With lithium-ion at the cathode, there is a process involved called intercalation that layers in molecules in such a way that they can come together and then reverse. This second research effort investigates replacing the intercalation step with a true chemical reaction. Chemical bonds store more energy than intercalated ions. One process could involve lithium reacting with oxygen. An analogous process is a fuel cell, where hydrogen produces water, except in the case of the battery the chemical process is reversible.
Liquids could be used to replace crystalline anodes and cathodes, which opens up more space for working ions. This approach makes it possible to use different types of materials for energy storage, including organics. The problem is finding a liquid that can support enough working ions. There are several major challenges, including finding a reaction that stores high energy from many tens of thousands of possible reactions. Another challenge is finding a solvent with enough voltage capability.
The researchers intend to study the various reactions at an atomic and molecular level, and build a battery based on their findings. They will also rely heavily on high-performance computing systems for simulations, and then limit physical testing to those things that show the most promise.
The goal is achievable, said Crabtree. "I think there's no doubt that it can be achieved, in my mind, because there are so many unexplored pathways to new battery systems beyond lithium-ion that have not been explored carefully," he said.
Even if the 5-5-5 team meets its goals, a commercial product may be years away. The research team hopes to develop a prototype working battery that proves the technology works within five years. But commercializing a new type of battery, building out the manufacturing processes and developing a battery for various applications could take many years beyond that.
Lithium-ion technology was developed in the U.S., but it wasn't until the early 1990s — two decades after its initial development — that one company, Sony, successfully commercialized the battery. A 20-year time frame for a new technology to travel from the lab to consumers is typical. Crabtree hopes to reduce the time to commercialization, but is reluctant to estimate when consumers may see products.
He acknowledged that cutting the development cycle to 10 years would be fast.
Taking part in the projects are other U.S. national labs, along with Northwestern University, the University of Chicago, the University of Illinois-Chicago, the University of Illinois-Urbana Champaign and University of Michigan. Private-sector firms involved are Dow Chemical Company, Applied Materials, Johnson Controls and the Clean Energy Trust.
The partners will contribute to the patent pool, and whatever technology is developed will be available for license. "None of our partners has the expectation of getting an exclusive license," said Crabtree.
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