New-phased metastable V(2) O(3) porous urchinlike micronanostructures: facile synthesis and application in aqueous lithium ion batteries

New‐phased metastable V₂O₃ porous urchinlike micronanostructures were first fabricated on a large scale by a simple top‐down strategy of pyrolyzing a vanadyl ethylene glycolated precursor in the absence of any templates or matrices. The pyrolysis mechanism was clearly revealed by synchrotron vacuum ultraviolet (VUV) photoionization mass spectra for the first time. The new‐phased metastable V₂O₃ exhibits a body‐centered cubic bixbyite structure and shows structural evolution from metastable cubic symmetry to thermodynamically stable rhombohedral symmetry V₂O₃ (R) above 510 °C. Furthermore, the prepared V₂O₃ porous urchinlike micronanostructures, as anode materials in aqueous lithium ion batteries, exhibit improved electrochemical properties with relatively high first discharge capacity and better cycle retention relative to thermodynamically stable V₂O₃ (R), which is derived from its unique microscopic crystal structure and macroscopic 3D framework with rigid morphology, porous structure, and high specific surface area.