Covalent Organic Frameworks with Localized High Polarity via Defect Engineering for Interfacial Regulation of Aqueous Zinc Batteries
Shaochong Cao, Tianlin Zhou, Yongshuai Liu, Wenyi Lu, Aiwen Zhang, Shan He, Pengshu Yi, Longli Ma, Zhu Liu, Fengkai Zuo, Liang Cao, Zhouhong Ren, Mingxin Ye, Huayi Fang, Jianfeng Shen
Abstract
Aqueous zinc batteries are promising energy storage systems, but face significant challenges, including zinc dendrite growth, electrochemical corrosion, and poor reversibility for large-scale applications. Herein, we design a defective fluorinated covalent organic framework (FCOF) with localized high polarity based on a truncated monomer strategy. Controllable defect design in the FCOF framework produces polar amino groups with enhanced Zn 2+ trapping ability. Meanwhile, an additional transport pathway was formed at the well-designed defect sites, which reduced the migration energy barriers. The Zn 2+ diffusion coefficient of the optimal defective FCOF separators (FCOF-30, with 30% defect content) was calculated to be 9.83 × 10 –10 cm s –1 (2 times higher than FCOF). At 10 mA cm –2 (5 mAh cm –2 ), the symmetric cell using FCOF-30 exhibited excellent Zn 2+ deposition/stripping behavior with 1200 h cycling stability. This defect engineering concept provided in-depth insights into the ion transport regulation for the electrochemical energy storage applications.