Interface Modification Of LAGP Solid Electrolyte And Its Performance Study Of Solid-State Lithium Battery

With the increasingly serious shortage of primary energy and environmental pollution,the research and development of green and clean energy is urgent,therefore,electrochemical energy conversion and storage technology is crucial.Liquid lithium-ion batteries are widely used as storage devices for electronic devices and electric vehicles due to their high energy density,negligible memory effect,wide operating temperature range,environmental friendliness and other advantages.With the development of electric vehicles and smart grid technology,the market has higher requirements for the safety and energy density of secondary batteries.In recent years,the research and development of solid-state lithium batteries has become a research hotspot in the field of electrochemical energy conversion and storage.Solid-state electrolyte is an important component of solid-state lithium battery,among which the sodium superion conductor（NASICON）type solid electrolyte Li_1.5Al_0.5Ge_0.5P₃O₁₂（LAGP）has been widely studied due to its advantages of high room temperature ionic conductivity and low sensitivity to water and air.However,the interface between LAGP and lithium metal anode electrode is incompatible,and the uneven surface of LAGP will lead to poor wettability between LAGP and lithium metal anode electrode,resulting in huge interface impedance.At the same time,it also causes the growth of lithium dendrites,which seriously affects the electrochemical performance of solid-state lithium batteries,thus limiting its application in practical production.Therefore,improving the performance of the interface between LAGP and the lithiumanode,preventing LAGP from being reduced by the lithium anode,and reducing the interface impedance play a key role in realizing high-performance solid-state lithium batteries.This paper will adopt different interface design ideas to modify the interface between LAGP and lithiummetal as anode,and apply it to solid-state lithium batteries to improve their electrochemical performance.The details are as follows:（1）A layer of Cu S film is introduced on the surface of LAGP by radio frequency magnetron sputteringand after electrochemical cycling,it reacts with metal lithium to form a stable buffer layer-Li₂S/Cu ion/electron mixed conductive layer.While greatly improving the wettability of LAGP to lithium metal,the mixed conductive layer can effectively suppress the side reaction between LAGP and lithium metal,guide the uniform distribution of the interfacial electric field,and exhibit good lithium dendrite suppression ability.Under the synergistic effect of the ion-conducting Li₂S network and the electron-conducting Cu nanoparticles,the interfacial impedance is reduced,At a current density of 0.1 m A·cm^-2the symmetric cells after the introduction of the Cu S modified layer can stably cycle for more than 700 hours;The assembly of a-All-solid-state lithium batteries（ASSLBs） with lithium iron phosphate（Li Fe PO₄,LFP）as the cathode has significantly improved its electrochemical performance.（2）A layer of Sb ultra-thin nanometer layer is introduced on the surface of LAGP by DC magnetron sputtering to form an interface layer of Li₃Sb alloy with lithium anode.The interfacial layer can effectively improve the interfacial contact and promote the rapid transmission of Li⁺,thus providing a low interfacial impedance and low discharge/charge overpotential for the symmetric cells.In addition,the LAGP electrolyte with the presence of a Li₃Sb alloy interfacial layer exhibits a flat and continuous surface that enables uniform lithium deintercalation/electroplating during cycling.Therefore,the lithium symmetric cells after Sb-modified LAGP can cycle stably for 600 hours at room temperature and a current density of 0.1 m A·cm^-2,showing excellent cycle stability.The ASSLBs with LFP as the cathode also has high charge-discharge specific capacity and good stability.