Rational Design of V ₂ O ₅ Hierarchical Microspheres with Tunable Porosities and Primary Building Blocks for Enhanced Lithium Storage Performance

The lithium storage performance of vanadium pentoxide (V 2 O 5 ) 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 V 2 O 5 hierarchical structures by selecting the vanadium precursor and solvent system in a solvothermal process followed by calcination. Using ammonium metavanadate (NH 4 VO 3 ) in an ethylene glycol/nitric acid (EG/HNO 3 ) mixed solvent yields uniform hierarchical porous microspheres (V 2 O 5 –HPM) assembled from primary nanoparticles (40–60 nm) and possessing a large specific surface area of 17.3 m 2 g –1 . Replacing the vanadium precursor with vanadyl acetylacetonate [VO(C 5 H 7 O 2 ) 2 ] under otherwise identical conditions fabricates porous microspheroids (V 2 O 5 –PMS) with a lower surface area (11.1 m 2 g –1 ). Substituting EG with isopropanol (IPA) while retaining NH 4 VO 3 results in flower-like porous microspheroids (V 2 O 5 –FPM) assembled from coarse plates (>100 nm) with a reduced surface area (5.8 m 2 g –1 ). Electrochemical evaluation reveals that V 2 O 5 –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 V 2 O 5 –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 V 2 O 5 hierarchical structures and provides valuable insights into the structure–property relationships governing high-performance cathode materials.