LAGP Microwave Assisted Sintering And Group B Element Doping Process Mechanism And Experimental Research

All-solid-state batteries are batteries with solid components such as electrodes and electrolytes.They have high energy density,good safety performance,and long cycle life.They are ideal electric energy storage devices for electric vehicles.The low ionic conductivity of solid electrolytes and the unsatisfactory interface performance between electrodes and electrolytes limit the industrial development and application of all-solid-state lithium-ion batteries,which are the two major issues that need to be solved for all-solid-state lithium-ion batteries.Lithium-ion solid electrolytes can be divided into three categories: polymers,sulfides,and oxides.The polymer has a narrow electrochemical potential window,low room temperature conductivity,and there is still a certain flammability risk;the environment for the preparation and use of sulfides is harsh?sensitive to air,easy to oxidize,and easily generate toxic gases such as hydrogen sulfide in contact with water?Both lithium and oxide positive electrodes are unstable;the oxide solid electrolyte has a wide electrochemical potential window,is stable in air,can be used in high-potential positive electrode systems,and some electrolytes are stable to metallic lithium,which has a good application prospect.Among oxide solid electrolytes,NASICON-type solid electrolyte Li_1.5Al_0.5Ge_1.5?PO₄?₃?LAGP?has higher ionic conductivity,stability,and a wider electrochemical potential window,which is better than metallic lithium.Chemical and electrochemical stability,but there is still a certain gap between its ionic conductivity and practical level.Based on the optimization of the LAGP preparation process and the doping of Group B elements to improve the electrochemical performance of LAGP,the main research contents are as follows:?1?Study the scheme of preparing electrolyte flakes by melt quenching process.Studies have shown that a solid electrolyte sheet with a thickness of 0.2 mm can be stably prepared by using the melt quenching process combined with diamond wire cutting.?2?Investigate the scheme of crystallization of electrolyte flakes based on microwave sintering process,study the optimization of microwave sintering process parameters and the influence of process parameters on electrolyte performance.Studies have shown that microwave sintering can reduce the crystallization time from 6h to 30 min in traditional sintering without warping and microcracking.?3?Study the influence of doping of Group B elements on the electrochemical performance of LAGP.Studies have shown that B³⁺doping helps reduce the activation energy of the electrolyte,and Ga³⁺doping helps increase the ionic conductivity of the electrolyte.When the doping content of Ga³⁺is 0.1mol%,the obtained sample Li_1.5Al_0.4Ga_0.1Ge_1.5?PO₄?₃ has the highest electrical conductivity of 6.67×10^-4S cm-1,which is higher than that of pure LAGP electrolyte.In³⁺doping easily generates AlPO4 heterophase,which is not conducive to improving the ionic conductivity of electrolyte LAGP.?4?Assemble LNMO/LAGP-Ga0.1/RuO2 all-solid-state lithium-ion batteries,and study the coulomb efficiency and charge-discharge cycle performance of the all-solid-state lithium-ion battery.The study found that after 20 weeks of constant current charge-discharge cycles,the Coulomb efficiency was stable at 70%...