LiNi_(0.8)Co_(0.2)O_2表面包覆MgO及其性能

Surface modification and characterization of LiNi_(0.8)Co_(0.2)O_2 coated with MgO

锂离子蓄电池正极材料和电解液之间的恶性相互作用是引起正极材料和电池性能劣化的重要原因。用沉淀法在Ni0,8Co0.2(OH)2前驱体表面包覆一层Mg(OH)2,再与LiOH共混热处理,制备出表面包覆MgO的LiNi0.8Co0.2O2。用X光电子能谱、扫描电镜和X射线衍射分析对包覆前后的Ni0.8Co0.2O2与LiNi0.8Co0.2O2的结构进行了表征。充放电测试结果表明,经表面修饰处理后,LiNi0.8Co0.2O2正极材料的初始放电比容量略有降低,但循环稳定性显著改善。研究结果表明,表面修饰处理可以有效地抑制正极材料与电解液之间的恶性相互作用,是改善锂离子蓄电池正极材料循环性能的有效途径。

The harmful interactions between cathode materials and electrolyte is an important reason to deteriorate the performance of cathode materials and lithium ion battery. The LiNi0.8Co0.2O2 precursor was coated with Mg(OH)2 on the surface by precipitation and then was heattreated by mixing with LiOH, so the LiNi0.8Co0.2O2 coated with MgO was prepared. The structures of the LiNi0.8Co0.2(OH)2 and LiNi0.8Co0.2O2 materials before and after coating were characterized by XPS, SEM and XRD. The results of charge/discharge test show that after surface modification, the initial specific discharge capacity of LiNi0.8Co0.2O2 cathode material is decreased slightly whereas its cyclic stability is improved greatly. The surface modification is concluded to inhibit the harmful interactions between cathode materials and electrolyte and to improve the cyclic performance of cathode material for lithium ion battery effectively.