Interfacial Modulation with Phosphorylated Covalent Organic Framework Enabling Highly Durable Sodium Metal Batteries in Carbonate‐Based Electrolytes

Abstract

The practical usage of Na metal anode is severely prohibited by the instability of the natively formed solid electrolyte interface (SEI) layer and the uncontrollable Na dendrite growth, inducing short cycle life and serious safety concerns. Herein, phosphorylated covalent organic frameworks (P‐COF) is first synthesized and rationally used to construct the robust artificial interface layer for Na metal stabilization. The modified Na metal anode demonstrates high rate performance (5 mA cm−2) and ultralong cycling lifespan (1800 h) with dendrite‐free Na deposition in carbonate‐based electrolyte. And the assembled Na|Na3V2(PO4)3 (NVP) cell also reveals extraordinarily stable cycling at 5 C for 4000 cycles with a quite low decay rate of 0.002% per cycle. Moreover, the Na|NVP full cell with high areal capacity (2.0 mAh cm−2) and thin Na metal (30 µm) still demonstrates prolonged cycling over 500 cycles even under the harsh condition of a low negative‐to‐positive‐capacity (N/P) ratio of 2:3. Furthermore, the Na|NVP pouch cell with an ultrathick cathode (≈17 mg cm−2) also manifests significantly prolonged cycling performance. This work demonstrates a facile and effective strategy toward reliable Na metal batteries.