Understanding Dual‐Polar Group Functionalized COFs for Accelerating Li‐Ion Transport and Dendrite‐Free Deposition in Lithium Metal Anodes

• Published in: Energy & environmental materials (Hoboken, N.J.) Vol. 6; no. 2; pp. 324 - n/a
• Main Authors: An, Qi, Wang, Hong‐en, Zhao, Genfu, Wang, Shimin, Xu, Lufu, Wang, Han, Fu, Yao, Guo, Hong
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 01.03.2023; School of Materials and Energy,Yunnan University,No.2,Green Lake North Road,Kunming 650091,China%College of Physics and Electronics Information,Yunnan Key Laboratory of Optoelectronic Information Technology,Yunnan Normal University,Kunming 650500,China
• Subjects: Anions; Anodes; Batteries; Battery cycles; Carbonyl compounds; Carbonyls; covalent organic frameworks; Dendrites; dendrite‐free; Density functional theory; Deposition; Electrochemical potential; Electrochemistry; Electrostatic properties; functionalized separator; Ion transport; Ions; lithiophilicity groups; Lithium; Lithium batteries; Polypropylene; Separators; Specific capacity; covalent organic frameworks; lithiophilicity groups; functionalized separator; dendrite-free
• ISSN: 2575-0356; 2575-0348; 2575-0356
• DOI: 10.1002/eem2.12345

Lithium metal batteries (LMBs) have attracted wide attentions because of their high theoretical specific capacity and low electrochemical potential. However, the growth of lithium dendrites seriously affects the practical application of LMBs. Thus, the lithium‐philic carbonyl and carboxy dual‐group‐modified covalent organic framework (COF‐COOH) is designed to coat the polypropylene (PP) separator (COF‐COOH@PP separator), realizing the regulation of ion transport and uniform lithium deposition. The plentiful and negative charge sites in the COF‐COOH can suppress the diffusion of the freely movable lithium salt anion by the electrostatic interaction. Density functional theory (DFT) calculations demonstrate that the COF‐COOH possesses the function of anchoring anion and desolvation. Consequently, the Li+ transference number (0.7), ion conductivity (0.64 mS cm−1), and desolvating of Li+ are obviously improved by using the COF‐COOH@PP separator. The modified Li‐Li symmetric battery delivers stable cycle for more than 1000 h and lower voltage hysteresis (0.02 V). This dendrite‐free deposition strategy holds great promise for practical application of Li metal anodes. A novel dual‐polar group functionalized covalent organic framework is designed to coat the polypropylene separator, which is benefit for accelerating Li+ transport and achieving dendrite‐free deposition for Li metal anode.