Electrochemical behavior of Li incorporation in Al in LiTFSI/KTf molten salt electrolyte

The electrochemical behavior of lithium incorporated in aluminum electrode in LiTFSI/KTf (lithium bis (trifluoromethylsulfonyl) amide/CF3SO3K) molten salt electrolyte was studied by a variety of electrochemical techniques including cyclic voltammetry, chronopotentiometry and chronoamperometry. The reduction reaction is found involving a nucleation process on the aluminum electrode. The results of chronopotentiometry indicate that the process of lithium incorporation in aluminum is smooth and uniform. The galvanostatic cycle experiments show that the coulombic efficiency is very low in the first cycle, which is mainly due to the “retention capacity” of Li–Al alloys. This characteristic is testified by the results of XRD and SEM. The results of chronoamperometry indicate that the incorporation of lithium into aluminum for the formation of α-phase Li–Al alloy is limited by its diffusion rate, with a measured diffusion coefficient of 1.8×10−10 cm2/s.