Anionic covalent organic framework electrolyte with tailored ion channels for high-areal-capacity solid-state lithium metal battery

Covalent organic frameworks（COFs） are an emerging class for solid-state electrolytes due to their ordered and customizable ion transport nanochannels.Although high ionic conductivity(σLi+) and Li+ transference number(tLi+) are achieved,the high-arealcapacity solid-state lithium metal battery（LMB） still encountered challenges,which is mainly determined by homogeneous Li+flux through channels and interfaces.Herein,we design a COF coupling anionic skeletons with branched ion-conductive chains（COF-S） as tailored fast ion-transport channels to achieve high-areal-capacity solid-state LMB.Then the dispersed COF-S-based electrolyte is further obtained by incorporating ethoxylated trimethylolpropane triacrylate（ETPTA） and Li FSI（ETPTA-COF-S）via in situ light solidification.In this way,the abundant SO3- groups promote Li+adsorption and facilitate axial transport via 1D channels,thus enabling high σLi+of 1.29 m S cm-1and tLi+of 0.83.The branched chains can tailor ion channels to suppress largesize anions transport,disperse and uniform Li+ flux,thus leading to high average Coulombic efficiency（CE） up to 98.43%for 100 cycles（～800 h） at 0.5 m A cm-2under the high areal capacity of 2 mAh cm-2.When paired with 2 m Ah cm-2LiFePO4（LFP）cathode and thin Li anode of 20μm,Li||ETPTA-COF-S||LFP exhibits superior cyclic stability for 80 cycles.