Electrochemistry Performance for the Multiple Doping Spinel of Li-Mn-O at Elevated Temperature

摘要

The effect of doping on the electrochemical performance of modified spinel Li-Mn-0, which is used as cathode material in Lithium - ion battery, was studied. The spinel materials Li_(1.02)M_xMn_(2-x)Q_yO_(4-y) (M = Co, Cr, La; x = a + b + c; Q = Cl, F; ) doped with several ions was prepared by solid-state method after the pretreatment of conversion under low temperature, at elevated temperature. X-ray diffraction showed that all the samples have perfect spinel structure. The results of measurement by SEM indicated that the particles of the samples had uniform size and were distributed evenly. The results of the charge-discharge curves showed that Li_(1.02)M_xMn_(2-x)F_y O_(4-y) and Li_(1.02) M_xMn_(2-x) Cl_yO_(4-y) had better performance than those un-doped or single-element doped materials according to the inhibition of decline of reversible capacity of spinel Li-Mn-O material. Therefore, cycle performance had been improved so obviously that 94.5% of the initial capacity was preserved respectively after 80 cycles, and that 91.5% (102.1 (mA·h) /g) of the initial capacity was preserved respectively after 40 cycles at elevated temperature (at 55°C) .As cathode material of lithium-ion battery, this multiple doping spinel is one of the most competitive substitutes for LiCoO_2 .