Introducing NO₃^– into Carbonate‐Based Electrolytes via Covalent Organic Framework to Incubate Stable Interface for Li‐Metal Batteries

Abstract Lithium nitrate (LiNO₃) as an effective additive to construct stable solid electrolyte interface (SEI) is generally applied in ether‐based electrolytes, but its poor solubility in carbonate‐based electrolytes limits further application for Li metal batteries (LMBs). Therefore, an engineering of introducing NO₃^– into carbonate‐based electrolytes by synthesizing targeted covalent organic framework (EB‐COF:NO₃) to modify Li anode for incubating a reliable SEI is reported. Its unique structure not only facilitates the desolvation process of lithium ions (Li⁺) to accelerate the transport of Li⁺, but also releases NO₃^– to form beneficial Li₃N, LiN_xO_y species to in situ construct a stable SEI. With the application of EB‐COF:NO₃, the cycling and rate performance of (50 µm) Li//LiFePO₄ full cell is comprehensively improved under the conditions of poor electrolyte and high loading, significantly increasing capacity retention from 14% to 94% after 200 cycles. And the high voltage Li//LiNi_0.5Mn_1.5O₄ full cell still demonstrates excellent cycling stability with the capacity retention of 92% after 600 cycles. Accordingly, this strategy shares a prospect for the application of covalent organic frameworks (COFs) to build a stable SEI for high‐energy‐density LMBs, and also broadens the application of LiNO₃ in carbonate‐based electrolytes.