摘要
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 a-phase Li-Al alloy is limited by its diffusion rate, with a measured diffusion coefficient of 1.8× 10^-10 cm2/s.
采用循环伏安、计时电位和计时电流等电化学测试技术考察LiTFSI/KTf熔盐电解质中锂在铝电极上的电化学行为。结果表明:在该熔盐中,锂在铝电极上的电化学还原过程伴随着锂铝合金的成核过程,锂在铝电极上的嵌入过程平缓、稳定。恒电流充放电循环实验发现,首次循环的库仑效率很低,这主要归结于Li-Al合金对锂元素的持留能力。通过XRD和SEM表征了充放电前后铝电极的物相组成和表面形貌。计时电流实验发现,锂原子嵌入铝电极中形成α-Li-Al合金的过程受锂在铝基体内的扩散步骤控制,且该扩散系数为1.8×10-10cm2/s。
基金
Project (70510011) supported by Scientific Research Starting Foundation of Jiaxing University,China
Project (84209001B3) supported by Open Fund of Key Laboratory of Clean Chemical Process of Jiaxing,China
