Helper Membrane Anion Exchange Electrolyzer for CO2 Conversion
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Solution Overview
Problem
Current CO2 electrolyzers with liquid free cathodes have low faradaic efficiencies and conversion currents, failing to achieve practical levels of CO2 conversion, with faradaic efficiencies below 30% and CO2 conversion currents less than 5 mA/cm2.
Innovation Solution
An anion exchange membrane electrolyzer with a Helper Membrane, which increases faradaic efficiency and allows product formation at lower voltages, using non-liquid, ion-conducting materials like imidazolium, pyridinium, or phosphonium ligands, and specific catalysts such as silver and ruthenium oxide, to enhance CO2 conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If liquid free cathodes are used in CO2 electrolyzers, then device complexity is reduced, but faradaic efficiency and conversion current decrease to below 30% and 5 mA/cm2 respectively
Solution Approach 1:
The patent introduces an anion exchange membrane as an intermediary component between the cathode and anode. This membrane facilitates ion transport and enables the system to achieve high faradaic efficiency (≥50%) and conversion current (≥20 mA/cm2) while maintaining the liquid-free cathode design, thus resolving the contradiction between device simplicity and conversion efficiency
Solution Approach 2:
The patent changes the operating parameters by applying voltage at specific ranges and using particular catalyst compositions (silver and ruthenium oxide) to optimize the electrochemical reactions. This enables the system to achieve practical conversion levels while maintaining structural simplicity
2Ease of operation
If liquid free cathodes are used in CO2 electrolyzers, then ease of operation is improved, but conversion current remains below 5 mA/cm2
Solution Approach 1:
The anion exchange membrane acts as a mediator that enables efficient ion transport and reaction facilitation, allowing the liquid-free cathode design to achieve high conversion current (≥20 mA/cm2) without compromising operational simplicity
Solution Approach 2:
The patent employs composite catalytic materials (silver and ruthenium oxide) on the cathode surface that enhance reaction activity and conversion current while maintaining the simplicity of the liquid-free design, thus achieving both ease of operation and high productivity
3Productivity
If conventional electrolyzers are used, then CO2 conversion can occur, but faradaic efficiency and conversion current remain below practical levels
Solution Approach 1:
The anion exchange membrane serves as a critical intermediary that directs ion flow and enhances reaction efficiency, enabling the system to achieve faradaic efficiency ≥50% and conversion current ≥20 mA/cm2, thereby minimizing energy loss and maximizing CO2 conversion
Solution Approach 2:
The patent optimizes reaction parameters including voltage application and catalyst composition to enhance the efficiency of CO2 conversion reactions, achieving practical faradaic efficiency and conversion current levels while minimizing energy waste
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 use of Helper Membranes in anion exchange membrane electrolyzers achieves faradaic efficiencies of at least 50% and CO2 conversion currents of 20 mA/cm2 or more, significantly improving the efficiency and practicality of CO2 conversion processes.
Implementation Method 1
a polymer electrolyte membrane interposed between the anode and the cathode
Implementation Method 2
electrochemical conversion of carbon dioxide into useful products
Implementation Method 3
electrolysis of water
Implementation Method 4
an anode comprising a quantity of anode catalyst... a cathode comprising a quantity of cathode catalyst
Data Source
AI summary
An electrochemical device converts carbon dioxide to a reaction product. The device includes an anode and a cathode, each comprising a quantity of catalyst. The anode and cathode each has reactant introduced thereto. A polymer electrolyte membrane is interposed between the anode and the cathode. At least a portion of the cathode catalyst is directly exposed to gaseous carbon dioxide during electrolysis. The average current density at the membrane is at least 20 mA/cm2, measured as the area of the cathode gas diffusion layer that is covered by catalyst, and CO selectivity is at least 50% at a cell potential of 3.0 V. In some embodiments, the polymer electrolyte membrane comprises a polymer in which a constituent monomer is (p-vinylbenzyl)-R, where R is selected from the group consisting of imidazoliums, pyridiniums and phosphoniums. In some embodiments, the polymer electrolyte membrane is a Helper Membrane comprising a polymer containing an imidazolium ligand, a pyridinium ligand, or a phosphonium ligand.