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

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, LiNxOy 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//LiNi0.5Mn1.5O4 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.