Influence of Cr-Substitution on the Electrochemical Performance of LiNi0.5Mn0.5O2 Cathode Material for Lithium Ion Batteries

摘要:

采用低温燃烧法合成了锂离子电池正极材料LiNi0.5Mn0.5-xCrxO2 (x=0, 0.01, 0.02, 0.05, 0.1)，研究了Cr取代部分Mn对其结构和电化学性能的影响。充放电测试结果表明：Cr取代部分Mn对正极材料LiNi0.5Mn0.5-xCrxO2的电化学性能有重要的影响，用适量的Cr取代Mn（x=0.02）能够提高正极材料的放电比容量和循环稳定性。X射线衍射（XRD）分析和循环伏安（CV）测试显示，Cr对Mn的适量取代能抑制正极材料中的阳离子混排，降低电极材料的极化，改善其可逆性能。LiNi0.5Mn0.48Cr0.02O2在2.5~4.6 V之间以0.1 C速率充放电，首次放电容量为179.9 mAh/g，第50次循环放电容量仍保有171.0 mAh/g，容量保持率达到95.1%。

Abstract:

The cathode material LiNi0.5Mn0.5-xCrxO2 (x=0, 0.01, 0.02, 0.05, 0.1) was synthesized via a low temperature combustion process. The influence of the partial substitution of Cr for Mn on its electrochemical performance was investigated. Charge/discharge test results show that the partial substitution of Cr for Mn has a significant influence on the electrochemical performance of LiNi0.5Mn0.5-xCrxO2, and the proper amount substitution of Cr for Mn (x=0.02) can increase its discharge capacity and improve its cyclic stability. The X-ray diffraction (XRD) and Cycle Voltammetry (CV) analyses indicate that the proper amount substitution of Cr for Mn can suppress the cation mixing in the cathode material, reduce the electrochemical polarization of the electrode material and improve its reversibility. The discharge capacity of LiNi0.5Mn0.48Cr0.02O2 at 0.1 C between 2.5 and 4.6 V is 179.9 and 171.0 mAh/g in the 1st and the 50th cycle, respectively, with a capacity retention of 95.1%.