Rearrange SEI with artificial organic layer for stable lithium metal anode

Lithium metal (Li) has the highest theoretical capacity as an anode for Li based secondary batteries. However, commercialization of Li batteries has been impeded due to the formation of dendrites that are generated during cycling which can lead to capacity loss and even catastrophic short-circuit. Herein we report a method to form a protection layer on Li metal via a facile reaction between the Li surface and n-terminal alcohols. Under electrochemical cycling conditions the as formed Li-alkoxides effectively decreased the interfacial resistance and Li deposition overpotential. The performance was found to be dependent on carbon chain length and thickness of the Li-alkoxide layer. Specifically, the Li deposition overpotential in a symmetrical cell employing the protection layer was decreased from 0.19 V to 0.06 V at 0.5 mA cm−2. By applying in-situ optical cell, the volume expansion of protected Li anode was observed to be reduced from 30% to 10% when compared with untreated Li anode. Li||NCM full cell with Li-alkoxide layer also showed more stable cycling performance when compared to cells with untreated Li. Here we demonstrate a practical and scalable Li anode protection method that can enable Li metal as an anode in high energy density Li batteries.