LiNi_(0.8)Co_(0.2)O_2的表面修饰及性能

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

锂离子电池正极材料和电解液之间的恶性相互作用引起正极材料和电池性能的劣化。将 L i Ni0 .8Co0 .2 O2 ,L i OH.H2 O和 H3BO3以摩尔比 10 0 :1:2均匀混合 ,5 0 0℃热处理 10 h,在 L i Ni0 .8Co0 .2 O2 表面包覆上一层 L i2 O- 2 B2 O3玻璃层。用 X光电子能谱、扫描电镜和 X光衍射分析对包覆前后 L i Ni0 .8Co0 .2 O2 的结构进行了表征。结果表明 ,表面修饰有效地抑制了 L i Ni0 .8Co0 .2 O2 和电解液之间的恶性相互作用 ,材料的实际比容量提高 ,充放电循环稳定性改善 ,自放电速率减小。

The harmful interactions between the positive active materials and the electrolyte in lithium secondary batteries hurt the performance of the cathode materials and the batteries. A Li 2O 2B 2O 3 glass film was coated on the LiNi 0.8 Co 0.2 O 2 cathode material's surface by mixing LiNi 0.8 Co 0.2 O 2, LiOH·H 2O and H 3BO 3 with a molar ratio of 100∶1∶2 and heating the mixture at 500℃ for 10h. The structures of the coated and uncoated LiNi 0.8 Co 0.2 O 2 were characterized by X ray photoelectron spectrometry (XPS), scanning electron microscope (SEM), and X ray diffractometer (XRD). It was shown that the surface modification effectively reduced the harmful interactions between the LiNi 0.8 Co 0.2 O 2 and the electrolyte. The surface modified LiNi 0.8 Co 0.2 O 2 cathode material had increased actual specific capacity, stabilized cycling performance and reduced self discharge. Surface modification is an effective way to improve the properties of the positive active materials for lithium secondary batteries.