Ion-conducting polymers (called ionomers) are used as polymer electrolyte membranes which are a key component of electrochemical energy conversion and storage technologies such as fuel cells, electrolyzers, and flow batteries. The use of ion-conducting polymers in these electrochemical energy technologies has a long history but the lack of suitable low-cost, high-performance ion-conducting polymers has hampered wide adoption of these emerging energy technologies. In this presentation, we discuss some highlights from recent progress at the Bae group of Rensselaer Polytechnic Institute in the development of advanced ion-conducting (H+ and OH–) polymers, their state-of-the-art performance in redox flow battery technology application.[1,2]