Anion Exchange Membranes (AEMs) are important components in many electrochemical reactors and separation devices, where they serve as a physical barrier that controls the selective transport of ions. They are typically produced by evaporation casting ionomer solutions into thin flat sheets, which limits their use to parallel-stacked electrochemical devices. Attempts to manufacture these membranes using 3D printing have been demonstrated only through the use of sacrificial 3D printed molds or of similar UV sensitive resins. The following invention builds upon the capability of manufacturing surface features to designing and printing fully-formed 3D substrates, enabling significant enhancements in design flexibility over other processes.
The novel LLNL approach is to use projection microstereolithography (LAPµSL), starting with a photocurable methacrylate resin formulation consisting of a combination of a photoinitiator, photoabsorber, inhibitor, solvents, and other additives. Prior to use, the resin is pretreated to control viscosity for easier handling. The resin is fed to a LAPµSL printer which employs a near UV light source. The printed membranes are then post-processed to form cations within the polymer network that facilitate ion transport. Various process parameter optimizations have been explored including for example the effect of cure conditions on the crosslink density (or glassiness of the material) which affects the ability to create a functioning AEM material.
LLNL’s Projection Microstereolithographic Additively Manufactured Anion Exchange Membrane (AEM) Technology has numerous advantages over traditionally fabricated Anion Exchange Membranes, such as:
- Enables high resolution 3D printing of optimized AEM designs for enhanced mass transport.
- Enables new customizable electrochemical reactor designs for efficient conversion of CO2 into value added carbon products.
- Overcomes mass transport limitations of current ion exchange membrane technology based on layers of many thin evaporation cast ionomer sheets.
- Fuel cells
- Electrodialysis and Reverse Electrodialysis (RED)
- Membrane Chromatography
- Wastewater treatment
- Acid recovery
Current stage of technology development: TRL 3 (October 2022)