"If you imagine a trash can filled with paper crumples, you really get the idea," says Jiaxing Huang, Morris E. Fine Junior Professor in Materials and Manufacturing, the lead researcher of the study. "The balls can stack up into a tight structure. You can crumple them as hard as you want, but their surface area won't be eliminated, unlike face-to-face stacking."
"Crumpled paper balls usually express an emotion of frustration, a quite common experience in research," Huang says, "However, here 'frustration' quite appropriately describes why these particles are resistant to aggregation because their uneven surface frustrates or prevents tight face-to-face packing no matter how you process them."
To make crumpled graphene balls, Huang and his team created freely suspended water droplets containing graphene-based sheets, then used a carrier gas to blow the aerosol droplets through a furnace. As the water quickly evaporated, the thin sheets were compressed by capillary force into near-spherical particles.
The resulting crumpled graphene particles have the same electrical properties as the flat sheets but are more useful for applications that require large amounts of the material. The ridges formed in the crumpling process render the particles a strain-hardening property; the harder you compress them, the stronger they become. Therefore, the crumpled graphene balls are remarkably stable against mechanical deformation, Huang said.
"We expect this to serve as a new graphene platform to investigate application in energy storage and energy conversion," Huang said.
|Contact: Megan Fellman|