A LiA1Cl(4)center dot 3SO(2)-NaAlCl4 center dot 2SO(2) binary inorganic electrolyte with improved electrochemical performance for Li-metal batteries

摘要

A LiAlCl4 center dot 3SO(2)-NaAlCl4 center dot 2SO(2) binary inorganic electrolyte was prepared by using NaAlCl4 center dot 2SO(2) as the functional additive and mixing with LiAlCl4 center dot 3SO(2). The obtained LiAlCl4 center dot 3SO(2)-NaAlCl4 center dot 2SO(2) not only has good non-flammability but also exhibits improved electrochemical performance for Li-metal batteries. With the addition of NaAlCl4 center dot 2SO(2), the fabricated Li/Cu cells using mixed inorganic electrolyte display higher average coulombic efficiency and more excellent cycling stability. Through scanning electron microscopy (SEM) characterization, it is demonstrated that the surficial morphology of Li-deposited layer is smoother in LiAlCl4 center dot 3SO(2)-NaAlCl4 center dot 2SO(2) binary electrolyte system than pure LiAlCl4 center dot 3SO(2). Furthermore, the fabricated Li/graphite cells using LiAlCl4 center dot 3SO(2)-NaAlCl4 center dot 2SO(2) binary electrolyte also show higher specific capacity and better cycling stability than using pure LiAlCl4 center dot 3SO(2) electrolyte as well as the conventional organic electrolyte (1 M LiPF6 in ethylene carbonate/dimethyl carbonate mixed solvent with 1:1 in volume). Consequently, LiAlCl4 center dot 3SO(2)-NaAlCl4 center dot 2SO(2) is proposed to have great potential for the safe and high-performance Li-metal batteries.