Study On Improvement Of Performance Of Solid-state Batteries By Modifying Graphite And Solid Inorganic Electrolyte With Organosilicone

The silane coupling agent has both hydrophilic and hydrophobic ends,so two different materials can be combined by a third intermediate material-coupling agent.The surface modification of SiO₂ and natural flake graphite by silane coupling agent can not only effectively enhance the dispersibility and uniformity of SiO₂ and natural flake in organic solvents,but also combine the filler,negative electrode material and polymer matrix,availably combine to improve the interface affinity between the electrode and electrolyte.For the above purposes,the main research content of this paper is the preparation of PEO-based composite polymer electrolytes and carbon-based anode materials with high electrode/electrolyte interface affinity and excellent cycle performance.Firstly,study the influence for different mass ratio and components of fillers on the electrochemical performance of the electrolyte,try different modification methods to modify the inorganic filler,enhance the dispersion and uniformity of the inorganic filler in the polymer electrolyte,and improve electrochemical properties of polymer electrolytes.In addition,try different methods to modify the natural flake graphite,preparing carbon-based negative electrode materials with excellent electrochemical stability,high specific capacity,and strong interfacial compatibility with electrolyte materials.In this paper,a simple solution casting method was used to prepare PEO-based solid polymer electrolyte membranes.The effects of different molar ratios of EO: Li,different molecular weight of PEO,and different types of fillers and filler ratios on the performance of the synthesized PEO-based solid polymer electrolytes were discussed and compared.The PEO-based solid electrolyte prepared with EO: Li = 18: 1 molar ratio and molecular weight M = 500,0000 of PEO is uniform and has the highest ion conductivity of 8 × 10^-6 S/cm,PEO₁₈LiTFSI-10 mass% LAGP composite polymer electrolyte membrane has the best mechanical properties,tensile strength is 2.52 MPa,elastic modulus is 4.81 MPa,and the room temperature ion conductivity is the highest,reaching 7.5 × 10^-5 S/cm.In addition,the five kinds of electrolyte membranes tested have a stable potential window between 0.10 V-5.00 V,which lays a good foundation for the selection of positive electrode active materials in all-solid-state lithium batteries in the future and provides a broad selection space.In this paper,the nano-SiO₂ and natural flake graphite are modified with silane coupling agent.The nano-SiO₂ modified with silane coupling agent using a simple liquidphase mixing method.The results show that the composite polymer electrolyte PEO₁₈LiTFSI-10 mass % modified nano-SiO₂ has obvious improvement in surface dispersibility,ionic conductivity,tensile strength,lithium stability,etc.The ion conductivity is 4.94 × 10^-5 S/cm of the modified polymer electrolyte membrane,the tensile strength is 2.06 MPa,and the elastic modulus is 4.23 MPa;The natural flake graphite is modified with four modification methods and four silane coupling agent addition ratios,and the results show that the method of adding KH-570 directly after strong acid treatment and the adding ratio of 10 mass% KH-570 have the best cycle performance.The first reversible capacity is 255.6 m Ah/g,and the maximum reversible capacity after 18 cycles is 359.2 m Ah/g,the reversible capacity is still 359.2 m Ah/g after 50 cycles,and the capacity retention rate is 100.0%.