| Solid electrolyte films as the electronic insulating layers of all solid-state lithium-ion batteries and they need to possess high ionic conductivity.NASICON type Li1.3Al0.3Ti1.7?PO4?3?LATP?solid electrolyte is considered as one of the most promising solid electrolytes,primarily because of its high ionic conductivity,good thermal stability and wide electrochemical window.Therefore,it is of great significance for promoting the development of all solid-state lithium-ion battery technology to carry out in-depth preparation of thin films based on LATP solid electrolyte,further to explore both ion conductivity and electrochemical characteristics.Nanoscale LATP solid electrolyte particles are prepared by sol-gel method.The morphology and ionic conductivity of LATP are studied by SEM and EIS.It is found that the ionic conductivity of LATP particles is the highest at sintering temperature of 750?.The ionic conductivities are 6.11×10-6s/cm at room temperature and 9.74×10-5s/cm at 80?,and the grain size increases with the sintering temperature.However,there are agglomerations and impurities of particles at too high sintering temperatures.Thus,the ionic conductivities first increase then decrease with the increase of sintering temperatures.LATP thin films are prepared by magnetron sputtering technique successfully,and the effects of annealing temperatures on the phase and ionic conductivity of films are studied.It is found that the crystallinity of the films first increases and then decrease with the increase of annealing temperature by XRD.The crystallinity of the film is the best at the annealing temperature of 900?,and the grain size of the films increases with the increase of annealing temperature.The results of EIS show that the changes of ionic conductivity and crystallinity of LATP films with temperatures are consistent.When the annealing temperature is 900?,the highest ionic conductivity is 1.36×10-66 S/cm at room temperature,and the ionic activation energy is 0.492ev.LATP-PEO composite solid electrolyte films are prepared by casting method.The XRD results show that PEO is crystalline at room temperature,but the presence of LATP and LiTFSI inhibits the crystallization of PEO.The results of SEM show that a composite solid electrolyte film with a thickness of 25?m can be obtained when the PEO molar mass is5000kg/mol and the ratio of LATP to PEO is 7:3.The film processes a uniform particle distribution and high ionic conductivities of 1.36×10-5S/cm at 25?and 4.60×10-4S/cm at100?.In addition,the ion activation energies are 4.86eV and 0.22eV,respectively,when the temperatures are at-2060?and 60100?.LATP-PEO button cells are prepared with LATP-PEO?7:3?composite solid electrolyte films as electrolyte layers and Ni-Co-Mn ternary materials as anode materials.The cyclic voltammetry,charge-discharge performances,cycle properties and rate performances of the batteries are studied by electrochemical workstation and battery test system.The results show that the specific capacity of the first discharge is 141.59mAh/g and the coulomb efficiency is93.18%when charged and discharged at a rate of 0.1C at temperature of 60?.After 50 cycles,the specific discharge capacity is 93.31mAh/g. |
PDF Full Text Request