Template-free synthesis of hierarchical vanadium-glycolate hollow microspheres and their conversion to V2O5 with improved lithium storage capability

Abstract

Nanosheet-assembled hierarchical V2O5 hollow microspheres are successfully obtained from V-glycolate precursor hollow microspheres, which in turn are synthesized by a simple template-free solvothermal method. The structural evolution of the V-glycolate hollow microspheres has been studied and explained by the inside-out Ostwald-ripening mechanism. The surface morphologies of the hollow microspheres can be controlled by varying the mixture solution and the solvothermal reaction time. After calcination in air, hierarchical V2O5 hollow microspheres with a high surface area of 70 m2 g−1 can be obtained and the structure is well preserved. When evaluated as cathode materials for lithium-ion batteries, the as-prepared hierarchical V2O5 hollow spheres deliver a specific discharge capacity of 144 mA h g−1 at a current density of 100 mA g−1, which is very close to the theoretical capacity (147 mA h g−1) for one Li+ insertion per V2O5. In addition, excellent rate capability and cycling stability are observed, suggesting their promising use in lithium-ion batteries.