Published on June 3rd, 2016 | by James Ayre1
DOE Researchers Report Advance In Understanding Of Lithium-Rich Cathode Use
A “major” advance in the understanding of how exactly oxidation leads to the creation of extra capacity in lithium-rich cathodes has been reported by researchers at the Department of Energy’s Lawrence Berkeley National Laboratory.
The advance will reportedly open “the door to batteries with far higher energy density,” according to a recent press release on the subject. As always with battery “breakthroughs,” though, … remember, with a grain of salt.
“The specific nature of our findings shows a clear and exciting path forward to create the next-generation cathode materials with substantially higher energy density then current cathode materials,” the researchers stated in a recent paper outlining the findings.
The press release providers some background, and some further details:
In a conventional lithium-ion battery, the cathode material is a lithium transition metal oxide, with the content of the lithium and the transition metal, such as nickel or cobalt, balanced. In a lithium-rich (also called lithium-excess) cathode, there is a higher proportion of lithium than the transition metal. Because transition metals are heavy and also expensive, reducing its content is a big benefit. The battery can be significantly cheaper and lighter, which are especially important factors for vehicle applications, where the battery is often one of the heaviest components of the vehicle.
…A major stumbling block has been that scientists had lacked a clear understanding of the chemistry in a lithium-rich cathode — specifically the role of oxygen. Normally when a battery is charged and discharged, the transition metal in the cathode oxidizes and releases electrons; those electrons then travel between the cathode and anode and create electricity.
“What we and others have been claiming recently is that you can take an electron off the oxygen and put it back, which is fairly radical. That’s the big idea for this cathode design,” lead researcher Gerbrand Ceder commented. “This paper specifically shows that it’s true and more importantly, shows under which conditions that it becomes true.”
With regard to the implications of the new findings: “We can now use 15 or 20 different transition metals,” Ceder said. “We can use a much broader range of chemistry to look for cathodes, and we know exactly the kind of structures we want to engineer.”