Polymer Blend Proton Exchange Membrane for Vanadium Redox Batteries

The patent uses a composite membrane structure combining perfluorosulfonic acid polymer matrix with inorganic filler particles (such as metal oxides or ceramic materials). This composite structure maintains the chemical stability and ion conductivity of the perfluorosulfonic acid membrane while the inorganic filler provides selective permeability barriers that prevent vanadium ion passage, thus resolving the contradiction between chemical stability and permselectivity.

The patent employs a porous membrane structure with controlled pore size and distribution. The porous structure allows protons to conduct through the membrane while the specific pore dimensions (typically sub-nanometer scale) prevent larger vanadium ions from passing through. This approach maintains ion conductivity while achieving high permselectivity, addressing the contradiction between ion conductivity and vanadium ion permeability.

The patent modifies the perfluorosulfonic acid membrane by changing physical parameters such as thickness, pore size distribution, and filler particle concentration. By optimizing these parameters, the membrane achieves the required ion conductivity at reduced material quantities and simplified manufacturing processes, thereby lowering production costs while maintaining performance.

The patent replaces expensive perfluorosulfonic acid polymers with alternative polymer materials that have similar ion conductivity properties but lower cost. These alternative materials may include sulfonated polyetheretherketone (SPEEK) or other sulfonated polymers that provide comparable performance at a fraction of the cost, making the battery system more economically viable.

The patent implements a gradient structure where the membrane composition varies through its thickness. The regions closer to the electrodes have higher polymer density and cross-linking for mechanical strength, while the central region has optimized porosity and lower density to facilitate proton transport. This local quality variation allows the membrane to simultaneously achieve high mechanical strength and good proton conductivity.

The patent incorporates inorganic filler particles or nanofibers into the polymer matrix to create a composite membrane structure. These reinforcement elements provide mechanical strength and structural integrity, allowing the membrane to maintain adequate thickness for strength while the conductive pathways through the composite structure remain open for proton transport, thus decoupling the trade-off between strength and conductivity.