Research On Mechanical Properties And Preparation Process Of Coated Lib Separator Based On Micro-nano Scale

Lithium-ion batteries are efficient,environmentally friendly,and high-energy density batteries that are widely used in aerospace,energy storage systems,electric vehicles,portable electronic devices,and other fields.Among them,the porous membrane,as a key component inside the lithium-ion battery,is usually made of polyolefin materials.Polymer often has a very complex structure and characteristics that are closely related to the micro-molecular structure.However,traditional experimental methods are difficult to establish the relationship between macroscopic properties and micro-molecular interactions of polymer membranes,which hinders a more in-depth understanding of the membrane.Therefore,this paper uses a molecular dynamics method to explore the mechanical properties and coating preparation processes of the membrane at the nanoscale.This article explores the mechanical strength and structural changes of polyethylene under stress and deformation by using a molecular model.The relationship between molecular energy and stress-strain during the deformation process is calculated to help clarify the deformation mechanism in the elastic,yielding,and strain hardening regions.Different temperatures can affect the movement of molecules and the magnitude of their interactions,leading to different strength characteristics in materials at the macro level.Different stretching rates can affect the motion processes of molecular chains such as sliding,rotation,and twisting,slowing down the stretching rate allows enough time for molecular chains to move and reduce stress accumulation,thus exhibiting lower strength.During the puncture simulation process,the force state of the polyethylene substrate was obtained,which characterized the correlation between the load and the puncture depth.In the simulation study of coating mixture,the shear rate affects particle motion and distribution in the model.The adsorption of the binder on the surface of aluminum oxide particles increases with the increase of shear rate.Different shear actions also affect the aggregation state and molecular structure of polyacrylic acid（PAA）binder molecules.At low shear rates,shear may promote PAA molecular aggregation,increase system viscosity,and decrease system fluidity.At high shear rates,shear may break up the aggregated structure of PAA molecules,making them more evenly dispersed and improving system fluidity and dispersion.In the study of the drying process,different drying rates were simulated and calculated in this article.The research indicates that in the drying process,the migration of Al₂O₃occurs upwards,increasing the content at the surface,affecting the homogeneity of dispersion.Also,the faster the drying rate,the more severe the aggregation of Al₂O₃at the model’s top.By using the molecular simulation methods,the aggregation state and microstructural changes of polyacrylic acid molecules were obtained.Meanwhile,the bonding strength of the adhesive and the molecular structural changes during the failure process were explored at the nanoscale.The non-bonded interactions between adhesive molecules at the interface are the dominant factor in the bonding performance.During the deformation and failure process of the adhesive molecule,the structural deformation is mainly achieved through the slip motion and dihedral angle rotation between the molecular chains.