Mn掺杂LiFeP04的第一性原理研究
The first principles and experimental study on Mn-doped LiFeP04
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摘要: 采用基于密度泛函理论的第一性原理方法,计算了不同Mn掺杂浓度LiFel-xMn。P04(X=0,0.25,0.50,0.75)的电子结构.同时采用流变相辅助高温固相碳热还原法制备了LiFel-xMn。P04@=0,0.25,O.50,0.75)材料.理论计算表明:LiFeP04具有Eg=O.725eV的带隙宽度,为半导体材料.通过Fe位掺杂25%的Mn离子可最大程度地减小材料带隙宽度、降低Fe-0键及Li-O键键能,进而提高材料的电子电导率及锂离子扩散速率.实验结果亦表明,当Mn掺杂量0=0.25时,材料具有最优的电化学性能,其具有约为158mAh.g。的放电比容量以及551Wh.kg0的能量密度.理论计算与实验结果非常符合.Abstract: The electronic structures of pure and Mn-doped LiFePO4 are studied using density functional theory (DFT), The results demonstrate that the pure LiFePO4 has a band gap of 0.725 eV, while the 25% Mn doped LiFeo.75Mn0.25PO4 has the smallest band gap (0.469 eV), and the weakest Fe-O and Li-O bond, which indicates that the electronic conductivity and the ionic conductivity of the doped LiFePO4 are improved due to doping. On the other hand, the experimental results also show that the LiFeo.vsMno.25PO4 has the best electrochemical performance and it delivers a very high capacity of 158 mAh-g-1 and a high energy density of 551 Wh.kg-1.
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