掺铜锂锰氧化物的结构和循环稳定性

STRUCTURE AND CYCLE STABILITY OF COPPER-DOPED LITHIUM MANGANESE DIOXIDE

用熔盐法制备出掺铜的尖晶石锂锰氧化物LiCuxMn2 -xO4 (x =0 ,0 0 3,0 16 ) .研究合成掺杂样品的一些物理化学性质 .样品中锰的化合价分析结果表明 ,锰的平均化合价随样品中铜含量的增加而增加 .XRD结果表明 ,合成样品均属于立方晶系的尖晶石结构 .尖晶石型的锂锰氧化物掺入铜后晶胞常数 (a)减小 ,掺铜量x =0 ,0 0 3,0 16的锂锰氧化物尖晶石晶胞常数依次为 8 2 35× 10 - 10 m ,8 2 2 1× 10 - 10 m ,8 2 18× 10 - 10 m .恒电流充放电结果表明 ,随着掺铜量的增加 ,样品的初始容量降低 ,但循环稳定性增加 .掺铜量为x =0 ,0 0 3,0 16的锂锰氧化物初始容量分别为 97 9、 85 3、 71 1mA·h/g (0 5mA·cm- 2 ) ,但 5次循环后的容量损失依次为 34 5 %、13 1%、1 5 % .

Copper-doped lithium manganese oxides LiCu x Mn 2- x O 4( x =0,0. 03,0.16) were prepared by solid-state reaction method and some physical and che mical perfor mances of the products were studied. The average oxidation state of manganese in the product increased with increasing the dopant content . All the products had a spinel structure. The lattice parameter ( a ) of the products decreased wit h in creasing the dopant amount of copper, 8.235×10 -10 m, 8 221×10 -1 0 m, and 8 218×10 -10 m for x =0, 0.03 and 0 16 respectively. Th e cycling stability of the products increased with the dopant content. But the improvement in cycling stability was obtained at the expense of capacity. The discharge capacity fades of the products a fter 5 cycles for x =0, 0.03 and 0.16 were 34 5%,13 1% and 1 5 %, respectivel y However, the first discharge capacity were 97 9, 85 3 and 71 1 mA·h/g for x =0, 0 03, 0 16 respectively