【作者】 王超；

【导师】 张作泰；

【作者基本信息】 哈尔滨工业大学 ， 环境工程， 2020， 硕士

【摘要】 锂离子电池由于具有容量高、生命周期长、无记忆效应等特点,在电子产品、新能源交通工具和储能设备中得到了广泛应用。随着世界各国燃油车禁售条例的相继推出,更大规模的锂离子电池应用已经成为必然趋势。考虑到资源、环境和经济等因素,人们对废旧锂离子电池回收利用的关注度日益增加。氨法被认为是一种经济、环境友好的锂电池回收技术,可以用于废旧锂离子电池正极材料的高效浸出,但是目前对于氨浸过程中还原剂和缓冲溶液的研究缺乏系统性,也难以实现氨浸体系下有价金属元素的资源化利用。因此,本研究探索了废旧三元正极材料中有价金属元素在不同还原剂和缓冲溶液体系下的浸出行为差异,详细分析了氨浸过程的不同机制,发现了在不额外加入缓冲溶液的情况下,还原剂对三元材料中金属元素的浸出效率促进作用有以下排序:亚硫酸铵>亚硫酸钠≈硫代硫酸钠≈亚磷酸钠;在添加缓冲溶液的情况下,还原剂对三元材料中主要金属元素(镍元素、钴元素和锂元素)浸出效果的促进作用有以下顺序:亚硫酸钠≈亚硫酸铵>硫代硫酸钠>亚磷酸钠;铝元素的溶解更多受到缓冲溶液的影响,无缓冲溶液时大部分铝元素被溶解,使用亚硫酸铵为还原剂或者添加缓冲溶液时,铝元素的溶解受到抑制;缓冲溶液能够有效增加铝元素外其他金属元素的溶解效率,其中二元缓冲溶液比一元缓冲溶液的效果更好,这是由于二元缓冲溶液可以提供对氨浸络合产物而言更加适宜的酸碱度引起的。通过对NH3-(NH4)2CO3-Na2SO3选择性氨浸体系的研究,发现单阶段浸出过程中79.1%的锂元素、86.4%的钴元素和85.3%的镍元素被选择性浸出,仅有1.45%的锰元素进入溶液;多阶段浸出过程中几乎所有的金属(98.4%的锂元素,99.4%的钴元素和97.3%的镍元素)都被溶解了,同时合成了高纯(>99%)碳酸锰产品,碳酸根离子的引入不仅为碳酸锰的合成提供了基础,也大幅减少了还原剂用量;通过反应动力学分析,发现该体系下锂元素、钴元素和镍元素的浸出行为更符合表面化学反应模型,它们的表观活化能分别是48.58、49.84和48.96 k J/mol。更多还原

【Abstract】 Lithium-ion batteries are widely used in consumer electronics,electric vehicles,and energy storage equipment due to their advantages,such as high capacity,long life cycle and no memory effect.As many countries around the world have promulgated regulations prohibiting the sale of fuel vehicles,large-scale application of lithium-ion batteries will become inevitable.Taking into account many factors such as resources,environment and economy,more and more people pay attention to the recycling of spent lithium-ion batteries.The method of ammonia leaching is considered to be an economical and environment-friendly method that can be applied for the efficient leaching of spent lithium-ion batteries.However,the current research about reducing agents and buffer solutions in the ammonia leaching process lacks systematicity and it is difficult to carry out the resource utilization of valuable metal elements under the ammonia leaching system.Therefore,this study explored the differences between the leaching behaviors of valuable metal elements in the spent cathode material under different reducing agents and buffer solutions systems,then analyzed different mechanisms in the ammonia leaching process in detail,and found these results.Without the addition of buffer solution,the reducing agent could promote the leaching of metal elements and their promotion effect has the following order: ammonium sulfite>sodium sulfite≈sodium thiosulfate≈sodium phosphite.If some buffer solution was added,the leaching process of main metal elements(nickel,cobalt and lithium)would be promoted by reducing agents in the following order: sodium sulfite ≈ ammonium sulfite>sodium thiosulfate>sodium phosphite.The dissolution of aluminum was more easily affected by the buffer solution,and when there was no buffer solution,most of the aluminum element would be dissolved.When ammonium sulfite or some buffer solution was added,the dissolution process of the aluminum element would be inhibited.The buffer solution can significantly increase the dissolution efficiency of other metal elements except the aluminum element.Binary buffer solution has advantages over unary one,which might be because binary buffer solution can provide more suitable p H.Through the study of NH3-(NH4)2CO3-Na2SO3 selective ammonia leaching system,it was found that 79.1% of lithium,86.4% of cobalt and85.3% of nickel were leached out during the single-stage leaching process,and only1.45% of manganese was dissolved into the solution.Almost all the metals(98.4%for lithium,99.4% for cobalt and 97.3% for nickel)were dissolved during the multistage leaching process,and the manganese carbonate product with high purity(>99%)was simultaneously synthesized.The introduction of carbonate ions not onlyprovided the basis for the synthesis of manganese carbonate,but also greatly reduced the consumption of reducing agent.Through the reaction kinetic analysis,the leaching behaviors of lithium,cobalt and nickel under this system were mainly controlled by the surface chemistry reaction model,and the apparent activation energies of those elements were 48.58,49.84 and 48.96 k J/mol,respectively.更多还原