Preparation Of Lithium Titanium Phosphate And Its Application In Li-air Secondary Batteries

Since Li-air batteries offer high theoretical energy density，people have paymuch attention to its developcation. However，traditional Li-air batteries candegrade the lithium metal anode because of the moisture and carbon dioxide inambient environment dissolved in the aprotic electrolyte. As a result, it limitsthe stability and cycleability of the Li-air batteries. The application of solidelectrolyte became a great breakthrough to improve the cycleability of the Li-airbatteries. Therefore, the preparation of solid electrolyte with high conductivitybecomes the keypoint to improve the performance of Li-air batteries.In this article, the LATP solid electrolyte is depicted as the object of thestudy. The influence of preparation process, doping agent on the ionicconductivity is studied and the preparation process as well as the stoichiometricratio is determined. In addition, using the LATP as the electrolyte in the watersystem lithium-air batteries is explored.The structure of the lithium-air batteriesand the discharge and charge performance is studied.It is studied that when the high temperature solid state method is adopted toprepare the LATP solid electrolyte, the addition of the lithium phosphate haslittle influence on the conductivity of LATP. However, silicon dioxide cangreatly improve the performance of LATP. When the ratio of the silicon dioxide(y)is0.1as the solid electrolyte of Li1.3+yTi1.7Al0.3SiyP3-yO12(y=0、0.1、0.2、0.3)is prepared, LATP with the highest conductivity of1.1×10-4S·cm-1is prepared.The influence of the boric acid on the LATP glass-ceramic is also studied, Whenthe ratio of the boric acid is70%, LATP glass-ceramic with the highestconductivity of9.91×10-5S·cm-1is prepared.Using the LATP as the electrolyte in the water system lithium-air batteriesis explored to find that when the molarity of lithium hydrate and lithiumchloride is10M and0.1M, the Li-air battery shows good cycleability andstability. While the capacity is restricted as1mAh, the battery doesn’t showsignificant capacity fading.In order to study the crystallization mechanism of theLi1.4Ti1.7Al0.3Si0.1P2.9O12glass, it was found that the activation energy ofcrystallization values obtained through Differential Scanning Calorimetry was331.146KJ/mol. The value of Avrami index obtained from Matusita’s equationis3, suggesting bulk crystallization during their amorphous to crystallinetransformation.