Spider Silk Smooths Path to Better Batteries

A silk cocoon
Photo: iStockphoto

Spider silk could help boost the performance of lithium-ion batteries, say scientists at the Beijing Institute of Technology, in China.

Graphite is a key component of the lithium-ion batteries that power everything from mobile devices to electric cars. When lithium-ion batteries charge, ions of lithium diffuse from the positive electrode to the negative electrode and attach to the graphite there, and when they discharge, the lithium ions move from the graphite back to the positive electrode.

However, graphite is relatively bad at storing lithium ions, which substantially limits the energy capacity of conventional lithium ion batteries. Now scientists at the Beijing Institute of Technology now suggest that silk could help replace this graphite and significantly improve battery performance.

The strength and flexibility of silk has previously attracted research into whether or not it can be incorporated into electronics. For instance, a prior study coated spider silk fibers with carbon nanotubes to make it electrically conductive and three times tougher than regular spider silk fibers as well. And 

In the new work, the investigators found a way to chemically process natural silk turning it into porous nitrogen-laced sheets of carbon only 15 to 30 nanometers thick. The electron-rich nitrogen atoms improve the conductivity of the material and help create additional sites to put lithium ions.

They incorporated the new material into prototype batteries and supercapacitors in a one-step technique they say can easily be scaled up. In the battery, the new material could store five times more lithium than graphite, while the supercapacitor proved very stable, working for more than 10,000 cycles of recharging and discharging with only a 9 percent loss in stability.

The scientists detailed their findings online last month in the journal ACS Nano.

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