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Home / Technology / Energy & Propulsion / Optimized Alkaline anion exchange membranes ( AAEMs) enhance efficiency of alkaline exchange membrane fuel cells (AEMFCs), that convert fuels to electricity using nonplatinum electrode catalysts.

Optimized Alkaline anion exchange membranes ( AAEMs) enhance efficiency of alkaline exchange membrane fuel cells (AEMFCs), that convert fuels to electricity using nonplatinum electrode catalysts.

Since the Industrial Revolution, the environmental impacts of energy have posed a concern. Recently, this has driven researchers to search for viable options for clean and renewable energy sources. Due to its affordability and environmental friendliness, hydrogen is a feasible alternative to fossil fuels for energy applications. However, due to its low density, hydrogen is difficult to transport efficiently, and many on-board hydrogen generation methods are slow and energy intensive.

A fuel cell is a device that generates electricity by a chemical reaction. It converts hydrogen and oxygen into water, and in the process also creates electricity. Fuel cells provide many advantages, they are environment friendly as they don’t produce pollutants or greenhouse gasses, significantly improving our environment, high energy efficiency ( can be close to 80%  where they generate both heat and electricity), scalable providing power from milliwatts to megawatts, and complementary i.e.  readily be combined with other energy technologies, such as batteries, wind turbines, solar panels, and super-capacitors.

 

There are many types of fuel cells, and each can operate in a clean manner using different fuels including hydrogen, natural gas, methanol, ethanol, biogas.  All  fuel cells,  consist of an anode, a cathode, and an electrolyte that allows positively charged hydrogen ions (or protons) to move between the two sides of the fuel cell. The reactions that produce electricity take place at the electrodes. Every fuel cell also has an electrolyte, which carries electrically charged particles from one electrode to the other, and a catalyst, which speeds the reactions at the electrodes.

 

Fuel cells are classified primarily by the kind of electrolyte they employ. This classification determines the kind of electro-chemical reactions that take place in the cell, the kind of catalysts required, the temperature range in which the cell operates, the fuel required, and other factors. These characteristics, in turn, affect the applications for which these cells are most suitable. The six fuel cell types are : PEMFC, Proton Exchange Membrane Fuel Cell (PEMFC) ,  Direct Methanol Fuel Cell (DMFC), Phosphoric Acid Fuel Cell (PAFC), Alkaline Fuel Cell (AFC) ,  Molten Carbonate Fuel Cell (MCFC), and  Solid Oxide Fuel Cell (SOFC).

Recent advancements in applications of alkaline anion exchange membranes for polymer electrolyte fuel cells - ScienceDirect

An alkaline anion exchange membrane fuel cell (AAEMFC), also known as anion-exchange membrane fuel cells (AEMFCs), alkaline membrane fuel cells (AMFCs), hydroxide exchange membrane fuel cells (HEMFCs), or solid alkaline fuel cells (SAFCs) is a type of alkaline fuel cell that uses an anion exchange membrane to separate the anode and cathode compartments.

 

In an AAEMFC, the fuel, hydrogen or methanol, is supplied at the anode and oxygen through air, and water are supplied at cathode. Fuel is oxidized at anode and oxygen is reduced at cathode. At cathode, oxygen reduction produces hydroxides ions (OH−) that migrate through the electrolyte towards the anode. At anode, hydroxide ions react with the fuel to produce water and electrons. Electrons go through the circuit producing current.

 

These devices can efficiently convert chemical energy in fuels (e.g., H2, hydrazine, and direct alcohols) into electricity. In comparison with proton exchange membrane fuel cells and aqueous alkaline fuel cells, AEMFCs are advantageous because they allow for rapid reduction of oxygen at the cathode, limit fuel cross-over, prevent the formation of carbonate precipitates, and are compatible with nonnoble electrocatalysts.

 

NASA has used alkaline fuel cells since the mid-1960s, in the Apollo-series missions and on the Space Shuttle.  Alkaline Fuel Cells (AFCs) are easy to handle, have very high electrical efficiency and are very suitable for dynamic operating modes. They can be built into small compact systems as well as in large power plants. However, many groups in Europe have stopped working on this technology. An AFC can be operated at up to 230 °C depending on the fuel cell model used. New developments foresee the integration of stable anion exchange membranes, which can be used like the proton exchange membrane in a Proton Exchange Fuel Cell (PEFC) and hence the design will be similar to the PEFC stack.

