Polyol-Mediated Solvothermal Synthesis and Electrochemical Performance of Nanostructured V2O5 Hollow Microspheres

Hollow vanadyl glycolate nanostructured microspheres were synthesized via a highly scalable and template-free polyol-induced solvothermal process. Subsequent calcination transformed the precursor material into vanadium pentoxide, a well-studied transition metal oxide. The vanadyl glycolate nanoparticles were synthesized through a self-seeding process and then aggregated around N-2 microbubbles formed during the reaction that acted as "quasi-micelles" due to the large polarization discrepancy between nitrogen and water. The proposed formation mechanism provides a firm understanding of the processes leading to the observed hollow microsphere morphology. The thermally treated material was tested as a cathode for lithium-ion battery and showed excellent cycle stability and high rate performance. The exceptional electrochemical performance was attributed to the relatively thin-walled structure that ensured fast phase penetration between the electrolyte and active material and shortened lithium-ion migration distance. The prolonged cycling stability is ascribed to the inherent morphological void that can readily accommodate volume expansion and contraction upon cycling.