Ion-Transport Kinetics and Interface Stability Augmentation of Zinc Anodes Based on Fluorinated Covalent Organic Framework Thin Films

Abstract

Zinc (Zn) emerges as an ideal anode for aqueous-based energy storage devices because of its safety, non-toxicity, and cost-effectiveness. However, the reversibility of zinc anodes is constrained by unchecked dendrite proliferation and parasitic side reactions. To minimize these adverse effects, a highly oriented, crystalline 2D porous fluorinated covalent organic framework (denoted as TpBD-2F) thin film is in situ synthesized on the Zn anode as a protective layer. The zincophilic and hydrophobic TpBD-2F provides numerous 1D fluorinated nanochannels, which facilitate the hopping/transfer of Zn2+ and repel H2O infiltration, thus regulating Zn2+ flux and inhibiting interfacial corrosion. The resulting TpBD-2F protective film enabled stable plating/stripping in symmetric cells for over 1200 h at 2 mA cm−2. Furthermore, assembled full cells (Zn-ion capacitors) deliver an ultra-long cycling life of over 100 000 cycles at a current density of 5 A g−1, outperforming nearly all reported porous crystalline materials.