Fuel cells are quickly becoming a viable alternative to electric vehicles and battery packs, but they have a downside. Like conventional lead-acid batteries – which also use an electrode and an electrolyte – replacement is the only option once the electrode corrodes and fails. The cell’s capacity can drop so far that it stops being worth operating.
While researching ways to increase the life span of a fuel cell, MIT scientists stumbled upon a deceptively simple solution to the problem: Changing the pH. How is something as simple as pH poised to extend its life span?
Fuel Cell Failure
Fuel cells might represent the future of green energy, but their operational mechanisms are deceptively simple. Two electrodes – including one cathode and one anode – and an electrolyte can either generate storable fuel or use the stored fuel to generate electricity. Fuel cell design may vary from application to application, but it generally relies on individual cells stacked atop one another, connected by chrome-coated steel, to prevent oxidation.
Over time or under extreme conditions, the chrome evaporates and loses its noncorrosive tendencies, migrating into the space between the cathode and the electrolyte. This contamination interferes with the oxygen incorporation reaction. Eventually, the reaction gets so corrupted that the cell’s capacity becomes almost nonexistent. There’s no point in keeping the fuel cell connected because it’s no longer storing or generating electricity, or the amount is negligible.
The solution seems simple: If you can prevent the chrome anti-corrosive coating from wearing away, you can preserve the life span of the fuel cell. How do you manage that?
A Simple pH Shift
Most people only think of pH when testing or appraising their drinking water source or managing the chemical balance of their swimming pool. It’s impactful beyond these tasks, though. The easiest way researchers have found to prevent or at least mitigate the problem presented by the chrome coating is to take steps to control the acidity of the cathode surface. The solution? Lithium oxide.
Coating the fuel cell cathode with lithium oxide changed the pH of the electrolyte as it came into contact with the cathode, from acid to base. Adding one element was enough to recover performance in a corrupted cell and improve its overall efficiency many times over. The more lithium they added, the better the performance became.
Researchers observed, under an electron microscope, that the addition of lithium worked to dissolve the chromium that was disrupting the reaction. It leaves behind a glassy material that doesn’t interfere with the fuel cell’s operation.
The Future of Fuel Cells
The research doesn’t stop here. The MIT team is already working to see if this change in acidity could repair or restore fuel cells contaminated with other elements, such as silica. Improving fuel cell functionality, capacity, and efficiency is essential if researchers hope to get this technology into the mainstream and compete with electric vehicles.
The solution isn’t perfect. Lithium is already in high demand for its applications in battery technology. The International Energy Agency (IEA) reports that we could see a lithium shortage as early as 2025. It’s important to remember that the solution doesn’t always have to be complicated, even for big problems like this. Something as simple as manipulating the pH could make or break the future of fuel cell technology.
Jane Marsh, Contributor
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