Ion-Selective Composite Membrane for Salinity Gradient Power
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current ion-selective conduction membranes used in devices for producing electricity from salinity gradients have low electricity production capacity and are expensive to produce, with materials used in alternative membranes being harmful to the environment.
Innovation Solution
A composite membrane with a thickness of 4 μm to 100 μm, comprising outer layers of crosslinked nanofibers and microfibers and an inner layer of surface-functionalized nanoparticles, which develops high membrane power under a salinity gradient, is proposed. The membrane's porosity and surface charge enable nanofluidic properties, enhancing ion selectivity and reducing environmental impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional ion exchange membranes are used, then ion selectivity is achieved, but electricity production capacity is low and production cost is high
Solution Approach 1:
The patent applies composite materials by combining conductive polymer granules (such as polyaniline, polythiophene, or polypyrrole) with ion exchange resin granules in a matrix material. This composite structure enables the membrane to simultaneously achieve high electricity production capacity (several hundred W/m²) and selective ion conduction, while being more economical than conventional ion exchange membranes. The conductive polymer component enhances electrical conductivity and power generation, while the ion exchange resin maintains ion selectivity.
2Ease of manufacture
If alternative materials are used to reduce cost, then production cost decreases, but environmental harm increases
Solution Approach 1:
The patent changes the material parameters by using environmentally benign conductive polymers (polyaniline, polythiophene, polypyrrole) that can be synthesized from abundant precursors. These materials maintain the desired electrical and ion transport properties while eliminating the need for harmful substances. The conductive polymers provide sufficient electrical conductivity and catalytic activity for oxygen reduction reactions without the environmental toxicity associated with alternative materials.
3Power
If ion exchange membranes are used, then ion selectivity is achieved, but ionic current conduction is weak
Solution Approach 1:
The patent merges two distinct functionalities into a single membrane structure: ion exchange resin granules provide ion selectivity by allowing selective passage of ions based on charge, while conductive polymer granules embedded in the matrix provide enhanced ionic and electronic current conduction. This combination enables the membrane to simultaneously achieve strong ionic current conduction (supporting current densities of several hundred mA·cm⁻²) and reliable ion selectivity, resolving the trade-off between these two properties.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The composite membrane achieves membrane powers of several hundred W/m², specifically at least 300 W/m², while being economical and environmentally friendly, with a simple production method that reduces the need for harmful materials.
Implementation Method 1
outer layers (1, 3) which are each formed of a first material comprising a network of crosslinked nanofibers and/or microfibers and pores with a diameter of between 10 nm and 10 μm
Implementation Method 2
the inner layer (2) is formed of a second material comprising nanoparticles functionalized at the surface by charged groups and/or groups which become charged in the presence of water
Implementation Method 3
the circulation of alternating salt water and fresh water in these cells allows to establish an ion flux at each of the IEMs of the device
Implementation Method 4
Ion selective conduction according to the sign of their charge between two volumes separated by a membrane, under the effect of a stress on either side of this interface, for example a pressure gradient, an electric potential gradient or a concentration gradient
Data Source
AI summary
The present invention relates to an ion-selective composite membrane having a thickness of between 4 μm and 100 μm, comprising at least one inner layer disposed between two outer layers, wherein: —the outer layers are each formed of a first material comprising a network of nanofibres and/or crosslinked microfibres and pores with a diameter of between 10 nm and 10 μm, —the inner layer is formed of a second material comprising nanoparticles functionalized at the surface by charged groups and/or groups which become charged in the presence of water and having pores with a diameter of between 1 and 100 nm.