College of Chemical Engineering, Sichuan University, Chengdu 610064, China.
College of Chemical Engineering, Sichuan University, Chengdu 610064, China.
Waste Manag. 2023 Apr 15;161:52-60. doi: 10.1016/j.wasman.2023.02.032. Epub 2023 Mar 1.
Recycling graphitefrom spentlithium-ionbatteries has been largely ignored.In the present work, we propose a novel purification process, which modifies the structure of graphite through phosphoric acid leaching-calcination to obtain high-performance phosphorus (P)-doped graphite (LG-temperature) and lithium phosphate products. The content analysis of X-ray photoelectron spectroscopy (XPS), X-ray fluorescence (XRF) and scanning electron microscope focused ion beam (SEM-FIB) indicates that the LG structure is deformed by the doped P atom. The results of In-situ fourier transform infrared spectroscopy (In-situ-FTIR), density functional theory (DFT) calculation and XPS analysis show that the surface of the leached spent graphite contains rich oxygen groups, which react with phosphoric acid at high temperatures and form stable C-O-P and C-P bonds, making it easier to form stable solid electrolyte interface (SEI) layer. The increase of layer spacing is confirmed by X-ray diffraction (XRD), Raman and transmission electron microscope (TEM), which is conducive to the formation of efficient Li transport channels. What is more, Li/LG-800 cells possess high reversible specific capacities of 359, 345, 330 and 289 mA h g at 0.2C, 0.5C, 1C and 2C, respectively. After100cyclesat0.5C, the specific capacityis as high as 366 mAh g, demonstrating the outstanding reversibility and cycle performance. This study proves and highlights a promising recovery route for exhausted lithium-ion batteries anodes, making complete recycling possible.
从废旧锂离子电池中回收石墨一直被忽视。在本工作中，我们提出了一种新颖的提纯工艺，通过磷酸浸出-煅烧来修饰石墨的结构，得到高性能的磷（P）掺杂石墨（LG-温度）和磷酸锂产物。X 射线光电子能谱（XPS）、X 射线荧光（XRF）和扫描电子显微镜聚焦离子束（SEM-FIB）的含量分析表明，LG 结构被掺杂的 P 原子变形。原位傅里叶变换红外光谱（In-situ-FTIR）、密度泛函理论（DFT）计算和 XPS 分析的结果表明，浸出废旧石墨表面含有丰富的含氧基团，这些基团在高温下与磷酸反应，形成稳定的 C-O-P 和 C-P 键，从而更容易形成稳定的固体电解质界面（SEI）层。X 射线衍射（XRD）、拉曼和透射电子显微镜（TEM）证实了层间距的增加，有利于形成有效的 Li 传输通道。更重要的是，Li/LG-800 电池在 0.2C、0.5C、1C 和 2C 下分别具有 359、345、330 和 289 mA h g 的高可逆比容量。在 0.5C 下经过 100 次循环后，比容量高达 366 mAh g，表现出优异的可逆性和循环性能。这项研究证明并强调了一种有前途的废旧锂离子电池正极回收途径，使其完全回收成为可能。
