碱性体系选择性回收废旧锂离子电池的研究进展

Research progress on the alkaline-system selective recycling technology in spent lithium-ion batteries

由于锂离子电池中的杂质金属在氢氧化物中溶解度差,而锂、镍、钴由于本身氢氧化物溶解度较大,或能与氨根离子形成络合物,能大量存在于碱溶液中.因此碱浸对废旧电池正极活性物质中的金属具有较高的的选择性浸出能力,且回收工艺高效、清洁.本文依据碱浸回收的工业研究现状,总结了四种碱浸回收体系,包括氨浸−热加工−还原剂体系、氨浸-还原剂-电沉积体系、氨浸−还原剂−锂吸附体系、氨浸−还原剂−氧化分离体系,并着重介绍了不同体系的原理及优点.最后,总结了废旧锂离子电池的回收方法及前景.

Due to the issue of raw material depletion,lithium-ion batteries are becoming less value-added.In addition,the highly toxic organic electrolytes contained in them cause serious harm to humans and the environment.That is why the effective recovery of spent lithium-ion batteries is of great importance for the development and sustainable use of lithium-ion batteries.Currently,recovery of metals present in spent lithium-ion batteries mainly relies on hydrometallurgical extraction:The main metals are extracted through acid or alkali media followed by recovery of metal compounds through further processing or the resynthesis of high-performance materials.Among them,acid leaching is a short and highly efficient process;however,this process dissolves all the metal ions in the solution,making it difficult to subsequently separate and purify the valuable metals.Contrarily,the hydroxide of impure metal in lithium-ion batteries shows low solubility,whereas lithium,nickel,and cobalt have high solubility,allowing for the formation of complexes with ammonia ions that can exist in alkali solution in large quantities.Thus,alkaline leaching has better selective leaching of metals in electrode materials due to the high solubility of lithium,nickel,and cobalt ammonia complexes and has a more efficient and cleaner recovery process,which is of outstanding importance in the industry.Most research was mainly focused on various acid recovery systems and scales,and the research progress on the alkaline recovery process was insufficient.Here,based on the industrial research status of alkali leaching recovery,four alkali leaching recovery systems,which include the ammonia leaching-reductant-hot working system,ammonia leaching-reductant-electrodeposition system,ammonia leaching-reductant-lithium adsorption system,and ammonia leaching-reductant-oxidation separation system,were reviewed along with their principles and advantages.Finally,a brief summary of t he recovery methods for spent lithium-ion batteries was expressed.