Abstract:

In order to solve the inherent problems of poor cycling stability and serious cycling voltage attenuation of cobalt-free Mn-based lithium-rich materials of Li_1.2Ni_0.2Mn_0.6O₂,the effect of aluminum doping combined with solid phase calcination method on the micromorphology,structure and electrochemical properties of the material were studied in this paper.The resu-lts showed that the aluminum doping not only made the surface morphology of the material denser,but also brought a more stable crystal structure to the material,which was conducive to the resistance of the material to a series of adverse factors caused by the structural reversion in the long charge-discharge cycle,and finally led to its more excellent electrochemical per-formance.In addition,when the doping amount of aluminum was 1%,the discharge specific capacity,cycle stability and volt-age retention of the material at high rate all achieved the best optimization performance.The discharge specific capacity of the first cycle at 0.1C ratio was as high as 248.8 mA·h/g in the voltage range of 2.0~4.8 V.After 200 cycles of charging and dis-charging,the discharge specific capacity retention rate increased from 57.9% to 77.6%,and the cycle voltage retention rate also increased from 84.2% to 85.6%.The above results fully showed that 1% aluminum doping had excellent improvement effect on Mn-based lithium-rich materials of Li_1.2Ni_0.2Mn_0.6O₂.

Key words: lithium-ion battery, cathode materials, aluminum doping, Li_1.2Ni_0.2Mn_0.6O₂