Abstract:

The recycled cathode material was obtained after removing the binder of the scrap electrode by heat treatment. The regenerated materials were obtained by high temperature solid state method that adding different proportions of Li, Fe, and P element sources to the recycled material on the basis of quantitative analysis. In this paper, the influence of impurities on regenerated materials was investigated and the optimal proportion of regenerative reaction materials was obtained. The results showed that the Fe₂P impurity occurred during the regeneration process. The diffraction characteristic peak of the Fe₂P phase gradually declined with the increase of Li, Fe and P element sources. The presence of Fe₂P phase decreases the specific capacity of the sample due to the low content of LiFePO₄ active material. The morphology of regenerated materials tends to become densification as the proportion of Li, Fe and P element sources increases. The fine and close microstructure decreases the capacity and cycle performance of regenerated materials. The initial specific discharge capacities of the recycled material, stoichiometric regenerated material and excess element sources regenerated material were 103.4, 115.8 and 134.0 mA·h·g^-1, respectively. Compared with that of the recycled material, the initial specific discharge capacity of the two regenerated materials was improved by 11.99% and 29.59%, respectively. The discharge capacities of the above three materials after 50 cycles are 100.9, 108.0 and 115.3 mA·h·g^-1.

Key words: scrap Li-ion battery, lithium iron phosphate, element supplement, recovery, regeneration, electrochemistry

摘要：

热处理废旧电池正极片除去黏结剂后得到回收材料，在对回收材料元素定量分析的基础上，通过添加不同比例的Li、Fe、P源进行高温固相再生反应获得再生材料，研究杂质对再生材料的影响并优化再生反应原料比例。实验结果表明，再生反应过程中生成了Fe₂P杂质，该杂质衍射特征峰随着添加的Li、Fe、P源比例增加逐渐减弱；过多Li、Fe、P源添加时，导致再生材料结构致密性严重，Fe₂P杂质存在及材料结构过于致密，均降低了再生材料的容量性能。回收材料、化学计量比再生材料、过量元素源（1：1）再生材料首次放电容量分别为103.4、115.8和134.0 mA·h·g^-1，再生反应后分别提高了11.99%、29.59%。上述三种材料50次循环后放电容量分别为100.9、108.0和115.3 mA·h·g^-1。

关键词: 废旧电池, 磷酸铁锂, 元素补充, 回收, 再生, 电化学