Construction of novel polyaniline-intercalated hierarchical porous V2O5 nanobelts with enhanced diffusion kinetics and ultra-stable cyclability for aqueous zinc-ion batteries

Rechargeable aqueous zinc-ion batteries (ZIBs) have received considerable attention for large-scale energy storage applications due to the unique merits of high energy density, eco-friendliness and reliable safety. However, the development of high performance cathodes is still hampered by their inferior reversibility and sluggish Zn2+ diffusion kinetics, resulting in insufficient rate capability and poor cycling performances. Herein, we employed a feasible "two-in-one" strategy to intercalate conductive polymer (polyaniline, PANI) as pillar molecules into the V-MOF-derived hierarchical porous V2O5 (designated as PVO) and used as cathode for high-performance ZIBs. The high specific surface area and nanobelt-like porous structure endowed PVO with abun-dant accessible electrochemical active sites and shortened the electrons/ions transfer pathways, further deliv-ering a high discharge capacity (489 mAh g-1 at 0.1 A g-1 and 97.2% capacity retention after 100 cycles). Meanwhile, the intercalation of PANI not only effectively expanded the Zn2+ diffusion channels, but also improved the structural stability during cycling as "interlayer pillars". More importantly, the introduction of PANI could enhance the conductivity of the overall structure and weaken the electrostatic interaction between Zn2+ and PVO host, thereby suppressing the collapse of the layered structure. Accordingly, the obtained PVO cathode exhibited excellent rate capability (375 mAh g-1 at 5.0 A g-1) and satisfactory cycling stability (91.8% capacity retention after 2000 cycles at 8.0 A g-1). Moreover, the reversible Zn2+ storage mechanism was further investigated by kinetics analysis and DFT calculations. These ideal results provide key insights into the design of MOF-based cathode materials for high-performance aqueous zinc ion batteries.