Lithium fluoride additive for inorganic LiAlCl4·3SO2 electrolyte toward stable lithium metal anode

Lithium metal is considered to be one of the most promising anode materials for next-generation energy storage systems. However, low Coulombic efficiency and dendrite growth during cycling limit the practical applications of lithium metal. In this work, a non-combustible inorganic electrolyte-LiAlCl 4 · 3SO 2 is modified with LiF additive to achieve a more stable lithium metal anode . By adding 0.3  wt % LiF to LiAlCl 4 · 3SO 2 , the ionic conductivity and lithium ion transference number of LiAlCl 4 · 3SO 2 are increased, and lithium ion migration through the solid electrolyte interface (SEI) film of lithium metal anode is easier. Thus, a more stable lithium metal anode is achieved. Therefore, at 2.0 mA cm −2 and 2.0 mAh·cm −2 , Li|Cu cells with LiAlCl 4 · 3SO 2 containing 0.3  wt % LiF can provide a stable cycling for 310 h with an average Coulombic efficiency up to 97.0%. Moreover, the addition of 0.3  wt % LiF in LiAlCl 4 · 3SO 2 can also improve the electrochemical performance of Li-SO 2 full-cell. With an areal capacity of 2 mAh·cm −2 , Li-SO 2 cell with LiAlCl 4 · 3SO 2 containing 0.3  wt % LiF can deliver ∼900 mAh·g (carbon) −1 at a discharge current densities of 0.5 A g (carbon) −1 . Therefore, we believe that a simple and effective solution is provided in this work to improve the stability of lithium metal anode with LiAlCl 4 · 3SO 2 inorganic electrolyte.