Polyaniline intercalation induced great enhancement of electrochemical properties in ammonium vanadate nanosheets as an advanced cathode for high-performance aqueous zinc-ion batteries

Abstract

Layer-structured ammonium vanadate (NH4V3O8·0.5H2O) has attracted wide attention as one of the most promising cathode candidates for rechargeable aqueous zinc-ion batteries (AZIBs) due to its tunable two-dimensional (2D) layered structures; however, its sluggish Zn2+ diffusion dynamics and poor cycling stability inhibit the electrochemical properties of the material. Herein, we design the organic (polyaniline) -inorganic (ammonium vanadate) hybrid cathodes with expanded interlayer spacing by intercalating polyaniline into the interlayer of NH4V3O8·0.5H2O. Importantly, the interlayer distance of NH4V3O8∙0.5H2O is remarkably enlarged form 7.9 Å to 10.8 Å by polyaniline intercalating, offering fast channels for Zn2+ diffusion. Moreover, the polyaniline-intercalated hybrid material presents weak crystallinity and ultra-thin nanosheets morphology and owns high content of oxygen defect, which endows it with more Zn2+ active sites to improve the electrochemical kinetics of the electrode material. Benefitting from the above, the obtained organic–inorganic hybrid electrode exhibits excellent electrochemical properties, giving a high initial capacity of 397.5 mAh g−1 at 1 A g−1 and an excellent cycling stability of 300 mAh g−1 at current density of 10 A g−1 with the capacity retention of 95% over 1000 cycles. This study proposes an important guidance for the design of advanced cathodes of aqueous rechargeable zinc-ion batteries by tailoring the morphology and crystal characteristics of the materials.