Nav: Home

'Candy cane' polymer weave could power future functional fabrics and devices

March 20, 2018

NEW ORLEANS, March 20, 2018 -- If scientists are ever going to deliver on the promise of implantable artificial organs or clothing that dries itself, they'll first need to solve the problem of inflexible batteries that run out of juice too quickly. They're getting closer, and today researchers report that they've developed a new material by weaving two polymers together in a way that vastly increases charge storage capacity.

The researchers will present their work today at the 255th National Meeting & Exposition of the American Chemical Society (ACS). ACS, the world's largest scientific society, is holding the meeting here through Thursday. It features more than 13,000 presentations on a wide range of science topics.

"We had been developing polymer networks for a different application involving actuation and tactile sensing," Tiesheng Wang says. "After the project, we realized that the stretchable, bendable material we'd made could potentially be used for energy storage."

Batteries, specifically lithium-ion batteries, dominate the energy storage landscape. However, the chemical reactions underlying the charging and discharging process in batteries are slow, limiting how much power they can deliver. Plus, batteries tend to degrade over time, requiring replacement. An alternate energy storage device, the supercapacitor, charges rapidly and generates serious power, which could potentially allow electric cars to accelerate more quickly, among other applications. Plus, supercapacitors store energy electrostatically, not chemically, which makes them more stable and long-lasting than many batteries. But today's commercially available supercapacitors require binders and have low energy density, limiting their application in emerging go-anywhere electronics.

Wang, a graduate student in the lab of Stoyan Smoukov, Ph.D., at the University of Cambridge (U.K.) suspected that a flexible conducting polymer-based material from another project they were working on could be a better alternative. Conducting polymers, such as poly(3,4-ethylenedioxythiophene) (PEDOT), are candidate supercapacitors that have advantages over traditional carbon-based supercapacitors as charge storage materials. They are pseudocapacitive, meaning they allow reversible electrochemical reactions, and they also are chemically stable and inexpensive. However, ions can only penetrate the polymers a couple of nanometers deep, leaving much of the material as dead weight. Scientists working to improve ion mobility had previously developed nanostructures that deposit thin layers of conducting polymers on top of support materials, which improves supercapacitor performance by making more of the polymer accessible to the ions. The drawback, according to Wang, is that these nanostructures can be fragile, difficult to make reproducibly when scaled-up and poor in electrochemical stability, limiting their applicability.

So, Smoukov and Wang developed a more robust material by weaving together a conducting polymer with an ion-storage polymer. The two polymers were stitched together to form a candy cane-like geometry, with one polymer playing the role of the white stripe and the other, red. While PEDOT conducts electricity, the other polymer, poly(ethylene oxide) (PEO), can store ions. The interwoven geometry is instrumental to the energy storage benefits, Wang says, because it allows the ions to access more of the material overall, approaching the "theoretical limit."

When tested, the candy cane supercapacitor demonstrated improvements over PEDOT alone with regard to flexibility and cycling stability. It also had nearly double the specific capacitance compared to conventional PEDOT-based supercapacitors.

Still, there's room for improvement, Smoukov says. "In future experiments, we will be substituting polyaniline for PEDOT to increase the capacitance," he says. "Polyaniline, because it can store more charge per unit of mass, could potentially store three times as much electricity as PEDOT for a given weight." That means lighter batteries with the same energy storage can be charged faster, which is an important consideration in the development of novel wearables, robots and other devices.
-end-
A press conference on this topic will be held Tuesday, March 20, at 9:30 a.m. Central time in the Ernest N. Morial Convention Center. Reporters may check-in at the press center, Great Hall B, or watch live on YouTube http://bit.ly/ACSLive_NOLA. To ask questions online, sign in with a Google account.

Smoukov acknowledges funding from the European Research Council. Wang thanks the China Scholarship Council for funding and the U.K. Centre for Doctoral Training in Sensor Technologies and Applications of the Engineering and Physical Sciences Research Council for support.

The American Chemical Society, the world's largest scientific society, is a not-for-profit organization chartered by the U.S. Congress. ACS is a global leader in providing access to chemistry-related information and research through its multiple databases, peer-reviewed journals and scientific conferences. ACS does not conduct research, but publishes and publicizes peer-reviewed scientific studies. Its main offices are in Washington, D.C., and Columbus, Ohio.

