Preparation Of High Absorption Rate Polybenzimidazole Proton Exchange Membrane And Application Of Vanadium Battery

In recent years,the traditional energy has been exhausted,and the new energy industry is included in the national sustainable development strategy.The development and utilization of renewable energy such as solar energy,wind energy and so on urgently need to configure a large-scale energy storage device.Ion exchange membrane is the key to the operation of vanadium battery.At present,the most widely used Nafion membrane is from the DuPont Co.However,the high cost and high vanadium permeability of Nafion membrane show that it is not the best separator for vanadium battery.The goal of this paper is to prepare a class of polybenzimidazole ion exchange membranes with high proton selectivity and low cost for VRFB.The main contents are as follows:1.In this paper,3,3'-diaminobenzidine(DABz)and 4,4'-Dicarboxydiphenylether(DCDPE)have been used to synthesize OPBI polymer with an ether bond structure.The polymer was dissolved in 5 different solvents(MSA,DMF,DMAc,NMP,DMSO)and dense membranes were prepared by solution casting method.The effects of the type of solvents on the rate of acid absorption,proton conductivity,permeability of vanadium ion and the performance of the battery were investigated.The OPBI+MSA membrane prepared by using MSA as solvent has the highest proton conductivity(5.08 mS·cm-1)and the lowest vanadium ion permeability(7.2×10-9 cm2·min-1).Through the test of vanadium battery,it is known that the membrane also showed excellent battery performance,Coulombic efficiency(CE=99.87%),Voltage efficiency(VE=84.50%)was higher than that of Nafion 115 membrane,and after 480 cycles,the Energy efficiency(EE)value could still be maintained at 83.73%.The self discharge time of the single cell with the membrane is 1000 h,which is 22.2 times of that of the Nafion 115 membrane.2.OPBI with an ether bond structure and OOPBI with double ether bond structure porous membranes were prepared by vapor induced phase separation.The effects of temperature,relative humidity,film forming time,concentration of casting solution and casting solvent on the morphology of porous membranes were investigated,and the optimum conditions of preparing OPBI and OOPBI porous membranes by vapor induced method were determined:The water vapor temperature is 80?,the relative humidity is 60%,the membrane forming time is 30 min,MSA or DMAc is solvent,the OPBI polymer concentration is 5 wt%,and the OOPBI polymer concentration is 10 wt%.3.p-OPBI-1,p-OOPBI-1,p-OOPBI-2 porous membranes and d-OPBI-1,d-OOPBI-1 and d-OOPBI-2 dense membranes were prepared by vapor induced phase separation and solution casting respectively,and the battery performance was tested.The research found that the introduction of the porous structure can effectively improve the acid doping level.The membranes prepared with MSA as solvent have higher proton conductivity than those prepared with DMAc,while the membranes prepared by OPBI as the raw material have higher proton conductivity than those prepared by OOPBI.The porous membrane can effectively improve the proton conductivity,but compared with the dense membrane,its vanadium resistance,mechanical strength and oxidation resistance all decreased.