State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment , Tsinghua University , Beijing 100084 , China.
Environ Sci Technol. 2019 Aug 20;53(16):9781-9788. doi: 10.1021/acs.est.9b01919. Epub 2019 Aug 2.
Lithium (Li) is the most valuable metal in spent lithium iron phosphate (LiFePO) batteries, but its recovery has become a challenge in electronic waste recovery because of its relatively low content and inconsistent quality. This study proposes an acid-free and selective Li extraction process to successfully achieve the isomorphic substitution of Li in LiFePO crystals with sodium (Na). The method uses low-cost and nontoxic sodium chloride (NaCl) as a cogrinding reagent via a mechanical force-induced solid-phase reaction. X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX), and X-ray photoelectron spectroscopy (XPS) characterizations demonstrated the evidence of Li/Na isomorphic substitution, while XPS spectra of Fe 2p, P 2p, and O 1s revealed that the coordination environment of these elements was not significantly altered. Density functional theory calculations further provided evidence that Na and Li share similar outer electron arrangements and coordination environments, favoring Na over Fe as a replacement for Li in LiFePO. Additionally, the regeneration of NaCl and the recovery of precipitated LiCO were simultaneously achieved with NaCO as the sole reagent. This concise and efficient acid-free mechanochemical process for Li extraction is a promising candidate for feasible recycling technology of Li from spent LiFePO batteries. The proposed process is particularly appealing because of its high selectivity, considerable economic advantages, and environmental benefits.
锂（Li）是废旧磷酸铁锂（LiFePO）电池中最有价值的金属，但由于其含量相对较低且质量不一致，其回收在电子废物回收方面已成为一项挑战。本研究提出了一种无酸且具有选择性的 Li 提取工艺，成功地实现了 Li 在 LiFePO 晶体中与钠（Na）的同晶取代。该方法使用廉价且无毒的氯化钠（NaCl）作为共研磨试剂，通过机械力诱导的固相反应用于固态反应。X 射线衍射（XRD）、能谱（EDAX）和 X 射线光电子能谱（XPS）分析证明了 Li/Na 同晶取代的证据，而 Fe 2p、P 2p 和 O 1s 的 XPS 光谱表明这些元素的配位环境没有明显改变。密度泛函理论计算进一步证明了 Na 和 Li 具有相似的外层电子排列和配位环境，这使得 Na 比 Fe 更适合替代 LiFePO 中的 Li。此外，仅使用 NaCO 作为试剂，同时实现了 NaCl 的再生和沉淀 LiCO 的回收。这种简洁高效的无酸机械化学 Li 提取工艺为废旧 LiFePO 电池中 Li 的可行回收技术提供了有前景的候选方案。该方法具有高选择性、显著的经济优势和环境效益，因此特别有吸引力。
