Rational Design of V2O5 Hierarchical Microspheres with Tunable Porosities and Primary Building Blocks for Enhanced Lithium Storage Performance

Résumé fourni par la source

The lithium storage performance of vanadium pentoxide (V2O5) cathodes is intrinsically linked to their hierarchical architecture, yet achieving precise control over the morphology, porosity, and primary building block size remains a significant challenge. Herein, we report a systematic investigation into the controllable synthesis of V2O5 hierarchical structures by selecting the vanadium precursor and solvent system in a solvothermal process followed by calcination. Using ammonium metavanadate (NH4VO3) in an ethylene glycol/nitric acid (EG/HNO3) mixed solvent yields uniform hierarchical porous microspheres (V2O5–HPM) assembled from primary nanoparticles (40–60 nm) and possessing a large specific surface area of 17.3 m2 g–1. Replacing the vanadium precursor with vanadyl acetylacetonate [VO(C5H7O2)2] under otherwise identical conditions fabricates porous microspheroids (V2O5–PMS) with a lower surface area (11.1 m2 g–1). Substituting EG with isopropanol (IPA) while retaining NH4VO3 results in flower-like porous microspheroids (V2O5–FPM) assembled from coarse plates (>100 nm) with a reduced surface area (5.8 m2 g–1). Electrochemical evaluation reveals that V2O5–HPM exhibits superior lithium storage performance, delivering a reversible capacity as high as 240 mAh g–1 at 0.2C, a remarkable rate performance of 105 mAh g–1 at 5C, and a capacity retention of 82% after 100 cycles at 1C. These benefits arise from the synergistic architectural features of V2O5–HPM. Its high surface area and mesoporous network facilitate rapid electrolyte infiltration and Li+ transport, while the robust assembly of uniform nanoparticles effectively buffers volume changes during cycling. This work establishes a rational strategy for tailoring V2O5 hierarchical structures and provides valuable insights into the structure–property relationships governing high-performance cathode materials.

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