The Preparation And Performances Of High Ceramic Content PAN-Based Composite Solid Electrolytes

In order to achieve high energy density all-solid-state lithium batteries,current electrolytes and commercial PP membrane cannot meet the corresponding needs.A desirable solid-state electrolyte has the potential to achieve negative electrodes matched to lithium metal as well as positive electrodes matched to high-energy positive electrodes.Solid state electrolytes are divided into inorganic ceramic electrolytes and polymer-based electrolytes.Due to solid-solid contact at the interface with the electrode,inorganic ceramic electrolytes have a blocked ion transport,while the low ionic conductivity of polymer-based electrolytes at room temperature prevents both from being used in a single application in lithium metal batteries.By combining both of inorganic and polymers electrolytes is a common approach to solve the problem of matching solid electrolytes to lithium metal batteries.However,inorganic ceramic electrolytes often exist as 0-dimensional fillers in composite electrolytes,which have problems such as agglomeration and inability to conduct lithium ions effectively in a single presence,and the effect is not much different from that of solid-state electrolytes with inert fillers.Firstly,in this work,high ceramic content solid state electrolytes（x wt%SiO2@PAN SEs）with high ionic conductivity and dendrite suppression effect were prepared by electro spraying nanoscale SiO2particles and electro spinning polymer PAN nanofibers with rolling and infiltration of lithium salts.The prepared SiO2@PAN SEs formed a percolation network with an ionic conductivity of 1.17 m S/cm at 60°C and an electrochemical window of 4.9 V.A specific capacity of 157.1 m Ah/g at 2C rate was achieved by matching the NCM811 cathode with 10μL of1 M Li PF6 in DC/EMC electrolytes.This demonstrates that solid electrolytes with a high ceramic inert filler content have no less performance than inorganic fast ion conductors.In addition,0-dimensional inorganic electrolyte fillers are unable to conduct lithium ions effectively in the composite solid electrolytes.In this paper,Li_6.4La₃Zr₂Al_0.24O₁₂（LLZAO）nanofibers were prepared by sol-gel electrospinning combined with two-times sintering,by varying the concentration of polyvinyl pyrrolidone（PVP）in the spinning solution,and the crystalline shape and morphology of the products at different sintering temperatures.LLZAO nanofibers were final prepared by a two-step sintering method.By casting the LLZTO particles and LLZAO nanofibers into the PP separator with PEO solution,the prepared electrolyte films were tested for intrinsic impedance,critical current density and full-cell cycling,the results showed the Li6.4La3Zr2Al0.24O12（LLZAO）nanofibers with aspect ratio in PEO have better electrochemical properties and higher ionic conductivity.