Magnesium fluoride-engineered UiO-66 artificial protection layers for dendrite-free lithium metal batteries

초록

Li metal is considered an ideal anode material for high-energy-density rechargeable Li metal batteries (LMBs). Nevertheless, sluggish Li+ transport kinetics and uncontrolled Li dendrite growth result in poor cycling performance, impeding its practical application. In this study, MgF2-infiltrated UiO-66 nanoparticles (I-MgF2@UiO) with F-terminated groups are developed as artificial protective layers for Li metal anodes. The fluorination of UiO-66-based metal-organic framework nanoparticles modifies their nanopores to allow the permeation of MgF2. The F-terminated groups and infiltrated MgF2 in the I-MgF2@UiO electrode effectively facilitate the dissociation of the lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt and the desolvation of the solvated Li+ clusters, resulting in fast Li+ transport kinetics with a high Li+ transference number and ionic conductivity. Furthermore, lithiophilic MgxLiy alloys and LiF-rich solid electrolyte interphase (SEI) that form on the Li metal during the Li plating/stripping process provide a homogeneous Li+ flux and suppress Li dendritic growth. Benefiting from the I-MgF2@UiO artificial layer, full cells coupled with a LiFePO4 cathode show a long lifespan of over 2000 cycles even at a high current rate of 10C. The findings provide new insights and a promising strategy for the practical application of high-energy-density LMBs. The MgF2 and F-terminated groups effectively infiltrated the ion transport channels within UiO-66, thereby regulating the desolvation process and facilitating rapid Li+ transport kinetics.

키워드