Preparation And Performance Study Of Flexible Solid-state Lithium-ion Battery Electrolyt

In recent years,flexible and wearable electronic devices have become an important direction for the development of electronic technology.Soft robots are also applied in more scenarios.Soft robots and flexible electronics have increasingly strict requirements for the deformation performance of their energy storage components.Flexible solid-state lithium-ion batteries are an ideal choice.Flexible solid-state lithium-ion batteries can overcome the shortcomings of poor deformation performance and poor safety of traditional lithium batteries,and the most important thing is to transform liquid electrolytes into flexible solid-state electrolytes,tantalum doped lithium lanthanum zirconium oxygen(Li_6.4La₃Zr_1.4Ta_0.6O₁₂,LLZTO)with garnet like structure is a very promising electrolyte material.This paper will focus on preparing flexible solid-state electrolytes and studying flexible slid-state lithium-ion batteries.This article focuses on the material selection and ratio design of LLZTO electrolyte thin films and sets the electrochemical performance of the prepared electrolyte thin films.And prepare polymer composite positive and negative electrodes that match the electrolyte film,and test the mechanical properties of the electrolyte film and positive and negative electrode films.Finally,a flexible solid-state lithium-ion battery was prepared by layering.The specific research work of this paper is as follows:（1）To prepare the electrolyte for flexible solid lithium-ion batteries,LLZTO,diethylenetriamine,polyethylene glycol dimethyl ether,and polyethylene glycol di glycidol ether were used as the components to prepare the electrolyte film.In order to study the effect of polyethylene glycol dimethyl ether and polyethylene glycol di glycidol ether on the surface morphology of the electrolyte film,the film surface was characterized by SEM.The study showed that polyethylene glycol dimethyl ether and polyethylene glycol di glycidol ether had a modification effect on the surface of the electrolyte film.When LLZTO:PEGDME:PEGDE:DETA was 70:3:15:3（wt%）,the electrolyte film had a better and more regular surface micromorphology.（2）To explore the influence of polyethylene glycol dimethyl ether on the conductivity of electrolyte films,we measured the electrochemical impedance of electrolyte films with different polyethylene glycol dimethyl ether content and calculated the conductivity.The results show that the existence of polyethylene glycol dimethyl ether will reduce the ionic conductivity of the electrolyte film.Without polyethylene glycol dimethyl ether,the electrolyte film has the best ionic conductivity,which is 1.26×10^-6S/cm,at room temperature.To investigate the electrochemical performance of the electrolyte film,the electrolyte film was polarized and the lithium-ion transference number of the electrolyte film with an LLZTO content of 60wt%was calculated to be 0.27.（3）To study the mechanical properties of various parts of flexible solid-state lithium-ion batteries,a coating method was used to prepare flexible solid-state electrolyte films and flexible polymer composite electrodes,and tensile experiments were conducted on the electrolyte films and positive and negative electrode films.The research results indicate that the elongation of the electrolyte film containing 60wt%LLZTO is 25.87%.When LFP:EVA is 7:2（wt%）,the elongation of the positive electrode film is 8.09%.When LTO:EVA is 7:2（wt%）,the elongation of the negative electrode film is 15.92%,and the electrolyte film as well as the positive and negative electrode films have good flexibility.