Regulating the Interlayer Spacing of Vanadium Oxide by In Situ Polyaniline Intercalation Enables an Improved Aqueous Zinc-Ion Storage Performance.

Vanadium pentoxide (V2O5) possesses great potential for application as cathode materials for aqueous zinc-ion batteries due to abundant valences of vanadium. Unfortunately, the inferior electronic conductivity and confined interlayer spacing of pristine V2O5 are not able to support fast Zn2+ diffusion kinetics, leading to significant capacity degradation, the dissolution of active species, and unsatisfactory cycling life. Herein, Zn2+ (de)intercalation kinetics is improved by the design of in situ polyaniline (PANI)-intercalated V2O5. The intercalated PANI can not only improve the conductivity and structural stability of V2O5 but also efficiently expand its interlayer spacing (1.41 nm), offering more channels for facile Zn2+ diffusion. Benefiting from these virtues, a high specific capacity of 356 mA h g-1 at 0.1 A g-1 is achieved for the PANI-intercalated V2O5 (PVO) cathode as well as a superior cycling performance (96.3% capacity retention after 1000 cycles at 5 A g-1) in an aqueous electrolyte. Furthermore, the Zn2+ storage in PVO is mainly dominated by the capacitive contribution. This work suggests that intercalating PANI in V2O5 may aid in the future development of advanced cathodes for other multivalent metal ion batteries.