固相反应合成LiCoPO_4中间体的反应动力学  

Reaction Kinetics of the Intermediate in Synthesis of LiCoPO_4 by Solid-State Reaction

作　　者：黄映恒[1,2] 童张法[1] 韦藤幼[1] 李斌[1] 

机构地区：[1]广西大学化学化工学院,南宁530004 [2]桂林理工大学南宁分校冶金工程系,南宁530001

出　　处：《物理化学学报》2011年第6期1325-1334,共10页Acta Physico-Chimica Sinica

基　　金：国家自然科学基金(20766001);广西青年科学基金(0728101);广西教育厅科研项目(200505083)资助~~

摘　　要：以磷酸二氢铵、醋酸钴和氢氧化锂为原料,用低温固相反应合成含Li+的NH4CoPO4前驱体,再经过高温焙烧合成LiCoPO4粉体.应用傅里叶变换红外光谱(FTIR)、X射线衍射(XRD)和热重-差热分析(TG-DTA)等技术对合成产物进行表征.结果表明:焙烧气氛影响中间体的生成,含Li+的前驱体NH4CoPO4在210-500°C的空气水中生的发成反影生反应响脱应,生高水遵成温脱循L对iC氨界中o反面P间O应反4体,,应平制的幂均备分律表过解机观程产理活存物,化在表L"i能观C酸o约活P碱为O化共4能5和同4约.L体2iC5k"o0J的?P.0中Omk4J间的o?l?体晶1m.(物体oClo?系生1H,非过长PO晶程有4·化机利Li和理,C在o晶函P5化O数54·0过为C°程Cgo(2以对x(O)=上中H(1)温间P-O度α体)4·?中的1L.间i存中3P体在间O4可没体).分有继中解直续间脱接体得到完整的LiCoPO4晶体.A precursor NH4CoPO4 containing Li＋ was synthesized using a low temperature solid-state reaction with ammonium dihydrogen phosphate, cobalt acetate, and lithium hydroxide. LiCoPO4 powder was manufactured by high temperature baking. The products were characterized by Fourier transform infrared （FTIR） spectroscopy, X-ray diffraction （XRD） and thermogravimetry-differential thermal analysis （TG-DTA）. The results showed that the formation of the intermediates was effected by the baking atmosphere. NH4CoPO4 containing Li＋ was dehydrated and deaminated in air at 210-500 °C and then the （CoHPO4·LiCoPO4·Co2（OH）PO4·Li3PO4） intermediate （acid-base community） was emerged during the reaction process. The intermediate formation reaction mechanism followed the interfacial reaction power-law with an apparent activation energy of 50.0 kJ·mol-1. The kinetic function was found to be g（x）=（1-α）-1. The intermediate was dehydrated to form LiCoPO4 with an average apparent activation energy of 54.2 kJ·mol-1. The formation of the intermediate was not affected by the process of crystallization or non- crystallization of the materials. High temperatures accelerated the decomposition reaction of the intermediate and then the formation of LiCoPO4 crystals. A perfect crystal of LiCoPO4 was obtained by the decomposition of the intermediate at temperatures higher than 550 °C.

关 键 词：LiCoPO4 含锂磷酸盐 中间体 固相反应 反应机理 反应动力学 

分 类 号：O614.111[理学—无机化学]