Computational and Experimental Insights on the Role of ZnO Nanoplatelets Coated Separator in Stabilizing Lithium Metal Anodes

Severe interfacial instability, dendritic growth, poor reversibility, and compromised cycle life of lithium metal anode have limited its application as a potential anode. Herein, a lithiophilic ZnO-coated separator (ZnO-PP) is used to mitigate the interfacial instability by creating an artificial solid electrolyte interface (ASEI) in situ through the spontaneous reaction of ZnO with the lithium surface. The composite separator exhibited excellent wettability, high ionic conductivity, improved Li⁺ transference number, and exchange current density. Ascribed to the formation of Zn-rich ASEI, a substantially lower nucleation overpotential is observed in the presence of ZnO-PP with a 55% increase in the cycle life compared to the unmodified separator. The improved electrochemical performance and prolonged cycle life are a result of smooth and uniform metal plating due to Zn-based SEI, which is confirmed by the post-cycling measurements. The density functional theory and AIMD calculations further showed that the 'by-side' lithium plating is preferred in the case of ZnO-PP, resulting in smooth plating, and suppressed electrolyte degradation. Furthermore, a Li|Cu and full cell with lithium cobalt oxide showed substantially improved reversibility, rate performance, and capacity retention with ZnO-PP.