Template-free synthesis of β-Na_0.33V₂O₅ microspheres as cathode materials for lithium-ion batteries

In this work, hierarchical three-dimensional (3D) β-Na_0.33V₂O₅ microspheres have been synthesized for the first time by a simple solvothermal reaction with subsequent annealing treatment. The hierarchical microspheres are self-assembled from nanosheet subunits during the solvothermal process. Simultaneously, various hierarchical microspheres with different subunits can be produced by altering the solvothermal solution. After annealing in air, the solvothermal product can be converted into β-Na_0.33V₂O₅ with a well-retained structure. As cathode materials for lithium ion batteries, the as-prepared 3D microspheres exhibit high capacity and good rate capability. The superior electrochemical performance is attributed to the unique three-dimensional hierarchical microstructures, which mimic the advantages of nano- and micro-structures.