Organic framework membranes for electrochemical energy storage: structure–property insights

The transition to sustainable energy requires efficient storage technologies to manage the intermittency of renewables like solar and wind. Electrochemical devices such as supercapacitors, lithium-ion batteries, and redox flow batteries depend heavily on ion-conducting membranes for ionic transport, selectivity, and stability. Traditional membranes, including Nafion, SPEEK, and PVDF, face challenges like thermal instability and limited conductivity. To address these issues, organic framework materials have emerged as promising alternatives. This review focuses on four main classes: metal–organic frameworks (MOFs), covalent organic frameworks (COFs), porous organic polymers (POPs), and hydrogen-bonded organic frameworks (HOFs). MOFs provide high porosity and tunability; COFs offer crystallinity and chemical stability; POPs support scalable synthesis and mechanical strength; and HOFs enable the fabrication of reversible, self-healing structures. This review explores synthesis methods, structure–property relationships, and electrochemical performance, outlining strategies to improve membrane functionality and durability in advanced energy storage systems.