Highly Fluorinated Interphases Enable High-Voltage Li-Metal Batteries

摘要

We were able to demonstrate excellent cycling performance of Li-metal anodes in carbonate electrolytes by increasing the Li bis(fluorosulfonyl) imide (LiFSI) concentration to similar to 10 M. The high concentration (10 M) of FSI anion enabled interphases of high F content on both Li-metal anode and Ni-rich NMC (nickelmanganese- cobalt) cathode surfaces. Such F-rich interphases effectively suppressed Li dendrite formation, as demonstrated by a high Li plating/stripping Coulombic efficiency of similar to 99.3%, and stabilized the carbonatemolecules against oxidation at high cutoff voltages of 4.6 V on the surface of LiNi0.Mn-6(0).Co-2(0).O-2(2) (NMC622). The combination of unique stabilization on both Li-metal anode and NMC622 cathodes enabled high-energy Li-metal batteries constructed on the aggressive chemistry. Under the harsh conditions of a high charge voltage of 4.6 V and high loading of 2.5 mAh/cm(2), the NMC622 vertical bar vertical bar Li cells retained similar to 86% of their original capacity after 100 cycles. The electrolyte strategy presented here offers unique guidelines for further optimizing beyond Li-ion chemistries.