Preparation Of PVDF-HFP/MOFs Composite Solid Electrolyte And The Application In Lithium Battery

Metal-organic framework materials（MOFs）are an emerging field in the research of high-performance solid-state electrolytes（SSEs）today.The large specific surface area,abundant porosity,pore orderliness and structural tunability of MOFs offer a great potential for the improvement of electrolyte ionic conductivity and cation mobility number.In this paper,the performance of composite solid-state electrolytes（CPEs）with different ligands of Zn metal MOFs and H₂BDC ligand MOFs with different coordination metals as fillers is investigated in relation to PVDF-HFP as the polymer matrix and Li TFSI as the lithium salt,and the next refined research directions of this topic are prospected.In this paper,Zn-BTC,ZIF-8,ZIF-62 with Zn²⁺as the coordination metal and Ui O-66,MIL-101（Cr）,MIL-101（Fe）with H₂BDC as the ligand were prepared using MOF-5（Zn-BDC）as the entry point,and in addition,HKUST-1（Cu-BTC）,which is similar in configuration to Zn-BTC but more suitable for bulk synthesis,was investigated together with Zn-BTC.A total of eight MOFs were used as fillers in the preparation and performance of the composite solid electrolytes,and it was found that the addition of MOFs could effectively improve the performance of pure PVDF-HFP electrolytes.According to the comparison of eight types of PVDF-HFP/MOFs CPEs in various characterization tests,MOF-5,UIO-66 and HKUST-1 as composite solid electrolyte fillers performed better,in addition to the general advantages in reducing the crystallinity and enhancing the thermal stability of pure PVDF-HFP electrolyte,CPEs with MOF-5and Ui O-66 can have the electrochemical window of up to 5.0 V,the lithium ion migration number of CPEs with Ui O-66 and HKUST-1 is close to 0.5,while the ionic conductivity of the three can reach more than 2.6×10^-5 S cm^-1,ranking among the top eight types of CPEs.Moreover,it can significantly improve the mechanical strength of the electrolyte and show excellent electrochemical stability in lithium deposition stripping tests,rate performance tests and high current density charge/discharge cycles.This paper realizes the first exploration of molecular dynamics（MD）in the research work of our group,and explores the techniques of model establishment,force field selection,parameter influence,process and result processing of MD,and finally constructs various composite solid electrolyte system models and performs theoretical calculations to verify the ion sieving role played by MOFs in electrolytes.It is worth mentioning that MOF-5,as the entry point of the whole work,has the most prominent advantages both in Zn metal MOFs with different ligands and H₂BDC ligand MOFs with different ligand metals,and it is very worthy of further in-depth research in filler filling ratio and electrolyte structure design.