Interfacial Engineering Constructing TFSI‐ Ion‐Sieve Protective Umbrella Guiding Li‐Ion Selective Transport and Solid SEI Growth

A novel strategy is proposed by constructing TFSI− ion‐sieve interlayer to guide Li‐ion selective transport and solid SEI growth. The uniform MgF2 seeds on the fiber surface reacts rapidly with Li+ in electrolyte to form Mg and LiF dual functional sites for the first charging process. Benefiting from the high affinity of LiF, the TFSI− ions is enriched near the anode forming an ion‐sieve interlayer, which acts as a protective umbrella and guides priority penetration of Li+ due to the coordination reaction with Li+ and thus homogenize the Li+ flux. While the Mg sites induce Li nucleation with its strong lithiophilicity and facilitate uniform Li plating on fiber surface. Furthermore, as raw material of LiF, the TFSI− enrichment on anode surface is contribute to increasing LiF content in SEI, achieving the stability enhancement and densification of SEI. Of greater importance, the excess Li+ can spread to the adjacent Mg sites for nucleation by means of ultralow Li+ migration barrier on LiF and Mg. The combination of the ion‐sieve homogenization of Li+ flux in electrolyte and the uniformity of Li+ transport in LiF/Mg solid medium achieves the purpose of uniform Li metal plating/stripping. A new approach is proposed that selectively induces lithium salts in electrolyte to enrich into a uniform ion‐sieve on anode surface. Besides homogenizing Li+ flux, the ion‐sieve provides sufficient raw material for LiF generation, enhancing the densification of SEI by increasing LiF in the SEI. Furthermore, the modified host surfaces guide homogeneous plating of Li and realize dendrite‐free lithium metal anodes.