掺Cr对LiMnO2的影响

Abstract

采用固相反应合成了LiMnO2和LiMn0.9Cr0.1O2,Cr的加入改变了LiMnO2的结构,与LiMnO2 正交结构(空间群 Pmnm)相比,LiMn0.9Cr0.1O2具有单斜结构(空间群 C2/m).充放电过程中,LiMnO2和LiMn0.9Cr0.1O2结构产生向尖晶石结构的不可逆转变.在首次放电过程中,LiMnO2只存在2.9 V的电压平台,随着循环次数的增加,在2.9 V和4 V电压平台容量都有所增加.与LiMnO2不同,LiMn0.9Cr0.1O2在首次放电过程中存在有2.9 V和4 V电压平台,随着循环次数的增加,4 V电压平台容量逐渐减小,在一定循环次数下,只有2.9 V的电压平台存在.因此,Cr的掺杂不仅改变了LiMnO2的结构,而且改变其电化学行为.

LiMnO2 and LiMn0.9Cr0.1O2 were prepared by a high temperature solid-state route. In comparison with orthorhombic LiMnO2, monoclinic LiMnO2 was formed with Cr substitution. The research shows that the irreversible transformation to spinel-like structure during LiMnO2 cycling is a gradual phase transformation process. In comparison with the 2.9 V and 4 V plateaus of LiMnO2, LiMn0.9Cr0.1O2 shows only 2.9 V plateau for further cycling. So it is clear that the electrochemistry behavior change from LiMnO2 to LiMn0.9Cr0.1O2 phase is due to doping of Cr.