Abstract:Nitrogen-doped porous carbon (NPC) was successfully prepared by solvent evaporation combined with high temperature thermal polymerization in the present study. The microstructure and element composition of the samples were characterized by SEM, TEM, Thermogravimetric analyzer (TG), N2 adsorption-desorption and X-Ray Photoelectron Spectroscopy (XPS). The results showed that the nitrogen content of the nitrogen-doped porous carbon was 4.2 at% and the specific surface area was as high as 422.0 m2/g higher than that of the nitrogen-free sample(301.1 m2/g), and the specific surface area and pore volume of the samples were obviously increased by nitrogen element doped. Subsequently, the obtained NPC was also characterized with cyclic voltammetry curves, constant current charge discharge curves and AC impedance spectra.The electrochemical results showed that nitrogen doped method could significantly increase the specific capacitance of the sample, reduce the internal resistance of the porous carbon, and greatly improve the electrochemical properties of the carbon material. At the current density of 0.5 A/g, the specific capacitance of N-doped porous carbon was increased from 83.8 F/g to 162.8 F/g, and the internal resistance was reduced from 1.39 Ω to 0.47 Ω.Furthermore, nitrogen-doped porous carbon possessed good rate performance and cyclic stability

Abstract:A series of LiAlO2-Li3PO4 solid state lithium ion electrolyte materials were prepared through solid-phase reaction. The influences of experimental operating parameters such as the Molar ratio of materials, and the sintering temperature on the characteristics of the sintered samples were investigated. The results showed that, at 1∶1 stoichiometric ratio of LiAlO2 and Li3PO4, the specimens sintered at 1 000 ℃ consisted of γ-LiAlO2 flakes and γ-Li3PO4 spheres, and the sizes of particles ranged from 0.5 to 1 μm. When the stoichiometric ratio of LiAlO2 and Li3PO4 was 1∶3, the specimens sintered at 1 000 ℃ consisted of mainly Al doped spherical γ-Li3PO4 solid solution and its ionic conductivity was 6.4×10-5 S/cm. It indicated that Al doping could effectively improve the ionic conductivity of Li3PO4 inorganic solid electrolyte. When the Al doped specimens were sintered at 1 100 ℃, the ionic conductivity decreased. The results of cyclic voltammetry showed that the Al doped γ-Li3PO4 solid electrolyte materials had a good electrochemical reversibility in saturated LiNO3 solution, and an electrochemical window of 1.5V was observed.

Abstract:通过原位聚合方法制备了聚吡咯(PPy)/磷酸铁锂(LiFePO4)复合材料.傅立叶红外光谱测试表明PPy与LiFePO4之间发生了相互作用;采用扫描电镜观察了PPy在LiFePO4表面的分布情况;采用四探针法、电化学阻抗法及恒电流充放电法测试了复合材料的性能.结果表明:PPy的质量分数为4.69%的PPy/LiFePO4复合材料具有最佳的电化学性能,最小电荷转移电阻为98.83Ω,最大交换电流为0.256 mA,首次放电容量达到154.34 mAh/g,平台容量和平台率分别为133.48 mAh/g和86.48%,并且具有较好的循环性能及倍率性能.