纳米LiMnPO_4/C复合材料的制备及其电化学性能研究

Preparation and electrochemical performance of nano-LiMnPO_4/C composite materials

以LiOH·H2O、MnSO4?H2O和(NH4)3PO4为反应物,PVP为表面活性剂,采用水热法制备了LiMnPO4正极材料。通过化学气相沉积法,以甲苯为碳源,对材料进行表面碳包覆。利用X射线衍射(XRD)、扫描电镜(SEM)和透射电镜(TEM)对材料晶体结构和微观形貌进行表征。结果表明,合成的LiMnPO4粒径小(约100nm)且分布均匀,颗粒表面包覆了一层厚度约10nm的均匀、完整的导电碳层。在50℃0.1C倍率下LiMnPO4/C的放电容量达到124mAh/g,循环100次容量保持率达到96%,2C倍率下的放电容量保持了0.1C时的75%,表现出优异的循环稳定性和倍率性能。

LiMnPO4 anode material was synthesized via a hydrothermal method using LiOH H20,MnSO H20 and （NH4）3 PO4 as reactants and PVP as a surfactant. The material was covered with a carbon layer by chemical vapor dep osition from methylbenzene. Crystalline structure and morphology of the composite were characterized by X-ray diffraction （XRD）, scanning electron microscope （SEM） and transmission electron microscopy （TEM）. The results indicated that the particle size of LiMn_PO4 was ca. 100nm and a carbon layer of ca. 10nm thick was coated on the LiMnPO~ surfaces. The LiM- nPO4/C anode delivered a discharge capacity of 124mAh/g at 0. 1C rate under 50~C, along with the capacity retention of 96 % after 100 cycles. Furthermore, the capacity retention of LiMnPO4/C at 2 C was 75 % compared with the capacity at 0. 1C, presenting good high rate capability and cyclic stability.