Polyaniline-expanded the interlayer spacing of hydrated vanadium pentoxide by the interface-intercalation for aqueous rechargeable Zn-ion batteries

The metal ions or conductive macromolecules intercalated hydrated vanadium oxides for aqueous Zn-ion batteries (AZIBs) have received increasing attention in recent years. The strategy for the preparation of the intercalated hydrated vanadium oxides has been achieved great advances but is still a huge challenge. In this contribution, we develop an interface-intercalation method to synthesize the polyaniline-intercalated hydrated vanadium pentoxide (V₂O₅·nH₂O), denoted as PANI-VOH, as the cathode materials for AZIBs. The prepared PANI-VOH exhibits a 3D sponge-like morphology and the surface area of 190 m²·g^-1. The interlayer spacing of VOH is expanded to be 14.1 Å, which provides a lot of channels for the rapidly reversible (de)intercalation of Zn²⁺ ions. The coin-typed Zn//PANI-VOH battery shows the specific discharge capacity of 363 mAh·g^-1 at 0.1 A·g^-1 and stable cycling performance. Furthermore, the specific capacity remains 131 mAh·g^-1 after 2000 cycles at 5 A·g^-1, and the energy density is calculated to be 275 Wh·kg^-1 at 78 W·kg^-1 on the mass of PANI-VOH. The achieved values are comparable to or even much higher than that of the most state-of-the-art V-based cathode materials for AZIBs. The PANI intercalation can shorten the pathways and facilitate the transports for the migration of ions and electrons. Our finding guides a novel strategy for the intercalation of PANI into the layered materials to adjust their interlayer spacing, which exhibits super ions migration efficiency, as the cathode materials for AZIBs and even other multivalent ions batteries.