Tuning the Kinetics of Zinc‐Ion Insertion/Extraction in V₂O₅ 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 V₂O₅. 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 V₂O₅ 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 V₂O₅. Benefitting from the above, the overall electrochemical performance of PANI‐intercalated V₂O₅ 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. © 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.