Polymer Stabilized Droplet Templating towards Tunable Hierarchical Porosity in Single Crystalline Na ₃ V ₂ (PO ₄ ) ₃ for Enhanced Sodium‐Ion Storage

Na 3 V 2 (PO 4 ) 3 (NVP) is regarded as a potential cathode material for sodium-ion batteries, whereas, its performance is usually limited by the inherent low electronic conductivity and dense bulk structure. Herein, we develop a facile polymer stabilized droplet template strategy to synthesize porous single crystal structured NVP. The pore structures (macrostructures, hierarchically meso/macrostructures, and mesostructures), pore sizes (5 ~ 2000 nm), and specific surface areas (26 ~ 158 m 2 g -1 ) of the samples can be readily controlled by tuning the sizes of droplet templates. The resultant hierarchically meso/macropores NVP demonstrates superior sodium storage performances, because its porous single crystal structure owns solid-liquid Na + transmission mode, shortens ion diffusion distance and provides large electrode-electrolyte contact area, greatly facilitating fast ionic transport. We believe the presented method will supply a novel avenue to prepare porous single crystal structured materials for anticipative applications.