Biomimicry has served as the foundation for a significant portion of nanotech research. Nature has had a few billion years to work out the most effective way to get things done on the nanoscale so it makes sense to do a fair amount of cribbing from it solutions.
Now researchers at the University of Maryland, Baltimore County (UMBC) have borrowed a process from mollusks to develop a method for improving the properties of lithium-ion (Li-ion) batteries.
In research that was presented this week at the 59th annual meeting of the Biophysical Society, in Baltimore, the UMBC researchers demonstrated how a biological molecule called a peptide could bind itself strongly to nanoparticles of lithium manganese nickel oxide (LMNO), a material that can be used to make the cathode in high performance batteries. After the peptide has latched onto the nanoparticles, it then can connect them the particles to conductive components of a battery electrode. The result is an improvement to both the power and stability of the electrode, according to the researchers.
The use of nanomaterials for improving the properties and performance of Li-ion batteries is wide ranging. However, the UMBC researchers recognized that nanoparticles are difficult to control and hold in place.
To overcome this issue, the researchers turned to peptides whose role in nature is to bind themselves to different organic and inorganic substances. By arranging the amino acids that make up the more complex peptide molecule, the researchers understood that it was possible to program the peptide to bind to whatever they wanted.
The researchers found both inspiration and confirmation for their idea in how mollusks use peptides to control the growth of their shells, demonstrating a high-level of control in building intricate nano- and macrostructures from inorganic materials such as calcium carbonate.
Of course, figuring out the precise arrangement of amino acids that would get the peptide to bind to the LMNO was no easy feat. To accomplish it, the researchers used a technique known as "phage display", which is a laboratory technique that employs bacteriophages (viruses that infect bacteria) to quickly test millions of different types of peptides for their binding potential. The researchers screened more than one billion possible peptides to find one that would stick strongly to LMNO.
After identifying the peptide, the researchers then combined that peptide with one that had previously been identified as binding with carbon nanotubes. This was used because carbon nanotubes have been shown to act as conductive nanowires in Li-ion electrodes.
The hybrid peptide binds both the LMNO nanoparticles and the carbon nanotubes and keeps them close to each other so that they can maintain a connection through multiple charging cycles.
At present, the researchers are measuring just how much better the cathodes perform, and research will be expanding to look at how this biological approach could be used for the anodes of the batteries.