Abstract LiMnxFe1-xPO4 with high electronic conductivity is synthesized by a combination of wet ball milling, spray drying, carbon thermal reduction technology and using graphene oxide (denoted as GO) as the carbon additive. The effect of graphene content on morphology and structure of LiMn0.7Fe0.3PO4/C cathode material is systematically investigated. The graphene-LiMn0.7Fe0.3PO4 composite has ordered olivine structure and micro-spherical morphology assembles with nanosized primary particles. SEM and TEM images indicate that the particle size of LiMn0.7Fe0.3PO4-G2 is about 800 nm in diameter. The initial discharge capacity of LiMn0.7Fe0.3PO4-G2 nanoparticles is 153 mAh·g−1. It shows that graphene oxide can restrict the growth of LiMn0.7Fe0.3PO4 and improve the electrical conductivity. Through adding different amount of graphene, we get the best addition of graphene. The LiMn0.7Fe0.3PO4-G2 sample has a core-shell structure, not only does the surface of nanoparticles have a homogeneous and complete carbon coating but also exhibits a microspherical morphology. What ’s more the surface of microspheres is fully covered with GO sheets, which enhances electronic conductivity. All above mention factors lead to its excellent electrochemical performance at room temperature and low temperature.

中文翻译：

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湿球磨结合喷雾干燥法合成的LiMn 0.7 Fe 0.3 PO 4 /C正极材料中石墨烯的最佳添加量

摘要 采用湿式球磨、喷雾干燥、碳热还原技术，以氧化石墨烯（GO）为碳添加剂，合成了具有高电子电导率的LiMnxFe1-xPO4。系统研究了石墨烯含量对LiMn0.7Fe0.3PO4/C正极材料形貌和结构的影响。石墨烯-LiMn0.7Fe0.3PO4 复合材料具有有序的橄榄石结构和微球形形态，由纳米级初级粒子组装而成。SEM 和 TEM 图像表明 LiMn0.7Fe0.3PO4-G2 的粒径约为 800 nm。LiMn0.7Fe0.3PO4-G2纳米颗粒的初始放电容量为153 mAh·g-1。这表明氧化石墨烯可以限制 LiMn0.7Fe0.3PO4 的生长并提高电导率。通过添加不同量的石墨烯，我们得到了最好的石墨烯。LiMn0.7Fe0.3PO4-G2样品具有核壳结构，纳米颗粒表面不仅具有均匀完整的碳涂层，而且呈现出微球状形态。更重要的是，微球表面完全覆盖着 GO 片，这增强了电子导电性。所有上述因素导致其在室温和低温下具有优异的电化学性能。