LiNi0.5Co0.2Mn0.3O2三元正极材料表面残锂和pH值的后处理控制研究

摘要

LiNi0.5 Co0.2Mn0.3O2 was dried at 120 ℃ after washing,and then tempering treated at 400 ℃ for 4 h.In this paper,the effects of pre-washing and post-tempering of LiNi0.5Co0.2Mn0.3O2 material in water and mixture of water and ethanol on pH,dissolvable Li content,BET and phase structure were studied by chemical analy-sis,specific surface area and XRD analysis.Results show that by pre-washing and post-tempering treatment, pH value of LiNi0.5Co0.2Mn0.3O2 decreases from 11.5 to less than 11.Dissolvable Li is reduced from 4×10-4 to 2 ×10-4 with the control of specific surface area under 0.5 m2/g.Discharge capacity and performance of rate dis-charge are almost constant associated with common microstructure of LiNi0.5 Co0.2 Mn0.3 O2 .%利用溶液洗涤法,在水、水和乙醇溶液中对LiNi0.5Co0.2Mn0.3O2三元正极材料进行洗涤,120℃烘干后,400℃回火热处理4 h,得到处理后的LiNi0.5Co0.2Mn0.3O2三元正极材料.利用化学分析法、比表面分析仪、XRD分别对处理后的LiNi0.5Co0.2Mn0.3O2三元正极材料进行pH值、可溶Li含量、BET、物相结构进行测试.结果表明,采用水洗涤和回火热处理的后处理工艺,LiNi0.5Co0.2Mn0.3O2三元正极材料的pH值由11.5降至11以下,可溶Li含量由4×10-4左右降至2×10-4左右,比表面积控制在0.5 m2/g以下;材料的物相结构没有发生变化;材料的放电容量和倍率性能基本和原样相当.