Tuning the Kinetics of Zinc‐Ion Insertion/Extraction in V2O5 by In Situ Polyaniline Intercalation Enables Improved Aqueous Zinc‐Ion Storage Performance

Abstract

Rechargeable zinc‐ion batteries (ZIBs) are emerging as a promising alternative for Li‐ion batteries. However, the developed cathodes suffer from sluggish Zn 2+ diffusion kinetics, leading to poor rate capability and inadequate cycle life. Herein, an in situ polyaniline (PANI) intercalation strategy is developed to facilitate the Zn 2+ (de)intercalation kinetics in V 2 O 5. 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 Zn 2+ diffusion. Importantly, the electrostatic interactions between the Zn 2+ and the host O 2−, which is another key factor in hindering the Zn 2+ diffusion kinetics, can be effectively blocked by the unique π‐conjugated structure of PANI. As a result, the PANI‐intercalated V 2 O 5 exhibits a stable and highly reversible electrochemical reaction during repetitive Zn 2+ 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 Zn 2+ and host O 2−, which explains the favorable kinetics in PANI‐intercalated V 2 O 5. Benefitting from the above, the overall electrochemical performance of PANI‐intercalated V 2 O 5 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.