Preparation And Performance Of Garnet-and NASICON-based Solid Electrolytes

An all-solid-state lithium-ion battery can effectively improve the safety of the battery.However,the interface impedance between the electrode and the solid electrolyte is high,and the development of an electrolyte material that combines high ionic conductivity and electrochemical stability is an important challenge for achieving an all-solid-state battery application.In this work,the interfacial stability of garnet-type solid electrolytes was studied and modified,and the polymer and NASICON-type electrolytes were prepared into composite films,which significantly improved their electrochemical performance.It has played a positive role in improving the performance of all solid state batteries.Al and Ta co-doped garnet-type Li_6.75La₃Zr_1.75Ta_0.25O₁₂ solid electrolyte with cubic phase structure was successfully synthesized at 900?.Lithium halide was coated on the surface of the cubic phase LLZTO grains by a solution method and sintered at a low temperature to volatilize the solvent.LiCl acting as a binder can"fill"the grain boundaries,reducing the grain boundary impedance while increasing the density of LLZTO,changing the ion transport mode from point conduction to face conduction.The ionic conductivity of the optimized sample reached 0.56 mS/cm,which was three orders of magnitude higher than that of the original LLZTO sample.BMP-TFSI ionic liquid?IL?was introduced into LLZTO grain gap to improve its interfacial performance.IL without lithium salts has a low viscosity,which ensures a high Li⁺transference number and promotes the formation of lithium ion transmission conductive network.Continuous IL coating effectively inhibited the growth of lithium dendrites and showed good interfacial compatibility with the Li metal anode.All-solid-state batteries with cubic LLZO-IL solid electrolyte demonstrate relatively good cycling stability.According to Lewis acid-base theory,polycaprolactam?PCL?was used as the matrix,and inorganic fast ion conduction Li_1.5Al_0.5Ge_1.5?PO₄?₃ was added to prepare polymer composite electrolyte film which successfully improved its conductivity,electrochemical window and ion transference number.LAGP can effectively immobilize anions to induce uniform Li⁺distribution and further guide the deposition of non-dendrite Li,which greatly improves the ability of electrolyte to inhibit lithium dendrite.The all solid-state batteries based on this composite electrolyte membrane deliver outstanding cycling stability and superior rate capability.