M.I.T. researchers design a more energy-dense lithium-based battery.
Researchers at the Massachusetts Institute of Technology have come one step closer to replacing the lithium-ion batteries that power phones, laptops and electric cars with a device that stores far more energy for the same weight.
The device is known as a lithium-air or lithium-oxygen battery. Charged lithium atoms react with the oxygen from air flowing through the apparatus, forming lithium peroxide, and deposit on the structure. The peroxide can then be broken down to release electricity.
In a paper published in the journal Energy & Environmental Science, a team of materials scientists and mechanical engineers refined this design and made it hold almost four times the electricity of a lithium-ion battery by weight.
“The key benefit, I think, is energy density,” said Robert Mitchell, a Ph.D. student in materials science and engineering. Mitchell and Betar Gallant, a Ph.D. student in mechanical engineering, were the co-lead authors of the study. “In the last couple of years, there has been a flurry of new interest in these batteries,” said Mitchell.
The electrode of the battery is formed using carbon nanofibers: thin, hollow cylinders of pure carbon. The nanofibers are grown and aligned, forming a structure not unlike a carpet or a lawn. “The unique morphology of these carbon electrodes creates a low-density scaffold for lithium peroxide,” said Mitchell. The open spaces in the structure provide lots of room for electricity to be stored in the form of lithium compounds.