In the race to find materials of ever increasing thinness, surface area and conductivity to make better performing battery electrodes, a lump of clay might have just taken the lead. Materials scientists from Drexel University’s College of Engineering invented the clay, which is both highly conductive and can easily be moulded into a variety of shapes and sizes.
It represents a turn away from the rather complicated and costly processing, currently used to make materials for lithium-ion batteries and super capacitors and toward one that looks a bit like rolling out cookie dough with results that are even sweeter from an energy storage standpoint.
With the publication of their recipe for “conductive MXene clay” in the December edition of Nature, the researchers suggest a significant shift in the way electrodes for storage devices are produced. The clay, which already exhibits conductivity on par with that of metals, can be turned into a film for use 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 super capacitors,” said Yury Gogotsi, co-author of the paper.
“The procedure to make the clay also uses much safer, readily available ingredients than the ones we used to produce MXene electrodes in the past. The key to the utility of this material, according to Michel Barsoum, one of the inventors of MXenes, is in its form as anybody who has played with mud can attest, clay is hydrophilic water loving.
“Clay is also layered and when hydrated, the water molecules slide between the layers and render it plastic that in turn can be readily shaped into complex shapes. The same happens here; when we add water to MXene, water penetrates between the layers and endows the resulting material with plasticity and mouldability. “Graphene, a material widely studied for use in electrodes, is conductive but does not like water as it is hydrophobic. What we discovered is a conductive two-dimensional layered material that also loves water.
“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 from testing a new method for making MXenes, two-dimensional materials invented at Drexel that are among the leading candidates for use in next-generation batteries and super capacitors.
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