Employing “one for two” strategy to design polyaniline-intercalated hydrated vanadium oxide with expanded interlayer spacing for high-performance aqueous zinc-ion batteries

Several layer-structured hydrated vanadium oxides have been investigated for aqueous zinc-ion batteries (AZIBs), where one of the challenging issues is the relatively narrow interlayer spacing (~4.4 Å for (0 0 1) plane) and the poor electronic conductivity which usually lead to the sluggish Zn2+ ions/electrons transport kinetic and the instability of structure, thus resulting in low capacity, insufficient rate capability and shortened cycling life. Herein, we have successfully employed a “one for two” strategy to design a polyaniline-intercalated hydrated V2O5 composite (PANI/V2O5) through a mild, low consumptive molecule-exchange reaction at room temperature, in which the PANI can not only expand the interlayer spacing of V2O5 which is beneficial to the fast and reversible Zn2+ ions (de)intercalation, but also further improve the specific capacity of the cathode materials. Indeed, the 3D sponge-like architectured PANI/V2O5 composite possesses an expanded interlayer spacing as large as ~14 Å, which offers large space and abundant channels for efficient Zn2+ ions (de)intercalation. As a result, the as-assembled Zn//PANI/V2O5 battery exhibits a high specific capacity up to 353.6 mAh·g−1 at 0.1 A·g−1, and a stable cycling performance. Furthermore, a detailed electrochemical reaction mechanism of such a PANI/V2O5 composite cathode is investigated systematically through a series of in-depth analyses including ex-situ X-ray diffraction, and ex-situ X-ray photoelectron spectroscopy. Our finding provides an effective “one for two” strategy, introducing polyaniline macromolecules to tune the interlayer spacing and structure stability, to design high-performance cathodes for AZIBs and even other multivalent ions storages.