Strong Lewis Acid Effect in the Pores of Metal-Organic Framework Host for Dendrite-Free Lithium Deposition and Stripping.

The homogeneous introduction of Lewis acid sites into 3D hosts of Li-metal batteries (LMBs) is crucial for promoting Li+ dissociation and desolvation. Herein, the use of MIL-101, a well-known flexible metal-organic framework, loaded with uniformly distributed AlFx species with unsaturated Lewis acid sites, is proposed as a Li-metal anode (LMA) 3D host to promote Li+ dissociation and desolvation in LMBs. A symmetrical cell using an AlFx@MIL-101/Cu with pre-deposited lithium (Li@AlFx@MIL-101/Cu) exhibits stable performance for over 3600 h. In addition, a high-loading LFP||Li@AlFx@MIL-101/Cu full cell maintains high capacity after 4000 cycles at 1 C with an average coulombic efficiency of 99.87%. Experimental and theoretical analyses reveal that the AlFx species with strong Lewis acidity and MIL-101 with nanospace confinement effect promote Li+ dissociation and desolvation coupled with fast and uniform Li+ transport. The MIL-101 pores accommodate Li species, thereby inhibiting volume changes in the LMA. These results demonstrate that AlFx@MIL-101 ensures uniform and dendrite-free Li deposition on LMAs, making it a promising host for high-stability LMBs.