the capacitance retention rate is as high as 93.41 %) and good cycle stability (the assembled asymmetric supercapacitor advice delivers a capacitance retention rate of 94.74 % after 20 000 charge and discharge cycles) as well as a relatively high specific capacitance. These excellent electrochemical properties indicate that MnCo₂ O₄ /Ni-MOF has a good application prospect in the market.

Robust Pseudocapacitive Sodium Cation Intercalation Induced by Cobalt Vacancies at Atomically Thin Co1-x Se2 /Graphene Heterostructure for Sodium-Ion Batteries

Electronic structure engineering on electrode materials could bring in a new mechanism to achieve high energy and high power densities in sodium ion batteries. Herein, we design and create Co vacancies at the interface of atomically thin CoSe₂ /graphene heterostructure and obtain Co_1-x Se₂ /graphene heterostructure electrode materials that facilitate significant Na⁺ intercalation pseudocapacitance. Density functional theory (DFT) calculation suggests that the Na⁺ adsorption energy is dramatically increased, and the Na⁺ diffusion barrier is remarkably reduced due to the introduction of Co vacancy. The optimized electrode delivers a superior capacity of 673.6 mAh g^-1 at 0.1 C, excellent rate capability of 576.5 mAh g^-1 at 2.0 C and ultra-long life up to 2000 cycles. Kinetics analysis indicates that the enhanced Na⁺ storage is mainly attributed to the intercalation pseudocapacitance induced by Co vacancies. This work suggests that the creation of cation vacancy could bestow heterostructured electrode materials with pseudocapacitive Na⁺ intercalation for high-capacity and high-rate energy storage.