Interfacial engineering of perfluoroalkyl functionalized covalent organic framework achieved ultra-long cycled and dendrite-free lithium anodes  

作　　者：Yongxin Yang Conghui Zhang Zhiyuan Mei Yongjiang Sun Qi An Qi Jing Genfu Zhao Hong Guo 

机构地区：[1]International Joint Research Center for Advanced Energy Materials of Yunnan Province,Yunnan Key Laboratory of Carbon Neutrality and Green Low-carbon Technologies,School of Materials and Energy,Yunnan University,Kunming 650091,China

出　　处：《Nano Research》2023年第7期9289-9298,共10页纳米研究（英文版）

基　　金：The authors acknowledge financial supports provided by the National Natural Science Foundation of China(No.52064049);Key Laboratory of Solid-State Ions for Green Energy of Yunnan University(2019);Analysis and Measurements Center of Yunnan University for the sample testing service,the Electron Microscope Center of Yunnan University for the support of this work;the Postgraduate Research and Innovation Foundation of Yunnan University(No.KC-22221440)。

摘　　要：The finite lithium-ion utilization,short cycling life,and lower capacity retention caused by irreversible dendrite growth become the maximum dilemma in lithium metal batteries’(LMBs’)commercialization.Herein,a perfluoroalkyl-functionalized covalent organic framework(COF-F6)equipped with high stability and supernal proton conduction is introduced as an artificial solid electrolyte interface to stable the lithium metal anode.Benefiting from the strong electron-withdrawing effect of perfluoroalkyl,Li^(+)will be freed more by the competition of electronegative fluorine(F)and bis(trifluoromethanesulphonyl)imide anion(TFSI^(-)).The dissociation of LiTFSI and process of Li^(+)desolvation are easier to achieve.In addition,high electronegative fluorine can also regulate local electron-cloud density to induce the fast immigration of Li^(+).All the above roles contribute to improving the Li^(+)transfer number(0.7)and achieving the goal of inhibiting Li dendrite.As a result,the perfluoroalkyl COF-F6 modified LMB presents outstanding cycling stability.The symmetric batteries accomplish an overlong life-span of more than 5000 h with a lower hysteresis voltage(11 mV)at 5 mA·cm^(-2).Also,no dendrites are observed when using an in-situ optical microscope to learn the process of Li deposition.Therefore,this dendrite-free protection tactic holds broad prospects for the practical application of Li metal anodes.

关 键 词：perfluoroalkyl-functionalized covalent organic framework(COF-F6) artificial solid electrolyte interface strong electronwithdrawing effect dendrite-free lithium metal anode 

分 类 号：TM912[电气工程—电力电子与电力传动]