退役锂离子电池电化学还原浸出及热力学研究

Study on leaching and thermodynamic of spent lithium⁃ion batteries with electrochemical reduction

近年来锂离子电池的需求量快速增长,产生了大量退役锂离子电池(LIBs)。回收退役LIBs对保障中国的清洁能源安全具有重要意义。电化学浸出退役LIBs正极材料是一种绿色经济的回收方法。目前,电化学法回收退役LIBs存在浸出时间长、电流效率低、槽压高的问题。基于此,提出了一种牺牲阳极的电化学还原回收退役LIBs的方法。该方法以退役LIBs正极材料为阴极,以铜板为阳极,在盐酸体系下进行电化学浸出。在最佳条件下锂离子和钴离子的浸出率均达到99.9%、电流效率高达99.8%、槽压小于0.427 V。使用基于Eh-pH和Matlab的热力学计算方法,对电化学还原浸出体系进行了热力学研究。研究结果表明,温度升高,配合物种类增多、配位物种占比增大,有助于浸出反应平衡正向移动。

In recent years,the rapid increase of lithium-ion batteries(LIBs)demand has produced an enormous amount of spent LIBs.The recovery of spent LIBs is of great significance to securing clean energy in China.Electrochemical leaching of spent LIBs cathode materials is a green and economical method.At present,the recycling of spent LIBs with electrochemical methods are suffered from long leaching time,low current efficiency,and high cell voltage.Based on this,an electrochemical reduction for recycling of spent LIBs by sacrificing anodes was proposed.In the diluted hydrochloric acid solution,electrochemical leaching experiments were carried out with spent LIBs cathode materials as the cathodes and copper plates as the anodes.The leaching efficiencies were 99.9%for Li^(+) and Co^(2+),the current efficiency was up to 99.8%,and the cell voltage was less than 0.427 V under optimum conditions.The thermodynamic calculation methods based on Eh-pH and Matlab were utilized to study the electrochemical reduction leaching process,and the results showed that higher temperature,more complex species and more coordination species contributed to the positive shift of leaching reaction balance.