二元羧酸低共熔溶剂浸出钴酸锂中金属元素的研究

Leaching of Metal Elements from Lithium Cobalt Oxide with Dicarboxylic Acid-Based Deep Eutectic Solvent

为绿色、高效回收废旧锂离子电池正极材料中的金属元素,以氯化胆碱为氢键受体,丙二酸、丁二酸、己二酸分别为氢键供体,合成了3种低共熔溶剂(DES);采用这3种DES浸出钴酸锂正极材料中的Co和Li,研究了浸出时间、液固比和温度对浸出率的影响,并对浸出渣的形貌和物相进行了表征;利用红外吸收光谱和紫外可见吸收光谱探究了浸出机理。结果表明:延长浸出时间、增加液固比、升高温度均有助于金属元素的浸出,适宜的浸出条件为:浸出时间300 min、液固比100 mL/g、温度110℃;3种DES中,丙二酸组成的DES具有更好的浸出性能,Co和Li浸出率都大于99%;3种DES浸出钴酸锂时,Co在浸出液中以正二价形态存在,配位构型为四面体。

In order to recover metal elements from the cathode materials of spent Li-ion batteries in an environmentally friendly and efficient way,three deep eutectic solvents(DES)were synthesized with choline chloride as hydrogen bond acceptor,malonic acid,succinic acid and adipate respectively as hydrogen bond donors.Then,Co and Li in the cathode materials of spent Li-ion batteries were leached by adopting these three DESs respectively.The effects of leaching time,liquid-solid ratio and reaction temperature on the leaching rates of Co and Li were explored,and the leaching residues were also characterized in terms of morphology and phase.The leaching mechanism was analyzed by FT-IR spectrum and UV-Vis absorption spectrum.It is shown that the leaching efficiency of metal elements can be enhanced by prolonging leaching time,increasing liquid-solid ratio and temperature.It is found that under the optimal conditions,including leaching time of 300 minutes,liquid-solid ratio of 100 mL/g,and temperature of 110℃,malonic acid-based DES,among those three kinds of DESs,can bring better leaching effect,with leaching rates of Co and Li all exceeding 99%.During the leaching of lithium cobalt oxide with those three DESs,Co exists in the form of bivalent in the leaching solution,and the coordination compound is in a tetrahedral structure.