Bilayer Electrolyte Membrane and a Redox Flow Battery Comprising a Bilayer Electrolyte Membrane

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This invention relates to a bilayer electrolyte membrane designed for use in redox flow batteries, especially vanadium redox flow batteries. The membrane is constructed from two different polymer layers: a thin, ion-conducting polymer containing N-heterocycles (such as polybenzimidazoles) that serve as proton acceptor sites, and a mechanically robust support polymer (which can be either porous or a dense ion-exchange material). The innovative bilayer structure minimizes ionic resistance, reduces the crossover of redox-active ions like vanadium (which can otherwise reduce battery capacity), and provides mechanical strength and chemical stability needed for efficient, long-lasting battery operation.

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• Stationary large-scale energy storage systems for renewable energy (solar, wind) integration into the electrical grid.
• Grid stabilization, load leveling, and peak shaving applications in power networks.
• Industrial energy management and backup power supply systems using redox flow batteries.
• Advanced electrolytes in research and development of new types of redox flow batteries with improved longevity and efficiency.
• Potentially in other electrochemical devices requiring selective ion transport membranes with high mechanical strength.

BenefitsContent extracted from patent full text and abstract with AI.

• Greatly reduced ohmic/ionic resistance in the electrolyte membrane, improving battery efficiency and performance.
• Lower permeability to redox-active species (especially vanadium ions), reducing capacity fading and cross-contamination between battery electrolytes.
• Enhanced mechanical robustness and chemical stability for better device durability and longer operational lifetime.
• Ability to customize membrane properties (thickness, transport, selectivity) by adjusting the composition and structure of the bilayer.
• Potential for reduced manufacturing costs by using thinner active layers and robust support materials.
• Improved round-trip energy efficiency and maintained capacity over many charge/discharge cycles compared to standard commercial membranes.

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Patent Abstract

The present invention has the objectives to provide an electrolyte membrane and a method for generating such an electrolyte membrane wherein the resistance of the electrolyte membrane should be as low as possible to minimize ohmic losses. Concurrently, the electrolyte membrane should have a low permeability for the redox-active species. If redox-active species are still crossing the electrolyte membrane, this transport should be balanced during charge and discharge in order to prevent a net vanadium flux and the associated capacity fading. Moreover, the electrolyte membrane should be mechanically robust, chemically stable in the respective electrolyte solution, and be of low cost.The present invention describes a family of ion exchange membranes comprising a bilayer architecture to achieve these requirements. The bilayer membrane comprises two polymers, i) a polymer comprising N-heterocycles with electron lone pairs acting as proton acceptor sites and ii) a mechanically robust polymer that acts as a support, which can be a dense cation exchange membrane or a porous support layer as shown in Figure 2. This bilayer architecture allows the use of a very thin (