Experimental Study On Preparation Of Anode Material Of Lithium Ion Battery With Spent Pickling Liquor

Pickling is a necessary process in stainless steel making.Plenty of spent pickling liquor generated as a waste,which has the features of toxicity and complex composition.Recovery and utilization of the valuable components is still a challenge in harmless treating of the spent pickling liquor.Earlier studies have reported that the spent pickling liquor and lithium-ion battery anode material have similar elemental composition.Inspired by this fact,a method of preparing lithium-ion battery anode materials with spent pickling liquor was proposed by the author.A simulated spent pickling liquor was prepared and employed as a raw material in this study.Some issues of preparation of precursor by co-precipitation method,the preparation of composite transition metal oxide powder by high temperature ball milling method,and the preparation and electrochemical performance evaluation of lithium-ion battery anode materials were investigated.The influence of key parameters on the preparation of intermediate products and the performance of anode materials were studied,and the feasibility of preparing anode materials for lithium-ion batteries with spent pickling liquor was evaluated.Under the experimental conditions employed in this work,the main conclusions are obtained as follows:(1)Precursor of composite transition metal oxide were prepared by co-precipitation method.The pH values of co-precipitation in Fe-Cr-O system and Fe-Cr-Ni-O system were 6.5 and 11,respectively.The co-precipitation products(precursors)were composite transition metal hydroxide or hydroxyl-bearing insoluble phases.After co-precipitation treatment,the recovery yields of all metals from spent pickling liquor were about 99%,and the pollutant concentration in the filtrate is far lower than the national standard of sewage discharge.The dual goals of harmless treatment and recovery of valuable components of spent pickling liquor are achieve.(2)The composite transition metal oxide powder was prepared by high temperature ball milling method.The Fe,Cr and Ni elements in the powder exist in the forms of Fe3+,Cr3+ and Ni2+,respectively,and no pollutants were generated in this treatment.The precursor cannot be completely transformed into oxide under the condition of low milling temperature or short milling duration.Increasing the milling temperature and prolonging the milling duration can help the precursor phase transformation.The results indicated that the full transformation of Fe-Cr-Ni-O precursor to composite transition metal oxide was realized when the samples were milled at 600℃ for 3h.Moreover,the appropriate mass ratio of ball-to-powder is helpful to refine the particles and alleviate the agglomeration of particles.High mass ratio of ball-to-powder may reduce the efficiency of milling.(3)Treated by carbon coating process,a uniform carbon film was formed on the surface of Fe-Cr-Ni-O composite oxide powder,and a carbon skeleton network was formed between the particles.Experimental results illustrated that milling temperature,duration and mass ratio of ball-to-powder significantly affected the electrochemical performance of Fe-Cr-Ni-O composite oxide anode materials.(4)The electrochemical performance of the composite transition metal oxide anode material prepared in this study reached the standard of lithium-ion battery anode material.Furthermore,the composite transition metal oxide anode material exhibited a better electrochemical performance than that of single-phase oxide anode material.Results obtained in the current work verified the feasibility of preparing anode material for lithium-ion battery with spent pickling liquor.