采用绿色有机酸对磷酸铁锂电池正极粉末进行回收,考察了浸出过程的影响因素。结果表明,柠檬酸+抗坏血酸体系对Li浸出率最高可达92.7%,最佳反应条件为:柠檬酸浓度为1.5 mol/L、抗坏血酸浓度为0.3 mol/L、酸浸温度为80℃、酸浸时间为60 min、固液比为1∶20。采用液体边界层传质控制模型和化学反应控制模型对浸出过程进行分析,结果表明,Li的浸出过程符合化学反应控制模型,反应活化能为30.56 kJ/mol。SEM和XRD表征结果表明,在浸出反应过程中,Li以Li₃Cit的形式释放到溶液中,LiFePO₄正极粉末中的Fe²⁺被氧化为Fe³⁺,酸浸反应后LiFePO₄可以直接转化为FePO₄,而不需要形成其他铁化合物。

A sustainable approach is explored for recovering lithium from lithium iron phosphate (LiFePO₄) cathode powder by green organic acids,and the effectiveness at various leaching parameter is evaluated.It is revealed that the highest extraction rate of lithium reaches 92.7% under a combination of citric acid (1.5 mol·L^-1) and ascorbic acid (0.3 mol·L^-1) system.The optimal reaction conditions are obtained as follows:citric acid concentration is 1.5 mol·L^-1,ascorbic acid concentration is 0.3 mol·L^-1,leaching temperature is 80℃,leaching time is 60 minutes,and solid-liquid ratio is 1∶20.The leaching process is analyzed by using liquid boundary layer mass transfer controlling model and chemical reaction controlling model.Results indicate that the extraction process of lithium conforms to the chemical reaction control model,with an activation energy of 30.56 kJ·mol^-1.SEM and XRD characterization analysis confirms that Li in the form of Li₃Cit is released into the solution during the leaching reaction process.Fe²⁺ in LiFePO₄ cathode powder is oxidized to Fe³⁺.After the leaching reaction,LiFePO₄ can be directly converted to FePO₄ without forming other iron compounds.

罗家玲(2002-),女,本科生,研究方向为绿色化工,2712536136@qq.com;文婕(1982-),女,博士,副教授,硕士生导师,研究方向为废旧锂离子电池回收,通讯联系人,wenjie@swpu.edu.cn。