Engineered Interface and Spatial Arrangement of Inorganic Components for Dendrite-Free Li Anodes in Carbonate-Based Electrolyte

Abstract

The practical application of lithium metal batteries (LMBs) in carbonate-based electrolytes is hindered by uncontrolled lithium (Li) deposition behavior. Here, a calcium fluoride (CaF2) functionalized polyethylene (PE) separator (CF-PE) is developed to spatially rearrange the inorganic components at the Li anode interface. A spontaneous cation exchange reaction between CaF2 and detrimental lithium carbonate (Li2CO3) generates a high modulus lithium fluoride (LiF) layer on the surface of the CF-PE separator with a robust calcium carbonate (CaCO3) enriched solid electrolyte interphase (SEI), enabling dense Li deposition behavior. As a result, the CF-PE separator enabled an extended Li deposition lifespan of more than 1100 h at 1 mAh cm-2 and 650 h at 3 mAh cm-2. In Li||NMC622 full cells, the CF-PE separator enabled stable operation over 850 cycles with a low capacity decay rate of 0.025% per cycle. Additionally, the separator retained its structural integrity at 150 degrees C, with stable cycling of the full cell at 80 degrees C, greatly outperforming a commercial PE separator. This work presents a practical strategy for constructing dendrite-free LMBs using carbonate-based electrolytes with enhanced electrochemical and environmental tolerance.