Construction And Electrochemical Performance Of Electrode-aligned And Three-layer All Ceramic Lithium Ion Battery

With the demand for clean and efficient energy,the development and utilization of energy have attracted much attention.With the rapid development of portable electronic products,electric vehicles,and grid energy storage,lithium-ion batteries?LIBs?with high energy density have become the dominant power source.Traditional lithium-ion batteries that use liquid organic solvents as electrolytes have some safety and electrochemical issues,including leakage,flammability,high toxicity,and poor chemical stability.Solid electrolytes are used to develop safe lithium batteries for safety requirements.The main research content of this paper is the full ceramic lithium-ion battery.All-ceramic lithium-ion battery,which uses ceramic electrolyte and ceramic electrode,has a broad development prospect because its safety performance can be greatly improved.The research of all-ceramic lithium-ion batteries should settle the following problems:?1?the ionic conductivity of the ceramic electrode needs to be further improved;?2?the interface stability and mechanical properties still need to be improved;?3?the interface impedance of the ceramic electrolyte and the electrode needs further decrease.This work is based on the shortcomings of low ion conductivity of the ceramic electrode material of lithium-ion batteries.A three-layer?pore-dense-pore?electrolyte structure with vertical alignment is designed and constructed.Low conductivity electrode materials are synthesized in situ in electrolyte channels with high conductivity through the impregnation sintering process,which is used to assemble all-ceramic lithium-ion batteries.The three-layer electrolyte structure constructed in this work can enable lithium ions in the battery to be transmitted mainly through the electrolyte with high conductivity,thereby shortening the migration distance of lithium ions from the electrode into the electrolyte and achieving the purpose of accelerating the transmission of lithium ions.Besides,the electrode materials are evenly distributed in the vertically aligned porous electrolyte layer through the in-situ synthesis process,which can significantly reduce the high interface impedance of the electrolyte and electrode materials exhibited by traditional all-ceramic batteries.First,this work systematically studied the solid-phase preparation process?sintering system,sintering time and other relevant process parameters?of garnet-type ceramic lithium-ion electrolyte,and determined the optimal sintering temperature required to prepare the three-layer electrolyte structure.For example,the optimal sintering temperature for the Li_0.33La_0.557TiO₃ three-layer electrolyte structure is 1350?.And its structure and thermodynamic properties were deeply characterized and analyzed,and the structure-effect relationship between its electrochemical performance and structure was studied.Second,an electrolyte membrane structure with a vertical pore structure was prepared by the template method,and lithium borate was used as a sintering aid to further improve the mechanical strength of the electrolyte membrane.By optimizing the formulation and related sintering process,a high-density intermediate electrolyte layer was prepared,and then a three-layer garnet electrolyte structure with pore-dense-pore channels was successfully constructed.Third,two precursor solutions that can be used for in-situ synthesis of lithium cobaltate and lithium titanate electrodes were designed.In the LLTO electrolyte with the micropore structure,the electrode material was impregnated in situ,and the chemical compatibility and thermal stability of the electrode?positive electrode/negative electrode?and the electrolyte material were systematically studied.We found that the optimal in-situ synthesis temperature of Li₄Ti₅O₁₂anode material and electrolyte material LLTO is 800?.The optimal in-situ synthesis temperature of the positive electrode material LiCo O₂ and the electrolyte material LLTO is also800?.