Tuning the Kinetics of Zinc-Ion Insertion/Extraction in V2 O5 by In Situ Polyaniline Intercalation Enables Improved Aqueous Zinc-Ion Storage Performance.

Rechargeable zinc-ion batteries (ZIBs) are emerging as a promising alternative for Li-ion batteries. However, the developed cathodes suffer from sluggish Zn2+ diffusion kinetics, leading to poor rate capability and inadequate cycle life. Herein, an in situ polyaniline (PANI) intercalation strategy is developed to facilitate the Zn2+ (de)intercalation kinetics in V2 O5 . In this way, a remarkably enlarged interlayer distance (13.90 Å) can be constructed alternatively between the VO layers, offering expediting channels for facile Zn2+ diffusion. Importantly, the electrostatic interactions between the Zn2+ and the host O2- , which is another key factor in hindering the Zn2+ diffusion kinetics, can be effectively blocked by the unique π-conjugated structure of PANI. As a result, the PANI-intercalated V2 O5 exhibits a stable and highly reversible electrochemical reaction during repetitive Zn2+ insertion and extraction, as demonstrated by in situ synchrotron X-ray diffraction and Raman studies. Further first-principles calculations clearly reveal a remarkably lowered binding energy between Zn2+ and host O2- , which explains the favorable kinetics in PANI-intercalated V2 O5 . Benefitting from the above, the overall electrochemical performance of PANI-intercalated V2 O5 electrode is remarkable improved, exhibiting excellent high rate capability of 197.1 mAh g-1 at current density of 20 A g-1 with capacity retention of 97.6% over 2000 cycles.