| Metal-organic-frameworks (MOFs) are novel porous materials, composing metal ion andorganic ligands. Due to the diversity of organic ligands, MOFs are designable, better thantraditional of zeolite material, is becoming a hot star materials. Zeolite ImidazolateFrameworks (ZIFs) represent a special kind of MOFs, composing imidazolate agents andmetal ions, having similar structure as zeolite. In this paper, we introduce a method usingionothermal synthesis to prepare ionic liquid (IL) modified metal-organic frameworks (MOFs)denoted as IL@ZIF-8. Ionic liquid are not only a solvent, but also playing a role as templateagent. Therefore ZIF-8nanoparticles exist with ionic liquid-choline hydroxide in theframeworks, which we called IL@ZIF-8. With the modification of ionic liquid, theperformance of ZIF-8has also been changed. After testing, we found that, IL@ZIF-8nanoparticles at room temperature, in98%relative humidity, have a higher conductivity thanunmodified nanoparticles four orders of magnitude, which is about4×10-7. In addition, IL@ZIF-8nanoparticles respond obviously different at various humidity, which means that, withionic liquids modifying, hydrophilicity of ZIF-8material is improved.Starting from the point of the ionic liquid, we focus on the electrochemical properties ofionic liquid, because of its low boiling point, not combustion, and high conductivity, etc.,makes the research of ionic liquid/polymer composite films reflect a great deal of potential.However, the greatest problem facing this type of composite membrane is the loss of the ionicliquid. Because of the inherent liquid state, ionic liquid would flux at the actual operatingenvironment and the loss of the ionic liquid can greatly affect the performance of the entirebattery system. To solve this problem, we think through the ionothermal synthesis, there ionicliquid can be fixed in ZIFs material, and then ZIFs can be doped into the polymer. Bypreparing IL@ZIF-8/polymer composite film in this indirect method, ionic liquid is fixed inthe polymer. We use polyvinyl alcohol as polymer matrix, which is very common. Ionic liquidsynthesized by ionothermal method remains in the pores of ZIF-8. Through In-situ synthesismethod, ZIF-8nanoparticles uniformly dispersed in the polymer matrix (PVA). Ionic liquids as solvents and a template, is retained within the framework of ZIF-8, which makes thesynthesized composite membrane having a stable electrochemical properties of conductinghydroxyl ions, to solve the problems of the loss of ionic liquids existing in conventionalcomposite membranes. With different content of IL@ZIF-8nanofillers, we found that, withincreasing nanoparticle doping level, conductivity of composite polymer electrolytemembrane showed an increasing tendency, when the IL@ZIF-8nanoparticles doping amountincreases to48%, its conductivity reaches2.6×10-4S cm-1.Ionic liquid/polymer composite membranes are commonly used in high-temperatureproton electrolyte membrane, the choice of ionic liquids are also protonated ionic liquids. Inthis work, we focus on anionic ionic liquid electrolyte membrane. So our work is aroundanother part in the preparation of ionic liquid/anionic polymer electrolyte membrane. Ourselected ionic liquid is still choline hydroxide. In order to improve the electrochemicalperformance and mechanical properties of the ionic liquid-based polymer compositeelectrolyte, we add IL@ZIF-8nanoparticles as fillers in the preparation of IL@ZIF-8/PVA/ILcomposite membrane. IL@ZIF-8nanoparticles in the composite film formed channels forionic liquid conducting; at the same time, as inorganic fillers, IL@ZIF-8nanoparticles canalso increase the mechanical strength of the composite membrane, which is very important forIL@ZIF-8/PVA/IL composite membranes used for future practical applications. |
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