My watch list


Paper-based supercapacitor uses metal nanoparticles to boost energy density

Ko et al., published in Nature Communications

Images show the difference between paper prior to metallization (left) and the paper coated with conductive nanoparticles.

09-Oct-2017: Using a simple layer-by-layer coating technique, researchers from the U.S. and Korea have developed a paper-based flexible supercapacitor that could be used to help power wearable devices. The device uses metallic nanoparticles to coat cellulose fibers in the paper, creating supercapacitor electrodes with high energy and power densities - and the best performance so far in a textile-based supercapacitor.

By implanting conductive and charge storage materials in the paper, the technique creates large surface areas that function as current collectors and nanoparticle reservoirs for the electrodes. Testing shows that devices fabricated with the technique can be folded thousands of times without affecting conductivity.

"This type of flexible energy storage device could provide unique opportunities for connectivity among wearable and internet of things devices," said Seung Woo Lee, an assistant professor in the Woodruff School of Mechanical Engineering at the Georgia Institute of Technology. "We could support an evolution of the most advanced portable electronics. We also have an opportunity to combine this supercapacitor with energy-harvesting devices that could power biomedical sensors, consumer and military electronics, and similar applications."

Energy storage devices are generally judged on three properties: their energy density, power density and cycling stability. Supercapacitors often have high power density, but low energy density - the amount of energy that can be stored - compared to batteries, which often have the opposite attributes. In developing their new technique, Lee and collaborator Jinhan Cho from the Department of Chemical and Biological Engineering at Korea University set out to boost energy density of the supercapacitors while maintaining their high power output.

The researchers began by dipping paper samples into a beaker of solution containing an amine surfactant material designed to bind the gold nanoparticles to the paper. Next they dipped the paper into a solution containing gold nanoparticles. Because the fibers are porous, the surfactants and nanoparticles enter the fibers and become strongly attached, creating a conformal coating on each fiber.

By repeating the dipping steps, the researchers created a conductive paper on which they added alternating layers of metal oxide energy storage materials such as manganese oxide. The ligand-mediated layer-by-layer approach helped minimize the contact resistance between neighboring metal and/or metal oxide nanonparticles. Using the simple process done at room temperatures, the layers can be built up to provide the desired electrical properties.

"It's basically a very simple process," Lee said. "The layer-by-layer process, which we did in alternating beakers, provides a good conformal coating on the cellulose fibers. We can fold the resulting metallized paper and otherwise flex it without damage to the conductivity."

Though the research involved small samples of paper, the solution-based technique could likely be scaled up using larger tanks or even a spray-on technique. "There should be no limitation on the size of the samples that we could produce," Lee said. "We just need to establish the optimal layer thickness that provides good conductivity while minimizing the use of the nanoparticles to optimize the tradeoff between cost and performance."

The researchers demonstrated that their self-assembly technique improves several aspects of the paper supercapacitor, including its areal performance, an important factor for measuring flexible energy-storage electrodes. The maximum power and energy density of the metallic paper-based supercapacitors are estimated to be 15.1mWcm?2 and 267.3 μWh cm?2, respectively, substantially outperforming conventional paper or textile supercapacitors.

The next steps will include testing the technique on flexible fabrics, and developing flexible batteries that could work with the supercapacitors. The researchers used gold nanoparticles because they are easy to work with, but plan to test less expensive metals such as silver and copper to reduce the cost.

During his Ph.D. work, Lee developed the layer-by-layer self-assembly process for energy storage using different materials. With his Korean collaborators, he saw a new opportunity to apply that to flexible and wearable devices with nanoparticles.

"We have nanoscale control over the coating applied to the paper," he added. "If we increase the number of layers, the performance continues to increase. And it's all based on ordinary paper."

Original publication:
Yongmin Ko, Minseong Kwon, Wan Ki Bae, Byeongyong Lee, Seung Woo Lee & Jinhan Cho; "Flexible supercapacitor electrodes based on real metal-like cellulose papers"; Nature Comm.; 2017

Facts, background information, dossiers

  • paper
  • energy storage
  • supercapacitors

More about Georgia Institute of Technology

  • News

    Pores with a Memory

    Whether for separation processes, photovoltaics, catalysis, or electronics, porous polymer membranes are needed in many fields. Membranes with micropores that switch between different shapes and/or sizes would expand the possibilities. Scientists have introduced a process that produces poro ... more

    Are 20 percent of materials chemistry papers wrong?

    Can companies rely on the results of one or two scientific studies to design a new industrial process or launch a new product? In at least one area of materials chemistry, the answer may be yes -- but only 80 percent of the time. The replicability of results from scientific studies has beco ... more

    Low-cost technique converts bulk alloys to oxide nanowires

    A simple technique for producing oxide nanowires directly from bulk materials could dramatically lower the cost of producing the one-dimensional (1D) nanostructures. That could open the door for a broad range of uses in lightweight structural composites, advanced sensors, electronic devices ... more

q&more – the networking platform for quality excellence in lab and process

The q&more concept is to increase the visibility of recent research and innovative solutions, and support the exchange of knowledge. In the broad spectrum of subjects covered, the focus is on achieving maximum quality in highly innovative sectors. As a modern knowledge platform, q&more offers market participants one-of-a-kind networking opportunities. Cutting-edge research is presented by authors of international repute. Attractively presented in a high-quality context, and published in German and English, the original articles introduce new concepts and highlight unconventional solution strategies.

> more about q&more

q&more is supported by:

Your browser is not current. Microsoft Internet Explorer 6.0 does not support some functions on Chemie.DE