低温固相反应/水热法合成LiMn_(0.4)Fe_(0.6)PO_4/C材料的微观结构及其电化学性能  

Microstructure and electrochemical characteristics of LiMn_(0.4)Fe_(0.6)PO_4/C composites by low temperature solid-state reaction/hydrothermal synthesis

作　　者：李荐[1,2] 杨俊[1] 李良东 周宏明[1,2] 姚书恒 杨亮 方珍奇[1] 

机构地区：[1]中南大学材料科学与工程学院,湖南长沙410083 [2]湖南省正源储能材料与器件研究所,湖南长沙410083 [3]中冶葫芦岛有色金属集团有限公司,辽宁葫芦岛125003

出　　处：《中南大学学报（自然科学版）》2013年第9期3612-3618,共7页Journal of Central South University:Science and Technology

基　　金：国家科技支撑计划项目(2009BAE71B04);湖南省科技计划项目(2010FJ4061);长沙市科技计划项目(K1201039-11)

摘　　要：以Li2CO3,MnCO3,FeC2O4·2H2O和NH4H2PO4为原料,采用低温固相反应/水热法制备LiMn0.4Fe0.6PO4/C材料。采用XRD,SEM和TEM对LiMn0.4Fe0.6PO4/C的晶体结构、形貌以及颗粒表面形貌进行表征,并采用恒流充放电实验对其电化学性能进行评价。研究结果表明:于400℃处理4 h后可获得晶体结构的LiMPO4(M为Fe,Mn);传统固相法和低温固相反应/水热法合成的LiMn0.4Fe0.6PO4材料均为单一的橄榄石结构,表面包覆无定形的碳。由低温固相反应/水热法合成的材料颗粒粒径为100 nm左右,电化学性能优良,在0.1C(C为充放电电流倍率)下的首次放电容量为157 mA·h/g,是传统固相法合成产品的1.07倍,0.5C下循环50次容量保持在133 mA·h/g左右,是传统固相法合成产品的1.21倍。The olivine type LiMn0.4 Fe0.6 PO4 was synthesized via the low temperature solid-state reaction combined with hydrothermal synthesis from Li2 CO3,FeC2 O4 ·2H2 O,MnCO3 and NH4 H2 PO4.The product from the low temperature solid-state reaction was studied.The structure,particle size and surface morphology of these cathode active materials were investigated by XRD,SEM and TEM.Electrochemical characteristics of the composites were evaluated using galvanostatic charge/discharge tests.The results show that olivine LiMPO4(M=Fe,Mn) is obtained after the raw materials are fired at 400 ℃for 4 h.All Li(Mn0.4 Fe0.6)PO4 samples are simple pure olive-type phase with a conductive,thin web of carbon surrounding them.The composite synthesized via the low temperature solid-state reaction/hydrothermal synthesis has homogeneous particles of size 100 nm,an initial discharge capacity of 157 mA·h/g at 0.1C and a specific capacity of about 133 mA·h/g after 50 times cycling at 0.5 C rate.They are 1.07 times and 1.21 times of the products from the traditional solid-state,respectively.

关 键 词：LiMn0.4Fe0.6PO4 固相反应 水热合成 电化学性能 

分 类 号：TM912[电气工程—电力电子与电力传动]