Capacitive Deionization Electrode Binder with Anion Exchange Groups
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Solution Overview
Problem
Existing capacitive deionization technologies face challenges in efficiently removing ions from hard water, which can lead to energy inefficiencies and lime scale formation, and lack environmentally friendly solutions for desalination and water softening.
Innovation Solution
A capacitive deionization apparatus using an electrode composition with a hydrophilic polymer and a bifunctional cross-linking agent, capable of cross-linking with the polymer and incorporating anion exchange groups, is developed. This composition enhances bonding within the electrode active material and between the material and the current collector, improving ion conductivity and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrode materials and binders are used in CDI apparatus, then the structure is simple and ease of manufacture is maintained, but ion conductivity is insufficient and ion removal efficiency is low
Solution Approach 1:
The patent employs a composite binder system comprising a hydrophilic polymer (such as polyacrylic acid or polyvinyl alcohol) cross-linked with a bifunctional cross-linking agent containing anion exchange groups. This composite structure combines the bonding capabilities of traditional binders with the ion exchange functionality, thereby enhancing ion conductivity and removal efficiency without requiring entirely new material systems
Solution Approach 2:
The patent modifies the chemical and physical parameters of the electrode composition by introducing cross-linked hydrophilic polymers with specific functional groups. The cross-linking degree, polymer molecular weight, and concentration of anion exchange groups are optimized to achieve optimal ion conductivity and mechanical stability, representing parameter-based improvement over conventional binders
2Reliability
If traditional hydrophobic binders are used, then ease of manufacture is maintained, but electrode dissolution in solvents occurs and reliability decreases
Solution Approach 1:
The patent changes the fundamental chemical parameter of the binder from hydrophobic to hydrophilic character. The hydrophilic polymer (e.g., polyacrylic acid, polyvinyl alcohol) exhibits superior resistance to dissolution in aqueous and alcoholic solvents compared to traditional hydrophobic binders, thereby enhancing electrode stability while remaining processable through conventional coating and drying methods
3Reliability
If high potential difference is applied for ion removal, then ion removal efficiency is improved, but energy consumption increases
Solution Approach 1:
The patent implements a self-service mechanism where the anion exchange groups within the cross-linked hydrophilic polymer binder actively attract and concentrate cations through electrostatic interaction. This internal ion concentration mechanism occurs at low applied potentials, enabling efficient ion removal without requiring high potential differences, thereby reducing energy consumption while maintaining high ion removal efficiency
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 proposed solution effectively increases ion conductivity and ion removal efficiency, providing a high-energy efficiency and environmentally friendly method for desalination and water softening, while preventing electrode dissolution in solvents.
Implementation Method 1
a polymer including a carboxyl group side chain being capable of ester-bonding with the hydroxy group of the bifunctional cross-linking agent
Implementation Method 2
the at least one anion exchange group in the bifunctional cross-linking agent may be one of a quaternary ammonium group (—NR′2—) and a quaternary phosphonium group (—PR′′2—)
Data Source
AI summary
Disclosed are a composition for an electrode binder of a capacitive deionization apparatus including at least one a hydrophilic polymer and a bifunctional cross-linking agent having a hydroxy group or a carboxyl group at both terminal ends, and at least one anion exchange group therein, and the bifunctional cross-linking agent being cross-linkable with the at least one hydrophilic polymer, an electrode for a capacitive deionization apparatus including the composition, a capacitive deionization apparatus including the electrode, and a method of removing ions from a liquid by using the capacitive deionization apparatus.