废旧锂离子电池预处理的绿色放电技术研究

Research on pretreatment green discharge technology of spent lithium-ion batteries

废旧锂离子电池中仍残留一部分电压,需要进行放电处理。当前盐溶液介质放电是主流的放电方法,但缺少对不同盐溶液放电效果系统的评测。本文重点从放电效率和环境影响2个方面对不同盐溶液作为放电介质时的效果进行评测对比,对放电过程中的气态、液态和固态污染物进行定性和定量分析,同时对放电机理进行讨论。研究结果表明:以质量分数为5%的Na2S溶液为放电介质,在放电时间为8 h时,电池残压即可降至0.5 V以下,在放电过程中,S2-在正极失去电子转变为单质硫,同时,在负极析出氢气逐渐消耗废旧锂离子电池的残压;将Na2S溶液作为放电介质时,放电过程产生的渣量少,放电后液引入的其他离子质量分数低,气态产物主要由氮气和水蒸气组成,污染物排放少,放电效率高。

Spent lithium-ion batteries with a residual voltage need to be discharged. Salt solution discharge is the mainstream discharge method, but there is a lack of systematic evaluation of the discharge effect of different salt solutions. In terms of discharge efficiency and environmental impact, the effects of different salt solutions were evaluated and compared when salt solution was used as discharge media. Qualitative and quantitative analyses of gaseous, liquid and solid pollutants in the discharge process were carried out, while the discharge mechanism was discussed. The results show that the residual pressure of the battery can be reduced to less than 0.5 V within 8 h of discharge time when 5% Na2S solutions are used as the discharge medium. During the discharge process, S2-is transformed into S at the positive electrode, while H2is produced at the negative electrode,consuming the residual power of the battery. When Na2S solution is used as the discharge medium, the discharge process produces less slag and the concentration of other ions in the solution after discharge is low. The gaseous product comprises N2and H2O(g) and exhibits low pollutant emissions and excellent discharge efficiency.