A research team at Rochester Institute of Technology has been awarded patents for discoveries that will improve and extend the life of lithium-ion batteries, which are used in a variety of technological applications.
Lead faculty-researchers Ryne Raffaelle and Brian Landi, and Ph. D. graduate Cory Cress, received the patents for two related discoveries “Methods of making nano-composite structures” and “Methods of making, and devices containing, freestanding carbon nanotube paper.”
The research, conducted in RIT’s NanoPower Laboratories, addresses the increasing demand for better materials and more robust battery structures for electronic devices by introducing new nano-composite materials that will extend both battery life and gravimetric energy density—the energy-to-weight ratio of a battery storage system.
“The use of lithium ion batteries has proved to be a transformative technology for applications ranging from electrical grid storage and automobiles to portable electronics,” said Raffaelle, RIT vice president for research and associate provost. “Both these patents exploit the remarkable properties of carbon nanotubes to improve electrical conduction within the battery and to reduce its overall mass.”
Researchers replaced conventional metal foil current collectors used in batteries with carbon nanotube sheets or “papers.” Using lightweight carbon nanotube papers in place of conventional metal foils results in a dramatic reduction in overall battery weight without sacrificing performance, Raffaelle explained.
“Additionally, carbon nanotubes can replace the normal conductive additives for the composite anodes and cathodes and actually improve performance and cycling lifetime,” he said. “These breakthrough discoveries transform not just traditional battery materials but the nano-structuring within batteries. The results represented by these patents speak for themselves; this performance exceeds that of any of the current commercial, off-the-shelf battery today.”
Carbon nanotubes are structures of carbon atoms that have better electrochemical and mechanical properties than copper, provide more strength than steel, but are significantly lighter. They are used to make integrated circuits for enhanced cell phones, or as composite materials for automobiles, because lighter vehicles are more energy efficient.
Over the past several years, the researchers have been synthesizing nano-composite materials in-house for lithium ion batteries in RIT’s NanoPower Research Labs, part of RIT’s Golisano Institute for Sustainability.
“Ours is a multi-disciplinary team consisting of chemical and mechanical engineers, physicists, sustainability graduate students and post-doctoral researchers,” said Landi, an associate professor of chemical engineering in RIT’s Kate Gleason College of Engineering. “The idea was to be good at materials science, and we always had in mind applications which involved some kind of device, whether it was a battery, a fuel cell or a solar cell. We found devices that always required materials development, so it created an iterative cycle where you got good at the materials development and you got good at making devices. The two informed one another.
“And because we were in both ‘spaces,’ we could advance the materials for the devices faster. We are taking the ideas and applying them in real prototype cells today, made and tested at RIT. In some sense, RIT is seeing these patent inventions incorporated throughout the entire technology development process.”
Much of that development work is being done in RIT’s new Battery Prototype Center a $1.5 million state-of-the-art facility that will conduct research and work with companies in this rapidly growing local industry. The center is part of a plan to establish a comprehensive battery and energy storage hub in the region, a priority of the Finger Lakes Regional Economic Development Council. Beyond the region, energy storage is expected to be a $33 billion global industry, according to LUX Research.