Development of Sodium-Ion Exchange Membranes for Polysulfide-Based Redox Flow Batteries to Overcome the Cross Shuttling of Electrolytes

Project: Research

Project Details


Steady growth in the renewable energy sources, necessitates the upscaling of grid-level energy storage facilities. Amongst these energy storage systems, redox flow batteries (...(RFB) are considered one of the better options due to their effective decoupling of power and energy ability, comparatively longer projected life, and improved safety standards for electricity storage from medium to large scale applications. Among RFBs, polysulfide-based redox chemistries are considered the best option for grid storage applications. Sulfur is one of the main precursor materials needed for manufacturing polysulfide-based RFBs. Notably, Saudi Arabia produces 7.1 million tons of sulfur annually and exports 3.5 million tons. This places the kingdom among the largest sulfur-producing countries in the world. For example, the Abqaiq facility alone, is able to produce 100,000 tons of sulfur on an annual basis. The availability of a local precursor for polysulfide based RFB can compensate for the cost challenge while producing polysulfide RFB within the Kingdom. However, other challenges such as severe cross-over of sulfide, self-discharge, low solubility, precipitation of colloidal sulfur, stability, and particularly ion-exchange selectivity of membranes are the main obstacles that prevent the commercialization of this technology currently. If we can overcome the above-mentioned shortcomings and exploit local resources available, it will aid in lowering the cost further i.e., at present US$0.15 kAh−1. This would help in realizing the commercialization of polysulfides-based RFBs in the Kingdom. Our research group is already working to improve the solubility of polysulfides challenge in water (currently achieved solubility ~8.8 molL−1) [1,2]. However, the fabrication of membranes that could prevent the preferable channelling of water between half-cells to avoid concentration gradient as well as the cross shuttling of polysulfide ions between anolytes and catholytes still poses an immense challenge to overcome. Therefore, in this project, we aim to develop cation-selective exchange membranes that: (i) are selective in the transfer of sodium ions between anode and cathode, (ii) have high ionic conductivity, (iii) show excellent chemical/thermal stability, and (iv) reasonably cost-competitive.
Effective start/end date1/04/221/10/23


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