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

Abstract A novel strategy is proposed by constructing TFSI − ion‐sieve interlayer to guide Li‐ion selective transport and solid SEI growth. The uniform MgF 2 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.