掺铬锂锰氧化物的湿化学法合成与性能  

Synthesis and performance of chromium-doped spinel lithium manganese oxide prepared by wet chemical method

作　　者：常建卫[1] 李运姣[1] 孙召明[1] 洪良仕[1] 

机构地区：[1]中南大学冶金科学与工程学院,湖南长沙410083

出　　处：《电池》2004年第4期263-265,共3页Battery Bimonthly

基　　金：国家自然科学基金资助(50174058)

摘　　要：为了寻求新的合成方法,改善锂锰氧化物的电化学性能,采用湿化学法合成了掺铬尖晶石锂锰氧化物LiMn2-xCrxO4(x=0 00,0 04,0 08,0 12),并通过热重-差热(TG DTA)、X射线衍射(XRD)、扫描电镜(SEM)与恒电流充放电等测试方法考查了材料的结构、形貌与电化学性能。TG DTA测试证明:湿化学法所制得的LiMn2-xCrxO4(x=0 04)前驱体在100～900℃之间有一个较大的放热峰,在此温度范围内,前驱体由非晶态向晶态转变。XRD结果表明:合成产物具有尖晶石结构,随掺铬量的增加,样品的晶格常数变小,晶胞体积收缩。SEM观测结果表明:合成材料的颗粒粒度较小,分布均匀,结晶性能良好,掺铬后样品(x=0 04)的粒径为0 4μm,大于未掺铬时的0 2μm。恒电流充放电实验结果表明:随掺铬量的增加,样品的首次放电比容量降低,当掺铬量由x=0 00增至x=0 12时,初始放电比容量由123 3mAh/g降至113 6mAh/g。兼顾比容量与循环性能,以LiMn1 92Cr0 08O4性能最佳。In order to seek a new synthetic method and improve the electrochemical property of lithium manganese oxide, chromium-doped spinel lithium manganese oxides LiMn_(2- x )Cr_ x O_4( x =0.00,0.04,0.08,0.12)were synthesized by wet chemical method.The structures, morphologies and electrochemical performance of the products were studied by means of modern method, such as thermal gravimetric and differential thermal analysis (TG-DTA), X-ray diffraction(XRD), scanning electron microscope (SEM) and constant current cyclic test. There was a large exothermic peak corresponding to the transition from an amorphous structure to a crystal one within the temperature rang of 100～900?℃ on the DTA curves of the precursor of LiMn_(2- x )Cr_ x O_4( x =0.04). The XRD results showed that all the samples had a spinel structure and the lattice parameters decreased with the increasing amount of the chromium-doped. The SEM micrographs of the products revealed that the particle size distribution was narrow and the average grain sizes of LiMn_2O_4 and LiMn_(2- x )Cr_ x O_4( x =0.04) were 0.2 μm and 0.4 μm, respectively.The results of constant current cyclic tests showed that the cyclic performance of the products increased with the amount of chromium-doped, while their initial capacities decreased from 123.3?mAh/g of LiMn_2O_4 to 113.6?mAh/g of LiMn_(2- x )Cr_ x O_4( x =0.12). According to both the special capacity and the cyclic performance, the product with chromium-doped of x =0.08 had the optimized performance.

关 键 词：掺铬 尖晶石锂锰氧化物 湿化学法 电化学性能 

分 类 号：TM912.9[电气工程—电力电子与电力传动]