Suppressing the Growth of Dendrites On Ultrathin Lithium Metal Anodes by an Amide Electrolyte Additive

Abstract

The practical applications of high energy density lithium (Li) metal rechargeable batteries are hindered by the formation of lithium dendrites. Besides, using the thick Li anodes (typically 50 μm to 750 μm) provide more Li inventory than is needed in the cell as well as disappears the advantage of high energy density of Li metal over Li-ion batteries.Therefore, in this study, N-N-diallyl-2,2,2-trifluoroacetamide (NDT) is proposed as an electrolyte additive to inhibit the growth of dendrites on the ultrathin Li anode (20 μm). By virtue of its preferential reduction as well as its participation in the primary Li+ solvation shell, NDT contributes to the formation of a Li3N-contained uniform SEI layer on the Li metal, leading to a low polarization in LillLi cells. Be benefited, the LillLFP cell, utilizing a carbonate-based electrolyte containing 2 wt% NDT, exhibits a prolonged life-span, an enhanced reversibility, along with a retention capacity of 72% after 75 cycles, while the cell using baseline electrolyte shows a retention capacity of 68% after 50 cycles at 0.3 C. Additionally, NDT improves the ionic conductivity, and wettability of the electrolyte to the separator. These significant findings provide valuable insights for designing electrolyte additives to stabilize ultrathin Li metal anodes.