Sulfonated poly(arylene ether ketone) impregnated porous PTFE electrolyte membranes with ultra-low vanadium ion permeability for vanadium redox flow battery
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초록
내용
The proton conductive electrolyte membranes were prepared by impregnating sulfonated poly(arylene ether ketone) (SP) into the porous polytetrafluoroethylene (PTFE) substrates for vanadium redox flow battery application. To impregnate SP, the surface of porous PTFE was chemically hydrophilized with catechol and polyethyleneimine. The SP filled PTFE membranes (trPTFE/SP) showed enhanced thermal, and mechanical stability, compared with the pristine SP membranes. Also, this pore filling process slightly decreased the proton conductivity of the pure SP membranes by 10 %, it hugely decreased the vanadium ion permeability about 5 times. The lowest vanadium permeability of prepared membranes (1.37 × 10-7 cm2 min-1) was even 15 times lower than that of Nafion117 (20.28 × 10-7 cm2 min-1). This low vanadium permeability led to high coulombic efficiency over 96 % and energy efficiency around 84 % during the 100 charge-discharge cycling tests, which are better than Nafion 117 membrane.