Tuning the Kinetics of Zinc-Ion Insertion/Extraction in V O 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 Zn 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 (de)intercalation kinetics in V O . 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 diffusion. Importantly, the electrostatic interactions between the Zn and the host O , which is another key factor in hindering the Zn diffusion kinetics, can be effectively blocked by the unique π-conjugated structure of PANI. As a result, the PANI-intercalated V O exhibits a stable and highly reversible electrochemical reaction during repetitive Zn 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 and host O , which explains the favorable kinetics in PANI-intercalated V O . Benefitting from the above, the overall electrochemical performance of PANI-intercalated V O electrode is remarkable improved, exhibiting excellent high rate capability of 197.1 mAh g at current density of 20 A g with capacity retention of 97.6% over 2000 cycles.