 

One of the most important applications for AAEMs is their use as polyelectrolytes in alkaline exchange membrane fuel cells (AEMFCs), which facilitate the efficient conversion of fuels to electricity using nonplatinum electrode catalysts. Alkaline anion exchange membranes (AAEMs) are a class of polymer electrolytes constructed from immobilized cations with hydroxide counteranions. AAEMs have been widely used for a variety of electrochemical applications, such as redox flow batteries, electrodialysis, and water electrolysis.

 

Because of their essential role in AEMFCs, AAEMs have been extensively studied to optimize their performance and, in particular, to improve their hydroxide conductivity and alkaline stability.  However, low hydroxide conductivity and poor long-term alkaline stability of AAEMs are the major limitations for the widespread application of AEMFCs. The challenge is to fabricate AEM with high OH− ion conductivity and mechanical stability without chemical deterioration at elevated pH and temperatures.

 

Hydroxide conductivity is one of the most important parameters used to evaluate AAEMs, because it is directly related to the ohmic resistance and power density of an AEMFC. There are several strategies to enhance the hydroxide conductivity of AAEMs. The most straightforward method is to increase the ion exchange capacity (IEC), such that more ions are present in AAEMs. However, a higher IEC typically results in higher water uptake. While the presence of water facilitates hydroxide transportation, excess water uptake decreases the membrane’s mechanical strength and dilutes the ions, reducing the overall conductivity. Although AAEM hydroxide conductivity has significantly improved in the past decade and several AAEMs exhibit a hydroxide conductivity above 100 mS/cm at 80 °C, long-term alkaline stability remains a major problem

 

Ionomr Innovations’ Breakthrough Technology Tapped by Shell and U.S. Department of Energy’s National Renewable Energy Lab for Hydrogen Technology Advancement in March 2021

Ionomr Innovations Inc.’s breakthrough Aemion+™ technology has been identified by the Shell GameChanger AcceleratorTM Powered by NREL (GCxN) for its potential to make a significant difference in the development of technologies to de-carbonize the global economy. Ionomr is developing next generation alkaline ion exchange membranes and polymers that are key to converting intermittently generated power, such as solar, hydro or wind, into storable green hydrogen, renewable fuels and chemicals.

 

Ionomr has designed its polymers and membranes from the ground-up for maximum durability. Alkaline membranes allow the most expensive materials like Iridium and Titanium to be replaced with less expensive materials while increasing performance. Ionomr membranes allow more reliable, efficient and compact intermittent power-to-renewable fuel conversion processes, enabling production of the lowest-cost green hydrogen and green fuels, which are needed to de-carbonize the global economy.

 

It is challenging to de-carbonize heavy duty transportation, aviation and chemical feedstock industries, which require dense fuels and high temperatures. Ionomr membranes and polymers can help convert electricity generated from renewable energy into energy-dense clean fuels such as green hydrogen and alcohol that can be stored and used in heavy industry when needed.

 

The Shell GameChanger AcceleratorTM Powered by NREL (GCxN) is a multimillion-dollar, multiyear program developed in collaboration between Shell GameChanger and the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) focused on advancing emerging clean technologies with the greatest potential to dramatically alter the future global energy landscape. The invitation-only program identifies high-impact technologies to partner with technical resources, expertise and world class facilities available through NREL and Shell’s incubator program, Shell GameChanger, to reduce technology development risk and accelerate the technology to market. Ionomr was selected for advancement in the Electrosynthesis for Fuels and Chemicals category.

 

Bill Haberlin, CEO of Ionomr Innovations, said, “Ionomr is driven to define and exceed the highest performance metrics needed to allow for rapid commercialization and global acceleration of affordable green hydrogen technologies. We are honoured to be chosen to work with world leaders like Shell and the experts at NREL to maximize the performance of AEM electrolyzer technology using Ionomr membranes and polymers for the conversion of renewable energy into green fuels.”

 

“Almost every aspect of our modern lives depends on certain materials and fuels, but with great consequence. For example, the American manufacturing industry is on-track to become the nation’s largest source of greenhouse gas emissions within the next ten years,” said Katie Richardson, GCxN program manager at NREL. “The selected GCxN startups are restructuring essential building blocks to reduce the carbon impact of essential goods and services.”

 

“GCxN’s fourth cohort will help prove that electrochemistry technologies can replace carbon-intensive legacy processes. As renewable energy costs continue to drop, cross-industry initiatives and partnerships will prove that it’s possible to cost-effectively scale these technology applications and achieve real-world impact,” said Haibin Xu, Shell’s GCxN program manager.

 

References and Resources also include:

https://www.newswire.ca/news-releases/ionomr-innovations-breakthrough-technology-tapped-by-shell-and-u-s-department-of-energy-s-national-renewable-energy-lab-for-hydrogen-technology-advancement-841886757.html

 

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