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题名: 废旧锂电池中锂和钴的机械化学回收方法与机制研究
作者: 王萌萌
学位类别: 硕士
答辩日期: 2016-05
授予单位: 中国科学院研究生院
授予地点: 北京
导师: 张付申
关键词: 废旧锂离子电池,机械化学活化,固-固反应,锂钴分离,磁性功能材料 ; Spent lithium-ion battery, Mechanochemical avtication, Solid-solid reaction, Seperation of Li and Co, Magnetic functional materials
其他题名: Mechanochemical Recycling of Lithium and Cobalt from Spent Lithium-ion Battery and Clarification of Reaction Mechanisms
学位专业: 环境工程
中文摘要:        随着电子电器产品的不断更新换代以及新能源汽车产销量的不断提高,废旧锂离子电池的数量急剧增加。本研究以废旧锂离子电池正极材料为研究对象,采用绿色环保的机械化学法回收其中的锂,同时将钴定向转化为磁性功能材料,反应过程中未使用强酸、强碱和氧化剂,为锂离子电池的资源化提供一条清洁环保的新途径,同时阐明了相关反应机理。取得的主要结论如下:
(1)废旧锂电池中锂和钴的机械化学螯合回收方法与机制研究中,将LiCoO2粉末与金属螯合剂EDTA共磨后直接加水浸出,金属Li和Co的回收率达到99%和98%。在LiCoO2/EDTA共磨时,EDTA中的两个N原子、四个羧基O原子,均能进入金属Li和Co的空轨道,形成环状结构的螯合物,即LiCoO2/EDTA通过固-固反应形成了稳定的水溶性的五元环螯合物Li-EDTA和Co-EDTA。确立的最佳机械化学活化条件为:LiCoO2:EDTA为1:4,球磨时间为4 h,球磨转速为600 r/min,球料比为80:1。本方法直接加水浸出,未使用强酸、氧化剂,环境友好,金属回收效率高。
(2)废旧锂电池中锂和钴的机械活化和定向转化方法与机制研究中,重点考察了不同供氯体和操作参数对Li回收率和Co转化率的影响。共磨剂筛选研究发现,共价类的供氯体不适于Li的回收和磁性功能材料的制备,离子类的供氯体具有高的反应活性,不仅可以促进Li的氯化,同时还可以保证Co完整地保留在反应残渣中转化为CoFe2O4。将LiCoO2/Fe/NaCl共磨,既可以保证将Li转化为水溶性的盐,又可以将Co与Fe进行晶格重组,保存在球磨残渣中形成磁性功能材料。确立的最佳操作参数为:LiCoO2:Fe:NaCl为1:2.5:5,球料比为50:1,球磨转速为600 r/min,时间为12 h,此时Li回收率达到92%,100%的Co与Fe保留在残渣中转化为CoFe2O4。对产物的晶相组成、形貌和磁性能进行表征发现,所得CoFe2O4结构紧密,具有良好的磁学性能,饱和磁化强度Ms为56.1 emu·g-1,剩余磁化强度Mr为25.8 emu·g-1,矫顽力Hc为1165.3 Oe。
(3)废旧锂电池正极材料与PVC共处理回收锂和钴并同步脱氯的方法与机制研究中,LiCoO2/PVC与添加剂共磨后直接加水浸出,重点考察了不同共磨剂和操作参数对Li和Co的回收率以及PVC脱氯率的影响。研究筛选出最优的共磨剂为单质Fe,Fe主要通过与PVC中的Cl原子形成过渡态产物实现PVC的脱氯,同时回收Li和Co。确立的最佳操作参数为:物料比为LiCoO2:PVC:Fe=1:1:2,球料比为50:1,球磨转速为600 r/min,时间为12 h,此时Li回收率达到100%,92%的Co保留在残渣中与Fe转化为CoFe2O4,同时PVC的脱氯率达96.4%。产物性能表征显示,所得磁性功能材料(CoFe2O4和α-Fe2O3)结构致密、轮廓分明、呈晶体结构,同时具有良好的磁学性能,饱和磁化强度Ms为54.14 emu·g-1,剩余磁化强度Mr为22.87 emu·g-1,矫顽力Hc为934.93 Oe。本研究为废旧锂电池的资源化回收提供了一条清洁环保的新途径。
英文摘要:       Along with the continuous upgrading of electrical and electronic products and new energy vehicles, the number of spent lithium-ion batteries (LIBs) in China increased sharply. In the present study, cathode material of typical spent LIBs were utilized as experimental materials and lithium (Li) was recovered and cobalt (Co) was transformed into magnetic functional materials efficiently employing novel green mechanochemical methods. And neither corrosive acid nor strong oxidant was applied during the process. The related reaction mechanisms were clarified as well. The major research outcomes were as follows:
(1) During the experiment of mechanochemical chelating recovery lithium and cobalt from spent LIBs, LiCoO2 powder was firstly co-grinded with various additives in a hermetic ball milling system, then Co and Li could be easily recovered by a water leaching procedure. During the ball milling process, lone pair electrons provided by nitrogen and oxygen atoms of EDTA could enter the empty orbit of Co and Li by solid-solid reaction, forming stable and water-soluble metal complexes Li-EDTA and Co-EDTA, respectively. It was found that EDTA was the most suitable co-grinding reagent, and 99% of Li and 98% of Co were respectively recovered under optimum conditions: LiCoO2 to EDTA mass ratio 1:4, milling time 4 h, rotary speed 600 r/min and ball-to-powder mass ratio 80:1, respectively. No corrosive acid or strong oxidant was applied during the process, accordingly, it is believed that the process is environmental friendly and high recovery rates for Li and Co.
