Polyaniline and alkali cations co-intercalated V₂O₅ composites with a tremelliform nanosheet structure for high...

Aqueous zinc-ion batteries (AZIBs) have drawn great attention owing to the high intrinsic safety, high power density and numerous advantages of the zinc metal anode. As a cathode material for AZIBs, vanadium pentoxide has a high theoretical capacity of 589 mA h g^-1, but it suffers from sluggish Zn²⁺ diffusion kinetics and rapid capacity degradation. Herein, a co-intercalation strategy of polyaniline (PANI) and alkali cations (Li⁺, Na⁺, and K⁺) is employed to enhance the Zn²⁺ storage capability of vanadium oxides. As control groups, the sample with only PANI intercalation and the sample without PANI and alkali cation intercalation are synthesized. The evolution of the phase, interlayer distance, morphology and structure for the five samples is investigated. Compared with the intercalation of only PANI, the co-intercalation of PANI and alkali cations further enlarges the interlayer distance (14.80 Å) and maintains the tremelliform nanosheet structure. This co-intercalation strategy promotes the Zn²⁺ diffusion kinetics, enhances the stability of the layered structure and improves the electronic conductivity. As a result, the electrochemical performance is significantly improved, showing high capacity (409.2 mA h g^-1 at 0.2 A g^-1), excellent rate capability (261.8 mA h g^-1 at 5 A g^-1), and favorable cycling stability (capacity retention of 65.4% after 1200 cycles at 5 A g^-1).