| The increasing demand for portable power supply of people has greatly promoted the development of lithium battery technology,the research of new energy storage battery has become the trend of development in the future.The solid electrolyte has the advantages of high ionic conductivity,wide electrochemical stability window,good chemical compatibility,good thermal stability,strong mechanical properties,simple preparation process,low price,easy integration,and environment friendly,it is the key material for the new generation of energy storage batteries.However,the solid electrolyte as a substitute for liquid electrolytes is far from being required.In particular,the conductivity and stability of solid electrolyte materials need further improvement.Solid electrolyte can be divided into two categories:inorganic solid electrolyte and organic solid electrolyte.This paper mainly studies two kinds of NASICON inorganic solid electrolytes,Li1+xAlxGe0.2Ti1.8-x?PO4?3?LAGTP?and Li1+x-y+x-y AlxNby Ti2-x-y?PO4?3?LANTP?.The precursor powders of the inorganic solid electrolyte were prepared by solid-state reaction.Then LAGTP or LANTP plate samples?abbreviate samples?were prepared by tape casting method and pressing method.The influence of epoxy resin modification on mechanical strength and water permeation of samples was also studied.Impedance spectroscopy,XRD,three point bending strength and water permeability were tested and analyzed for different samples.Finally,the aqueous lithium-air battery was assembled used LAGTP-epoxy resin,and its performance was tested.The results show that the tape casting performance of LAGTP sample is slightly better than that of pressing method.Through the study of different sintering temperatures,it is found that high conductivity and relative density can be obtained when the sintering temperature is 900°C,and the impurity phase is not found in the XRD spectrum.By studying the preparation of LAGTP samples of different components,it is found that the conductivity of LAGTP samples at room temperature is the highest when x=0.45,and the conductivity of the sample prepared by the tape casting method is 1.03×10-33 S/cm,and the conductivity of the samples prepared by the pressing method is 1.01×10-33 S/cm.At that time,the relative density of LAGTP samples reached 95.8%?tape casting method?and 95.5%?pressing method?,respectively.Through three point bending strength test,it is found that the strength of LAGTP samples prepared by the two methods are the same,all are 90 N mm-2.In the study of different composition of LANTP samples at different sintering temperatures and tablets method,it was found that the conductivity of the samples prepared by tape casting method was highest when the sintering temperature was900°C,x=0.5,y=0.2,and the impurity phase was not found by XRD.And for samples prepared by pressing method,the conductivity was highest when the sintering temperature was 900°C,x=0.55,y=0.2 and the impurity phase was not found by XRD.It is found that the LANTP sample prepared by tape casting is superior to the pressing method in conductivity performance.The conductivity of LANTP samples prepared by the tape casting method and the pressing method are 6.7×10-44 S/cm and5.8×10-44 S/cm,respectively,and the relative density is 97%and 96%,respectively,and three point bending strength is 101 N/mm2 and 99 N/mm2,respectively.Although the LAGTP samples prepared by tape casting method have higher mechanical strength and relative density,they still cannot completely isolate the water molecules.The mechanical properties of LAGTP samples can be improved by epoxy resin?three point bending strength can reach 125 Nmm2?,and has good water insulating property,and the lithium-ion conductivity of 5.0×10-44 S/cm?slightly lower than that without epoxy resin?.The modified LAGTP sample is used as the electrolyte toassemblelithiumairbattery.Thelithiumbatterystructureis Li/LiPF6-EC-DEC/LAGTP-epoxy/saturated LiOH-1M+LiCl/KB.When the charge and discharge current density is 0.53 mA/cm2,Overvoltage of charge and discharge is0.4V,and the open circuit voltage is 2.9V. |
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