采用循环伏安法研究了锂电解过程中杂质元素的电化学行为。电解过程中杂质元素镁将优先于锂在阴极析出, 然后是金属锂的欠电位沉积形成镁锂合金, 最后才是金属锂的析出, Mg ²⁺的还原电极过程受扩散控制, 扩散系数为1.44×10 ^-5 cm ²/s;微量的Ca ²⁺即发生钙锂共沉积;在含少量氯化钠的熔盐体系中, 杂质元素钠被锂还原并形成合金, 随着电解质体系中氯化钠含量的增加, 金属锂中的钠含量有较大的增加;杂质元素铁优先于锂在阴极析出, 在阴极被还原成海绵铁使阴极钝化, 引起熔盐体系锂的析出电流急剧降低, Fe ³⁺的还原电极过程受扩散控制, 扩散系数为3.14×10 ^-5 cm ²/s。

The electrochemical behavior of impurity elements in lithium electrolysis was studied by cyclic voltammetry.In the process of electrolysis, the deposition of impurity element Mg was prior to Li at the cathode, followed by the underpotential deposition of lithium metal to form magnesium-lithium alloy, and finally the deposition of lithium metal.The reduction electrode process of Mg ²⁺ was controlled by diffusion with diffusion coefficient of 1.44×10 ^-5 cm ²/s.Calcium-lithium co-deposition can occur with a small amount of Ca ²⁺.In the molten salt system with a small amount of NaCl, the impurity element Na was reduced by Li and formed into alloy.With the increase of NaCl content in the electrolyte system, the sodium content in lithium metal increased greatly.The impurity element Fe was preferentially formed at the cathode than Li which was reduced to spongeiron at the cathode to passivate the cathode, resulting in a sharp decrease in the precipitation current of lithium in molten salt system.The reduction electrode process of Fe ³⁺ was controlled by diffusion with diffusion coefficient of 3.14×10 ^-5 cm ²/s.