Intercalated polyaniline in V2O5 as a unique vanadium oxide bronze cathode for highly stable aqueous zinc ion battery

Layered vanadium oxides have been promising cathodes for rechargeable aqueous zinc ion batteries (AZIBs) owing to multiple valences of vanadium and relatively high interplanar spacing. However, it undergoes significant capacity decay due to vanadium dissolution and structural instability during cycling, especially at low current densities. Herein, PANI-intercalated V2O5 ((PANI)xV2O5, PAVO) hybrid bronzes with an ultra-high interlayer spacing of 13.9 Å for use as an AZIB cathode have been reported. The inserted polyaniline not only acts as structural pillars because of the hydrogen bond between -NH2 group and V-O layer but also plays the role of ‘H+’ reservoir to prevent V-O matrix from H+ attacking. Accordingly, PAVO cathode delivers a specific capacity of 350 mAh g−1 with a capacity of ~90% over 100 cycles at a current density of 0.1 A g−1, which operates for about 1 month. This study unveils the dissolution mechanism of vanadium-based electrodes and improves the stability and electronic conductivity with organic molecule intercalation. Besides, the intercalation of guest molecule generates pros and cons (favorable higher interlayer, while adverse steric hindrance) to the Zn2+ diffusion and accordingly presents a different rate performance when compared to most of the previously reported work. Therefore, a new set of molecular-scale hybrid bronzes would be designed to achieve an optimized performance in the future.