摘要
采用共沉淀法合成了无定形磷酸亚铁与磷酸锂的混合前驱体，这种前驱体在700℃下于还原性气氛中保温5．5h制得橄榄石型磷酸铁锂。采用XRD、FTIR、SEM和TG／DSC等手段对前驱体和焙烧产物的成分、结构、形貌及其热分解过程进行了研究。由不同热处理温度及反应时间下的LiFePO4转化率算得磷酸锂与磷酸亚铁在400～700℃下生成磷酸铁锂的反应速率常数和表观反应活化能（26．9kJ／mol）。结果表明，Fe3（PO4）2与Li3PO4反应生成LiFePO4的过程主要由Li^＋、Fe^2＋在固相介质中的扩散速率所控制。因此，Fe3（PO4）2和Li3PO4的均匀混合有利于降低LiFePO4的焙烧温度和缩短反应时间。
The olivine-type LiFePO4 was synthesized by a wet eopreeipitation of Fe3 （PO4）2 and Li3 PO4 to form an amorphous precursor and subsequent calcination of this precursor at 700℃ for 5.5h. The precursors and produets derived from calcination of these precursors at different temperatures and time were characterized by XRD, FTIR, SEM and TG/DSC. The apparent activation energy calculated based on LiFePO4 reaction rates at the temperature range of 400-700℃ was 26.9kJ/mol, and the reaction rate for LiFePO4 formation was reasoned to be likely controlled by the diffusion rate of Li^＋ and Fe^2＋ ions in solid phases of Fe3 （PO4）2 and Li3PO4. An enhancement of mixing Fe3 （PO4）2 and Li3PO4 is therefore necessary to produce olivine-type LiFePO4 materials with high electrochemical activities at lower temperature.
出处
《功能材料》
EI
CAS
CSCD
北大核心
2006年第8期1198-1200,1203,共4页
Journal of Functional Materials
基金
国家自然科学基金资助项目(50134020)
