锂离子电池橄榄石结构正极材料LiMnPO_4的合成与性能

Synthesis and characterization of olivine type positive material LiMnPO_4 for lithium ion batteries

采用固相反应法合成掺碳锂离子电池正极材料LiMnPO4。利用XRD、SEM和充放电测试表征LiMnPO4的结构、形貌与充放电性能，并研究LiMnPO4电极的交流阻抗和锂离子的扩散行为。研究表明：适当提高合成温度与延长反应时间有利于促进晶体结构的完整，提高材料的放电平台和放电容量，改善电极反应表面电荷传递和材料中的锂离子扩散特性。在600℃烧结时间为24h的条件下可合成出一次颗粒大小为0．1-0．3μm的纯相LiMnPO4，样品容量达到95mA·h／g，充电态下锂离子的扩散速度为5．65x10^13cm^2／s。

Carbon-containing LiMnPO4 was synthesized by solid-state reaction. The structure, surface morphology and charge-discharge performance of LiMnPO4 were characterized by X-ray diffractometry, scanning electron microscopy and electrochemical measurement respectively. The AC impedance and diffusion coefficient of lithium ion for LiMnPO4 were also studied, The results show that proper increase of temperature and sintering time improve the crystal structure, increase the discharge voltage plateau and capacity, and enhance the transfer of surface electrons and lithium ion diffusion, Good samples with pure phase and primary particle size of 0.1-0.3 μm can be prepared at 600 ℃ for 24 h. These samples possess capacity of 95 mA.h/g and lithium ion diffusion coefficient of 5.65 × 10^-13 cm^2/s,