However, most fuel cell lithium-ion batteries are too expensive, too inefficient, or both. Inspired by biology, a team at the University of Wisconsin-Madison has pioneered a new approach, designing a fuel cell lithium-ion battery that uses cheaper materials and an organic compound that allows electrons and protons to shuttle between each other.
These devices, invented in the 1830s, generate electricity directly from chemicals such as hydrogen and oxygen, with only water vapor as an emission. However, most fuel cell lithium batteries are too expensive, too inefficient, or both.
Inspired by biology, a team at the University of Wisconsin-Madison published an article in the journal "Joule" on October 3, 2018, outlining a new research approach. They designed a fuel cell-powered lithium battery using cheaper materials and an organic compound that allows electrons and protons to shuttle between each other.
In traditional fuel cell lithium-ion batteries, electrons and protons from hydrogen are transferred from one electrode to another, where they combine with oxygen to form water. This process converts chemical energy into electrical energy. To allow a meaningful charge to form within a sufficiently short time, a catalyst is used to accelerate the reaction.
Currently, the best catalyst on the market is platinum, but it is very expensive. This makes lithium-ion fuel cell batteries expensive, which is one of the reasons why only a few thousand cars on the road in the United States currently use hydrogen fuel.
Shannon Stahl, a chemistry professor at the University of Wisconsin-Madison, who co-led the study with Thatcher Root, a professor of chemical and biological engineering, said that lower-cost metals could be used as catalysts in current fuel cell-powered lithium batteries, but only in large-scale applications. “The problem is that when you attach too much catalyst to the electrode, the material becomes less effective,” she said. “That leads to a loss of energy efficiency.”
The team's approach was to load lower-cost cobalt into a nearby reactor, where a larger quantity of the material would not affect its performance. They then devised a strategy to transfer electrons and protons back and forth between the reactor and the fuel-powered lithium-ion battery.
The ideal carrier for this transport has been found to be an organic compound called quinone, which can carry two electrons and a proton simultaneously. In the research team's design, quinone picks up these particles at the electrodes of a fuel cell, transports them to a nearby reactor containing an inexpensive cobalt catalyst, and then returns to the fuel cell to pick up more particles.
After several cycles, many quinone compounds degrade into tar-like substances. However, Stahl's lab designed an ultra-stable quinone derivative. By altering its structure, the team significantly slowed the degradation of quinones. In fact, the compound they assembled lasted up to 5,000 hours, more than 100 times longer than previous quinone structures.
“While this isn’t a final solution, our concept introduces a new approach to this category of problems,” Stahl said. He noted that his new design generates about 20% of the energy currently available in hydrogen fuel cell lithium-ion batteries on the market. On the other hand, the system is approximately 100 times more efficient than biofuel lithium-ion batteries using related organic shuttles.
Stahl and his team's next plan is to improve the performance of quinone media, enabling them to shuttle electrons more efficiently and generate more energy. This advancement will allow their designs to match the performance of traditional fuel cell lithium-ion batteries, but at a lower price.
“The ultimate goal of this project is to provide industry with a carbon-free power generation option,” said Colin Anson, a postdoctoral researcher at Stahl’s lab and co-author of the publication. “Our goal is to figure out what the industry needs and create a fuel-powered lithium battery that can fill that gap.”
This step toward developing cheaper alternatives could ultimately benefit companies like Amazon and Home Depot, which already use hydrogen fuel cell-powered lithium-ion batteries to drive forklifts in their warehouses.
“Despite significant obstacles, the hydrogen economy appears to be steadily rising,” Stahl added. Financial support for the project is provided by the Center for Molecular Electrocatalysis, a frontier energy research center funded by the U.S. Department of Energy, the Office of Science, the Office of Basic Energy Sciences, and the Wisconsin Alumni Research Foundation (WARF) through the WARF Accelerator Program.
