Electrochemical Reduction Mechanism Of Valuable Metals In Waste Lithium Manganate Battery

With the excellent performance lithium-ion batteries（LIBs）have been widely used in power vehicles and electronic products,etc.Massive LIBs are retired,which has continued to increase the number of waste LIBs.There are a large number of metal ions（Co,Mn,Ni）in waste LIBs anode material.Without effectively treated in time,waste of resources and environmental pollution will be caused.The risk of secondary pollution in environment increased by waste gas and liquid produced by traditional recycling methods.Using molten salt electrochemical methods,the mechanism of manganese extraction and lithium enriching from lithium manganite（LiMn₂O₄）was studied,and the electrolytic experiment of LiMn₂O₄was performed.Li⁺are obtained in the molten salt while metal manganese is recovered.The main research contents are as follows:Research on the dissolution behavior of LiMn₂O₄:The dissolution behavior of LiMn₂O₄was studied at 750℃in NaCl-CaCl₂ molten salt.The results showed that a small amount of chemical decomposition products appeared at 0.1h were CaMn₂O₄ and MnO.LiMn₂O₄ was completely decomposed,after 2h of reaction.Study on the electrochemical behavior of LiMn₂O₄ in molten salt:The electrochemical test method,cyclic voltammetry and etc,were used to study the behavior and reduction mechanism of Mn ions on working electrodes surfaces（Pt,W,Mo）.The results show that Mn（IV）is reduced to Mn（III）by spontaneous process,the Mn（III）reduced to Mn by electrochemical reduction process.In electrochemical reduction process,an electron transfered in the first step is an irreversible process and two electrons transfered in the second step are a quasi-reversible process.The electron transfer process,Mn（IV）→Mn（III）→Mn（II）→Mn,of LiMn₂O₄ on the electrode surface was revealed.The results of electro-deoxidation of LiMn₂O₄ shows that manganese could be reduced at 750℃、2.6V for 12h.Increasing the voltage can accelerate the deoxygenation kinetics.At 750℃,12h,3V,the metal Mn are produced and the content about 98%.Figure 61;Table 15;Reference 62...