Fullerene-Derivative C60-(OLi)n Modified Separators toward Stable Wide-Temperature Lithium Metal Batteries

Lithium metal anode has been considered as the “holy grail” for realizing the next-generation high-energy rechargeable batteries, yet its practical use has been plagued by hazardous dendrite evolution owing to hostless metal deposition/dissolution at Li-electrolyte interface. To address the above issue, here we show that a Li+-contained fullerene derivative, C60-(OLi)n, has been prepared and used to modify conventional polypropylene separators for suppressing the Li dendrites at the interface. During the electrochemical reaction, the -OLi groups attached to the fullerene easily react with Li, forming a Li2O-enriched, artificial solid electrolyte interphase between the anode and the electrolyte. Owing to high Li+ conductivity of Li2O, the Li2O-enriched interphase serves as ion redistributor to guide homogeneous Li deposition/dissolution at the Li-electrolyte interface. By employing the C60-(OLi)n-modified separator, symmetric Li-Li cells and LiNi0.8Co0.1Mn0.1O2||Li full cells show ultra-long cycle lives and a wider range of operation temperature down to −40 °C. This work provides insights into surface protection and dendrite control of Li-metal anode towards practical realization of high-performance rechargeable Li-metal batteries.