Energy & Power
Electrodes made of mud? “We’re talking about quite a special lump of clay here”
By Anthony Capkun
November 26, 2014 – Materials scientists from Drexel University’s College of Engineering believe that a lump of clay they invented may have taken the lead in the race to find materials of ever-increasing thinness, surface area and conductivity to make better-performing battery electrodes.
The MXene (pron. “Maxine”) clay they invented is conductive and can be moulded into a variety of shapes and sizes, and can be turned into a film—usable in an electrode—simply by rolling or pressing it.
“Both the physical properties of the clay, consisting of two-dimensional titanium carbide particles, as well as its performance characteristics, seem to make it an exceptionally viable candidate for use in energy storage devices like batteries and supercapacitors,” said Yury Gogotsi, Ph.D.
Michel Barsoum, Ph.D., explained “when we add water to MXene, water penetrates between the layers and endows the resulting material with plasticity and moldability […] The fact that we can now roll our electrodes rapidly and efficiently—and not have to use binders and/or conductive additives—renders this material quite attractive from a mass production point of view.”
The discovery came about while Michael Ghidiu, a doctoral student advised by Barsoum and Gogotsi, was testing a new method for making MXenes (two-dimensional materials that are among the candidates for use in next-generation batteries and supercapacitors).
“I would say the most important benefit to the new method—besides its increased capacitance—is that we can now make an electrode ready-to-go in about 15 minutes, whereas the total process before from the same starting point would be on the order of a day,” Ghidiu said.
The availability of its ingredients also makes the clay rather appealing from a production standpoint, noted Barsoum. “Being able to make a conductive clay, essentially out of titanium carbide with the help of a common fluoride salt and hydrochloric acid is the materials equivalent of making a chocolate chip cookie—everybody has these ingredients in the pantry.”
As for electrochemical performance, the clay’s ability to store an electrical charge should enable it to find use in the batteries that power cell phones and start cars, or even in a supercapacitor that could help renewable energy sources fit into a regional power grid.
“Keep in mind this is the very first generation of the material that we’re testing,” said Maria Lukatskaya, a doctoral student advised by Gogotsi and Barsoum. “We haven’t done a thing to augment its abilities and, at 900F/cm3, it’s already showing a higher capacitance per unit of volume than most other materials. We’re also reporting that it does not lose any of its capacitance through more than 10,000 charge/discharge cycles, so we’re talking about quite a special lump of clay here.”
— With files from Britt Faulstick, Drexel