High-throughput studies of Li1-xMgx/2FePO4 and LiFe1-yMgyPO4 and the effect of carbon coating
High-throughput studies of Li1-xMgx/2FePO4 and LiFe1-yMgyPO4 and the effect of carbon coating
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DOI：
10.1016/j.jpowsour.2008.01.034
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发表时间：
2008-05-01
影响因子：
9.2
通讯作者：
Owen, John R.
中科院分区：
文献类型：
--
作者：
Roberts, Matthew R.;Vitins, Girts;Owen, John R.
采用二维样品阵列法，从x、y和碳含量等方面对碳包覆Li 1-xMgx/2FePO 4和LiFe 1-yMgyPO 4粉末进行了筛选。合成路线，使用蔗糖作为碳源以及粘度增强添加剂，允许引入的Mg掺杂剂从溶液到溶胶-凝胶热解前体。高通量XRD和循环伏安法证实了在蔗糖与磷酸盐的比率在0.15和0.20之间时橄榄石相的形成和电子传导路径的渗滤。每次放电循环通过的电荷的测量表明，在Li 1-xMgx/2FePO 4中，随着镁的增加，容量劣化，但在LiFe 1-yMgyPO 4中，特别是在高扫描速率下，随着镁的增加，容量提高。通过固态路线制备的LiFe 1-yMgyPO 4样品的Rietveld精细XRD结果显示，根据晶胞体积随着y的增加而逐渐增加，直到y = 0.1时为单相。相同材料的无碳样品显示电导率从10（-10）增加到10（-8）S cm（-1），活化能从0.62降低到0.51 eV。恒电流循环显示接近理论容量y = 0.1相比，在相同条件下，未掺杂的材料只有80%的容量。(c)2008 Elsevier B. V.保留所有权利。
A two-dimensional sample array synthesis has been used to screen carbon-coated Li1-xMgx/2FePO4 and LiFe1-yMgyPO4 powders as potential positive electrode materials in lithium ion batteries with respect to x, y and carbon content. The synthesis route, using sucrose as a carbon source as well as a viscosity-enhancing additive, allowed introduction of the Mg dopant from solution into the sol-gel pyrolysis precursor. High-throughput XRD and cyclic voltammetry confirmed the formation of the olivine phase and percolation of the electronic conduction path at sucrose to phosphate ratios between 0.15 and 0.20. Measurements of the charge passed per discharge cycle showed that the capacity deteriorated on increasing magnesium in Li1-xMgx/2FePO4, but improved with increasing magnesium in LiFe1-yMgyPO4, especially at high scan rates. Rietveld-refined XRD results on samples of LiFe1-yMgyPO4 prepared by a solid-state route showed a single phase up to y = 0.1 according to progressive increases in unit cell volume with increases in y. Carbon-free samples of the same materials showed conductivity increases from 10(-10) to 10(-8) S cm(-1) and a decrease of activation energy from 0.62 to 0.51 eV. Galvanostatic cycling showed near theoretical capacity for y = 0.1 compared with only 80% capacity for undoped material under the same conditions. (c) 2008 Elsevier B.V. All rights reserved.