Preparation And Performance Research Of LATP-based Quasi-solid-state Electrolyte

Safety accidents caused by lithium-ion batteries using organic electrolytes are an urgent problem to be solved.The all-solid-state battery proposed by the researchers is considered an ideal solution to solve the hidden safety hazard of lithium-ion batteries.All solid-state batteries are composed of flame-retardant solid materials and they have higher safety performance.However,compared with conventional liquid lithium batteries,the electrochemical performance and interface problems of all-solid-state lithium batteries have not yet reached the standard for commercialization.As an effective alternative to liquid organic electrolytes,solid-state electrolytes are the key materials for next-generation high-performance energy storage devices.Therefore,the research and development of solid electrolytes is an important research project.The problem of poor ionic conductivity inherent in common solid electrolytes and slow interfacial charge transfer due to large interfacial resistance between solid electrolyte and electrodes hinder the practical application of all-solid-state batteries.In recent years,all solid-state electrolytes considered to have better safety have been developed.However,compared with ionic liquid electrolytes,most of them still have low ionic conductivity and high interfacial resistance with electrodes.As an alternative,quasi-solid electrolytes including liquid-solid mixed phases that have been proposed have been vigorously developed.Ion-containing quasi-solid-state electrolytes composed of ionic liquids and solid matrices have attracted much attention due to their non-flammability,good contact,and superior chemical and electrochemical properties.Liquid-solid hybrid quasi-solid-state batteries that combine the excellent ionic conductivity and good interfacial contact of liquid electrolytes with the good mechanical properties,high safety,and thermal stability of solid-state electrolytes have both advantages and better electrochemical performance.NASICON-type inorganic oxide solid electrolyte Li_1.4Al_0.4Ti_1.6（PO₄）₃（LATP）has high ionic conductivity at room temperature,is stable to water and oxygen in air,and has high applicability prospect.However,there are still problems such as excessive interface impedance,complex preparation process,difficult battery assembly,and serious interface side reactions.In this paper,the typical NASICON solid electrolyte LATP is used as the research object,such as morphology construction,interface construction,organic-inorganic composite,etc.,to form a composite quasi-solid electrolyte,and related tests and researches are carried out.The research works are as follows:1.Aiming at the problem of safety and the interface impedance between ceramic solid electrolyte LATP and electrode material,quasi solid electrolyte was prepared by taking two kinds of LATP solid electrolyte with different morphology as matrix.The quasi-solid electrolyte based on the cross-linking morphology had high room temperature ionic conductivity.The results showed that due to the particularity of morphology,the cross-linked quasi-solid electrolytes increased the adsorption capacity with the electrolytes,reduced the grain boundary resistance,and sped up the ion conduction.2.Due to the contact between LATP quasi solid electrolyte and lithium metal,During the electrochemical cycle,the interfacial reaction continuously occurs and the battery capacity decreases.An alumina buffer layer was constructed on the surface of two LATP electrolyte films with different morphologies by atomic layer deposition（ALD）to act as the physical barrier between LATP and lithium metal.On the basis of the quasi-solid electrolyte films with the optimum deposition cycles of alumina corresponding to the two morphologies,the relevant physical characterizations and electrochemical tests were carried out respectively.The experimental results showed that the LATP benchmark solid electrolyte constructed through the alumina interface has better cycling stability.3.The processability of inorganic solid electrolytes is obviously insufficient in the preparation of electrolyte films and subsequent operations.Therefore,the quasi-solid composite solid electrolytes with high ceramic content were formed by adding a small amount of organic polymer PVDF material to the inorganic solid electrolyte LATP material and blending it with the electrolyte.The ionic conductivity,rate capability and electrochemical cycle performance of composite quasi-solid electrolytes prepared by adding different contents of organic polymer materials were tested.The experimental results showed that 20 wt.%The quasi-solid electrolyte films with PVDF content had relatively good ionic conductivity and good cycle performance.