Based on the method of in situ polymerization synthesis combined with two-step sinter- ing process, LiFel-xVx（PO4）（3-y）/3Fy/C was prepared. The effects of V and F co-doping on the structure, morphology, and electr...Based on the method of in situ polymerization synthesis combined with two-step sinter- ing process, LiFel-xVx（PO4）（3-y）/3Fy/C was prepared. The effects of V and F co-doping on the structure, morphology, and electrochemical performances of LiFePO4/C were in- vestigated by X-ray diffraction, Fourier transform infrared spectra, scanning electron mi- croscope, charge/discharge tests, and electrochemical impedance spectroscopy, respectively. The results indicated that the V and F co-doping did not destroy the olivine structure of LiFePO4/C, but it can stabilize the crystal structure, decrease charge transfer resistance, enhance Li ion diffusion velocity, further improve its cycling and high-rate capabilities of LiFePO4/C.展开更多
首先基于聚合反应合成FePO_4/PANI前驱体,再以为Li OH·H2O,FePO_4/PANI和PVA原料制备了Li FePO_4正极材料,此外再对其进行碳包覆以及Ti^(4+)掺杂,三种试样分别标记为Li FePO_4,Li FePO_4/C及LiFe_(0.96)Ti_(0.02)PO_4/C。通过XRD、...首先基于聚合反应合成FePO_4/PANI前驱体,再以为Li OH·H2O,FePO_4/PANI和PVA原料制备了Li FePO_4正极材料,此外再对其进行碳包覆以及Ti^(4+)掺杂,三种试样分别标记为Li FePO_4,Li FePO_4/C及LiFe_(0.96)Ti_(0.02)PO_4/C。通过XRD、EDS及充放电测试等手段表征了材料的微观结构与电化学性能。实验结果证明:试样的XRD图谱均与标准Li FePO_4图谱一致,不存在无定形碳衍射峰。与未掺杂试样Li FePO_4/C相比,LiFe_(0.96)Ti_(0.02)PO_4/C的电子电导率与其相近,但离子扩散系数有所改善,Ti^(4+)在晶格中均匀分布,因此与其他两试样相比,其电化学性能更好。试样在C/10、C/2、1C、3C及5C倍率下的放电比容量为158.7 m Ah·g^(-1)、153.3 m Ah·g^(-1)、147.6 m Ah·g^(-1)、136.4 m Ah·g^(-1)及123.5 m Ah·g^(-1),具有良好的倍率性能与电位稳定性。展开更多
文摘Based on the method of in situ polymerization synthesis combined with two-step sinter- ing process, LiFel-xVx（PO4）（3-y）/3Fy/C was prepared. The effects of V and F co-doping on the structure, morphology, and electrochemical performances of LiFePO4/C were in- vestigated by X-ray diffraction, Fourier transform infrared spectra, scanning electron mi- croscope, charge/discharge tests, and electrochemical impedance spectroscopy, respectively. The results indicated that the V and F co-doping did not destroy the olivine structure of LiFePO4/C, but it can stabilize the crystal structure, decrease charge transfer resistance, enhance Li ion diffusion velocity, further improve its cycling and high-rate capabilities of LiFePO4/C.
文摘分别以四水磷酸铁(Fe PO4·4H2O)和二水草酸亚铁(FeC_2O_4·2 H_2O)为铁源,采用简单便捷的流变相法制备了碳包覆LiFe_(0.5)Co_(0.5)PO_4固溶体材料(LiFe_(0.5)Co_(0.5)PO_4/C,简称为LFCP/C)。采用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、恒流充放电等测试手段对复合材料的物相、形貌结构和电化学性能进行了表征和测试。结果表明,2种铁源得到的材料均为橄榄石晶型结构且结晶度良好,二者在颗粒尺寸分布、碳包覆效果和电化学性能方面具有显著的差别。用作锂离子电池正极材料时,以FeC_2O_4·2 H_2O为原料得到的LFCP/C具有更优异的电性能:在2.5~5.0 V电压范围内,0.1C倍率下(1C=150 m A·g^(-1)),放电比容量为137.5m Ah·g^(-1),在10C仍具有57.6 m Ah·g^(-1)的放电比容量;0.5C循环100次后容量仍保持78.1%。该样品更佳的电化学性能主要得益于其更小的平均颗粒尺寸,更高的比表面积和理想的碳包覆效果。
文摘首先基于聚合反应合成FePO_4/PANI前驱体,再以为Li OH·H2O,FePO_4/PANI和PVA原料制备了Li FePO_4正极材料,此外再对其进行碳包覆以及Ti^(4+)掺杂,三种试样分别标记为Li FePO_4,Li FePO_4/C及LiFe_(0.96)Ti_(0.02)PO_4/C。通过XRD、EDS及充放电测试等手段表征了材料的微观结构与电化学性能。实验结果证明:试样的XRD图谱均与标准Li FePO_4图谱一致,不存在无定形碳衍射峰。与未掺杂试样Li FePO_4/C相比,LiFe_(0.96)Ti_(0.02)PO_4/C的电子电导率与其相近,但离子扩散系数有所改善,Ti^(4+)在晶格中均匀分布,因此与其他两试样相比,其电化学性能更好。试样在C/10、C/2、1C、3C及5C倍率下的放电比容量为158.7 m Ah·g^(-1)、153.3 m Ah·g^(-1)、147.6 m Ah·g^(-1)、136.4 m Ah·g^(-1)及123.5 m Ah·g^(-1),具有良好的倍率性能与电位稳定性。
基金supported by the China Postdoctoral Science Foundation (2014M562322)Research Fund for the Doctoral Program of Higher Education, Ministry of Education of China (20120181120103)~~
