Hydrothermal Synthesis and Electrochemical Properties of Li2CoSiO4/C Nanospheres
Hydrothermal Synthesis and Electrochemical Properties of Li2CoSiO4/C Nanospheres
复制标题
DOI：
10.1021/cm302823f
复制
发表时间：
2013-04-09
影响因子：
8.6
通讯作者：
Nazar, Linda F.
中科院分区：
文献类型：
--
作者：
He, Guang;Popov, Guerman;Nazar, Linda F.
以高度有序的介孔碳/二氧化硅（MCS）骨架为硅酸盐前驱体和碳源，采用水热法制备了Li 2CoSiO 4/碳纳米复合材料。TEM-EDX和TGA测量表明，类似于2wt%的碳被纳入纳米级的Li 2CoSiO 4晶体聚集体。我们发现Li 2CoSiO 4/C复合材料的形貌和颗粒尺寸都受到前驱体中LiOH浓度的显著影响。通过控制LiOH：Si：Co = 8：1：1的摩尔比，得到了非常均匀的Li 2CoSiO 4/C球，平均直径为300-400 nm。许多具有中空或核壳结构。提出了一种机制来解释不寻常的形态和碳掺入。尽管在高电位下电解质会发生氧化，但Li 2CoSiO 4/C复合材料的电化学性能表明，与在类似条件下使用气相二氧化硅作为硅酸盐源制备的Li 2CoSiO 4相比，纳米碳在提高电化学性能方面发挥了重要作用。
A highly ordered mesoporous carbon/silica (MCS) framework was used as both a silicate precursor and carbon source to prepare Li2CoSiO4/carbon nanocomposites via hydrothermal synthesis. TEM-EDX and TGA measurements showed that similar to 2 wt % carbon was incorporated within Li2CoSiO4 crystal aggregates on the nanoscale. We find that both the morphology and particle size of the Li2CoSiO4/C composites are significantly influenced by the LiOH concentration in the precursors. By controlling the molar ratio of LiOH:Si:Co = 8:1:1, very uniform Li2CoSiO4/C spheres were obtained with an average diameter of 300-400 nm. Many exhibit hollow or core-shell structures. A mechanism is proposed to account for both the unusual morphology and carbon incorporation. Despite some electrolyte oxidation at high potential, the electrochemical properties of the Li2CoSiO4/C composites showed that the nanocarbon played an important role in enhancing the electrochemical performance, when compared with Li2CoSiO4 prepared using fumed silica as the silicate source under similar conditions.