摘要
采用液相共沉淀法合成了纯相橄榄石型LiFePO4和LiFePO4/C复合正极材料。利用原子吸收(AAS)、X射线衍射(XRD)、扫描电镜(SEM)、振实密度测定等方法对其进行表征,并组装成电池研究其电化学性能。结果表明:LiFePO4和LiFePO4/C都具有单一的橄榄石型晶体结构,且前者的振实密度可达1.67 g/cm2,掺碳后制成的LiFePO4/C振实密度有所降低,但充放电平台非常平稳。与纯相LiFePO4相比,LiFePO4/C具有更高的放电比容量和循环性能,室温下以0.2 mA/cm2和0.4 mA/cm2电流密度充放电,首次放电比容量分别达到158.1 mA.h/g、150.0 mA.h/g。充放电循环20次后放电比容量仍分别保持在154.2 mA.h/g,137.2 mA.h/g。
Pure phase olivine-type LiFePO4 and composite cathode material LiFePO4/C were synthesized by the liquid-state co-precipitation method. The properties of LiFePO4 and LiFePO4/C were systemically studied via the methods ofAAS, XRD, SEM, tapped density, etc. The electrochemical properties were tested by using analogous assembled cells. The results showed that LiFePO4 and LiFePO4/C were both simple pure phase olivine-type and the tapped density of the former could reach 1.67 g/cm^3. After carbon coating, the tapped density decreased a little but had a good charge-discharge voltage plateau. Compared with pure phase LiFePO4, LiFePO4/C had better discharge capacities and excellent cycle performance, and its first discharge capacity was 158.1 mA · h/g at 0.2 mA/cm^2 and even at 0.4 mA/cm^2at room temperature, LiFePO4/C also had high discharge capacity of 150.0 mA · h/g. After 20 times cycling, the specific capacities were 154.2 mA · h/g, 137.2 mA · h/g respectively.
出处
《化工进展》
EI
CAS
CSCD
北大核心
2007年第2期238-241,共4页
Chemical Industry and Engineering Progress
