Preparation And Properties Of Microporous Polymer Cation Conducive Membranes

Ion exchange membranes have attracted great interest as key components in energy storage and conversion devices.Ion exchange membrane should have high ion conductivity,good mechanical properties,thermal and electrochemical stability.Its basic function is to prevent short circuit caused by contact between cathode and anode.In the new generation of lithium air battery,liquid flow battery and lithium sulfur battery,it is hoped that the membrane can effectively prevent the penetration of molecules such as gas and solvent.The molecular structure of intrinsic microporous polymer is distorted,which can prevent effective space from being filled and pore collapse,make it have microporous characteristics and prevent the penetration of small molecules.In this paper,based on the structural characteristics of intrinsic microporous polymer,a series of new ion exchange membranes,such as mixed matrix membrane,carboxyl functionalized membrane and sandwich structure membrane,were prepared.The thermal stability,mechanical strength and electrochemical stability of the membranes were studied in detail.The ion exchange characteristics of the membranes were explored.A conceptual Li/Na-H₂O₂ mixed electrolyte flexible battery was constructed.In the experiment,the battery could be flat.The stable discharge proves that the intrinsic microporous polymer membrane can be used as ion selective conduction membrane and in the construction of new generation energy devices.The details are as follows:（1）Intrinsic microporous polymer（PIM-1）with molecular weight greater than 50000g/mol was successfully synthesized,which has good film-forming properties and provides a basis for the preparation of subsequent cationic conductive membranes.（2）Two kinds of mixed matrix films were prepared by filling metal-organic framework nanocrystals（UiO-66-NH₂）and lithium salts with intrinsic microporous polymer（PIM-1）as film-forming matrix.The morphology,structure and ionic conductivity were studied.It was found that the cationic conductivity of the membrane mixed with MOF and lithium salt was significantly enhanced.（3）The carboxyl（-COOM）functionalized cationic conductive membrane was obtained by hydrolysis of the self-contained microporous polymer membrane.The nitrile group（-CN）in the main chain was hydrolyzed to-COOM without changing the stacking mode of its molecular structure.The hydrolyzed membrane not only has high specific surface area and microporous structure,good mechanical properties and thermal stability,acid and alkali resistance,adjustable thickness and good flexibility,but also has good lithium ion conductivity in water(1.6?10^-3 S cm^-1)and organic(1?10^-5 S cm^-1)electrolytes.The lithium metal-hydrogen peroxide battery was constructed to discharge smoothly.When the current density was 0.2 mA cm^-2,the output voltage was 2.9 V.（4）By in-situ hydrolysis of polymer membranes mixed with lithium salts,sandwich membranes with large pore surfaces can be constructed.The ionic conductivity of the membranes is greatly improved compared with the original membranes,and the electrochemical window of the membranes is also significantly increased to 0-4.5 V.The conductivity of lithium ion in aqueous and organic electrolytes is 6.63?10^-3 and 5?10^-4 S cm^-1,respectively.The flexible aluminum-plastic film lithium metal-hydrogen dioxide battery made of lithium ion can light blue LED at different bending angles.