The all-vanadium redox flow battery(VRFB)plays an important role in the energy transition toward renewable technologies by providing grid-scale energy storage.Their deployment,however,is limited by the lack of membran...The all-vanadium redox flow battery(VRFB)plays an important role in the energy transition toward renewable technologies by providing grid-scale energy storage.Their deployment,however,is limited by the lack of membranes that provide both a high energy efficiency and capacity retention.Typically,the improvement of the battery’s energy efficiency comes at the cost of its capacity retention.Herein,novel N-alkylated and N-benzylated meta-polybenzimidazole(m-PBI)membranes are used to understand the molecular requirements of the polymer electrolyte in a vanadium redox flow battery,providing an important toolbox for future research toward next-generation membrane materials in energy storage devices.The addition of an ethyl side chain to the m-PBI backbone increases its affinity toward the acidic electrolyte,thereby increasing its ionic conductivity and the corresponding energy efficiency of the VRFB cell from 70%to 78%at a current density of 200 mA cm^(-2).In addition,cells equipped with ethylated m-PBI showed better capacity retention than their pristine counterpart,respectively 91%versus 87%,over 200 cycles at 200 mA cm^(-2).The outstanding VRFB cycling performance,together with the low-cost and fluorine-free chemistry of the N-alkylated m-PBI polymer,makes this material a promising membrane to be used in next-generation VRFB systems.展开更多
基金supported by the Swiss National Science Foundation(grant number 188631).
文摘The all-vanadium redox flow battery(VRFB)plays an important role in the energy transition toward renewable technologies by providing grid-scale energy storage.Their deployment,however,is limited by the lack of membranes that provide both a high energy efficiency and capacity retention.Typically,the improvement of the battery’s energy efficiency comes at the cost of its capacity retention.Herein,novel N-alkylated and N-benzylated meta-polybenzimidazole(m-PBI)membranes are used to understand the molecular requirements of the polymer electrolyte in a vanadium redox flow battery,providing an important toolbox for future research toward next-generation membrane materials in energy storage devices.The addition of an ethyl side chain to the m-PBI backbone increases its affinity toward the acidic electrolyte,thereby increasing its ionic conductivity and the corresponding energy efficiency of the VRFB cell from 70%to 78%at a current density of 200 mA cm^(-2).In addition,cells equipped with ethylated m-PBI showed better capacity retention than their pristine counterpart,respectively 91%versus 87%,over 200 cycles at 200 mA cm^(-2).The outstanding VRFB cycling performance,together with the low-cost and fluorine-free chemistry of the N-alkylated m-PBI polymer,makes this material a promising membrane to be used in next-generation VRFB systems.
