Electrolyte interphase built from anionic covalent organic frameworks for lithium dendrite suppression

Lithium (Li) metal batteries hold considerable promise for numerous energy-dense applications. However, the dendritic Li anode produced during Li${}^{+}$/Li deposition-stripping endangers battery safety and shortens cycle lifespan. Herein, an electrolyte interphase built from 2D anionic covalent organic frameworks (ACOF) is coated on Li for dendrite suppression. The ACOF with Li${}^{+}$-affinity facilitates rapid and exclusive passage of Li-ions from the electrolyte, yielding near-unity Li${}^{+}$ transference number (0.82) and ionic conductivity beyond 3.7 mS cm${}^{-1}$ at the interphase. Such high transport efficiency of Li-ions can fundamentally circumvent the Li${}^{+}$ deficiency that results in dendrite formation. Pairing the ACOF-coated Li against a high-voltage LiCoO${}_2$ cathode (4.5 V) achieves exceptional cycle stability, mitigated polarization, as well as improved rate capability. Accordingly, this strategy vastly expands the pool of electrolyte interphases that can be used for coating and protecting Li anode. (© 2021 Wiley-VCH GmbH)