Researchers at Michigan State University in East Lansing are building stronger circuits that are better equipped to function in extreme conditions, including on Mars.
The team has developed more heat resistant silver circuitry with the help of nickel. The work was funded by the U.S. Department of Energy Solid Oxide Fuel Cell Program and published in the journal, Scripta Materialia, on April 15.
The technology could one day power next-generation fuel cells, high-temperature semiconductors, and solid oxide electrolysis cells and have applications in the auto, energy, and aerospace industries.
NASA developed a solid oxide electrolysis cell that enabled the Mars 2020 Perseverance Rover to make oxygen from gas in Mars’ atmosphere on April 22. NASA hopes the prototype will one day lead to equipment that allows astronauts to create rocket fuel and breathable air while on Mars.
To help such prototypes become commercial products, they’ll need to maintain their performance at high temperatures over long periods of time, according to Jason Nicholas, leader of the MSU team and associate professor in the College of Engineering.
Nicholas was drawn to the field after years of using solid oxide fuel cells, which work like solid oxide electrolysis cells in reverse. Rather than using energy to create gases or fuel, they create energy from those chemicals.
“Solid oxide fuel cells work with gases at high temperature,” he says. “We’re able to electrochemically react those gases to get electricity out, and that process is a lot more efficient than exploding fuel like an internal combustion engine does,” said Nicholas.
“These devices commonly operate around 700 to 800 degrees Celsius, and they have to do it for a long time — 40,000 hours over their lifetime.”
That’s approximately 1,300 to 1,400 degrees Fahrenheit, or about double the temperature of a commercial pizza oven.
“And over that lifetime, you’re thermally cycling it,” Nicholas says. “You’re cooling it down and heating it back up. It’s a very extreme environment. You can have circuit leads pop off.”
One of the hurdles facing this technology is simple — the conductive circuitry, often made from silver, needs to stick better to the underlying ceramic components. The researchers found adding a layer of porous nickel between the silver and ceramic improves adhesion.
The team optimized how it deposited the nickel on the ceramic. To create the thin nickel layers on the ceramic in a pattern or design of their choosing, the researchers used screen printing.
“It’s the same screen printing that’s used to make T-shirts,” Nicholas says. “We’re just screen-printing electronics instead of shirts. It’s a very manufacturing-friendly technique.”
Once the nickel is in place, the team puts it in contact with silver that’s melted at a temperature of about 1,000 degrees Celsius. The nickel withstands the head and distributes the silver uniformly over its fine features.
“It’s almost like a tree,” Nicholas says. “A tree gets water up to its branches via capillary action. The nickel is wicking up the molten silver via the same mechanism.”
Once the silver cools and solidifies, the nickel keeps it locked onto the ceramic.
Jon Debling, a technology manager with the MSU Innovation Center’s tech transfer and commercialization office, works to commercialized Spartan innovations. He’s working to help patent this process.