Preparation And Properties Of Lithium Ion Conductor LATP

Lithium-ion batteries are widely used in mobile electronic equipment,military technology,aerospace,and medical equipment as kinetic energy or energy storage devices.However,at present,liquid electrolytes are currently used on a large scale,which are flammable and explosive,and have a low energy density.The lithium ion solid electrolyte,that is,the lithium ion conductor,replaces the liquid electrolyte and the separator in the traditional battery,which not only can overcome the safety problem of the liquid electrolyte,but also has the advantages of higher energy density and reduced costs.NASICON type fast lithium ion conductor Li_1+xAl_xTi_2-x?PO₄?₃?LATP?is one of the electrolytes with the highest room temperature conductivity among the oxide lithium ion fast conductors so far.The advantages of high ionic conductivity,good thermal stability,wide electrochemical window,chemical stability and electrical conductivity have been attracted the attention of many researchers,but the problems of complicated preparation process,high energy consumption and unstable interface contact limits its application.In this paper,Li_1.3Al_0.3Ti_1.7?PO₄?₃ is used as the research object.The effects of Al source and flux Li₂B₄O₇ on the structure and properties of LATP during solid-phase preparation of LATP are investigated,and the preparation process is optimized.The aim is simplify preparation process of lithium ions conductor LATP and improve its electrochemical performance.The main research contents and results are as follows:?1?The influence of the grinding ball dielectric on the preparation of LATP conductor was investigated.Select agate and corundum as two commonly used grinding ball media.The results show that the prepared LATP powder is uneven and easy to agglomerate when the abrasive ball is agate,and the prepared sample has low conductivity.The LATP powder prepared when the abrasive ball medium is corundum has uniform particle size,good dispersibility,and there is no obvious agglomeration phenomenon.The prepared LATP conductor has better ionic conductivity,and its total ionic conductivity when sintered at 900?is 4.52x10^-5 S/cm,and the relative density is 96.04%.?2?The effects of different Al sources on the structure,shape and properties of LATP were explored.Using different Al sources??-Al₂O₃,?-Al₂O₃ and AlOOH?,LATP was prepared by sintering at 900?for 6 h by solid phase method.The best results were obtained by analyzing the sample phase,measuring the density and the ionic conductivity.The best Al source is AlOOH.The ionic conductivity of LATP sintered at 900?is 2.04x10^-4 S cm^-1.Then,the best preparation process of LATP with AlOOH as Al source was explored.Using controlled variable method,a series of investigations were carried out on its sintering temperature and time.It has good properties,the grains are uniform and closely arranged,and the electrical conductivity is 3.44x10^-4 S/cm,and the relative density is 96.04%.?3?The influence of flux Li₂B₄O₇ on the structure,shape and properties of LATP was studied.The flux Li₂B₄O₇ will reduce the decomposition temperature and crystallization temperature of LATP,and reduce its preparation temperature.The prepared powder is relatively pure and has a uniform element distribution.When the molar ratio of Li₂B₄O₇ is between 0.02 and 0.12 mol,LATP is prepared in pure phase.Its relative density increases with the increase of the amount of addition,and its total ion conductance first increases with the increase of Li₂B₄O₇ It tends to decrease after being large.The sample has a maximum ionic conductivity of 5.40x10^-4 S/cm.When it is added to 0.1 mol,which is about 1.5 times that of the unadded sample.When the crystallization temperature is between 750?and 850?,the characteristic diffraction peaks of LiBO₂ appear,which may be due to the completion of Li₂B₄O₇decomposition and incomplete melting into the amorphous state into the LATP structure.When the crystallization temperature is 900?At the same time,the characteristic diffraction peak of the LATP sample is the strongest and the highest density is 96.58%.The electrochemical analysis shows that its ionic conductance first increases and then decreases with the increase of the crystallization temperature.The maximum value obtained at 900?is 7.05x10^-4 S/cm.