Redox Mediator Decouples Hydrogen Oxygen Evolution in PEM Electrolysis

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Solution Overview

Problem

Conventional polymer electrolyte membrane (PEM) electrolysis systems degrade when operated with intermittent energy sources and face high electricity costs, hindering large-scale adoption of electrochemical hydrogen production, while existing energy storage systems face inefficiencies and high costs that do not meet long-duration energy storage requirements.

Innovation Solution

The use of a mediator with reversible redox potential outside the onset of hydrogen and oxygen evolution reactions, allowing for decoupled generation of hydrogen and oxygen in time and space, and the implementation of a synergistic hydrogen redox energy storage system that stores energy in hydrogen and generates electricity through a polymer-electrolyte fuel cell, optimizing energy and power components independently.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional PEM electrolysis systems are operated with intermittent energy sources, then flexibility to power grids is improved, but system performance degrades

Engineering Contradiction:

Improveflexibility to power gridsVSAvoidsystem performance

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The water splitting process is divided into two separate electrochemical cells: one dedicated to hydrogen evolution and another to oxygen evolution. This segmentation allows each cell to be optimized independently and operate under stable conditions even when energy input is intermittent, resolving the contradiction between grid flexibility and system performance reliability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A redox mediator (such as iodide/triiodide couple) is introduced to decouple the hydrogen and oxygen evolution reactions. The mediator shuttles electrons between the two half-reactions, allowing the system to buffer intermittent energy input while maintaining stable reaction rates, thus preserving performance reliability while adapting to variable power supply.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If decoupled electrolysis systems are used to separate hydrogen and oxygen evolution, then safety is improved, but efficiency reduces and electricity costs increase

Engineering Contradiction:

ImprovesafetyVSAvoidefficiency

Core Design Contradiction:

Object-affected harmful factorsVSProductivity

Solution Approach 1:

While the hydrogen and oxygen evolution are spatially separated into different cells for safety, the system merges the electrical circuits and uses a common redox mediator to maintain high efficiency. The mediator enables rapid electron transfer between cells, minimizing energy losses and preventing the efficiency drop that would normally accompany physical separation of the half-reactions.

Inventive Principle:

Principle #5Merging (Combining)

3Quantity of substance

If conventional energy storage systems are used for long-duration storage, then energy storage capacity is improved, but round-trip efficiency is low and costs are high

Engineering Contradiction:

Improveenergy storage capacityVSAvoidround-trip efficiency

Core Design Contradiction:

Quantity of substanceVSLoss of energy

Solution Approach 1:

The electrochemical system serves multiple functions: it acts as both the hydrogen production device and the energy storage system. The same redox couples and electrochemical reactions used for hydrogen evolution also enable energy storage and discharge, eliminating the need for separate storage infrastructure and achieving high round-trip efficiency while providing long-duration storage capacity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

This approach enhances the efficiency and reduces the cost of hydrogen and oxygen production, achieving high round-trip efficiency and flexible energy storage, enabling the system to operate effectively with intermittent renewable energy sources and providing a cost-effective solution for long-duration energy storage.

Implementation Method 1

use of a mediator (e.g., a redox intermediate) having a reversible redox potential lying outside the onset of the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER)

Methodology Applied

Scientific EffectRedox reactions: Redox Reactions

Implementation Method 2

Water electrolyzers, i.e. devices used for hydrogen (H2) production

Methodology Applied

Scientific EffectElectrolysis: Electrolysis

Implementation Method 3

generates electricity through a polymer-electrolyte fuel cell

Methodology Applied

Scientific EffectFuel cell: Fuel Cell

Data Source

PatentUS11203812B2Methods and electrochemical cells for redox mediated hydrogen production

Publication Date: 2021.12.21 NEW YORK UNIV

AI summary

Provided are electrochemical cells for hydrogen production and methods for hydrogen production. The electrochemical cell and methods use a mediator that may have a reversible redox potential lying outside the onset of the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER). Also, provided are systems for generating hydrogen and water from oxygen and generating water from oxygen and hydrogen.