What is the use of ion exchange membranes? Membrane materials provide safety and convenience for our production and daily life, such as film for vegetable greenhouses, explosion-proof film on car glass, and protective film on mobile phone panels. Membrane materials are also key components of fuel cells and flow cells, and membrane materials for this purpose are called ion membranes. Ionic membranes are polymer membranes that contain functional groups and have selective permeability to ions in solution. Traditional ion membrane materials have insufficient "robustness" in the channels used for conducting ions, and after prolonged use, the structure will age, leading to a decrease in performance. The team and collaborators of Professor Xu Tongwen and Professor Yang Zhengjin from the University of Science and Technology of China (hereinafter referred to as USTC) have designed a new type of ion membrane - microporous framework polymer ion membrane, which solves the problem of mutual restriction between conductivity and selectivity of ion membrane materials. On April 26th, the research results were published in the international academic journal Nature. It is reported that this type of ion membrane is expected to achieve the "curve overtaking" of domestic polymer ion membranes, providing technical support for achieving the national "dual carbon" strategic goal and sustainable development. The "small film" plays a "big role" as a key component of electrochemical devices or equipment such as liquid flow batteries and fuel cells. Ionic membranes not only need to block active substances between positive and negative electrodes, prevent short circuits, but also ensure efficient passage of ions and reduce losses during the charging and discharging process. However, traditional ionic membranes generally face the problem of "conductivity selectivity" mutual constraints and cannot be achieved simultaneously. "Just like screening sand with a sieve, the best sieve can block coarse sand (selectivity), screen fine sand and make it pass quickly (conductivity)." Zuo Peipei, the lead author of the achievement and a postdoctoral fellow of Xu Tongwen's team, introduced that the research focus of ionic membrane is how to build an efficient channel in the membrane that only allows "fine sand" to pass quickly. It is understood that the team has innovatively designed a microporous framework ion membrane material with interconnected sub nano ion channels, which solves the problems of ion channel aging and water absorption swelling in traditional ion membrane materials. In addition, the team chemically modified the channel wall to make the diffusion coefficient of ions in the membrane close to the state in water, achieving almost "zero friction" conduction, thereby breaking the mutual constraint between conductivity and selectivity. The design concept of the microporous framework ion membrane involved in this achievement can also be expanded to other functionalized framework polymer membranes, and based on this, high-performance membrane materials can be directionally designed, "said Xu Tongwen. It is worth mentioning that this research has a strong potential for achievement transformation - based on this core achievement, the research and development team of the research group "water system organic liquid flow battery pack" focuses on emerging large-scale energy storage and combines with photovoltaic power generation, which is expected to solve the intermittent problem of solar and wind power generation, and the special ion film products incubated by the project will also be introduced to the market. From "hard pursuit" to "overtaking on curves", Americans invented the ion exchange membrane in 1949 and successfully developed the first commercially available ion exchange membrane in 1950. The research on ion exchange membranes in China started in 1958, as the earliest field of functional membrane research in China, with the original intention of supporting the development of atomic energy industry. Until the end of the 20th century, the research on ion exchange membranes in China had been limited to the separation of