Preparation And Electrochemical Performance Of Li_1.3Al_0.3Ti_1.7?PO₄?₃ Solid-state Electrolyte

Now,the energy density of liquid and semi-solid lithium-ion batteries is difficult to exceed300 Wh/kg,and solid-state batteries have significant safety and energy density advantages,which is the future development direction of Li-ion Batteries.The Li_1.3Al_0.3Ti_1.7?PO₄?₃ of NASICON-type solid-state electrolyte?SSE?has been a wide study for its stable structure and facilitates lithium ion migration.However,Li_1.3Al_0.3Ti_1.7?PO₄?₃ still has the problems of poor sintering performance and low ionic conductivity.It is an effective way to improve the electrochemical performance of Li_1.3Al_0.3Ti_1.7?PO₄?₃ material by improving the preparation process and adjusting the composition structure.Therefore,in this paper,the Li_1.3Al_0.3Ti_1.7?PO₄?₃ SSE was prepared by optimizing solution method and using additives modified.And the means of X-ray Diffractometer?XRD?,Scanning Electron Microscope?SEM?and Energy Dispersive Spectrometer?EDS?were been used to characterize phase composition,micro-morphology and electrochemical properties of the solid-state electrolyte samples.To compare the ion conductivity,density of samples to evaluate the performance of solid electrolytes.And then,Li_1.3Al_0.3Ti_1.7?PO₄?₃ prepared with the best parameters was used to modify the cathode material LiNi_0.5Mn_1.5O₄ of the Li-ion batteries,and evaluate its electrochemical performance by cyclic charge and discharge test,Electrochemical Impedance Spectroscopy?EIS?and Cyclic Voltammetry?CV?means.The Li_1.3Al_0.3Ti_1.7?PO₄?₃ was prepared by solution method.The effects of reactant concentration,calcination temperature and additive type on the phase,morphology and properties of the sample were studied.The results show that when the concentration of the reactant was 0.2mol/L,the sample prepared by calcination at 900?for 6h had good crystallinity,uniform grain size,and ion conductivity of 1.37×10^-5 S/cm.Using B₂O₃,SiO₂,B₂O₃+SiO₂ three kinds of additives to modify Li_1.3Al_0.3Ti_1.7?PO₄?₃ SSE,it was found that when B₂O₃ and SiO₂ were added in a combined amount of 2 wt%,and got the highest density and ion conductivity of 95.2%and3.04×10^-4 S/cm,respectively.In order to verify the electrochemical performance of Li_1.3Al_0.3Ti_1.7?PO₄?₃,the solution method was used to grow Li_1.3Al_0.3Ti_1.7?PO₄?₃ on the surface of the spherical LiNi0.5Mn1.5O4cathode material.The results show that:Li_1.3Al_0.3Ti_1.7?PO₄?₃ was evenly coated on the surface of LiNi_0.5Mn_1.5O₄ microspheres,and the electrochemical performance was significantly improved after coating.Among them,the LiNi_0.5Mn_1.5O₄ sample coated with 5wt%Li_1.3Al_0.3Ti_1.7?PO₄?₃ had a best performance.Its specific discharge capacity at 0.2 C rate and 10 C rate were 140.6 mAh/g and 102.4 mAh/g,respectively.And the capacity retention rate was up to 96.3%after 100 cycles at 1 C rate.