异质双碳源对LiMn0.8Fe0.2PO4复合材料电化学性能的影响

采用水基流变相辅助的固相法，以异质碳蔗糖和石墨为碳源，合成了LiMn_0.8Fe_0.2PO₄/C复合材料，研究了不同石墨加入方式对所制复合材料电化学性能的影响，并对所制备的LiMn_0.8Fe_0.2PO₄/C复合材料进行了X射线衍射(XRD)、N₂吸附-脱附测试、扫描电子显微镜(SEM)、透射电子显微镜(TEM)等表征。结果表明，不同石墨包覆工艺对材料结构和电化学性能具有显著影响。前驱体煅烧后再加入石墨获得的样品纯度高，形貌呈均一的椭圆形，在0.1C下的放电比容量为149 mAh·g^-1，达到其理论比容量的87%；在5C下最大的放电比容量为133 mAh·g^-1；在2C倍率下经过300次循环后比容量维持在127 mAh·g^-1，衰减率仅为1.9%，表现出了优良的循环稳定性。

Effect of heterogeneous dual carbon sources on electrochemical properties of LiMn0.8Fe0.2PO4/C composites

LiMn_0.8Fe_0.2PO₄/C composite was synthesized using sucrose and graphite as heterogeneous carbon sources through a solid - state method assisted by aqueous rheological phase. The effect of different addition methods of graphite on electrochemical performances was studied. The LiMn_0.8Fe_0.2PO₄/C composite was characterized by the X-ray diffraction (XRD), N₂ adsorption-desorption, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results showed that different graphite coating processes had obvious effects on the structure and electrochemical properties of the materials. The sample, which the graphite was added after the precursor was calcined, showed a high purity and uniform elliptic morphology. And its specific discharge capacity was 149 mAh·g^-1 (87% of the theoretical specific capacity) at 0.1C. The specific discharge capacity was 133 mAh·g^-1 at 5C. After 300 cycles at 2C, its capacity was maintained at 127 mAh·g^-1, whose decay rate was 1.9%, showing excellent electrochemical performances.