Anchoring Polar Organic Molecules in Defective Ammonium Vanadate for High-Performance Flexible Aqueous Zinc-Ion Battery.

Ammonium vanadate (NVO) often has unsatisfactory electrochemical performance due to the irreversible removal of NH 4 + during the reaction. Herein, layered DMF-NVO nanoflake arrays (NFAs) grown on highly conductive carbon cloth (CC) are employed as the binder-free cathode (DMF-NVO NFAs/CC), which produces an enlarged interlayer spacing of 12.6 Å (against 9.5 Å for NH 4 V 4 O 10 ) by effective N, N-dimethylformamide (DMF) intercalation. Furthermore, the strong attraction of highly polar carbonyl and ammonium ions in DMF can stabilize the lattice structure, and low-polar alkyl groups can interact with the weak electrostatic generated by Zn 2+ , which allows Zn 2+ to be freely intercalated. The DMF-NVO NFAs/CC//Zn battery exhibits an impressive high capacity of 536 mAh g -1 at 0.5 A g -1 , excellent rate capability, and cycling performance. The results of density functional theory simulation demonstrate that the intercalation of DMF can significantly reduce the band gap and the diffusion barrier of Zn 2+ , and can also accommodate more Zn 2+ . The assembled flexible aqueous rechargeable zinc ion batteries (FARZIBs) exhibit outstanding energy density and power density, up to 436 Wh kg -1 at 400 W kg -1 , and still remains 180 Wh kg -1 at 4000 W kg -1 . This work can provide a reference for the design of cathode materials for high-performance FARZIBs.