Fluorine-Enriched Interfaces Enhance Cycling Stability of 4V Class Li Metal Batteries

Abstract

Lithium (Li) metal has been regarded as an ideal anode for energy storage system because it has high theoretical specific capacity (3860 mAh g-1) and the most negative electrochemical potential (-3.04 V versus standard hydrogen electrode) and it is the lightest metal (0.534 g cm-3). On basis of these outstanding features, the combination with Ni-based intercalation-type layered oxides that can deliver a reversible capacity of ~200 mAh g-1 will conduce to the realization of high-energy density batteries. However, dendritic Li growth and low Coulombic efficiency (CE) of Li plating and stripping reaction place a hurdle the practical uses of Li metal on batteries due to safety concerns and low lifespan of battery.4,5 To resolve these critical issues, a considerable exertion has been made to find desirable electrolyte systems including high salt concentration, sacrificial additives protecting reactive Li metal and less reactive solvents. The use of ether-based electrolytes to lithium batteries with 4V-class cathodes have been precluded, mainly due to their low upper voltage limits of lower than 4 V vs. Li/Li+ and high flammability causing the safety concerns of batteries. Here, we present tailored electrolyte systems that can provide a solution for long-lasting Li metal batteries without sacrificing energy density, by constructing a controlled and robust solid electrolyte interphase. The interfacial engineering of electrode materials by electrolyte additives offers great promise for high-energy-density batteries.