Regulating the Interlayer Spacing of Vanadium Oxide by In Situ Polyaniline Intercalation Enables an Improved Aqueous...

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.