Key Takeaways
- Stress conditions in batteries lead to dangerous emissions and potential thermal runaway.
- Ford’s patent proposes a catalyst in the battery pack vent to convert harmful gases into carbon dioxide and water.
- Cheaper catalyst substitutes like copper may be used over palladium, for example, but efficiency drops substantially.
A patent filed by Ford with the United States Patent and Trademark Office has been discovered by CarBuzz, and it details a means of preventing dangerous gases from escaping the battery pack of electric vehicles like the Mustang Mach-E or F-150 Lightning. Much like the catalytic converter that helps to filter the worst of the emissions from an exhaust system, the patent describes a vent for the battery pack within which a catalyst can promote the breakdown of carbon monoxide, hydrogen, and hydrocarbons. To understand how it works, let’s first explore why the invention is necessary and under what conditions it would come into play.
Stress Conditions Cause Emissions
The patent notes that lithium-ion battery cells “are known to undergo transformations when subjected to stress conditions.” As a result, the commonly used polyolefin-based separator starts to melt, initiating exothermic chemical reactions between the electrodes and electrolyte that start the generation of gases, increasing pressure within the battery pack and, as a result, increasing the temperature within the battery pack. This rising heat increases the rate of chemical reactions, and that’s how thermal runaway starts, potentially creating an uncontrollable blaze.
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The patent describes these stress conditions as instances where “one or more battery cells irreversibly deviate from the designed operation and/or [are] exposed to high temperatures.” What constitutes a high temperature depends greatly on the materials used in the construction of each component, but Ford’s focus is particularly on what happens when the melting point of the separator in the battery cells is reached or exceeded. That’s when the bad stuff happens, completely scorching an electric vehicle.
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The Solution
Ford envisions giving the battery pack a vent port within which the catalyst would be housed. This catalyst would be configured to spring into action when temperatures get to around 100 degrees Celsius (around 212° Fahrenheit). When that happens, the materials in the catalyst would help break the aforementioned gases into carbon dioxide and water. Laboratory testing using Fourier-transform infrared spectroscopy reveals that the catalyst helps these reactions occur at a much lower temperature and that 100% of carbon monoxide and hydrogen and 50% of polyethylene can be converted to carbon dioxide and water at 212° when the catalyst features palladium particles on a mixture of cerium oxide and zirconium oxide. At double the temperature, the catalyst can convert all of the polyethylene. The patent notes that palladium and other materials in its invention are very expensive but that cheaper substitutes, such as copper, can do the job, too. However, a copper-based catalyst takes 50% more heat (around 302° F) to convert carbon monoxide and hydrogen and triple (572° F) to convert only 70% of the polyethylene compared to a palladium-based catalyst at 212° F.
This innovation may not be the most exciting patent from Ford in recent weeks, but it shows the Blue Oval’s commitment to increasing efficiency and safety in its electric vehicles. The more progress is made in these fields, the cheaper and better tomorrow’s EVs will be.
Patent filings do not guarantee the use of such technology in future vehicles and are often used exclusively as a means of protecting intellectual property. Such a filing cannot be construed as production intent.
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