Structure Design And Performance Characterization Of A Novel Solid State Lithium Air Battery Based On Li₇La₃Zr₂O₁₂

Solid-state lithium batteries,especially solid-state lithium-air batteries,are the hot spots of recent researches.The deep research and development of solid-state lithium-air batteries is expected to solve a series of problems such as the safety and practicality.The premise of preparing high output performance and high stability solid-state lithium-air batteries are to develop electrolyte materials with good ionic conductivity,high mechanical properties and machinability,which can be fully sealling the lithium metal anode.The Li₇La₃Zr₂O₁₂?LLZO?solid-state electrolyte with garnet structure is a kind of ceramic electrolyte has great potential in recent years.It has excellent electrochemical stability,which shows that the solid electrolyte can be applied directly to the lithium metal anode and shows good ionic conductivity and excellent chemical stability at room temperature.In this dissertation,?i?LLZO,?ii?Ta doped LLZO,?iii?Al doped LLZO as the research object,the preparation and physical,chemical and electrochemical properties of the ceramic electrolyte support materials are systematically studied,and the comprehensive properties of the three materials as the ceramic electrolyte support for the construction of the lithium-air battery are analyzed.In this dissertation,LLZO,Li_6.4La₃Zr_1.4Ta_0.6O₁₂?LLZTO?and Li_6.9Al_0.1La₃Zr₂O₁₂?LALZO?samples were synthesized by solid-state method and cold isostatic pressing.The results show that the highest density of the LALZO electrolyte support is 96.4%,and the ionic conductivity of the three materials increases with the increase of the test temperature.The lithium ion conductivity of the LLZO can reach 10^-55 S cm^-11 at room temperature.The high temperature sintering process of the three materials is systematically analyzed and compared to guide the optimization of the subsequent high temperature sintering process.A new type of "self-absorbing solid-state lithium-air battery" is designed to solve the problem that the water solution is constantly consumed in the traditional lithium-air battery but can not be supplemented in time.In this dissertation,the physical,chemical and electrochemical properties of three kinds of ceramic electrolytes in the water battery were studied in detail,as well as the influence of the evaporation of the electrolyte on the performance of the battery and the design and optimization of the structure of the battery.A new type of "three-layer gradient pore structure battery" is proposed to solve the problem that the electrolyte thickness and the electrolyte-electrode contact interface are the most concerned in the solid-state battery.The optimized ceramic electrolyte support has been used for the construction of a solid-state lithium-air battery after acid etching and three layers of ceramic structures with a gradient porous layer on both sides.After the in-situ deposition of the electronic conductive layer and the catalyst layer,it is used to build solid-state lithium-air batteries.The total specific discharge capacity of the battery can reach 2386 m Ah g^-1,and the battery has a stable charging and discharging voltage platform,which effectively improves the discharge capacity of the battery and the efficiency of Kulun,and effectively solves the problem of excessive charging voltage and low energy efficiency of the lithium-air battery.The electrolyte support after acid etching can increase the contact interface between the active material and the solid electrolyte because of the small pore and dense hole inside,which solves the problem that the contact interface between the electrode and the solid electrolyte is less,and the output performance of the battery is improved;The design of the three-layer structure symmetrical gradient hole also provides a space advantage for the deposition process of the subsequent lithium metal,the deposition of solid products,the process of storage and the process of deep oxygen transport.