阳离子掺杂对LiMn_2O_4结构和电性能的影响

Effect of cation ion doping on structure and electrochemical performance of LiMn_2O_4

采用固相法合成了尖晶石LiMn_(2-x)M_xO_4(M=Co、Cr、Al、Ti,x=0、0.05、0.1、0.15)正极材料,研究了不同金属阳离子掺杂和掺杂量对LiMn_(2-x)M_xO_4结构及电性能的影响。通过X射线衍射图谱分析,离子半径较小的Co、Cr、Al掺杂使材料晶胞收缩,尖晶石结构更加稳定。材料初始容量随着掺杂量提高而降低,但循环性能显著提高。其中Co掺杂在x=0.1时,LiMn_(2-x)M_xO_4样品1 C首次放电比容量为117.6 mAh/g,前20次容量保持率达92.9%,综合性能最优。

The spinel LiMn2-M O4(M=Co,Cr,Al,Ti,=0,0.05,0.1,0.15)was synthesized by solid-state reaction method as cathode materials.In this work,the effects of different metal cation ions doping and the amount into LiMn2-M O4on the crystal structure and electrochemical properties were studied.The results confirmed by X-ray diffraction(XRD)show that the samples doped with the samller ionic radius(such as Co,Cr and Al)make the volume of unit cell decrease and the spinel structure more stable.The initial capacity of the material is decreased with the increase of the doping amount,but the cycling performance is significantly improved.When=0.1,the Co-doping samples can deliver the first discharge specific capacity of117.6mAh/g at1rate,and the rate of capacity retention reaches92.9%after20cycles,which exhibit the optimal comprehensive performance.