Preparation And Properties Of Li_1.3Al_0.3Ti_1.7（PO₄）₃Solid Electrolyte

Recently, lithium-air battery has attracted worldwide attention due to itsrelatively the highest theoretical specific energy among a variety of electrochemicalenergy storage systems. The theoretical specific energy of lithium-air battery is5.21kWh.kg-1, comparable to gasoline. Therefore, it becomes the most promisingcandidate for the future electric vehicle battery system.In this study, the LTAP (Li_1.3Al_0.3Ti_1.7（PO₄）₃) electrolyte powder for preparingthe lithium-air battery separator was synthesized by the sol-gel method. Thepreparation technique was optimized and the best one was determined: water as asolvent by adding ethylene glycol （with citric acid molar ratio of1:1） andconcentrated nitric acid （consumption30g tetrabutyl titanate, add20ml ofconcentrated nitric acid）, vacuum drying temperature of220℃, calciningtemperature of precursor of800℃. Electrolyte conductivity of1.899×10-4S.cm-1was obtained. The increase of the electrolyte density and the ionic conductivitywere observed after doping Si into LTAP. A higher ionic conductivity of2.767×10-4S.cm-1was reached in the Si incorporated electrolyte phase （LTASP-1）, and2.019×10-4S.cm-1in the SiO2incorporated LTAP electrolyte into its grainboundary （LTASP-2）.Thin electrolyte film with large surface area was prepared by casting method.The best casting formula was determined as follows: mass ratio of LTAP powder:water: ammonium polyacrylate:PVA:glycerol was100:130:2:12:30, and the optimalsintering temperature was900°C. And the electrical conductivity was obtained as2.546×10-5S.cm-1.Stability of the electrolyte in a variety of aqueous solution was detected bydipping the prepared LTAP electrolyte tablets into different aqueous solution. Theresults reviewed that LTAP electrolyte was unstable in acidic and alkaline aqueoussolution. Structural damage to LTAP dipped in acid solution was from the outside tothe inside, while dipped in the alkali solution the damage was from the inside to theoutside. LTAP was stable in neutral lithium salt solution, and the stability wasstrengthened as the concentration of the solution increase. Lithium-air battery system with a mixed electrolyte was designed and installedusing the LTASP-1electrolyte tablets, the open circuit voltage of the battery wasabout3.1V. However, the discharge capacity was very low, and the structure of thebattery needs to be further improved.