尖晶石型Li-Mn-O多元素掺杂的高温电化学特性

采用高温固相浸渍法合成了多元复合掺杂尖晶石型锰酸锂Li 1.02MxMn 2-xQyO 4-y正极材料.XRD表征合成的产物均为良好的尖晶石型结构材料;SEM表明所合成的产物颗粒均匀且有良好的粒径分布.以该物质作为锂离子电池的正极材料组装成扣式电池,经充放电循环测试可知:多元素掺杂的尖晶石型锰酸锂正极材料Li 1.02CoaCrbLacMn 2-a-b-cFyO 4-y较富锂尖晶石和单元素Co、Cr掺杂的正极材料能够更好地抑制电池的可逆容量在充放电过程中的衰减,循环性能有了很大改善,表现出很好的电化学可逆特性,80次循环后放电容量仍能保持94.5%以上;特别是高温(55 ℃)性能更加突出,40次循环后放电容量仍能保持102.1mA.h/g(91.5%)以上.作为锂离子电池的正极材料,该复合掺杂材料是众多取代钴酸锂材料中最具竞争力的材料之一,也有望成为锂离子动力电池的正极材料.

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

The effect of doping on the electrochemical performance of modified spinel Li-Mn-O, which is used as cathode material in Lithium-ion battery, was studied. The spinel materials Li 1.02MxMn 2-xQyO 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 1.02MxMn 2-xFyO 4-y and Li 1.02 MxMn 2-x ClyO 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 ℃) . As cathode material of lithium-ion battery, this multiple doping spinel is one of the most competitive substitutes for LiCoO2.