Highly Conductive Imidazolate Covalent Organic Frameworks with Ether Chains as Solid Electrolytes for Lithium Metal Batteries

Abstract Poly(ethylene oxide) (PEO)-based electrolytes show low Li + conductivity due to high entanglement of the polymer chains and strong interaction between EO and Li + . However, ionic covalent organic frameworks (iCOFs) with periodical structures provide highly ordered pathways for ion conduction, leading to improved conductivity. Here, we present imidazolate COFs having methoxyethoxy chains, synthesized by Debus–Radziszewski multicomponent reactions. The base COFs were further ionized and treated with LiClO 4 salts to be Li + @PI-TMEFB-COFs and to show the high total conductivity of 8.81 mS cm − 1 and single-ion conductive transference number of 0.97. The mechanism for such excellent electrochemical properties is that methoxyethoxy chains dissociate LiClO 4 , making free Li + , then those Li + are transported through the imidazolates on the COFs’ pores. The synthesized Li + @PI-TMEFB-COFs show a stable interface and low interfacial impedance with Li metal. Li + @PI-TMEFB-COFs based LiFePO 4 batteries show an initial discharge capacity of 119.2 mAh g − 1 at 0.5 C. After 400 cycles, 82.0% capacity and 99.9% Coulombic efficiency were maintained. These results show that ether-functionalized iCOFs via multicomponent reactions can set up a new perspective for making solid electrolytes.