High energy density lithium-selenium batteries enabled by a covalent organic framework-coated separator

The shuttle effect from the dissoluble polyselenide intermediates in lithium-selenium (Li-Se) battery is a critical problem. In order to explore the effective solution, a specific composite ceramic separator including a covalent organic framework prepared by the polymerization of 2,5-Dimethoxy-1,4-Dicarboxaldeh yde and Tetrakis(4-aminophenyl) ethane (DMTA-COF) was used to enhance electrochemical performance of Li-Se battery for the first time. It should be noted that the cathode with pure selenium of 80% by weight leads to a high selenium loading of similar to 3 mg/cm(2) for the simply-made cells. Due to the small pore channel of the DMTA-COF-coated separator, the dissolution of the polyselenide LiSen (n > 4) can be effectively restrained. As a consequence, the cells delivered a long cycling performance of up to 700 cycles with high capacity of 126 mA h/g at 6 C and good capacity of 51 mA h/g at 20 C. Obviously, our study elucidates the COF-integrated separator is a promising pathway to improve the capacity and stability of the lithiumselenium battery. (C) 2019 Elsevier B.V. All rights reserved.