掺杂尖晶石型锂锰氧化物的合成与电化学性能研究

Preparation and Electrochemical Properties of Doped Spinel Lithium Manganese Oxides

用液相法合成出掺锂、镍、钛的尖晶石锂锰氧化物.用FT-IR、XRD、XPS对合成的材料进行了表征,并研究了电化学性能.研究结果表明:掺锂、镍、钛样品在进行充放电时,在4V区域,其初始放电容量高达140.9mAh/g,循环性能明显好于纯尖晶石样品,主要原因可以归结于掺入的镍、钛离子替换了部分处于16d位置的锰离子,导致尖晶石晶胞出现收缩和锰的价态提高,从而抑制Jahn-Teller效应,提高了尖晶石结构的稳定性.

Spinel lithium manganese oxides doped with lithium, nickel and titanium were prepared by a liquid method. FT-IR, XRD and XPS were used to analyse the appearance of samples. Meantime, electrochemical properties of the materials in the organic electrolyte were researched. The results show that the materials doped with nickel and titanium have a platform in 4V region and have high first discharge capacity (140.9mAh/g), better cyclic stability than pure spinel lithium manganese oxides. The reason is that nickel and titanium ions displace part manganese ions in 16d positions and lead to the shrinkage of spinel cells and the increase of valence state of manganese, thus the structure of spinel becomes more steady and Joan-Teller effect is restrained.