Electoplating boosts battery capacity and design
Developed with a team from University of Illinois at Urbana-Champaign, the DirectPlate technique provides up to 30% higher power density and faster charging.
“This is an entirely new approach to manufacturing battery cathodes, which resulted in batteries with previously unobtainable forms and functionalities,” said Paul Braun (above left), professor of materials science and engineering and director of the Frederick Seitz Materials Research Lab at Illinois.
In a conventional electrode fabrication, cathode material powders such as like LiCoO are synthesized at temperatures between 700-1000°C and made into slurries which also contain polymer binders and conductive additives. The slurries are cast onto metal foils, which are cut and assembled into batteries.
Xerion deposits the same materials directly on metal foils, using an electroplating technique at temperatures less than 300°C. This new method completely eliminates the need for any inactive additives or glue materials that are used to bind the material to the foil, giving the higher energy density.
“The glue is not active. It doesn’t contribute anything to the battery, and it gets in the way of electricity flowing in the battery,” said Hailong Ning, director of research and development at Xerion (above right). “You have all this inactive material taking up space inside the battery, while the whole world is trying to get more energy and power from the battery.”
This means the cathode can be more than 90% dense, and is compatible with both flat and 3D substrates as the substrate is dipped into the slurry. Directly electroplating of active materials on final current collectors also greatly simplifies the electrode fabrication procedure allowing a less refined slurry to be used and supporting high production throughput.
This new growth method also significantly broadens the opportunity for new battery form factors such as flexible cells and wire-based batteries. The researchers have used the technique to coat a 3D carbon sponge and curved substrates. “These designs are impossible to achieve by conventional processes,” said Braun. “But what’s really important is that it’s a high-performance material and that it’s nearly solid. By using a solid electrode rather than a porous one, you can store more energy in a given volume. At the end of the day, people want batteries to store a lot of energy.”
Xerion has prototyped pouch cells with capacities up to several Ah which lasted significantly longer and produced noticeably higher power than comparable commercial cells.
Back in 2011, Xerion licensed fast charging technology from the team at the University of Illinois. This StructurePore nanomaterial consists of an electrolytically active material sandwiched between rapid ion and electron transport pathways. The team achieved rates of up to 400 cycles for lithium-ion and 1000 cycles for nickel-metal hydride chemistries, enabling fabrication of a lithium-ion battery that can be 90% charged in just two minutes.
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