Abstract
Lithium metal batteries (LMBs) are regarded as the potential alternative of lithium-ion batteries due to their ultrahigh theoretical specific capacity (3860 mAh g-1). However, severe instability and safety problems caused by the dendrite growth and inevitable side reactions have hindered the commercialization of LMBs. To solve them, in this contribution, a design strategy of soluble lithiophilic covalent organic frameworks (COFs) is proposed. By introducing polyethylene glycol as the side chains, two COFs (CityU-28 and CityU-29) not only become soluble for the facile spin-coating technique, but also can facilitate the lithium-ion migration in batteries. Furthermore, when coated on the lithium anode of LMB, both COFs can act as artificial solid electrolyte interphase to prevent dendrite growth thus enabling the long-term stability of the cells. Notably, the symmetric CityU-29@Li cell can work for more than 5000 h at a current density of 2 mA cm-2 and an areal capacity of 1 mAh cm-2. A remarkable capacity retention of 78.9% after 1500 cycles and a Coulombic efficiency of about 99.9% at 1.0 C can also be realized in CityU-29@Li||LiFePO4 full cell. This work could provide a universal design strategy for soluble COFs and enlighten their application in diverse scenarios, especially energy-related fields.
Published Version
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