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

Abstract

Ammonium vanadate (NVO) often has unsatisfactory electrochemical performance due to the irreversible removal of NH4+ 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 NH4V4O10) 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 Zn2+, which allows Zn2+ 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 Zn2+, and can also accommodate more Zn2+. 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.

Defect engineering and morphology adjustment assist NH4V4O10 to be a high-performance aqueous zinc ion battery cathode

“…Furthermore, the peaks located at 281, 692, and 992 cm −1 represent distinct vibration modes associated with the VO and V–O bonds. 42–44 The characteristic peaks of SNVO remain unshifted when compared to those of NVO. The Fourier transform infrared (FTIR) spectra of SNVO and NVO are shown in Fig.…”

High-rate and long-life flexible aqueous rechargeable zinc-ion battery enabled by hierarchical core–shell heterostructures

“…Although vanadium-based materials exhibit high specific capacity, they are limited by their toxicity, low operating voltage (≈0.7 V vs. Zn 2+ /Zn) and high raw material cost. 24,25 Prussian blue analogs have high operating voltages (>1.4 V vs. Zn 2+ /Zn), but poor cycling stability and low specific capacity are non-negligible drawbacks. 26 Manganese-based materials represent promising cathode materials because of their satisfactory operating voltages and specific capacity.…”

Bulk-to-surface co-modification of layered hydrated vanadate cathode for aqueous zinc ion batteries

“…Considerable efforts have been undertaken to enhance the cyclability of vanadium-based cathodes, such as introducing guest ions or molecules (K + , Na + , Zn 2+ , Mn 2+ , PANI, and DMF) 4,15–19 in the V–O layers to stabilize the bulk phase of cathodes constructing artificial CEIs (PA/PPy, HfO 2 , and conductive heterocyclic aromatic chains), 20–22 and adopting highly concentrated electrolytes, 23,24 to stabilize the surface structure of cathodes or retard the side reactions. Although these strategies have achieved some success, the improvement in cyclability at lower current densities is still limited.…”