| Lithium-ion battery(LIB)as a highly efficient energy storage equipment,is widely used in mobile phones,laptops,solar power plants,and even electric vehicles and other equipment,plays an important role in the modern social energy chain.But these applications are mostly restricted by safety issues such as poor thermal stability,flammable reaction products,and leakage of electrolyte and internal short circuits for the use of liquid electrolytes in LIB.The use of solid electrolyte to replace liquid electrolyte preparation of all solid lithium-ion battery is expected to overcome the above shortcomings,which makes solid electrolyte an important research direction in the field of energy.In this paper,lithium ion solid electrolyte Li1.3Al0.3Ti1.7(P04)3 · x at.%SiO2(LATPS,x:0-10 at.%)and Li1-xSrTiTaO6-xFx were prepared by wet chemical method and solid phase method,respectively.The main research content is as follows:1.The crystal structures of LATPS were determined by Rietveld analysis of powder X-ray diffraction patterns.The microstructures of the prepared materials were investigated by using of scanning electron microscope(SEM).Ionic conductivities were measured by Electrochemical Impedance Spectroscopy(EIS)measurement.The results show that the LATPS glass-ceramics have the rhombohedral crystalline structure with the space group of R3-C,which has 3-dimensional ionic conducting path.A maximum conductivity in the order of 10-4 S cm-1 and the lowest activation energy of 0.36 eV at room temperature are achieved by a short sintering time of 2 hours at 1100 ℃.The added SiO2 may exist in the form of SiO4 tetrahedra substituting for PO4 tetrahedra in LATPS grain,which has a positive impact on ionic conductivity and improve stability for LATPS.2.The calcination temperature and the sintering temperature of LiSrTiTaO6 and LiSr1-0.5xTiTaO6-xFx were studied.The final calcination process was carried out at 800 ℃ for 2 h and then heated to 1100 ℃ for 10 h.The LiSr1-0.5xTiTaO6-xF,(0.1<x<0.3)system was found to have a higher lithium ion conductivity than that of LiSrTiTa06.LiSr1-0.5xTiTaO6-xFx(x = 0.1)samples have uniform grain growth,close contact between crystals,high bulk density,whose ionic conductivity is 3.67 × 10-4 S cm-1,and activation energy is 23.2 kJ mol-1.The synthesized solid electrolyte is a cubic perovskite structure.Refined data show that F-replacement O2-can shorten the distance between B site atoms and oxygen atoms in perovskite structure ABO3,so that the B-O bond is enhanced,and the A-O bond is weakened due to the competition.So that the mobility of Li+ becomes improved,which helps the ionic conductivity,but this process will make the bottleneck of Li+ when it jumps to an adjacent A site decrease,and activation energy will increase,so excessive increase in F content will reduce the ionic conductivity. |
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