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The high capacity and cycling performance are important for the lithium-ion battery (LIB). V2O5 is considered a good active material among various potential candidates due to its low cost, abundant availability, and high energy density, however, the disadvantage of lower cycling performance is difficult to solve due to structural instability during the charging and discharging process. Here, we prepared composite microspheres of Co-doped V2O5 by a simple solvothermal method for solving structural instability. As the cathode material in LIBs, the V2O5-Co0.1 composite microspheres exhibit a specific capacity of 171 mAhg−1 at a current density of 0.08 Ag−1 (except for the first cycle). After 10 cycles, the specific capacity of V2O5-Co0.1 composite microspheres did not change, it exhibited better cycling stability. When the current density is increased to 0.1 Ag−1 and 0.3 Ag−1, 241 mAhg−1 and 200 mAhg−1 specific capacities are obtained. Although the initial specific capacity of pure V2O5 microspheres was higher than that of V2O5-Co0.1, its capacity retention after cycling was 86%, which was lower than that of V2O5-Co0.1. The reason for the enhanced stability of V2O5-Co0.1 composite microspheres is that Co ions are fixed between the layered structures of V2O5, which increases the stability of the V2O5 structure. [ABSTRACT FROM AUTHOR]

2D metal phosphorus trichalcogenides (MgPX3) have attracted tremendous research interests in spintronic, electrocatalytic, and photoelectronic applications due to their unique magnetic and optical properties. Herein, a systematical investigation on the electronic structures and optical properties of 2D MgPX3 (X = S and Se) monolayers is performed by density functional theory. Owing to small cleavage energy, 2D MgPX3 monolayers can be obtained by mechanical exfoliation with an excellent structure stability of 2D MgPX3 monolayers demonstrated by elastic tensor, phonon dispersion, and molecular dynamics, respectively. 2D MgPX3 behaves as a direct bandgap semiconductor with a strong optical absorption in UV range whereas a weak adsorption near the band edge, demonstrated by both single‐ and quasiparticle approximations. Upon analyses on transition dipole moment along with the wave function symmetry, the weak optical absorption is attributed to the parity‐forbidden effect where the wave functions almost show the same parity between top valence band and bottom conduction band. The findings indicate that 2D MgPX3 monolayers hold promise as candidate materials for flexible UV photoelectronics devices and provide a theoretical insight into the optical properties of 2D semiconductors. [ABSTRACT FROM AUTHOR]

Aqueous zinc-ion batteries (AZIBs) have shown potential applications in energy storage systems due to their lower cost and higher safety, but their performance is strongly influenced by the choice of the cathode material. Herein, we propose V2O5 nanoribbons with reduced graphene oxide (rGO) sheets encapsulating and magnesium ions (Mg2+) inserting between the V2O5 molecular layers. The rGO outside has an excellent electrical conductivity to obtain high reaction kinetically and alleviates the anode dissolution problem, while the magnesium ions inside increase the V2O5 layer spacing and support the molecular layer structure, which finally significantly improves the structural stability. The graphene-supported Mg2+ intercalated V2O5 nanoribbon composite (MVG) electrode delivers the reversible capacity (530 mAh g–1 specific capacity at 0.1 A g–1 current density), unbelievable cycle (89% retention of capacity after 5000 cycles at 5 A g–1), and extraordinary power and energy density (441 Wh kg–1 and 5028.46 W kg–1, respectively). The excellent electrochemical performance proves that MVG is a more suitable cathode material for AZIBs. The combined internal and external modification strategy also provides an idea for the generation of superior cathode materials for AZIBs. [ABSTRACT FROM AUTHOR]

The mechanical and electronic properties of perovskite compounds Cs2KFeF6, Cs2KVF6, Cs2TiVF6 and Cs2TlVF6 were comprehensively studied. It was found that the four compounds have 100% spin polarizability in the equilibrium state, Cs2KFeF6 exhibits bipolar magnetic semiconductor with a band gap of 1.72 eV, and Cs2KVF6, Cs2TiVF6 and Cs2TlVF6 show half-metallic properties with half-metallic gap of 1.75 eV, 0.94 eV and 1.76 eV, respectively. All four compounds show mechanical stability and varying degrees of anisotropy, and calculations of the ideal tensile strength show that they resist well in one direction at different strains. It is found that Cs2KFeF6 exhibits stable semiconductor characteristics under strain and strong light absorption in visible region under tensile strain. Cs2KVF6, Cs2TiVF6 and Cs2TlVF6 maintain robust half-metallic properties throughout the strain interval. The total magnetic moments of the equilibrium and strains are always kept at integer values, and the transition metal atoms contribute the most to the total magnetic moments. The high spin polarizability, modulable visible light absorption and wider half-metallic gap of these four perovskite compounds indicate that have demonstrated significant potential and wide-ranging application prospects in the exploration of next-generation optoelectronic devices and spintronics. [ABSTRACT FROM AUTHOR]