Interfacial Engineering Constructing TFSI- Ion-Sieve Protective Umbrella Guiding Li-Ion Selective Transport and Solid...

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.