溶胶凝胶法合成LiMn_(2-x)Co_xO_4及其性能研究

Properties of LiMn_(2-x) Co_xO_4 obtained by sol-gel method

为了改善LiMn2 O4 作为锂离子蓄电池正极材料的循环可逆性能 ,我们采用溶胶 凝胶法掺杂合成了形如LiMn2 x CoxO4 的化合物 ,并用粉末X射线衍射技术 (XRD)研究了产物的晶体结构与电化学性能的关系。研究结果表明 ,在掺杂量 (即x值 )不是很大时 ,材料都能保持较好的尖晶石结构。在LiMn2 O4 中掺杂Co可明显地改善LiMn2 O4 的循环可逆性能。当x =0 .0 5时 ,5 0次循环后的容降由LiMn2 O4 的 10 %降低到 4%。同时 ,掺Co还可提高材料的大电流放电性能。当x =0 .1时 ,1C倍率放电容量与 0 .2C倍率放电容量的百分比值由LiMn2 O4 的 78%提高到 89%。

In order to improve the cycle properties of LiMn 2O 4 for lithium-ion batteries cathode material,LiMn 2-x Co xO 4 was synthesized by sol-gel method.Meanwhile,relationship between framework and electrochemical properties by X-ray diffractor were studied.The results show that when the doping content of Co is low,the material can keep the spinel structure,and improve the cycle properties and charge-discharge properties with high current.But its specific capacity is dropped.The capacity loss of LiMn 1.95 CO 0.05 O 4 was observed to be 4% comparing to 10% of the LiMn 2O 4 after 50 cycles. The specific capacity of LiMn 1.9 Co 0.1 O 4 at 1.0 C discharge current was 89% of at 0.2 C discharge current,and the specific capacity of LiMn 2O 4 at 1.0 C discharge current was 78% at 0.2 C discharge current,respectively.