锰掺杂钴酸锂LiMnxCo1-xO2的性能研究

采用XRD、循环伏安和恒电流充放电等方法研究了用Mn(NO3)2做锰源掺杂合成的锂离子电池正极材料LiMnxCo1-xO2的结构及其电化学行为.结果表明,以0.5 mA/cm2充放电,Li/LiMnxCo1-xO2电池充电容量有所下降;但放电工作电压平台均在3.6 V左右,放电容量随着x从0.05增至0.25,从98.88 mAh/g下降到55.70 mAh/g;与LiCoO2相比,放电容量分别减少了10.6%和49.6%.XRD结果显示,随着x的增加,充放电前后LiMnxCo1-xO2中均含有MnO2的特征峰,充电后相应的晶胞参数c和a分别略有增大和减小.然而,循环伏安结果显示与LiCoO2相比,LiMnxCo1-xO2并没有新的氧化还原峰产生,说明其中的MnO2并未参加充放电反应.

Studies on the performance of LiMnxCo1-xO2 synthesized by doping LiCoO2 with Mn for the Li-ion battery

In this paper,both the structures and electrochemical behaviors of the LiMnxCo1-xO2 obtained by doping LiCoO2 with Mn from Mn(NO3)2 have been stud ied by the XRD,cyclic voltammetry,and constant current charge and discharge. T he results show that discharge capacities of the Li/LiMnxCo1-xO2 batteries seem to decrease linear with the increase of x,along with a slight reduction of the corresponding charge capacities. For examples,at the current density 0.5 mA/cm 2,with the variations of x from 0.05 to 0.25,the discharge capacities of the b atteries Li/LiMnxCo1-xO2 are 98.88 mAh/g and 55.70 mAh/g respectively. Compared these with that of LiCoO2,the capacity losses are 10.6%and 49.6%separately. But the related working voltages of all those Li/LiMnxCo1-xO2 batteries are abo ut 3.6 V,almost the same as that of LiCoO2. Furthermore,with the increment of x,the XRD spectra indicate a little enlargement of the cell parameter c and a s mall reduction of the cell parameter a,and the presence of MnO2 even though cyc lic voltammetry studies reveal that MnO2 does not participate into both the char ge and discharge reactions.