(2) During the experiment of mechanochemical activation and simultaneous transformation of lithium and cobalt in spent LIBs, the study mainly focused on the effects of different chlorine donors and operating parameters on Li recovery rate and Co transformation efficiency. It was found that ionic chlorine donor was much more suitable for Li recovery and Co transformation compared with covalent chlorine donor, since it had much higher activity for improving the chlorination of Li and retaining Co inside the residue. By milling LiCoO2 with NaCl and Fe powder, it was effective to transform Li into water soluble form and reshape Co and Fe crystals so as to form magnetic material. The optimum conditions of LiCoO2:Fe:NaCl, ball-to-powder mass ratio, rotation speed and milling time were 1:2.5:5, 50:1, 600 r/min and 12 h, respectively. Furthermore, the crystal structure, morphology and magnetic properties of the products were characterized. The results indicated the prepared cobalt ferrite was featured with close structure and better magnetic property. The saturation magnetization Ms, residual magnetization Mr and coercivity Hc were 56.1 emu·g-1, 25.8 emu·g-1 and 1165.3 Oe, respectively.
(3) During the experiment of mechanochemical co-processing cathode material of spent LIBs and waste PVC for lithium and cobalt recovery and simultaneous dechlorination, LiCoO2/PVC and additives co-gringed with each other, followed by water leaching. The study mainly focused on the effects of different additives and operating parameters on Li and Co recovery rates and PVC dechlorination rate. It was found that iron was the optimum additive, which could increase recovery rates of Li and Co by formation transition state production. The optimum conditions of LiCoO2:PVC:Fe, ball-to-powder mass ratio, rotation speed and milling time were 1:1:2, 50:1, 600 r/min and 12 h, respectively, 100% Li and 92% were recovered and PVC dechlorination was 96.4%. Furthermore, the prepared cobalt ferrite was featured with close structure and better magnetic property. The saturation magnetization Ms, residual magnetization Mr and coercivity Hc were 54.14 emu·g-1, 22.87 emu·g-1 and 934.93 Oe, respectively. This study provides an efficient and green approach for spent LIBs recycling.
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/36977
Appears in Collections:固体废弃物处理与资源化实验室_学位论文

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Recommended Citation:
王萌萌. 废旧锂电池中锂和钴的机械化学回收方法与机制研究[D]. 北京. 中国科学院研究生院. 2016.
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