LiNi0.8 Co0.15 A10.05 O2正极材料的表面包覆改性研究

LiNi_0.8 Co_0.15 A1_0.05 O₂正极材料具有容量高、价格低等优点,被认为是最具发展前景的锂离子电池正极材料之一.但LiNi 0.8Co 0.15A1 0.05O₂材料本身存在充放电过程中容量衰减较快、倍率性能差和储存性能差等缺陷,影响了其进一步发展.本文以 LiNi 0.8Co 0.15A1 0.05O₂为研究对象,采用共沉淀法制备氢氧化物前驱体,在前驱体的表面包覆一层Ni 1/3Co 1/3 Mn 1/3(OH)₂,制备成具有核壳结构的正极材料.通过XRD、SEM、EDX、电化学测试等分析手段,系统地研究了其结构、形貌以及电化学性能.分析表明:包覆改性后,LiNi 0.8Co 0.15Al 0.05O₂正极材料在0.1、0.2、0.5、1 C倍率下,材料的首次充放电比容量分别为167.6,160.1,0.4,8.5 mAhg -1.由0.1到1 C,包覆改性前后的正极材料的放电比容量衰减量由34.7 mAhg -1降为29.1 mAhg -1,容量衰减百分比由22.1%降低到17.4%.综合性能分析认为,包覆改性后电化学性能有一定的改善.

Surface coating modification of LiNi0.8 Co0.15 A10.05 O2 cathode materials

The LiNi_0.8 Co_0.15 A1_0.05 O₂ cathode material, which is considered to be one of the most promising lithium-ion battery cathode materials, has several advantages, such as high capacity, low cost and low toxicity. However, there are also some disadvantages of this material, such as the loss of capacity in charging and discharging process, poor rate performance and storage performance, which have seriously effect on the application. In this paper, the LiNi 0.8Co 0.15A1 0.05O₂ was taken as the research object. The precursor was prepared through the co-precipitation method, which was coated with Ni 1/3Co 1/3Mn 1/3(OH)₂ and in the form of core-shell structure. The structure, morphology and electrochemical performance of LiNi 0.8Co 0.15A1 0.05O₂ were studied systematically by the XRD, SEM, EDX and electrochemical testing. The results showed that the initial discharge capacities of 167.6,0.1,0.4,8.5 mAhg -1 at 0.1,0.2,0.5,1 C for coated LiNi 0.8Co 0.15Al 0.05O₂, respectively. This leads to an irreversible capacity loss of 22.1% and 17.4% at 0.1 C to 1 C before and after coated. The electrochemical performance can be improved through the modification.