SBIR Phase I: Nanostructured Ceramics Membranes for Redox Flow Batteries with Superior Performance and Low Cost

This SBIR Phase I project seeks to develop a novel low-cost molecular filter for use in harsh environments. This is accomplished using commodity silica gel, commonly found as a desiccant in food packing, whose pores can be made to be only a few molecules wide. Accurate tuning of the size and shape of the silica gel pores enables certain molecules to pass through while others are block from passing. One promising application for these molecular filters is their use in grid-scale energy storage. Flow batteries have the ability to store city-sized quantities of renewable energy. However, they require the use of expensive molecular filters that are not easily replaced due to the harsh battery environments. The low-cost filters developed during this SBIR Phase I project have the potential to reduce the cost of flow batteries by as much as 30%. Lower cost grid-scale storage means that more renewable energy generation (e.g., solar & wind) can be added without overwhelming the grid. Low cost molecular filter also have commercial upside with the potential to capture a $1.3 billion dollar market. Because of this, this project is expected to generate nearly 20 jobs and $79 million dollars in tax revenue over the next 5 years. This SBIR Phase 1 Project is developing a molecularly selective sol-gel ceramic membrane that does not require calcination or high polymer loading but also does not fracture during compression in stack applications (e.g., fuel cells and flow batteries). This is accomplished by decoupling the selective region from the region of the membrane being compresses by the stack. These membranes will be utilized to improve the performance and reduce the costs of all-vanadium redox flow batteries (VRFB). These membranes require selective transport of hydronium ions but not vanadium ions. Size exclusion membranes must therefore have tight control over the pore size and size distribution, shape and network structure in order to selectively transport ions. Towards this end, sol-gel processing and surface chemistry modification will be utilized to maximize proton conductivity and limit vanadium ion permeability. Optimized membrane formulations must also have excellent chemical and mechanical stability; showing no degradation after hundreds of VRFB cycles. Finally, membranes must be scaled from lab size (1 cm2) to commercial size (630 cm2) while maintaining performance uniformity. The low-cost membranes developed during this SBIR Phase I project have the potential to reduce the cost of VRFBs by as much as 30%. Lower cost grid-scale storage means that more renewable energy generation (e.g., solar & wind) can be added without overwhelming the grid.