废旧锂离子电池正极材料除铝技术研究进展

Research progress of aluminum removal technology for cathode materials of spent lithium-ion batteries

近年来,随着锂离子电池的快速发展,相应的废旧锂离子电池回收和再循环过程受到了越来越多的关注。铝作为废旧锂离子电池正极材料的主要杂质之一,吸引了学者们的广泛讨论和深入研究。现阶段工业上主要采用中和法除铝,通过向酸性浸出液中加入CaO等碱性物质生成Al(OH)3脱除,但存在渣量大、过滤难、易造成镍、钴等有价金属损失等问题。针对上述问题,学者们在预处理除铝、中和除铝和萃取除铝等方法上开展了广泛的研究。本工作通过分析调研国内外相关文献,详细评述了现有的废旧锂离子电池正极材料除铝方法,简要介绍了各方法的原理和优缺点,并展望了除铝方法技术的发展方向。要点:(1)综述了现有废旧锂离子电池正极材料除铝方法。(2)选取除铝方法应重点考虑效率、成本、环境污染、适用范围、可操作性等方面。(3)指出了现阶段工业上中和法除铝所存在问题,并对未来发展进行了展望。

In recent years,lithium-ion batteries(LIBs)have been widely used in portable electronic devices and electric vehicles,because of their lightweight,small volume,low self-discharge,high voltage,high specific energy,no memory effect and long storage life.It is estimated that by 2020,the number and weight of spent LIBs will exceed 25 billion and 500000 tons,respectively,and the recycling and reuse of spent LIBs are receiving more and more attention.The spent LIBs are generally physically disassembled,crushed,sieved,magnetically selected,washed,and thermally pretreated,to obtain LiNixCoyMnOz positive electrode powders containing a small number of impurities such as Al,Cu,Fe,etc.As one of the main impurities in the LiNixCoyMnOz positive electrode powders,aluminum has attracted extensive attention from many scholars.At present,the neutralization method is mainly adopted to remove aluminum,and the Al(OH)3 is removed by adding an alkaline substance such as CaO to the acidic leachate.However,a large amount of slag,difficulty infiltration,and heavy loss of valuable metals such as Ni and Co make it unfavorable for the clean production.Various methods have been developed to solve these problems such as pretreatment,neutralization,solvent extraction methods,etc.In this work,the existing methods of removing aluminum from the LiNixCoyMnOz positive electrode powders were reviewed in detail.The principles,advantages and disadvantages of these methods were briefly introduced,and the development direction of the technology of removing aluminum was prospected.Key learning points:(1)The existing aluminum removal method for cathode materials of spent lithium-ion batteries was reviewed.(2)The selective method should focus on the aspects of efficiency,cost,environmental pollution,application scope and operability.(3)The problems existing in the current industrial neutralization method for removing aluminum was pointed out,and the future development was prospected.