Modification Of SiC-doped PVDF-HFP And Its Application As Separator For Lithium-ion Batteries

In the face of increasingly severe environmental pollution and traditional non-renewable energy consumption,finding a pollution-free and sustainable green energy as a substitute for traditional energy has become a major research hotspot in the energy field.Among many new energy sources such as solar energy and wind energy,lithium battery has attracted extensive attention due to its advantages such as high energy density,high output voltage,high output power,and no memory effect.The separator is one of the main components of lithium-ion batteries(LIBs),and its performance directly affects the electrochemical performance and working stability of LIBs.Polyvinylidene fluoride hexafluoropropylene(PVDF-HFP)separator has good high-temperature resistance,corrosion resistance,and electrochemical performance,but its thermal stability and mechanical strength still need to be improved.Based on the characteristics of high strength,hardness,good wear resistance,and good oxidation resistance of silicon carbide(SiC).Among inorganic materials,SiC ranks fourth in hardness,second only to diamond,boron carbide,and cubic boron nitride.This paper uses SiC nanoparticles doped with ordinary PVDF-HFP separators to further improve the liquid absorption and porosity of the separators.Based on the different doping ratios of SiC and PVDF-HFP,modified SiC/PVDF-HFP artificial composite separators were prepared,and then assembled into LFP batteries for various tests,The results indicate that the modified composite film can not only meet the electrochemical performance requirements of LIBs for normal operation,but also improve the uniformity of lithium ion deposition on the negative electrode surface,effectively suppress the growth of dendrites,and greatly improve the cycling stability of LIBs.This paper uses SiC nanoparticles to modify the PVDF-HFP separator and synthesize a SiC/PVDF-HFP composite separator for lithium-ion batteries.The separator has high thermodynamic stability.Comparative study was conducted between polymer separators(PVDF-HFP and Celgard2500)and SiC/PVDF-HFP separators.SiC doped separators with different doping ratios were prepared using PVDF-HFP as the matrix material through non solvent induced phase separation method.The forming process of the separator was determined,and the influence of different SiC doping ratios on the performance of the separator was explored.It was compared with PVDF-HFP separator and commercial separator,and tested and characterized.Theoretical analysis was conducted through modeling and calculation,and the structure of lithium dendrites inside the separator was explored through the study of lithium symmetric batteries.The thermodynamic stability,electrochemical performance,and inhibition of lithium dendrite puncture effect of the battery separator were improved through doping modification,thereby improving the safety of lithium batteries.This strategy provides a feasible solution for the composite separator of high-temperature and impact resistant high safety lithium batteries.