Study On The Preparation And Properties Of B₂O₃ Enhanced LATP Solid Electrolyte

Lithium-ion batteries play a great role in the social life and commercial production of human beings.More and more lithium-ion batteries are widely used in military equipment,aerospace technology,mobile electronic devices,medical devices and other fields.Most of the researches on improving the performance of lithium ion batteries are about the synthesis of new electrode materials and electrolyte materials.And optimizing the existing material systems and the modification research of known materials are also of great significance.In this paper,the optimization of the preparation method and the modification of the flux of a solid electrolyte material Li_1.3Ti_1.7Al_0.3P₃O₁₂（LATP）are studied.LATP samples were prepared by ball milling solid phase method at different sintering temperatures at 600℃¹100℃,and the structures and elemental composition of them were analyzed by XRD and FT-IR.It is found that the LATP samples are well crystallized and are determined as pure phase LATP.The morphology,density and ionic conductivity of LATP were studied by SEM,Archimedes drainage method,TG-DSC and electrochemical workstation,found that the density of LATP improving continuously with increasing sintering temperature.But the sintering temperature above 900℃ is too high caused the crystal structure of the samples was destroyed,continuous cracks appeared in LATP sample.With the increase of sintering temperature,the ionic conductivity of it increases first and then decreases,and the sample with the highest ionic conductivity 4.16 x 10-4S/cm was sintered at 900℃.Two kinds of fluxes Li BO₂ and B₂O₃ were separately added into the sintered precursor powder,and the Li BO₂-LATP and B₂O₃-LATP samples were synthesized.Through SEM observation and ion conductivity measurement,it is found that with the increase of addition of Li BO₂ and B₂O₃,the porosity of the sample decreases,the density increases,and the ionic conductivity increases.When the adding amount of flux is larger than 2wt.%,while the density of the samples is to continue to improve,but the flux accumulation occurs at the surface of the sample,the amorphous layer affects the ion transport,resulting in lower ionic conductivity.The sample adding 2wt.%flux B₂O₃ has the highest ionic conductivity of 1.61 x10-4S/cm,and its activation energy is 0.3eV.LATP of nanometer grade were prepared by a new fast sol-gel method,the ionic conductivity of the sample sintered at 900℃is 5.88 x10^-6S/cm.The heat absorption and exothermic process of samples were studied by TG-DSC,and the crystallization process of the samples from dry glue powder to LATP was analyzed.The structure and properties of the LATP solid electrolyte samples were improved by adding the flux B₂O₃,and the ionic conductivity of B₂O₃-LATP increased firstly and then decreased with the increase of flux amount.The sample with the addition of 2wt.%B₂O₃ has the highest ionic conductivity of1.19x10^-5S/cm,which is increased by an order of magnitude compared with that without adding flux.The activation energy is also reduced to 0.411eV.