Department of Chemical Engineering, Michigan Technological University, USA.
Department of Material Science and Engineering, Michigan Technological University, USA.
Waste Manag. 2020 Mar 15;105:39-48. doi: 10.1016/j.wasman.2020.01.035. Epub 2020 Feb 1.
Direct recycling of Li-ion batteries (LIBs) reclaims electrode materials using physical separation followed by materials' rejuvenation processes. The cathode composites in LIBs contain both carbon black and PVDF binders in its chemistry. For the rejuvenation process to work, an ability to remove these impurities is desirable. In the present work, de-agglomeration of individual components from the cathode composites has been carried out using a mechanical process that is developed for preserving functional integrity of the cathode active materials. It has been shown that the size of the cathode composites is effectively reduced upon a de-agglomeration process due to a liberation of PVDF binders from the cathode composites. The de-agglomeration performance has been evaluated by separating mixed materials by the degree in surface hydrophobicity using the froth flotation method. The performance improves with end-of-life (EOL) LIBs compared to new LIBs, benefiting from a degradation of PVDF binders after charging-discharging cycles. X-ray photoelectron spectra suggests that the de-agglomeration is done by breaking intermolecular bond between PVDF and cathode active materials as well as covalent bond within PVDF binders. The present work demonstrates a non-chemical method for liberating individual components from cathode composites for the direct recycling of LIBs.
锂离子电池（LIB）的直接回收利用采用物理分离，然后进行材料的再生处理来回收电极材料。LIB 中的阴极复合材料在其化学组成中既包含炭黑又包含 PVDF 粘结剂。为了使再生过程能够进行，需要能够去除这些杂质。在本工作中，采用一种机械方法对阴极复合材料中的各个组分进行解团聚，该方法是为了保持阴极活性材料的功能完整性而开发的。研究表明，在解团聚过程中，由于阴极复合材料中的 PVDF 粘结剂的释放，阴极复合材料的尺寸有效地减小了。通过使用泡沫浮选法根据表面疏水性的程度来分离混合材料，评估了解团聚性能。与新的 LIB 相比，EOL LIB 的性能得到了改善，这得益于在充放电循环后 PVDF 粘结剂的降解。X 射线光电子能谱表明，解团聚是通过打破 PVDF 和阴极活性材料之间的分子间键以及 PVDF 粘结剂内的共价键来完成的。本工作证明了一种从阴极复合材料中释放各个组分的非化学方法，用于 LIB 的直接回收利用。
