熔盐法再生修复退役三元动力电池正极材料

Degraded LixNi0.5Co0.2Mn0.3O2(0 < x < 1)via eutectic solutions for direct regeneration of spent lithium ion battery cathodes

本文主要针对普遍使用的废弃锂离子电池正极材料NCM523进行绿色回收,工艺极富创新性,且简单可行,直接对废弃三元正极材料进行NCM523再生修复。在空气气氛中,采用低共熔混合物LiNO3-LiOH为锂盐进行补锂修复再生,从而把废弃失效的NCM523重新修复成初始比容量的材料。X射线衍射(XRD)、电感耦合等离子光谱发生仪(ICP)、扫描电子显微镜(SEM)结果表明通过熔融的锂盐为失效正极材料补锂,并加以短暂煅烧过程可以将失效的正极材料组分和晶体结构都恢复至原始状态,电化学结果显示,在0.1 C的充放电电流密度和2.8~4. 25 V的电压范围内,300℃/3 h-850℃/4 h修复再生后的LiNi0.5Co0.2Mn0.3O2首次放电比容量为161. 2mA·h/g (0.1 C),充放电库仑效率为87. 8%。1 C条件下循环100次后,放电比容量为132. 6 mA·h/g,相比于未处理的废弃三元正极材料,倍率性能和循环性能得到大幅度提高,与商业NCM523材料相差无几。本研究有助于推动废旧三元正极材料回收产业化推广,也为回收再生其它的锂电池正极材料,例如锰酸锂、磷酸铁锂等材料的绿色回收提供了独特的思路,此方法在锂电池回收领域有良好的应用前景。

Spent NCM523 was regenerated by a green method which is simple, feasible, and innovative. A low-eutectic mixture(LiNO3-LiOH) was used as the lithium salt for regeneration in an air atmosphere. The regenerated product was characterized by X-ray diffraction, inductively coupled plasma spectroscopy, and scanning electron microscopy. The composition and crystal structure confirmed that the spent cathode was restored to its original state. Moreover, electrochemical results show that under the condition 300 ℃/3 h^850 ℃/4 h, the specific capacity of the regenerated material reached 161.2 mA·h/g(0.1 C, 2.8~4. 25 V) in the first discharge, and the coulomb efficiency was 87.8%. After 100 cycles at 1 C, the specific discharge capacity was 133.6 mA·h/g, confirming the high electrochemical performance of the rejuvenated material. The rate and recycling performance were much improved from those of untreated cathode materials and were similar to those of commercial anode materials. This research can promote the industrialization of cathode material recovery and provides a unique idea for the green recovery of other cathode materials such as LiMn2O4 and LiFePO4.This method has good application prospects in lithium battery recovery.