CAS OpenIR
废旧磷酸铁锂电池中Li和FePO4的选择性回收
JAI KUMAR
Thesis Advisor赵君梅
2020-07-01
Degree Grantor中国科学院大学
Degree Name硕士
Degree Discipline化学工程
Keyword废旧 LiFepo4 正极粉体,Li 和 Fepo4 回收,生物质基浸出,柠檬汁,再生 LiFepo4
Abstract

锂离子电池(LIBs)因其高工作电压和高能量密度而被公认为是电动汽车(EV )、便携式电子设备和混合电动汽车(HEV)的理想供电来源。其中,以LiFePO4(LFP)为正极的动力电池体系由于寿命长、成本低廉和无毒害的特点,在电动汽车所用电池中占有很大的市场份额。随着电动汽车行业的迅速发展,越来越多的废旧锂离子电池随之产生,这不仅会导致严重的环境问题,还在一定程度上引起人们对固有资源短缺问题的更多担忧。众所周知,锂是重要的战略元素,但其储量不丰、分布不均。在过去的几十年中,日益增长的和极其有限的供应使得锂化合物的成本不断攀升,回收电池行业大量淘汰的废旧锂离子电池对于缓解锂资源短缺和拓展锂资源来源都具有十分重要的意义。本文基于回收废弃锂电池的技术现状,提出了一种在室温下采用天然有机酸的浸出方法,从废弃LiFePO4阴极粉末中回收Li和FePO4。富含柠檬酸和苹果酸等有机酸的柑橘类果汁(CFJs)由于其操作简单、效率较高而被用作浸出剂,主要负责金属离子的浸出.在这项工作中,我们研究了以CFJs为浸出剂从废LiFePO4阴极中选择性回收Li和FePO4的方法。并考察了不同类型柑橘类果汁的浸出影响因素、对应的浸出机理和Li2CO3产物的纯度。此外,我们将回收的FePO4应用于新活性LiFePO4阴极材料的再生,并讨论了新生材料的电化学性能。在此过程中,我们采用配备能量色散X射线光谱仪(EDS)的扫描电子显微镜(SEM),电感耦合等离子体发射光谱(ICP-OES),X射线粉末衍射(XRD)等表征技术用于表征产品的形貌结构、提取液中的金属成分和回收产物的结晶度信息。经过实验分析,我们得出以下结论:在柠檬,橙和苹果中,柠檬汁由于其合适的反应体系pH值显示出最佳的浸出效果。在优化的条件下(包括柠檬汁百分比,反应时间,固液比和过氧化氢量),Li, Cu和Al的浸出率可分别达到94.83%,96.92%和47.24%,而Fe和P分别低至4.05%和0.84%。 Li2CO3和FePO4可以分别从浸出液和浸出残渣中回收。回收后的FePO4用于制备新的正极材料LiFePO4,再生的LiFePO4正极材料在0.1 C倍率下的放电容量为155.3 mAh g-1,与工业产品中的磷酸铁锂颇为接近。另外,在1 C下循环100周后依然展示出98.30%的容量保持率,每个循环的衰减率仅为0.017%。综上所述,基于有机酸的策略对于回收废LFP阴极材料具有重要意义,并将为LIB的可持续发展提供无限的助力。;Lithium-ion batteries (LIBs) have been widely believed in the best energy sources for electric vehicles (EVs), portable electronic devices, and hybrid electric vehicles (HEVs) due to their high voltage and high energy density. Particularly, LiFePO4-type LIBs occupy large market share in electric vehicles due to the long-life cycle, cost-effective, and nontoxicity. More and more spent LIBs may lead to a severe environmental issue and aggravate the concerns about the shortages of resources. Particularly, Li is an important strategic element. In the past decades, the rising demand and limited supply of lithium increase the cost of lithium compounds. To recycle the sharply growing spent lithium-ion batteries and alleviate concerns over shortages of resources, particularly Li, is still an urgent issue. In this thesis, state of the art for recycling spent LIBs are discussed, and a natural organic acid-based leaching approach at room temperature is proposed to recover Li and FePO4 from spent LiFePO4 (LFP) cathode powder. Citrus fruit juices (CFJs), rich in organic acids, such as citric acids and malic acids, have been used as leaching agents in this work owing to its benign operation, and relatively high efficiency, where the natural organic acids are mainly responsible for metal leaching. In this work, the selective recovery of Li and FePO4 from spent LiFePO4 cathode has been investigated taking CFJs as leaching agents. The influence of coexistence metal ions of Cu and Al, different types of CFJs, leaching parameters, leaching mechanism, the purity of Li2CO3 products, regeneration of new active LiFePO4 cathode from the recovered FePO4, and the effect of crystalline carbon on the electrochemical properties have been discussed. Inductively coupled plasma optical emission spectroscopy (ICP-OES), X-ray powder diffractions (XRD) and scanning electron microscopy (SEM) equipped with an energy-dispersive X-ray spectroscope (EDS) have been used for characterization of metal composition in leachate, crystallinity and morphology of the recovered products.After experimental analysis, we concluded that among lemon, orange and apple, lemon juice shows the best leaching effect based on its suitable pH of the reaction system. Under the optimized conditions (i.e., Citric juice percentage, reaction time, solid to liquid ratio and amount of hydrogen peroxide), the leaching rates of Li, Cu and Al can reach up to 94.83%, 96.92% and 47.24%, while Fe and P remain as low as 4.05% and 0.84%, respectively. Li2CO3 and FePO4 can be recovered from the leachate and the leaching residue, respectively. The recovered FePO4 was used to prepare new cathode material LiFePO4. The crystalline carbon, present in the spent LFP cathode scraps, has a significant effect on the electrochemical performances of the regenerated LiFePO4. The regenerated LiFePO4 cathode material delivered a comparable discharge capacity of 155.3 mAh g-1 at 0.1 C and rate capacity to the fresh LiFePO4. For the cycling stability, it displays a capacity retention of 98.30% over 100 cycles at 1 C with a fading rate of 0.017 % per cycle. In comparison with reported work, the proposed organic acid-based recycling strategy is much benign for recycling the spent LFP cathode materials and helpful to the sustainable development of LIBs. 

Language中文
Document Type学位论文
Identifierhttp://ir.ipe.ac.cn/handle/122111/49642
Collection中国科学院过程工程研究所
Recommended Citation
GB/T 7714
JAI KUMAR. 废旧磷酸铁锂电池中Li和FePO4的选择性回收[D]. 中国科学院大学,2020.
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