Co-Electrolysis Membrane Assembly That Blocks Parasitic CO2 Pumping

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Solution Overview

Problem

Existing co-electrolysis systems using alkaline ionomer membranes suffer from parasitic CO2 pumping from the cathode to the anode side due to carbonate/bicarbonate anions transport, leading to inefficiency in CO2 reduction and Faradaic efficiency loss.

Innovation Solution

A membrane electrode assembly design with a cathode catalyst layer incorporating an anion exchange ionomer and a cation exchange membrane, featuring a discontinuous interface and an additional thin anion exchange ionomer film, prevents direct contact between the cathode catalyst and the cation exchange membrane, thereby stopping carbonate/bicarbonate anion transport to the anode.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If an alkaline ionomer membrane is used to provide alkaline conditions for CO2RR, then CO2 reduction efficiency is improved, but parasitic CO2 pumping occurs due to carbonate/bicarbonate anion transport to the anode

Engineering Contradiction:

ImproveCO2 reduction efficiencyVSAvoidCO2 loss due to parasitic pumping

Core Design Contradiction:

ProductivityVSLoss of substance

Solution Approach 1:

The patent applies local quality by creating a dual-layer membrane structure where the first layer (anion exchange membrane) provides alkaline conditions for CO2RR at the cathode interface, while the second layer (cation exchange membrane) blocks carbonate/bicarbonate transport to the anode. This local differentiation of membrane properties resolves the contradiction by maintaining alkaline conditions only where needed for catalysis while preventing parasitic CO2 pumping in the transport path to the anode.

Inventive Principle:

Principle #3Local quality

2Productivity

If ionomers are incorporated into the cathode catalyst layer to increase catalytically active area, then reaction efficiency is improved, but liquid electrolytes evaporate or creep out in gas phase environment

Engineering Contradiction:

Improvecatalytic reaction efficiencyVSAvoidelectrolyte stability in gas phase

Core Design Contradiction:

ProductivityVSStability of the object's composition

Solution Approach 1:

The patent applies parameter changes by transitioning from liquid electrolytes to solid ion-conducting polymers (ionomers) in the cathode catalyst layer. This phase change from liquid to solid state eliminates evaporation and creeping issues while maintaining ion conductivity and catalytic activity. The solid ionomer provides both structural stability in gas phase environment and the necessary ionic conductivity for CO2RR.

Inventive Principle:

Principle #35Parameter changes

3Loss of substance

If a cation exchange membrane is used to prevent anion transport, then CO2 pumping is stopped, but direct contact between cathode catalyst and membrane increases hydrogen evolution

Engineering Contradiction:

ImproveCO2 loss preventionVSAvoidhydrogen evolution side reaction

Core Design Contradiction:

Loss of substanceVSObject-generated harmful factors

Solution Approach 1:

The patent applies the intermediary principle by introducing a first anion exchange membrane layer between the cathode catalyst and the second cation exchange membrane layer. This intermediate alkaline layer prevents direct contact between the catalyst and the cation exchange membrane, thereby suppressing hydrogen evolution side reactions, while still allowing the cation exchange membrane to block carbonate/bicarbonate transport and prevent CO2 pumping.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 design maintains high Faradaic efficiency for CO2 reduction by preventing CO2 pumping to the anode, enhancing the energetic efficiency and reducing hydrogen evolution, while maintaining CO selectivity.

Implementation Method 1

a cation exchange membrane between the anode electrode layer and the cathode electrode layer

Methodology Applied

Scientific EffectIon Exchange: Ion Exchange

Implementation Method 2

different polymeric anion exchange membranes (AEMs) have been applied in gas phase co-electrolysis, which are chemically designed to conduct anions (e.g. OH−, HCO3−, CO32−)

Methodology Applied

Scientific EffectIon Exchange: Ion Exchange

Implementation Method 3

They contain a membrane electrode assembly (MEA) which comprises a cathode electrode, an anode electrode and a polymer electrolyte layer in-between

Methodology Applied

Scientific EffectMembrane Separation: Semipermeable Membrane

Data Source

PatentUS12509782B2Co-electrolysis cell design for efficient CO2 reduction from gas phase at low temperature

Publication Date: 2025.12.30 PAUL SCHERRER INSTITUT

AI summary

A membrane electrode assembly for an electrochemical cell, in particular a co-electrolysis cell for CO2 reduction reaction, can overcome the problem of parasitic CO2 pumping from cathode to anode side and, at the same time, maintain good Faradaic efficiency towards CO2 reduction reaction in a co-electrolysis system where pure or diluted gaseous CO2 is used. The assembly includes an MEA, having an anode, a cathode, a polymer ion exchange membrane between cathode and anode, an additional ion exchange polymer film between the cathode and the polymer ion exchange membrane and a discontinuous interface formed between the additional polymer film located at the cathode side and the ion exchange membrane.