Search

The catalytic process of Li2S formation is considered a key pathway to enhance the kinetics of lithium‐sulfur batteries. Due to the system's complexity, the catalytic behavior is uncertain, posing significant challenges for predicting activity. Herein, we report a novel cascaded dual‐cavity nanoreactor (NiCo−B) by controlling reaction kinetics, providing an opportunity for achieving hierarchical catalytic behavior. Through experimental and theoretical analysis, the multilevel structure can effectively suppress polysulfides dissolution and accelerate sulfur conversion. Furthermore, we differentiate the adsorption (B−S) and catalytic effect (Co−S) in NiCo−B, avoiding catalyst deactivation caused by excessive adsorption. As a result, the as‐prepared battery displays high reversible capacity, even with sulfur loading of 13.2 mg cm−2 (E/S=4 μl mg−1), the areal capacity can reach 18.7 mAh cm−2. [ABSTRACT FROM AUTHOR]

The high electrochemical performance of Li2MnO3‐derived Li‐rich layered oxides suggests that Na2MnO3 might be a promising cathode material for sodium‐ion batteries for its effective anionic oxygen redox. However, experimental and theoretical evidence for anionic redox and enhanced Na+ capacity of Na2MnO3 has not been established. In the present work, the structural and thermal stability, and the anionic oxygen redox mechanism of Na2MnO3 were studied by using first‐principle calculations based on density functional theory. About 1.75 Na+ per formula unit were extracted from Na2‐xMnO3 through partial O2− oxidation while the local structure remained intact, resulting in a large theoretical capacity of 315 mA h g−1. Surface Na+ was extracted before bulk Na+, which might have led to oxygen loss and structural transformation from the surface to the material bulk. Given the importance of high capacity in practical applications, Na2MnO3 and its derived Na‐rich layered oxides might be considered promising cathode materials for sodium ion batteries. [ABSTRACT FROM AUTHOR]

It is of paramount importance but challenging to construct interface structure in metals with good interfacial compatibility and high conductivity to yield superior bifunctional oxygen electrocatalyst for rechargeable Zn‐air battery (ZAB). In this work, bowl‐like hybrid structures have been designed and fabricated by decorating cognate cobalt core‐shell structure on the N‐doped hollow porous carbon bowls. Such a unique design not only can systematically boost the advantages of hollow porous bowl‐like structure but also demonstrate the universality of synthetic strategy. The experimental and density functional theory calculations elucidate that the excellent bifunctional electrocatalytic activity (ΔE = 0.71 V) of the hybrid catalyst is attributed to the spontaneous integration of a conductive Co metal core with cognate active Co3O4 shell (≈ 4 nm). The core‐shell configuration facilitates the optimization of the desorption/adsorption energy barriers for oxygen‐containing intermediates through efficient electron transfer mediated by the heterogeneous structure. As a flexible ZAB cathode, the cognate cobalt catalyst exhibits long‐term durability (60 h at 1 mA cm−2) and excellent bendable stability, demonstrating its promising potential in practical applications. [ABSTRACT FROM AUTHOR]

Two-dimensional transition metal dichalcogenides are promising anode materials for Na ion batteries (NIBs). In this study, we carried out a comprehensive investigation to analyze the structural, electrochemical characteristics, and diffusion kinetics of bulk WX 2 (X = Se, Te) by employing first-principles calculation in the framework of density functional theory. We deeply studied the full intercalation of Na + in WX 2 and diagnosed Na y X phase through conversion reaction mechanism. The voltage range of 2.05-0.48 V vs Na/Na + for Na y WSe 2 and 2.26-0.65 V for Na y WTe 2 ( y = 0-3) have been noted. Density of states analysis showed metallic behavior of WX 2 (X = Se, Te) during sodiation. The facile pathways for Na + mobility through WX 2 have shown that tungsten dichalcogenides are inferred as excellent electrode material for NIBs., (© 2022 IOP Publishing Ltd.)

Transition metal polysulfides with high S content, such as VS 4 , TiS 4 , and MoS 3 , have high specific Li + capacities, but their reaction mechanisms for lithium-ion batteries remain unclear due to unknown intermediate products. In this work, first-principles calculations based on the density functional theory were performed to reveal the electrochemical properties of VS 4 for lithium-ion batteries. The results demonstrated multiple phase transformations during Li + insertion, starting with nucleation transformation from VS 4 to Li 3 VS 4 and followed by gradual decomposition reactions. Enthalpy-driven long-range migration of Li 2 S molecules resulted in crystalline to amorphous transformation during decomposition. S and V successively behaved as redox centers for Li x VS 4 before and after x = 3. Moreover, low activation energy and high Li + diffusivity were observed at room temperature, revealing superior rate capability of the material.