To automatically receive press releases from the American Chemical Society, contact newsroom@acs.org.

Note to journalists: Please report that this research was presented at a meeting of the American Chemical Society.

Follow us: Twitter | Facebook

Title

Candy cane-like semi-interpenetrating polymer networks for enhanced fast-charging power source of electronics

Abstract

Pseudocapacitance is a material property that allows ions to enter inside the material and thus pack much more charge than carbon ones that mostly store the charge near the surface (in the so-called double layer). Conducting polymers show great promise as supercapacitor materials due to their high pseudocapacitance, low cost, toughness, and flexibility. The problem with polymer-based supercapacitors, however, is that the ions necessary for these chemical reactions can only access the top few nanometers below the material surface, leaving the rest of the electrode as dead weight. Here, we use semi-interpenetrating networks (sIPNs) of a pseudocapacitive polymer in an ionically conductive polymer matrix to decrease ion diffusion length scales and make virtually all of the active material accessible for charge storage. Our freestanding poly(3,4-ethylenedioxythiophene)/poly(ethylene oxide) (PEDOT/PEO) sIPN films yield simultaneous improvements in three crucial elements of supercapacitor performance: specific capacitance (182 F/g, approaching the theoretical limit of PEDOT), cycling stability (97.5% capacitance retention after 3000 cycles), and flexibility (the electrodes bend to a <200 μm radius of curvature without breaking). The supercapacitor based on our material, which is known as "Candy Cane Supercapacitor", could power electronics embedded in smart clothing, wearable and implantable devices, and soft robotics.

American Chemical Society

Related Energy Storage Articles:

Magnetoelectric memory cell increases energy efficiency for data storage
A team of researchers has now developed a magnetoelectric random access memory (MELRAM) cell that has the potential to increase power efficiency, and thereby decrease heat waste, by orders of magnitude for read operations at room temperature.
Thin layers of water hold promise for the energy storage of the future
Researchers have found that a material which incorporates atomically thin layers of water is able to store and deliver energy much more quickly than the same material that doesn't include the water layers.
Current Graphene Science tours its journey of high-performance energy storage devices
Graphene has made its fathomable pathway over wide range of user-friendly energy storage devices.
Bio-inspired energy storage: A new light for solar power
Inspired by the western Swordfern, a groundbreaking prototype could be the answer to the storage challenge still holding solar back as a total energy solution.
Stabilizing energy storage
University of Utah and University of Michigan chemists, participating in a US Department of Energy consortium, predict a better future for these types of batteries, called redox flow batteries.
New hydronium-ion battery presents opportunity for more sustainable energy storage
A new type of battery shows promise for sustainable, high-power energy storage.It's the world's first battery to use only hydronium ions as the charge carrier.
Nanoscale view of energy storage
Through long shifts at the helm of a highly sophisticated microscope, researchers at Stanford recorded reactions at near-atomic-scale resolution.
Sandia Labs, Singapore join forces to develop energy storage
Sandia National Laboratories has signed a Cooperative Research and Development Agreement (CRADA) with the government of Singapore's Energy Market Authority (EMA) that will tap into the labs' expertise in energy storage.
New biofuel cell with energy storage
Researchers have developed a hybrid of a fuel cell and capacitor on a biocatalytic basis.
Energy storage system of tomorrow tested for the first time in Lake Constance
How can the enormous amounts of electricity generated through offshore wind power be temporarily stored on site?

Related Energy Storage Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Digital Manipulation
Technology has reshaped our lives in amazing ways. But at what cost? This hour, TED speakers reveal how what we see, read, believe — even how we vote — can be manipulated by the technology we use. Guests include journalist Carole Cadwalladr, consumer advocate Finn Myrstad, writer and marketing professor Scott Galloway, behavioral designer Nir Eyal, and computer graphics researcher Doug Roble.
Now Playing: Science for the People

#529 Do You Really Want to Find Out Who's Your Daddy?
At least some of you by now have probably spit into a tube and mailed it off to find out who your closest relatives are, where you might be from, and what terrible diseases might await you. But what exactly did you find out? And what did you give away? In this live panel at Awesome Con we bring in science writer Tina Saey to talk about all her DNA testing, and bioethicist Debra Mathews, to determine whether Tina should have done it at all. Related links: What FamilyTreeDNA sharing genetic data with police means for you Crime solvers embraced...